Improved Model

Added Keyboard Selection Support
Added Mouse Selection Support
Added Keyboard Editing Support
Corrected Some Bugs
Abstracted the Layout System further
Added Functions Button (test)

MathPad.xcodeproj/project.pbxproj

@@ -27,12 +27,13 @@
 		3BBBA35E1903FD3600824E74 /* MPRangePath.m in Sources */ = {isa = PBXBuildFile; fileRef = 3B87E35C1900933200259938 /* MPRangePath.m */; };
 		3BBBA35F1903FD3600824E74 /* MPRangePath.m in Sources */ = {isa = PBXBuildFile; fileRef = 3B87E35C1900933200259938 /* MPRangePath.m */; };
 		3BBBA3951905704200824E74 /* MPRangeTests.m in Sources */ = {isa = PBXBuildFile; fileRef = 3BBBA3941905704200824E74 /* MPRangeTests.m */; };
+		3BC4660B19B2425A0033F13A /* MPDocument.xib in Resources */ = {isa = PBXBuildFile; fileRef = 3BF9978318DE623E009CF6C4 /* MPDocument.xib */; };
+		3BC4661419B245C60033F13A /* Fonts in Resources */ = {isa = PBXBuildFile; fileRef = 3BC4661319B245C60033F13A /* Fonts */; };
 		3BF9976F18DE623E009CF6C4 /* Cocoa.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 3BF9976E18DE623E009CF6C4 /* Cocoa.framework */; };
 		3BF9977918DE623E009CF6C4 /* InfoPlist.strings in Resources */ = {isa = PBXBuildFile; fileRef = 3BF9977718DE623E009CF6C4 /* InfoPlist.strings */; };
 		3BF9977B18DE623E009CF6C4 /* main.m in Sources */ = {isa = PBXBuildFile; fileRef = 3BF9977A18DE623E009CF6C4 /* main.m */; };
 		3BF9977F18DE623E009CF6C4 /* Credits.rtf in Resources */ = {isa = PBXBuildFile; fileRef = 3BF9977D18DE623E009CF6C4 /* Credits.rtf */; };
 		3BF9978218DE623E009CF6C4 /* MPDocument.m in Sources */ = {isa = PBXBuildFile; fileRef = 3BF9978118DE623E009CF6C4 /* MPDocument.m */; };
-		3BF9978518DE623E009CF6C4 /* MPDocument.xib in Resources */ = {isa = PBXBuildFile; fileRef = 3BF9978318DE623E009CF6C4 /* MPDocument.xib */; };
 		3BF9978818DE623E009CF6C4 /* MainMenu.xib in Resources */ = {isa = PBXBuildFile; fileRef = 3BF9978618DE623E009CF6C4 /* MainMenu.xib */; };
 		3BF9978A18DE623E009CF6C4 /* Images.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = 3BF9978918DE623E009CF6C4 /* Images.xcassets */; };
 		3BF9979118DE623E009CF6C4 /* XCTest.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 3BF9979018DE623E009CF6C4 /* XCTest.framework */; };
@@ -80,6 +81,7 @@
 		3BBBA3591903EA9B00824E74 /* MPModel.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = MPModel.h; sourceTree = "<group>"; };
 		3BBBA38419047FC900824E74 /* MPView.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = MPView.h; sourceTree = "<group>"; };
 		3BBBA3941905704200824E74 /* MPRangeTests.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = MPRangeTests.m; sourceTree = "<group>"; };
+		3BC4661319B245C60033F13A /* Fonts */ = {isa = PBXFileReference; lastKnownFileType = folder; path = Fonts; sourceTree = "<group>"; };
 		3BF9976B18DE623E009CF6C4 /* MathPad.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = MathPad.app; sourceTree = BUILT_PRODUCTS_DIR; };
 		3BF9976E18DE623E009CF6C4 /* Cocoa.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = Cocoa.framework; path = System/Library/Frameworks/Cocoa.framework; sourceTree = SDKROOT; };
 		3BF9977118DE623E009CF6C4 /* AppKit.framework */ = {isa = PBXFileReference; lastKnownFileType = wrapper.framework; name = AppKit.framework; path = System/Library/Frameworks/AppKit.framework; sourceTree = SDKROOT; };
@@ -179,6 +181,8 @@
 			children = (
 				3BF9978318DE623E009CF6C4 /* MPDocument.xib */,
 				3BF9978618DE623E009CF6C4 /* MainMenu.xib */,
+				3BF9978918DE623E009CF6C4 /* Images.xcassets */,
+				3BC4661319B245C60033F13A /* Fonts */,
 			);
 			name = Resources;
 			sourceTree = "<group>";
@@ -268,7 +272,6 @@
 				3B87E351190082BB00259938 /* View */,
 				3B87E352190082C000259938 /* Controller */,
 				3B87E353190082E200259938 /* Resources */,
-				3BF9978918DE623E009CF6C4 /* Images.xcassets */,
 				3BF9977518DE623E009CF6C4 /* Supporting Files */,
 			);
 			path = MathPad;
@@ -384,7 +387,8 @@
 			files = (
 				3BF9977918DE623E009CF6C4 /* InfoPlist.strings in Resources */,
 				3BF9978A18DE623E009CF6C4 /* Images.xcassets in Resources */,
-				3BF9978518DE623E009CF6C4 /* MPDocument.xib in Resources */,
+				3BC4660B19B2425A0033F13A /* MPDocument.xib in Resources */,
+				3BC4661419B245C60033F13A /* Fonts in Resources */,
 				3BF9977F18DE623E009CF6C4 /* Credits.rtf in Resources */,
 				3BF9978818DE623E009CF6C4 /* MainMenu.xib in Resources */,
 			);

MathPad/Base.lproj/MPDocument.xib

@@ -14,37 +14,23 @@
         <customObject id="-3" userLabel="Application"/>
         <window title="MathPad" allowsToolTipsWhenApplicationIsInactive="NO" autorecalculatesKeyViewLoop="NO" releasedWhenClosed="NO" visibleAtLaunch="NO" animationBehavior="default" id="xOd-HO-29H" userLabel="Window">
             <windowStyleMask key="styleMask" titled="YES" closable="YES" miniaturizable="YES" resizable="YES"/>
-            <windowPositionMask key="initialPositionMask" leftStrut="YES" rightStrut="YES" topStrut="YES" bottomStrut="YES"/>
+            <rect key="contentRect" x="525" y="411" width="507" height="251"/>
-            <rect key="contentRect" x="133" y="235" width="507" height="240"/>
             <rect key="screenRect" x="0.0" y="0.0" width="1920" height="1178"/>
-            <value key="minSize" type="size" width="94" height="86"/>
+            <value key="minSize" type="size" width="500" height="200"/>
             <view key="contentView" id="gIp-Ho-8D9">
-                <rect key="frame" x="0.0" y="0.0" width="507" height="240"/>
+                <rect key="frame" x="0.0" y="0.0" width="507" height="251"/>
                 <autoresizingMask key="autoresizingMask"/>
                 <subviews>
                     <customView translatesAutoresizingMaskIntoConstraints="NO" id="lcd-Ip-jjR" customClass="MPExpressionView">
-                        <rect key="frame" x="20" y="124" width="467" height="96"/>
+                        <rect key="frame" x="20" y="20" width="467" height="211"/>
                         <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMinY="YES"/>
                     </customView>
-                    <button verticalHuggingPriority="750" translatesAutoresizingMaskIntoConstraints="NO" id="IMg-L0-qdu">
-                        <rect key="frame" x="209" y="13" width="88" height="32"/>
-                        <autoresizingMask key="autoresizingMask" flexibleMaxX="YES" flexibleMinY="YES"/>
-                        <buttonCell key="cell" type="push" title="Change" bezelStyle="rounded" alignment="center" borderStyle="border" imageScaling="proportionallyDown" inset="2" id="Xxz-j2-fsI">
-                            <behavior key="behavior" pushIn="YES" lightByBackground="YES" lightByGray="YES"/>
-                            <font key="font" metaFont="system"/>
-                        </buttonCell>
-                        <connections>
-                            <action selector="changeExpression:" target="-2" id="k8U-3Y-8Ch"/>
-                        </connections>
-                    </button>
                 </subviews>
                 <constraints>
-                    <constraint firstAttribute="trailing" secondItem="lcd-Ip-jjR" secondAttribute="trailing" constant="20" symbolic="YES" id="3tX-J3-Wte"/>
+                    <constraint firstItem="lcd-Ip-jjR" firstAttribute="leading" secondItem="gIp-Ho-8D9" secondAttribute="leading" constant="20" symbolic="YES" id="8Li-0i-x3o"/>
-                    <constraint firstItem="IMg-L0-qdu" firstAttribute="top" secondItem="lcd-Ip-jjR" secondAttribute="bottom" constant="83" id="62S-rU-IWO"/>
+                    <constraint firstItem="lcd-Ip-jjR" firstAttribute="top" secondItem="gIp-Ho-8D9" secondAttribute="top" constant="20" symbolic="YES" id="MPQ-lK-4d0"/>
-                    <constraint firstItem="lcd-Ip-jjR" firstAttribute="leading" secondItem="gIp-Ho-8D9" secondAttribute="leading" constant="20" symbolic="YES" id="XN3-k3-tOU"/>
+                    <constraint firstAttribute="bottom" secondItem="lcd-Ip-jjR" secondAttribute="bottom" constant="20" symbolic="YES" id="hi3-fp-zJn"/>
-                    <constraint firstItem="lcd-Ip-jjR" firstAttribute="top" secondItem="gIp-Ho-8D9" secondAttribute="top" constant="20" symbolic="YES" id="gqS-BG-xpS"/>
+                    <constraint firstAttribute="trailing" secondItem="lcd-Ip-jjR" secondAttribute="trailing" constant="20" symbolic="YES" id="xiK-zs-2rs"/>
-                    <constraint firstItem="IMg-L0-qdu" firstAttribute="centerX" secondItem="lcd-Ip-jjR" secondAttribute="centerX" id="sCM-Pj-4wd"/>
-                    <constraint firstAttribute="bottom" secondItem="IMg-L0-qdu" secondAttribute="bottom" constant="20" symbolic="YES" id="tNe-R6-QlG"/>
                 </constraints>
             </view>
             <connections>

