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/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 = expressionStorage;
+        _expression = expression;
     }
     return self;
 }
 
-- (instancetype)initWithPath:(NSIndexPath *)path
-                      parent:(MPLayout *)parent
+- (instancetype)initWithElementAtPath:(NSIndexPath *)path
+                     inRootExpression:(MPExpression *)rootExpression
+                               parent:(MPLayout *)parent
 {
-    self = [super initWithPath:path
-                        parent:parent];
+    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;
-    for (NSUInteger index = 0; index < self.expression.numberOfElements; index++) {
-        NSSize elementSize = [self sizeForElementAtIndex:index];
-        width += elementSize.width;
-        height = MAX(height, elementSize.height);
+    if (self.expression.numberOfElements == 0) {
+        return NSMakeRect(0, [self.font descender], kMPEmptyBoxWidth, self.fontSize);
     }
-    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];
-        CGFloat dy = (self.size.height - elementSize.height) / 2;
-        CGFloat y = point.y + dy;
+        NSRect elementBounds = [self boundsOfElementAtIndex:index];
         
         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);
 }