MathPad/MPExpression.h

@@ -216,6 +216,32 @@
 - (NSUInteger)indexOfElement:(id<MPExpressionElement>)element;
 
 
+/*!
+    @method     indexOfElementAtSymbolLocation:offset
+    @brief      Calculates the index of the element the specified location points
+                to.
+ 
+    @discussion The @c location is in the length reference frame whereas the
+                returned value is an element index. This method converts from
+                the former to the latter.
+ 
+                If the location exceeds the receiver's bounds a @c
+                NSRangeException will be raised.
+ 
+    @param      location
+                The location of which you want the corresponding element index.
+ 
+    @param      offset
+                An output parameter that gets set to the offst into the symbol
+                whose index is returned. If location for example points to the
+                symbol @c '2' in the string element @c '123' the offset @c would
+                be set to @c 1.
+ 
+    @return     The index of the element the location points to.
+ */
+- (NSUInteger)indexOfElementAtSymbolLocation:(NSUInteger)location offset:(out NSUInteger *)offset;
+
+
 /*!
     @method     replaceSymbolsInRange:withElements:
     @brief      Replaces the elements in the given range with the contents of the
@@ -242,7 +268,6 @@
  */
 - (void)replaceSymbolsInRange:(NSRange)range
                  withElements:(NSArray *)elements;
-// TODO: - (NSUInteger)indexOfElementAtSymbolLocation:(NSUInteger)location;
 
 #warning Evaluating must possibly return error
 - (double)doubleValue; // Evaluates Expression
@@ -304,6 +329,18 @@
 #pragma mark Working With the Expression Tree
 
 
+/*!
+    @method     rootExpression
+    @brief      Returns the root expression from the receiver's expression tree.
+ 
+    @discussion The root expression is the ultimate parent of all expressions and
+                functions in the expression tree.
+ 
+    @return     The root expression from the receiver's expression tree.
+ */
+- (MPExpression *)rootExpression;
+
+
 /*!
     @method     elementAtIndexPath:
     @brief      Returns the element at the specified index path.
@@ -511,6 +548,19 @@
  */
 - (NSArray *)elements;
 
-// TODO: - (NSMutableArray *)mutableElements;
+
+/*!
+    @method     mutableElements
+    @brief      Returns a proxy mutable array object that responds to all methods
+                defined by @c NSMutableArray.
+ 
+    @discussion Mutations on the proxy object also change the receiver. The proxy
+                object does not respond to coding methods. Copying the proxy
+                object will not duplicate it.
+
+    @return     A proxy object that responds to all methods defined by @c
+                NSMutableArray.
+ */
+// - (NSMutableArray *)mutableElements;
 
 @end

MathPad/MPExpression.m

@@ -20,13 +20,10 @@
 @interface MPExpression (MPExpressionPrivate)
 
 - (NSUInteger)lengthOfElements:(NSArray *)elements;
-- (NSUInteger)indexOfElementAtLocation:(NSUInteger)location;
 
 - (void)validateElements:(NSArray *)elements;
 - (BOOL)splitElementsAtLocation:(NSUInteger)location
                  insertionIndex:(out NSUInteger *)insertionIndex;
-- (NSUInteger)calculateSplitOffsetForSplitLocation:(NSUInteger)location
-                                  inElementAtIndex:(out NSUInteger *)elementIndex;
 
 @end
 
@@ -41,13 +38,6 @@
     return length;
 }
 
-- (NSUInteger)indexOfElementAtLocation:(NSUInteger)location
-{
-    NSUInteger index = 0;
-    [self calculateSplitOffsetForSplitLocation:location inElementAtIndex:&index];
-    return index;
-}
-
 - (void)validateElements:(NSArray *)elements
 {
     for (id element in elements) {
@@ -66,18 +56,14 @@
         *insertionIndex = 0;
         return NO;
     }
-    NSUInteger splitElementIndex;
+    
-    NSUInteger splitOffset = [self calculateSplitOffsetForSplitLocation:location
+    NSUInteger splitOffset;
-                                                       inElementAtIndex:&splitElementIndex];
+    NSUInteger splitElementIndex = [self indexOfElementAtSymbolLocation:location
-    id<MPExpressionElement> splitElement = self.elements[splitElementIndex];
+                                                                 offset:&splitOffset];
-    if (splitOffset == splitElement.length) {
-        splitOffset = 0;
-        splitElementIndex++;
-    }
     if (splitOffset != 0) {
-        NSString *stringElement = (NSString *)splitElement;
+        NSString *splitElement = (NSString *)self.elements[splitElementIndex];
-        NSString *leftPart = [stringElement substringToIndex:splitOffset];
+        NSString *leftPart = [splitElement substringToIndex:splitOffset];
-        NSString *rightPart = [stringElement substringFromIndex:splitOffset];
+        NSString *rightPart = [splitElement substringFromIndex:splitOffset];
         [self.elements replaceObjectsInRange:NSMakeRange(splitElementIndex, 1)
                         withObjectsFromArray:@[leftPart, rightPart]];
         ++splitElementIndex;
@@ -86,24 +72,6 @@
     return splitOffset != 0;
 }
 
-- (NSUInteger)calculateSplitOffsetForSplitLocation:(NSUInteger)location
-                                  inElementAtIndex:(out NSUInteger *)elementIndex
-{
-    NSUInteger length = 0;
-    NSUInteger index = 0;
-    NSUInteger elementLength = 0;
-    for (id<MPExpressionElement> element in self.elements) {
-        elementLength = element.length;
-        length += elementLength;
-        if (length >= location) {
-            break;
-        }
-        ++index;
-    }
-    *elementIndex = index;
-    return elementLength - (length - location);
-}
-
 @end
 
 @implementation MPExpression {
@@ -215,6 +183,41 @@
     return [self.elements indexOfObject:element];
 }
 
+- (NSUInteger)indexOfElementAtSymbolLocation:(NSUInteger)location
+                                      offset:(out NSUInteger *)offset
+{
+    if (location == 0) {
+        if (offset != NULL) {
+            *offset = 0;
+        }
+        return 0;
+    }
+    
+    // Calculating elementIndex and splitOffset
+    NSUInteger totalLength = 0;
+    NSUInteger elementIndex = 0;
+    NSUInteger elementLength = 0;
+    for (id<MPExpressionElement> element in self.elements) {
+        elementLength = element.length;
+        totalLength += elementLength;
+        if (totalLength >= location) {
+            break;
+        }
+        ++elementIndex;
+    }
+    NSUInteger splitOffset = elementLength - (totalLength - location);
+
+    id<MPExpressionElement> element = self.elements[elementIndex];
+    if (splitOffset == element.length) {
+        splitOffset = 0;
+        elementIndex++;
+    }
+    if (offset != NULL) {
+        *offset = splitOffset;
+    }
+    return elementIndex;
+}
+
 - (void)replaceSymbolsInRange:(NSRange)range
                   withElements:(NSArray *)elements
 {
@@ -276,7 +279,7 @@
 }
 
 #pragma mark Basic NSObject Methods
-
+/*
 - (BOOL)isEqual:(id)object
 {
     if (self == object) {
@@ -295,7 +298,7 @@
 {
     return [self.elements isEqualToArray:anExpression.elements];
 }
-
+*/
 - (NSString *)description
 {
 #warning Bad Implementation
@@ -359,6 +362,14 @@
 @implementation MPExpression (MPExpressionExtension)
 
 #pragma mark Working With the Expression Tree
+- (MPExpression *)rootExpression
+{
+    if (self.parent == nil) {
+        return self;
+    }
+    return [self.parent rootExpression];
+}
+
 - (id)elementAtIndexPath:(NSIndexPath *)indexPath
 {
     if (indexPath.length == 0) {
@@ -369,7 +380,7 @@
         return element;
     }
     if ([element isFunction]) {
-        return [(MPFunction *)element elementAtIndexPath:[indexPath indexPathByRemovingLastIndex]];
+        return [(MPFunction *)element elementAtIndexPath:[indexPath indexPathByRemovingFirstIndex]];
     }
     return nil;
 }

MathPad/MPExpressionLayout.h

@@ -12,7 +12,7 @@
 
 @interface MPExpressionLayout : MPLayout
 
-- (instancetype)initRootLayoutWithExpressionStorage:(MPExpressionStorage *)expressionStorage;
+- (instancetype)initRootLayoutWithExpression:(MPExpression *)expression;
 
 @property (readonly, nonatomic, weak) MPExpression *expression;
 

MathPad/MPExpressionLayout.m

@@ -9,6 +9,10 @@
 #import "MPExpressionLayout.h"
 #import "MPFunctionLayout.h"
 
+#import "NSIndexPath+MPAdditions.h"
+
+#define kMPEmptyBoxWidth (self.usesSmallSize ? 2.0 : 3.0)
+
 @interface MPExpressionLayout (MPLineGeneration)
 
 - (CTLineRef)lineForElementAtIndex:(NSUInteger)index;
@@ -34,9 +38,8 @@
 
 - (CTLineRef)createLineForString:(NSString *)aString
 {
-    
     NSAttributedString *text = [[NSAttributedString alloc] initWithString:aString
-                                                               attributes:@{NSFontAttributeName: [NSFont fontWithName:@"Lucida Grande" size:18.0]}];
+                                                               attributes:@{NSFontAttributeName: self.font}];
     CFAttributedStringRef attributedString = CFBridgingRetain(text);
     CTLineRef line = CTLineCreateWithAttributedString(attributedString);
     CFRelease(attributedString); // TODO: Is this release appropriate?
@@ -48,49 +51,38 @@
 @implementation MPExpressionLayout
 
 # pragma mark Creation Methods
-- (instancetype)initRootLayoutWithExpressionStorage:(MPExpressionStorage *)expressionStorage
+- (instancetype)initRootLayoutWithExpression:(MPExpression *)expression
 {
     self = [super init];
     if (self) {
-        _expressionStorage = expressionStorage;
+        _expression = expression;
-        _expression = expressionStorage;
     }
     return self;
 }
 
-- (instancetype)initWithPath:(NSIndexPath *)path
+- (instancetype)initWithElementAtPath:(NSIndexPath *)path
+                     inRootExpression:(MPExpression *)rootExpression
                                parent:(MPLayout *)parent
 {
-    self = [super initWithPath:path
+    self = [super initWithElementAtPath:path
+                       inRootExpression:rootExpression
                                  parent:parent];
     if (self) {
-        _expression = [parent.expressionStorage elementAtIndexPath:path];
+        _expression = [rootExpression elementAtIndexPath:path];
     }
     return self;
 }
 
-#pragma mark Properties
-@synthesize expressionStorage = _expressionStorage;
-- (MPExpressionStorage *)expressionStorage
-{
-    if (_expressionStorage) {
-        return _expressionStorage;
-    }
-    return self.parent.expressionStorage;
-}
-
-//- (MPExpression *)expression
-//{
-//    return [self.expressionStorage elementAtIndexPath:self.path];
-//}
-
 #pragma mark Cache Methods
 - (MPLayout *)childLayoutAtIndex:(NSUInteger)index
 {
     id cachedObject = [self cachableObjectForIndex:index generator:^id{
         NSIndexPath *indexPath = [self.expression.indexPath indexPathByAddingIndex:index];
         MPFunctionLayout *layout = [MPFunctionLayout functionLayoutForFunctionAtIndexPath:indexPath
+                                                                         inRootExpression:self.expression.rootExpression
                                                                                    parent:self];
+        layout.flipped = self.flipped;
+        layout.usesSmallSize = self.usesSmallSize;
         return layout;
     }];
     if ([cachedObject isKindOfClass:[MPLayout class]]) {
@@ -99,51 +91,165 @@
     return nil;
 }
 
-- (NSSize)sizeForElementAtIndex:(NSUInteger)index
+- (NSRect)boundsOfElementAtIndex:(NSUInteger)index
 {
     id symbol = [self.expression elementAtIndex:index];
     if ([symbol isString]) {
         CTLineRef line = [self lineForElementAtIndex:index];
         CFRetain(line);
-        CGRect bounds = CTLineGetBoundsWithOptions(line, /*kCTLineBoundsUseOpticalBounds*/ 0);
+        CGRect bounds = CTLineGetBoundsWithOptions(line, 0);
         CFRelease(line);
-        return bounds.size;
+        return bounds;
     } else {
-        return [self childLayoutAtIndex:index].size;
+        return [self childLayoutAtIndex:index].bounds;
     }
 }
 
 #pragma mark Drawing Methods
-- (NSSize)generateSize
+- (NSRect)generateBounds
 {
-    CGFloat width = 0, height = 0;
+    if (self.expression.numberOfElements == 0) {
-    for (NSUInteger index = 0; index < self.expression.numberOfElements; index++) {
+        return NSMakeRect(0, [self.font descender], kMPEmptyBoxWidth, self.fontSize);
-        NSSize elementSize = [self sizeForElementAtIndex:index];
-        width += elementSize.width;
-        height = MAX(height, elementSize.height);
     }
-    return NSMakeSize(width, height);
+    CGFloat x = 0, y = 0, width = 0, height = 0;
+    for (NSUInteger index = 0; index < self.expression.numberOfElements; index++) {
+        NSRect elementBounds = [self boundsOfElementAtIndex:index];
+        width += elementBounds.size.width;
+        height = MAX(height, elementBounds.size.height);
+        y = MIN(y, elementBounds.origin.y);
+    }
+    return NSMakeRect(x, y, width, height);
 }
 
-- (void)drawAtPoint:(NSPoint)point
+- (NSRect)boundingRectForRange:(NSRange)range
+{
+    NSUInteger startOffset;
+    NSUInteger startElementIndex = [self.expression indexOfElementAtSymbolLocation:range.location
+                                                                           offset:&startOffset];
+    // Calculate x position
+    CGFloat x = 0, width = 0;
+    for (NSUInteger index = 0; index < startElementIndex; index++) {
+        x += [self boundsOfElementAtIndex:index].size.width;
+    }
+
+    if (startOffset > 0) {
+        CTLineRef line = [self lineForElementAtIndex:startElementIndex];
+        CFRetain(line);
+        CGFloat xOffset = CTLineGetOffsetForStringIndex(line, startOffset, NULL);
+        x += xOffset;
+        width += CTLineGetBoundsWithOptions(line, 0).size.width - xOffset;
+        CFRelease(line);
+    } else if (startElementIndex < self.expression.numberOfElements) { // Otherwise the selection is after the last symbol
+        width += [self boundsOfElementAtIndex:startElementIndex].size.width;
+    }
+    
+    // If we search the caret position we are done
+    if (range.length == 0) {
+        return NSMakeRect(x, self.bounds.origin.y, 0, self.bounds.size.height);
+    }
+
+    NSUInteger endOffset;
+    NSUInteger endElementIndex = [self.expression indexOfElementAtSymbolLocation:NSMaxRange(range)
+                                                                          offset:&endOffset];
+
+    // Selection is inside of one string element
+    if (startElementIndex == endElementIndex) {
+        CTLineRef line = [self lineForElementAtIndex:endElementIndex];
+        CFRetain(line);
+        CGFloat xStart = CTLineGetOffsetForStringIndex(line, startOffset, NULL);
+        CGFloat xEnd = CTLineGetOffsetForStringIndex(line, endOffset, NULL);
+        width = xEnd - xStart;
+        CFRelease(line);
+        return NSMakeRect(x, self.bounds.origin.y, width, self.bounds.size.height);
+    }
+    
+    // Calculate width
+    for (NSUInteger index = startElementIndex + 1; index < endElementIndex; index++) {
+        width += [self boundsOfElementAtIndex:index].size.width;
+    }
+    if (endOffset > 0) {
+        CTLineRef line = [self lineForElementAtIndex:endElementIndex];
+        CFRetain(line);
+        width += CTLineGetOffsetForStringIndex(line, endOffset, NULL);
+        CFRelease(line);
+    }
+    return NSMakeRect(x, self.bounds.origin.y, width, self.bounds.size.height);
+}
+
+- (NSPoint)offsetOfChildLayoutAtIndex:(NSUInteger)index
+{
+    CGFloat x = 0;
+    for (NSUInteger i = 0; i < index; i++) {
+        x += [self boundsOfElementAtIndex:i].size.width;
+    }
+    return NSMakePoint(x, 0);
+}
+
+- (NSIndexPath *)indexPathForMousePoint:(NSPoint)point
+{
+    NSUInteger currentPosition = 0;
+    for (NSUInteger index = 0; index < self.expression.numberOfElements; index++) {
+        NSRect elementBounds = [self boundsOfElementAtIndex:index];
+        NSPoint elementOffset = [self offsetOfChildLayoutAtIndex:index];
+        elementBounds.origin.x += elementOffset.x;
+        elementBounds.origin.y += elementOffset.y;
+        
+        id<MPExpressionElement> element = [self.expression elementAtIndex:index];
+        if (NSMouseInRect(point, elementBounds, self.flipped)) {
+            if ([element isString]) {
+                CTLineRef line = [self lineForElementAtIndex:index];
+                CFRetain(line);
+                CFIndex localIndex = CTLineGetStringIndexForPosition(line, point);
+                CFRelease(line);
+                return [NSIndexPath indexPathWithIndex:currentPosition+localIndex];
+            } else {
+                NSPoint pointInFunction = NSMakePoint(point.x - elementOffset.x, point.y + elementOffset.y);
+                NSIndexPath *subPath = [[self childLayoutAtIndex:index] indexPathForMousePoint:pointInFunction];
+                if (subPath.length == 1) {
+                    // A single index is used to communicate back wether the
+                    // selection should be before or after the function.
+                    // A 0 means before, a 1 means after.
+                    return [NSIndexPath indexPathWithIndex:currentPosition + [subPath indexAtPosition:0]];
+                } else {
+                    return [subPath indexPathByPreceedingIndex:index];
+                }
+            }
+        }
+        currentPosition += element.length;
+    }
+    if (point.x < self.bounds.size.width / 2) {
+        return [NSIndexPath indexPathWithIndex:0];
+    } else {
+        return [NSIndexPath indexPathWithIndex:self.expression.length];
+    }
+}
+
+- (void)draw
 {
     // Get the current context
     CGContextRef context =
         (CGContextRef)[[NSGraphicsContext currentContext] graphicsPort];
     CGContextSaveGState(context);
     
+    if (self.expression.numberOfElements == 0) {
+        
+        CGContextRestoreGState(context);
+        NSBezierPath *path = [NSBezierPath bezierPathWithRect:NSMakeRect(0, 0 + self.font.descender, kMPEmptyBoxWidth, self.fontSize)];
+        path.lineWidth = 0.5;
+        [path stroke];
+        return;
+    }
+    
     // Set the text matrix
     CGContextSetTextMatrix(context, CGAffineTransformIdentity);
     
     // Track the x position
-    CGFloat x = point.x;
+    CGFloat x = 0;
         
     for (NSUInteger index = 0; index < self.expression.numberOfElements; index++) {
         // The current element
         id element = [self.expression elementAtIndex:index];
-        NSSize elementSize = [self sizeForElementAtIndex:index];
+        NSRect elementBounds = [self boundsOfElementAtIndex:index];
-        CGFloat dy = (self.size.height - elementSize.height) / 2;
-        CGFloat y = point.y + dy;
         
         if ([element isString]) {
             // Get the line to draw
@@ -151,7 +257,7 @@
             CFRetain(line);
             
             // Move to the appropriate position
-            CGContextSetTextPosition(context, x, y);
+            CGContextSetTextPosition(context, x, 0);
                         
             // Perform the drawing
             CTLineDraw(line, context);
@@ -160,9 +266,9 @@
         } else {
             // Let the child layout draw itself
             MPLayout *layout = [self childLayoutAtIndex:index];
-            [layout drawAtPoint:NSMakePoint(x, y)];
+            [layout drawAtPoint:NSMakePoint(x, 0)];
         }
-        x += elementSize.width;
+        x += elementBounds.size.width;
     }
     CGContextRestoreGState(context);
 }

MathPad/MPExpressionStorage.h

@@ -12,14 +12,9 @@
 
 @interface MPExpressionStorage : MPExpression
 
-- (instancetype)initWithExpressionView:(MPExpressionView *)expressionView
+- (instancetype)initWithElements:(NSArray *)elements;
-                              elements:(NSArray *)elements;
 
-@property (readonly, nonatomic, weak) MPExpressionView *expressionView;
+@property (nonatomic, weak) MPExpressionView *expressionView; // Do not set
 @property (nonatomic, strong) MPExpressionLayout *rootLayout;
 
-- (NSLayoutManager *)layoutManager;
-- (NSTextContainer *)textContainer;
-- (NSTextStorage *)textStorage;
-
 @end

MathPad/MPExpressionStorage.m

@@ -20,53 +20,20 @@
 
 @implementation MPExpressionStorage
 
-- (instancetype)initWithExpressionView:(MPExpressionView *)expressionView elements:(NSArray *)elements
-{
-    self = [self initWithElements:elements];
-    if (self) {
-        _expressionView = expressionView;
-    }
-    return self;
-}
-
 - (instancetype)initWithElements:(NSArray *)elements
 {
     self = [super initWithElements:elements];
     if (self) {
-        _rootLayout = [[MPExpressionLayout alloc] initRootLayoutWithExpressionStorage:self];
+        _rootLayout = [[MPExpressionLayout alloc] initRootLayoutWithExpression:self];
     }
     return self;
 }
 
-- (NSLayoutManager *)layoutManager
+- (void)setExpressionView:(MPExpressionView *)expressionView
 {
-    [self ensureTextSystemObjects];
+    _expressionView = expressionView;
-    return _layoutManager;
+    self.rootLayout = [[MPExpressionLayout alloc] initRootLayoutWithExpression:self];
-}
+    self.rootLayout.flipped = expressionView.isFlipped;
-
-- (NSTextContainer *)textContainer
-{
-    [self ensureTextSystemObjects];
-    return _textContainer;
-}
-
-- (NSTextStorage *)textStorage
-{
-    [self ensureTextSystemObjects];
-    return _textStorage;
-}
-
-- (void)ensureTextSystemObjects
-{
-    if (_layoutManager == nil || _textContainer == nil || _textStorage == nil) {
-        _textStorage = [[NSTextStorage alloc] init];
-        NSTextContainer *textContainer = [[NSTextContainer alloc] initWithContainerSize:NSMakeSize(CGFLOAT_MAX, CGFLOAT_MAX)];
-        NSLayoutManager *layoutManager = [[NSLayoutManager alloc] init];
-        [layoutManager addTextContainer:textContainer];
-        [_textStorage addLayoutManager:layoutManager];
-        _textContainer = textContainer;
-        _layoutManager = layoutManager;
-    }
 }
 
 - (void)didChangeElementsInRangePath:(MPRangePath *)rangePath
@@ -76,11 +43,13 @@
         return;
     }
     MPLayout *current = self.rootLayout;
-    for (NSUInteger index = 1; index < rangePath.location.length-1; index++) {
+    for (NSUInteger position = 0; position < rangePath.location.length-1; position++) {
+        NSUInteger index = [rangePath.location indexAtPosition:position];
         current = [current childLayoutAtIndex:index];
     }
     [current clearCacheInRange:rangePath.rangeAtLastIndex
              replacementLength:replacementLength];
+    [self.expressionView invalidateIntrinsicContentSize];
     self.expressionView.needsDisplay = YES;
 }
 

MathPad/MPExpressionView.h

@@ -23,7 +23,6 @@
 @property (readonly, nonatomic, strong) MPExpressionStorage *expressionStorage;
 
 @property (nonatomic, getter = isEditable) BOOL editable;
-//@property (nonatomic, strong) MPRangePath *selection;
+@property (nonatomic, strong) MPRangePath *selection;
-@property (nonatomic, strong) NSIndexPath *caretLocation;
 
 @end

MathPad/MPExpressionView.m

@@ -6,34 +6,109 @@
 //  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
 //
 
+#warning X-Origin is not working yet
+
 #import "MPExpressionView.h"
 #import "MPExpressionStorage.h"
 #import "MPExpressionLayout.h"
 
+#import "MPRangePath.h"
+
+#import "NSIndexPath+MPAdditions.h"
+
 #import "MPSumFunction.h"
 
-@interface MPExpressionView (MPCursor)
+@interface MPExpressionView ()
+
+@property (nonatomic, weak) NSButton *functionsButton;
+
+@property (nonatomic, strong) NSTimer *caretTimer;
+@property (nonatomic) NSTimeInterval caretBlinkRate;
+@property (nonatomic) BOOL caretVisible;
+
+@property (nonatomic, getter = isSelectionModifyingStart) BOOL selectionModifyingStart;
+
+@end
+
+@interface MPExpressionView (MPDrawing)
+
+- (NSPoint)expressionOrigin;
+
+@end
+
+@interface MPExpressionView (MPSelection)
+- (void)restartCaretTimer;
+- (void)updateCaret:(NSTimer *)timer;
+
+- (NSRect)selectionRect;
+
+- (void)selectRangePathWithLocation:(NSIndexPath *)location length:(NSUInteger)length;
+@end
+
+@implementation MPExpressionView (MPDrawing)
+
+- (NSPoint)expressionOrigin
+{
+    NSRect expressionBounds = [self.expressionStorage.rootLayout bounds];
+    CGFloat y = (self.bounds.size.height - expressionBounds.size.height) / 2 + fabs(expressionBounds.origin.y);
+    return NSMakePoint(self.bounds.origin.x, self.bounds.origin.y + y);
+}
+
+@end
+
+@implementation MPExpressionView (MPSelection)
+
+- (void)restartCaretTimer
+{
+    if (self.caretTimer) {
+        if ([self.caretTimer isValid]) {
+            [self.caretTimer invalidate];
+        }
+    }
+    self.caretTimer = [NSTimer scheduledTimerWithTimeInterval:self.caretBlinkRate/2 target:self selector:@selector(updateCaret:) userInfo:nil repeats:YES];
+    self.caretVisible = NO;
+    [self updateCaret:self.caretTimer];
+}
+
+- (void)updateCaret:(NSTimer *)timer
+{
+    self.caretVisible = !self.caretVisible;
+    self.needsDisplay = YES;
+}
+
+- (NSRect)selectionRect
+{
+    NSRect selectionRect = [self.expressionStorage.rootLayout boundingRectForRangePath:self.selection];
+    if (self.selection.length == 0) {
+        selectionRect.size.width = 1;
+    }
+    return selectionRect;
+}
+
+- (void)selectRangePathWithLocation:(NSIndexPath *)location length:(NSUInteger)length
+{
+    MPExpression *targetExpression = [self.expressionStorage elementAtIndexPath:[location indexPathByRemovingLastIndex]];
+    NSUInteger locationIndex = location.lastIndex;
+    if (locationIndex > targetExpression.length) {
+        locationIndex = targetExpression.length;
+    }
+    NSUInteger lastSelectedIndex = location.lastIndex + length;
+    if (lastSelectedIndex > targetExpression.length) {
+        lastSelectedIndex = targetExpression.length;
+    }
+    self.selection = MPMakeRangePath([location indexPathByReplacingLastIndexWithIndex:locationIndex],lastSelectedIndex - locationIndex);
+}
 
 @end
 
 @implementation MPExpressionView
 
 #pragma mark Creation Methods
-
-- (instancetype)init
-{
-    self = [super init];
-    if (self) {
-        [self initializeObjects];
-    }
-    return self;
-}
-
 - (id)initWithFrame:(NSRect)frame
 {
     self = [super initWithFrame:frame];
     if (self) {
-        [self initializeObjects];
+        [self initializeExpressionView];
     }
     return self;
 }
@@ -42,25 +117,44 @@
 {
     self = [super initWithCoder:aDecoder];
     if (self) {
-        [self initializeObjects];
+        [self initializeExpressionView];
     }
     return self;
 }
 
-- (void)initializeObjects
+- (void)initializeExpressionView
 {
-    MPExpressionStorage *expressionStorage = [[MPExpressionStorage alloc] initWithExpressionView:self elements:@[@"12345", [[MPSumFunction alloc] init], [[MPSumFunction alloc] init]]];
+    MPExpressionStorage *expressionStorage = [[MPExpressionStorage alloc] initWithElements:@[@"12345", [[MPSumFunction alloc] init], [[MPSumFunction alloc] init]]];
+    expressionStorage.expressionView = self;
     _expressionStorage = expressionStorage;
-    _caretLocation = [[NSIndexPath alloc] initWithIndex:0];
+    NSRect frame = NSMakeRect(10, 10, 500, 500);
+    NSButton *button = [[NSButton alloc] initWithFrame:frame];
+    button.buttonType = NSSwitchButton;
+    [button setTitle:@"Functions"];
+    self.functionsButton = button;
+    [self addSubview:self.functionsButton];
+    self.selection = [[MPRangePath alloc] initWithRange:NSMakeRange(0, 0)];
+    self.caretBlinkRate = 1.0;
+    [self restartCaretTimer];
 }
 
 #pragma mark Properties
-
+- (void)setExpressionStorage:(MPExpressionStorage *)expressionStorage
-- (BOOL)isFlipped
 {
-    return NO;
+    _expressionStorage.expressionView = nil;
+    _expressionStorage = expressionStorage;;
+    _expressionStorage.expressionView = self;
+    [self invalidateIntrinsicContentSize];
 }
 
+- (void)setSelection:(MPRangePath *)selection
+{
+    _selection = selection;
+    [self restartCaretTimer];
+    self.needsDisplay = YES;
+}
+
+#pragma mark NSView Stuff
 - (BOOL)acceptsFirstResponder
 {
     return YES;
@@ -71,29 +165,226 @@
     return YES;
 }
 
-#pragma mark Event Handling
+- (BOOL)isFlipped
+{
+    return NO;
+}
+
+- (BOOL)isOpaque
+{
+    return YES;
+}
+
+- (void)layout
+{
+    NSSize buttonSize = [self.functionsButton fittingSize];
+    self.functionsButton.frame = NSMakeRect(self.bounds.size.width - buttonSize.width,
+                                            (self.bounds.size.height - buttonSize.height) / 2,
+                                            buttonSize.width,
+                                            buttonSize.height);
+    [super layout];
+}
+
+- (NSSize)intrinsicContentSize
+{
+//    return NSMakeSize(500, 500);
+//    return self.bounds.size;
+    return self.expressionStorage.rootLayout.bounds.size;
+}
+
+- (void)resetCursorRects
+{
+    [self addCursorRect:self.bounds
+                 cursor:[NSCursor IBeamCursor]];
+}
+
+#pragma mark Key Event Handling
 - (void)keyDown:(NSEvent *)theEvent
 {
+    NSString *characters = theEvent.characters;
+    if (characters.length == 1 && [characters stringByTrimmingCharactersInSet:[NSCharacterSet decimalDigitCharacterSet]].length == 0) {
+        MPExpression *targetExpression = [self.expressionStorage elementAtIndexPath:[self.selection.location indexPathByRemovingLastIndex]];
+        [targetExpression replaceSymbolsInRange:self.selection.rangeAtLastIndex withElements:@[characters]];
+        self.selection = MPMakeRangePath([self.selection.location indexPathByIncrementingLastIndex], 0);
+    } else {
         [self interpretKeyEvents:@[theEvent]];
+    }
 }
 
 - (void)moveRight:(id)sender
 {
-    [self.expressionStorage deleteElementsInRange:NSMakeRange(0, 1)];
+    if (self.selection.length > 0) {
+        self.selection = MPMakeRangePath(self.selection.maxRangePath, 0);
+    } else {
+        NSIndexPath *newSelectionLocation = [self.selection.location indexPathByIncrementingLastIndex];
+        [self selectRangePathWithLocation:newSelectionLocation
+                                   length:0];
+    }
+}
+
+- (void)moveLeft:(id)sender
+{
+    if (self.selection.length > 0) {
+        self.selection = MPMakeRangePath(self.selection.location, 0);
+        [self selectRangePathWithLocation:self.selection.location length:0];
+    } else {
+        NSUInteger selectionIndex = self.selection.location.lastIndex;
+        if (selectionIndex > 0) {
+            --selectionIndex;
+        }
+        NSIndexPath *newSelectionLocation = [self.selection.location indexPathByReplacingLastIndexWithIndex:selectionIndex];
+        [self selectRangePathWithLocation:newSelectionLocation
+                                   length:0];
+    }
+}
+
+- (void)moveWordRight:(id)sender
+{
+    NSIndexPath *location;
+    if (self.selection.length > 0) {
+        location = self.selection.maxRangePath;
+    } else {
+        location = self.selection.location;
+    }
+    MPExpression *targetExpression = [self.expressionStorage elementAtIndexPath:[location indexPathByRemovingLastIndex]];
+    NSUInteger locationInTarget = NSMaxRange(self.selection.rangeAtLastIndex);
+    NSUInteger offset;
+    NSUInteger elementIndex = [targetExpression indexOfElementAtSymbolLocation:locationInTarget
+                                                                        offset:&offset];
+    NSUInteger newLocation = locationInTarget + [targetExpression elementAtIndex:elementIndex].length - offset;
+    [self selectRangePathWithLocation:[location indexPathByReplacingLastIndexWithIndex:newLocation]
+                               length:0];
+}
+
+- (void)moveWordLeft:(id)sender
+{
+    MPExpression *targetExpression = [self.expressionStorage elementAtIndexPath:[self.selection.location indexPathByRemovingLastIndex]];
+    NSUInteger offset;
+    NSUInteger elementIndex = [targetExpression indexOfElementAtSymbolLocation:self.selection.location.lastIndex offset:&offset];
+    NSUInteger newLocation = self.selection.location.lastIndex;
+    if (offset > 0) {
+        newLocation -= newLocation - offset > 0 ? offset : newLocation;
+    } else if (newLocation > 0) {
+        newLocation -= [targetExpression elementAtIndex:elementIndex-1].length;
+    }
+    self.selection = MPMakeRangePath([self.selection.location indexPathByReplacingLastIndexWithIndex:newLocation], 0);
+}
+
+- (void)moveToBeginningOfLine:(id)sender
+{
+    self.selection = MPMakeRangePath([self.selection.location indexPathByReplacingLastIndexWithIndex:0], 0);
+}
+
+- (void)moveToEndOfLine:(id)sender
+{
+    
+}
+
+- (void)moveLeftAndModifySelection:(id)sender
+{
+    if (self.selection.length == 0) {
+        self.selectionModifyingStart = YES;
+    }
+    NSUInteger start = self.selection.location.lastIndex;
+    NSUInteger length = self.selection.length;
+    if (self.selectionModifyingStart) {
+        if (start > 0) {
+            --start;
+            ++length;
+        }
+    } else {
+        --length;
+    }
+    self.selection = MPMakeRangePath([self.selection.location indexPathByReplacingLastIndexWithIndex:start], length);
+}
+
+- (void)moveRightAndModifySelection:(id)sender
+{
+    if (self.selection.length == 0) {
+        self.selectionModifyingStart = NO;
+    }
+    NSUInteger start = self.selection.location.lastIndex;
+    NSUInteger length = self.selection.length;
+    if (self.selectionModifyingStart) {
+        ++start;
+        --length;
+    } else {
+        ++length;
+    }
+    [self selectRangePathWithLocation:[self.selection.location indexPathByReplacingLastIndexWithIndex:start]
+                               length:length];
+}
+
+- (void)moveWordRightAndModifySelection:(id)sender
+{
+    
+}
+
+- (void)moveWordLeftAndModifySelection:(id)sender
+{
+    
+}
+
+- (void)selectAll:(id)sender
+{
+    NSIndexPath *location = [NSIndexPath indexPathWithIndex:0];
+    self.selection = MPMakeRangePath(location, self.expressionStorage.length);
+}
+
+- (void)deleteBackward:(id)sender
+{
+    MPExpression *targetExpression = [self.expressionStorage elementAtIndexPath:[self.selection.location indexPathByRemovingLastIndex]];
+    if (self.selection.length > 0) {
+        [targetExpression replaceSymbolsInRange:self.selection.rangeAtLastIndex withElements:@[]];
+        self.selection = MPMakeRangePath(self.selection.location, 0);
+    } else if (self.selection.location.lastIndex > 0) {
+        [targetExpression replaceSymbolsInRange:NSMakeRange(self.selection.location.lastIndex-1, 1) withElements:@[]];
+        self.selection = MPMakeRangePath([self.selection.location indexPathByDecrementingLastIndex], 0);
+    }
+}
+
+#pragma mark Mouse Event Handling
+- (void)mouseDown:(NSEvent *)theEvent
+{
+    NSPoint pointInView = [self convertPoint:theEvent.locationInWindow
+                                    fromView:nil];
+    NSPoint expressionOrigin = self.expressionOrigin;
+    pointInView.x -= expressionOrigin.x;
+    pointInView.y -= expressionOrigin.y;
+    NSIndexPath *selectionPath = [self.expressionStorage.rootLayout indexPathForMousePoint:pointInView];
+    self.selection = MPMakeRangePath(selectionPath, 0);
 }
 
 #pragma mark Drawing Methods
-
 - (void)drawRect:(NSRect)dirtyRect
 {
+    // Draw the background
     [super drawRect:dirtyRect];
     [[NSColor whiteColor] set];
     NSRectFill(self.bounds);
+    
+    // Calculate the position of the expression (probably also forces layout of the expression the first time)
+    NSPoint expressionOrigin = self.expressionOrigin;
+    
+    // Draw the selection
+    if (self.caretVisible || self.selection.length > 0) {
+        if (self.selection.length == 0) {
             [[NSColor blackColor] set];
-    NSSize expressionSize = [self.expressionStorage.rootLayout size];
+        } else {
-    CGFloat y = (self.bounds.size.height - expressionSize.height) / 2;
+            [[NSColor selectedTextBackgroundColor] set];
-    NSPoint point = NSMakePoint(self.bounds.origin.x, self.bounds.origin.y + y);
+        }
-    [self.expressionStorage.rootLayout drawAtPoint:point];
+        NSAffineTransform *transform = [NSAffineTransform transform];
+        [transform translateXBy:expressionOrigin.x
+                            yBy:expressionOrigin.y];
+        [transform concat];
+        NSRectFill([self selectionRect]);
+        [transform invert];
+        [transform concat];
+    }
+    
+    // Draw the expression
+    [[NSColor textColor] set];
+    [self.expressionStorage.rootLayout drawAtPoint:expressionOrigin];
 }
 
 @end

MathPad/MPFunction.h

@@ -22,6 +22,7 @@
 
 #pragma mark Working With the Expression Tree
 @property (nonatomic, weak) MPExpression *parent; // Documentation: Do not set
+- (MPExpression *)rootExpression;
 - (NSIndexPath *)indexPath;
 
 - (NSUInteger)numberOfChildren; // Override

MathPad/MPFunction.m

@@ -24,6 +24,11 @@
 }
 
 #pragma mark Working With the Expression Tree
+- (MPExpression *)rootExpression
+{
+    return [self.parent rootExpression];
+}
+
 - (NSIndexPath *)indexPath
 {
     NSUInteger selfIndex = [self.parent indexOfElement:self];
@@ -60,7 +65,7 @@
 {
     NSUInteger index = 0;
     for (; index < [self numberOfChildren]; index++) {
-        if ([[self childAtIndex:index] isEqualToExpression:child]) {
+        if ([self childAtIndex:index] == child) {
             return index;
         }
     }
@@ -106,6 +111,7 @@
 }
 
 #pragma mark Working With Functions
+/*
 - (BOOL)isEqual:(id)object
 {
     if (self == object) {
@@ -123,7 +129,7 @@
 - (BOOL)isEqualToFunction:(MPFunction *)aFunction
 {
     return [aFunction isMemberOfClass:[MPFunction class]] && [self isMemberOfClass:[MPFunction class]];
-}
+}*/
 
 - (NSString *)description
 {

MathPad/MPFunctionLayout.h

@@ -12,6 +12,7 @@
 @interface MPFunctionLayout : MPLayout
 
 + (MPFunctionLayout *)functionLayoutForFunctionAtIndexPath:(NSIndexPath *)path
+                                          inRootExpression:(MPExpression *)rootExpression
                                                     parent:(MPExpressionLayout *)parent;
 
 @property (readonly, nonatomic, weak) MPFunction *function;
@@ -31,7 +32,9 @@
 // }
 
 #pragma mark Size and Drawing Methods
-- (NSSize)generateSize; // To be implemented
+- (NSPoint)offsetOfChildLayoutAtIndex:(NSUInteger)index; // To be implemented
+- (NSIndexPath *)indexPathForMousePoint:(NSPoint)point; // To be implemented
+- (NSRect)generateBounds; // To be implemented
 - (void)drawAtPoint:(NSPoint)point; // To be implemented
 
 @end

MathPad/MPFunctionLayout.m

@@ -17,33 +17,34 @@
 
 #pragma mark Creation Methods
 + (MPFunctionLayout *)functionLayoutForFunctionAtIndexPath:(NSIndexPath *)path
+                                          inRootExpression:(MPExpression *)rootExpression
                                                     parent:(MPExpressionLayout *)parent
 {
-    MPFunction *function = [parent.expressionStorage elementAtIndexPath:path];
+    MPFunction *function = [rootExpression elementAtIndexPath:path];
     Class class = [function class];
     if (class == [MPSumFunction class]) {
-        return [[MPSumFunctionLayout alloc] initWithPath:path parent:parent];
+        return [[MPSumFunctionLayout alloc] initWithElementAtPath:path
+                                                 inRootExpression:rootExpression
+                                                           parent:parent];
     }
-    return [[self alloc] initWithPath:path parent:parent];
+    return [[self alloc] initWithElementAtPath:path
+                              inRootExpression:rootExpression
+                                        parent:parent];
 }
 
-- (instancetype)initWithPath:(NSIndexPath *)path
+- (instancetype)initWithElementAtPath:(NSIndexPath *)path
+                     inRootExpression:(MPExpression *)rootExpression
                                parent:(MPLayout *)parent
 {
-    self = [super initWithPath:path
+    self = [super initWithElementAtPath:path
+                       inRootExpression:rootExpression
                                  parent:parent];
     if (self) {
-        _function = [parent.expressionStorage elementAtIndexPath:path];
+        _function = [rootExpression elementAtIndexPath:path];
     }
     return self;
 }
 
-#pragma mark Properties
-//- (MPFunction *)function
-//{
-//    return [self.expressionStorage elementAtIndexPath:self.path];
-//}
-
 #pragma mark Cache Methods
 - (CTLineRef)lineForPrivateCacheIndex:(NSUInteger)index
                             generator:(CTLineRef (^)())generator
@@ -62,26 +63,22 @@
 {
     return [self cachableObjectForIndex:index generator:^id{
         NSIndexPath *childPath = [self.function.indexPath indexPathByAddingIndex:index];
-        MPExpressionLayout *layout = [[MPExpressionLayout alloc] initWithPath:childPath
+        MPExpressionLayout *layout = [[MPExpressionLayout alloc] initWithElementAtPath:childPath
+                                                                      inRootExpression:self.function.rootExpression
                                                                                 parent:self];
+        layout.flipped = self.flipped;
+        layout.usesSmallSize = (index == 0 || index == 1) ? YES : self.usesSmallSize;
         return layout;
     }];
 }
 
 #pragma mark Size and Drawing Methods
-
+- (NSRect)generateBounds
-- (NSSize)sizeForChildAtIndex:(NSUInteger)index
 {
-    MPLayout *childLayout = [self childLayoutAtIndex:index];
+    return NSZeroRect;
-    return [childLayout size];
 }
 
-- (NSSize)generateSize
+- (void)draw
-{
-    return NSZeroSize;
-}
-
-- (void)drawAtPoint:(NSPoint)point
 {
     
 }

MathPad/MPLayout.h

@@ -15,11 +15,17 @@
 
 #pragma mark Creation Methods
 - (instancetype)init;
-- (instancetype)initWithPath:(NSIndexPath *)path
+- (instancetype)initWithElementAtPath:(NSIndexPath *)path
+                     inRootExpression:(MPExpression *)rootExpression
                                parent:(MPLayout *)parent;
 
-#pragma mark Text System Objects
+#pragma mark Properties
-@property (readonly, nonatomic, weak) MPExpressionStorage *expressionStorage;
+- (NSFont *)font;
+- (CGFloat)fontSize;
+- (NSFont *)normalFont;
+- (CGFloat)normalFontSize;
+- (NSFont *)smallFont;
+- (CGFloat)smallFontSize;
 
 #pragma mark Cache Tree
 @property (readonly, nonatomic, weak) MPLayout *parent;
@@ -35,14 +41,21 @@
 - (void)invalidate;
 
 #pragma mark Calculation and Drawing Methods
-// TODO: Implement Small Size
+@property (nonatomic, getter = isFlipped) BOOL flipped;
-// @property (nonatomic) BOOL usesSmallSize;
+@property (nonatomic) BOOL usesSmallSize;
-- (NSSize)size;
+- (NSRect)bounds;
+
+- (NSRect)boundingRectForRangePath:(MPRangePath *)rangePath; /* if rangePath.length is 0 the returned rect will have a width of 0 */
+
 - (void)drawAtPoint:(NSPoint)point;
 
 @end
 
 @interface MPLayout (MPSubclassImplement)
 - (MPLayout *)childLayoutAtIndex:(NSUInteger)index; // To be implemented
-- (NSSize)generateSize; // To be implemented
+- (NSRect)generateBounds; // To be implemented
+- (NSRect)boundingRectForRange:(NSRange)range; // To be implemented, use rangePath instead, this one has wrong origin
+- (NSPoint)offsetOfChildLayoutAtIndex:(NSUInteger)index;
+- (NSIndexPath *)indexPathForMousePoint:(NSPoint)point;
+- (void)draw; // To be implemented
 @end

MathPad/MPLayout.m

@@ -7,6 +7,9 @@
 //
 
 #import "MPLayout.h"
+#import "MPRangePath.h"
+
+#import "NSIndexPath+MPAdditions.h"
 
 @interface MPLayout ()
 
@@ -18,7 +21,7 @@
 
 @implementation MPLayout {
     NSMutableArray *_cache;
-    NSSize _cachedSize;
+    NSRect _cachedBounds;
 }
 
 #pragma mark Creation Methods
@@ -27,12 +30,13 @@
     self = [super init];
     if (self) {
         _cache = [[NSMutableArray alloc] init];
-        _cachedSize = NSZeroSize;
+        _cachedBounds = NSZeroRect;
     }
     return self;
 }
 
-- (id)initWithPath:(NSIndexPath *)path
+- (instancetype)initWithElementAtPath:(NSIndexPath *)path
+                     inRootExpression:(MPExpression *)rootExpression
                                parent:(MPLayout *)parent
 {
     self = [self init];
@@ -42,10 +46,37 @@
     return self;
 }
 
-#pragma Text System Objects
+#pragma mark Properties
-- (MPExpressionStorage *)expressionStorage
+- (NSFont *)font
 {
-    return self.parent.expressionStorage;
+    return self.usesSmallSize ? self.smallFont : self.normalFont;
+}
+
+- (CGFloat)fontSize
+{
+    return self.usesSmallSize ? self.smallFontSize : self.normalFontSize;
+}
+
+- (NSFont *)normalFont
+{
+    return [NSFont fontWithName:@"CMU Serif"
+                           size:self.fontSize];
+}
+
+- (CGFloat)normalFontSize
+{
+    return 18.0;
+}
+
+- (NSFont *)smallFont
+{
+    return [NSFont fontWithName:@"CMU Serif"
+                           size:self.smallFontSize];
+}
+
+- (CGFloat)smallFontSize
+{
+    return 12.0;
 }
 
 #pragma mark Cache Tree
@@ -92,22 +123,42 @@
 
 - (void)invalidate
 {
-    _cachedSize = NSZeroSize;
+    _cachedBounds = NSZeroRect;
     [self.parent invalidate];
 }
 
 #pragma mark Calculation and Drawing Methods
-- (NSSize)size
+- (NSRect)bounds
 {
-    if (NSEqualSizes(_cachedSize, NSZeroSize)) {
+    if (NSEqualRects(_cachedBounds, NSZeroRect)) {
-        _cachedSize = [self generateSize];
+        _cachedBounds = [self generateBounds];
     }
-    return _cachedSize;
+    return _cachedBounds;
+}
+
+- (NSRect)boundingRectForRangePath:(MPRangePath *)rangePath
+{
+    if (rangePath.location.length == 1) {
+        return [self boundingRectForRange:rangePath.rangeAtLastIndex];
+    }
+    NSUInteger nextIndex = [rangePath.location indexAtPosition:0];
+    NSIndexPath *newLocation = [rangePath.location indexPathByRemovingFirstIndex];
+    MPRangePath *newRangePath = [[MPRangePath alloc] initWithLocation:newLocation length:rangePath.length];
+    NSRect bounds = [[self childLayoutAtIndex:nextIndex] boundingRectForRangePath:newRangePath];
+    NSPoint offset = [self offsetOfChildLayoutAtIndex:nextIndex];
+    bounds.origin = NSMakePoint(bounds.origin.x + offset.x, bounds.origin.y + offset.y);
+    return bounds;
 }
 
 - (void)drawAtPoint:(NSPoint)point
 {
-    
+    NSAffineTransform *transform = [NSAffineTransform transform];
+    [transform translateXBy:point.x
+                        yBy:point.y];
+    [transform concat];
+    [self draw];
+    [transform invert];
+    [transform concat];
 }
 
 @end
@@ -119,14 +170,24 @@
     return nil;
 }
 
-- (NSSize)sizeForChildAtIndex:(NSUInteger)index
+- (NSRect)generateBounds
 {
-    return NSZeroSize;
+    return NSZeroRect;
 }
 
-- (NSSize)generateSize
+- (NSRect)boundingRectForRange:(NSRange)range
 {
-    return NSZeroSize;
+    return NSZeroRect;
+}
+
+- (NSPoint)offsetOfChildLayoutAtIndex:(NSUInteger)index
+{
+    return NSZeroPoint;
+}
+
+- (void)draw
+{
+    
 }
 
 @end

MathPad/MPRangePath.h

@@ -10,6 +10,8 @@
 
 #import "MPExpression.h"
 
+#define MPMakeRangePath(loc, len) [MPRangePath rangePathWithLocation:(loc) length:(len)]
+
 @class MPRangePath, MPExpression;
 
 @interface MPRangePath : NSObject <NSCopying, NSCoding>

MathPad/MPSumFunction.h

@@ -13,8 +13,8 @@
 
 @interface MPSumFunction : MPFunction
 
-@property (nonatomic, strong) MPExpression *startExpression;
+@property (nonatomic, strong) MPExpression *startExpression; // Index 0
-@property (nonatomic, strong) MPExpression *targetExpression;
+@property (nonatomic, strong) MPExpression *targetExpression; // Index 1
-@property (nonatomic, strong) MPExpression *sumExpression;
+@property (nonatomic, strong) MPExpression *sumExpression; // Index 2
 
 @end

MathPad/MPSumFunction.m

@@ -104,6 +104,7 @@
 }
 
 #pragma mark Working With Functions
+/*
 - (BOOL)isEqualToFunction:(MPFunction *)aFunction
 {
     if (![aFunction isKindOfClass:[MPSumFunction class]]) {
@@ -117,7 +118,7 @@
         return NO;
     }
     return [self.sumExpression isEqualToExpression:sumFunction.sumExpression];
-}
+}*/
 
 - (NSString *)description
 {

MathPad/MPSumFunctionLayout.m

@@ -9,6 +9,13 @@
 #import "MPSumFunctionLayout.h"
 #import "MPSumFunction.h"
 
+#import "NSIndexPath+MPAdditions.h"
+
+#define kSumFunctionStartExpressionOffset 3
+#define kSumFunctionTargetExpressionOffset 0
+#define kSumFunctionSumExpressionOffset 3
+#define kSumFunctionTrailingOffset 5
+
 @implementation MPSumFunctionLayout
 
 - (MPSumFunction *)sumFunction
@@ -21,7 +28,7 @@
     CTLineRef line = [self lineForPrivateCacheIndex:0 generator:^CTLineRef{
         NSAttributedString *text =
             [[NSAttributedString alloc] initWithString:@"∑"
-                                            attributes:@{NSFontAttributeName: [NSFont fontWithName:@"Lucida Grande" size:18.0]}];
+                                            attributes:@{NSFontAttributeName: self.font}];
         CFAttributedStringRef attributedString = CFBridgingRetain(text);
         CTLineRef line = CTLineCreateWithAttributedString(attributedString);
         CFRelease(attributedString); // TODO: Is this release appropriate
@@ -30,16 +37,85 @@
     return line;
 }
 
-- (NSSize)generateSize
+- (NSRect)localLineBounds
 {
-    CTLineRef line = [self line];
+    NSRect lineBounds = CTLineGetBoundsWithOptions(self.line, 0);
-    CFRetain(line);
+    CGFloat width = MAX(MAX([self childLayoutAtIndex:0].bounds.size.width, [self childLayoutAtIndex:1].bounds.size.width), lineBounds.size.width);
-    CGSize size = CTLineGetBoundsWithOptions(line, /*kCTLineBoundsUseOpticalBounds*/0).size;
+    CGFloat xPosition = (width - lineBounds.size.width) / 2;
-    CFRelease(line);
+    return NSMakeRect(xPosition, lineBounds.origin.y, lineBounds.size.width, lineBounds.size.height);
-    return size;
 }
 
-- (void)drawAtPoint:(NSPoint)point
+- (NSPoint)offsetOfChildLayoutAtIndex:(NSUInteger)index
+{
+    NSRect childBounds = [self childLayoutAtIndex:index].bounds;
+    NSRect localLineBounds = [self localLineBounds];
+    NSPoint offset;
+    if (index == 0) {
+        // Start Expression
+        offset.x = localLineBounds.origin.x + localLineBounds.size.width / 2 - childBounds.size.width / 2;
+        offset.y = -kSumFunctionStartExpressionOffset - childBounds.size.height;
+    } else if (index == 1) {
+        // Target Expression
+        offset.x = localLineBounds.origin.x + localLineBounds.size.width / 2 - childBounds.size.width / 2;
+        offset.y = localLineBounds.size.height + kSumFunctionTargetExpressionOffset;
+    } else {
+        // Sum Expression
+        MPLayout *startExpressionLayout = [self childLayoutAtIndex:0];
+        MPLayout *targetExpressionLayout = [self childLayoutAtIndex:1];
+        CGFloat sumWidth = MAX(MAX(localLineBounds.origin.x + localLineBounds.size.width, startExpressionLayout.bounds.size.width), targetExpressionLayout.bounds.size.width);
+        offset.x = sumWidth + kSumFunctionSumExpressionOffset;
+        offset.y = 0;
+    }
+    return offset;
+}
+
+- (NSIndexPath *)indexPathForMousePoint:(NSPoint)point
+{
+    // A single index is used to communicate back wether the
+    // selection should be before or after the function.
+    // A 0 means before, a 1 means after.
+    for (NSUInteger index = 0; index < self.function.numberOfChildren; index++) {
+        MPLayout *childLayout = [self childLayoutAtIndex:index];
+        NSRect childBounds = childLayout.bounds;
+        NSPoint childOffset = [self offsetOfChildLayoutAtIndex:index];
+        childBounds.origin.x += childOffset.x;
+        childBounds.origin.y += childOffset.y;
+        if (NSMouseInRect(point, childBounds, self.flipped)) {
+            NSPoint pointInChild = NSMakePoint(point.x + childOffset.x, point.y + childOffset.y);
+            NSIndexPath *subPath = [childLayout indexPathForMousePoint:pointInChild];
+            return [subPath indexPathByPreceedingIndex:index];
+        }
+    }
+    if (point.x < CTLineGetBoundsWithOptions(self.line, 0).size.width / 2) {
+        return [NSIndexPath indexPathWithIndex:0];
+    } else {
+        return [NSIndexPath indexPathWithIndex:1];
+    }
+}
+
+- (NSRect)generateBounds
+{
+    NSRect lineBounds = CTLineGetBoundsWithOptions(self.line, 0);
+    NSRect startExpressionBounds = [self childLayoutAtIndex:0].bounds;
+    NSRect targetExpressionBounds = [self childLayoutAtIndex:1].bounds;
+    NSRect sumExpressionBounds = [self childLayoutAtIndex:2].bounds;
+    NSRect bounds = lineBounds;
+    
+    bounds.size.width = MAX(lineBounds.size.width, startExpressionBounds.size.width);
+    bounds.size.height += startExpressionBounds.size.height + kSumFunctionStartExpressionOffset;
+    
+    bounds.size.width = MAX(bounds.size.width, targetExpressionBounds.size.width);
+    bounds.size.height += targetExpressionBounds.size.height + kSumFunctionTargetExpressionOffset;
+    
+    bounds.size.width += kSumFunctionSumExpressionOffset + sumExpressionBounds.size.width;
+    bounds.size.height = MAX(bounds.size.height, sumExpressionBounds.size.height);
+    
+    bounds.origin.y -= targetExpressionBounds.size.height + kSumFunctionStartExpressionOffset;
+    bounds.size.width += kSumFunctionTrailingOffset;
+    return bounds;
+}
+
+- (void)draw
 {
     // Get the current context
     CGContextRef context = (CGContextRef)[[NSGraphicsContext currentContext] graphicsPort];
@@ -47,14 +123,33 @@
     // Set the text matrix
     CGContextSetTextMatrix(context, CGAffineTransformIdentity);
     
-    // Get the line of text
+    // Draw the sum symbol
     CTLineRef line = [self line];
     CFRetain(line);
-    
+    NSRect localLineBounds = [self localLineBounds];
-    // Draw the line
+    CGContextSetTextPosition(context, localLineBounds.origin.x, 0);
-    CGContextSetTextPosition(context, point.x, point.y);
     CTLineDraw(line, context);
     
+    // Draw the start function
+    MPLayout *startExpressionLayout = [self childLayoutAtIndex:0];
+    NSPoint startExpressionLocation = NSMakePoint(localLineBounds.origin.x + localLineBounds.size.width / 2, 0);
+    startExpressionLocation.x -= startExpressionLayout.bounds.size.width / 2;
+    startExpressionLocation.y -= startExpressionLayout.bounds.size.height + kSumFunctionStartExpressionOffset;
+    [startExpressionLayout drawAtPoint:startExpressionLocation];
+    
+    // Draw the target function
+    MPLayout *targetExpressionLayout = [self childLayoutAtIndex:1];
+    NSPoint targetExpressionLocation = NSMakePoint(localLineBounds.origin.x + localLineBounds.size.width / 2, localLineBounds.size.height);
+    targetExpressionLocation.x -= targetExpressionLayout.bounds.size.width / 2;
+    targetExpressionLocation.y += kSumFunctionTargetExpressionOffset;
+    [targetExpressionLayout drawAtPoint:targetExpressionLocation];
+    
+    // Draw the sum function
+    MPLayout *sumExpressionLayout = [self childLayoutAtIndex:2];
+    CGFloat sumWidth = MAX(MAX(localLineBounds.origin.x + localLineBounds.size.width, startExpressionLayout.bounds.size.width), targetExpressionLayout.bounds.size.width);
+    sumWidth += kSumFunctionSumExpressionOffset;
+    [sumExpressionLayout drawAtPoint:NSMakePoint(sumWidth, 0)];
+    
     CFRelease(line);
 }
 

MathPad/MathPad-Info.plist

@@ -51,6 +51,8 @@
 	<string>Copyright © 2014 Kim Wittenburg. All rights reserved.</string>
 	<key>NSMainNibFile</key>
 	<string>MainMenu</string>
+	<key>ATSApplicationFontsPath</key>
+	<string>Fonts</string>
 	<key>NSPrincipalClass</key>
 	<string>NSApplication</string>
 </dict>

MathPad/NSIndexPath+MPAdditions.h

@@ -10,6 +10,10 @@
 
 @interface NSIndexPath (MPAdditions)
 
+- (NSUInteger)lastIndex;
+
+- (NSIndexPath *)indexPathByReplacingLastIndexWithIndex:(NSUInteger)index;
+
 /*!
  @method indexPathByRemovingFirstIndex
  @brief Provides an index path with the indexes in the receiving index path, excluding the first one.
@@ -27,4 +31,7 @@
  */
 - (NSIndexPath *)indexPathByPreceedingIndex:(NSUInteger)index;
 
+- (NSIndexPath *)indexPathByIncrementingLastIndex;
+- (NSIndexPath *)indexPathByDecrementingLastIndex;
+
 @end

MathPad/NSIndexPath+MPAdditions.m

@@ -10,6 +10,16 @@
 
 @implementation NSIndexPath (MPAdditions)
 
+- (NSUInteger)lastIndex
+{
+    return [self indexAtPosition:self.length-1];
+}
+
+- (NSIndexPath *)indexPathByReplacingLastIndexWithIndex:(NSUInteger)index
+{
+    return [[self indexPathByRemovingLastIndex] indexPathByAddingIndex:index];
+}
+
 - (NSIndexPath *)indexPathByRemovingFirstIndex
 {
     if (self.length <= 1) {
@@ -34,4 +44,18 @@
     return [[NSIndexPath alloc] initWithIndexes:newIndexes length:self.length+1];
 }
 
+- (NSIndexPath *)indexPathByIncrementingLastIndex
+{
+    NSUInteger lastIndex = [self lastIndex];
+    lastIndex++;
+    return [[self indexPathByRemovingLastIndex] indexPathByAddingIndex:lastIndex];
+}
+
+- (NSIndexPath *)indexPathByDecrementingLastIndex
+{
+    NSUInteger lastIndex = [self lastIndex];
+    lastIndex--;
+    return [[self indexPathByRemovingLastIndex] indexPathByAddingIndex:lastIndex];
+}
+
 @end