mathpad/MathPad/MPExpressionLayout.m

//
//  MPExpressionLayout.m
//  MathPad
//
//  Created by Kim Wittenburg on 22.04.14.
//  Copyright (c) 2014 Kim Wittenburg. All rights reserved.
//

#import "MPExpressionLayout.h"
#import "MPExpressionStorage.h"
#import "MPFunctionLayout.h"
#import "MPModel.h"

@implementation MPExpressionLayout

#pragma mark Creation Methods

- (instancetype)initRootLayoutWithExpressionStorage:(MPExpressionStorage *)expressionStorage
{
    self = [super init];
    if (self) {
        _symbolCache = [[NSMutableArray alloc] init];
        _expressionStorage = expressionStorage;
        _expressionPath = [[NSIndexPath alloc] init];
    }
    return self;
}

- (instancetype)initWithExpressionPath:(NSIndexPath *)expressionPath
                                parent:(MPFunctionLayout *)parent
{
    self = [super init];
    if (self) {
        _symbolCache = [[NSMutableArray alloc] init];
        _expressionPath = expressionPath;
        _parent = parent;
    }
    return self;
}

#pragma mark Properties

@synthesize expressionStorage = _expressionStorage;
- (MPExpressionStorage *)expressionStorage
{
    if (_expressionStorage) {
        return _expressionStorage;
    }
    return self.parent.expressionStorage;
}

- (MPExpression *)expression
{
    return [self.expressionStorage symbolAtIndexPath:self.expressionPath];
}

- (NSLayoutManager *)layoutManager
{
    return self.expressionStorage.layoutManager;
}

- (NSTextContainer *)textContainer
{
    return self.expressionStorage.textContainer;
}

- (NSTextStorage *)textStorage
{
    return self.expressionStorage.textStorage;
}

#pragma mark Cache Methods

- (void)invalidate
{
    _valid = NO;
}

- (void)expressionEditedInRange:(NSRange)range replacementLength:(NSUInteger)length
{
    while (_symbolCache.count < self.expression.numberOfSymbols) {
        [_symbolCache addObject:[NSNull null]];
    }
    NSMutableArray *newPlaceholders = [[NSMutableArray alloc] initWithCapacity:length];
    while (newPlaceholders.count < length) {
        [newPlaceholders addObject:[NSNull null]];
    }
    [_symbolCache replaceObjectsInRange:range withObjectsFromArray:newPlaceholders];
    _valid = NO;
}

- (BOOL)hasCacheForSymbolAtIndex:(NSUInteger)index
{
    if (index >= _symbolCache.count) {
        return NO;
    }
    return _symbolCache[index] != [NSNull null];
}

- (MPFunctionLayout *)functionLayoutForFunctionAtIndex:(NSUInteger)index;
{
    if ([self hasCacheForSymbolAtIndex:index]) {
        return _symbolCache[index];
    }
     MPFunctionLayout *layout = [MPFunctionLayout functionLayoutForFunctionAtIndexPath:[self.expressionPath indexPathByAddingIndex:index] parent:self];
    while (index >= _symbolCache.count) {
        [_symbolCache addObject:[NSNull null]];
    }
    _symbolCache[index] = layout;
    return layout;
}

- (NSSize)cachedSizeForSymbolAtIndex:(NSUInteger)index
{
    id cachedSymbol = _symbolCache[index];
    if ([cachedSymbol isKindOfClass:[NSValue class]]) {
        return [cachedSymbol sizeValue];
    }
    return [(MPFunctionLayout *)cachedSymbol sizeOfFunction];
}

- (void)cacheSize:(NSSize)size forSymbolAtIndex:(NSUInteger)index
{
    while (index >= _symbolCache.count) {
        [_symbolCache addObject:[NSNull null]];
    }
    _symbolCache[index] = [NSValue valueWithSize:size];
}

#pragma mark Size Calculation Methods

- (NSSize)sizeForAllSymbols
{
    if (!_valid) {
        _cachedSize = [self sizeForSymbolsInRange:NSMakeRange(0, self.expression.numberOfSymbols)];
        _valid = YES;
    }
    return _cachedSize;
}

- (NSSize)sizeForSymbolsInRange:(NSRange)range
{
    NSSize size = NSMakeSize(0, 0);
    for (NSUInteger index = range.location; index < NSMaxRange(range); index++) {
        NSSize symbolSize = [self sizeForSymbolAtIndex:index];
        size.width += symbolSize.width;
        size.height = MAX(size.height, symbolSize.height);
    }
    return size;
}

- (NSSize)sizeForSymbolAtIndex:(NSUInteger)index
{
    if ([self hasCacheForSymbolAtIndex:index]) {
        return [self cachedSizeForSymbolAtIndex:index];
    }
    id symbol = [self.expression symbolAtIndex:index];
    if ([symbol isString]) {
        [self.textStorage setString:symbol];
        NSRange glyphRange = [self.layoutManager glyphRangeForTextContainer:self.textContainer];
        NSSize symbolSize = [self.layoutManager boundingRectForGlyphRange:glyphRange
                                                          inTextContainer:self.textContainer].size;
        [self cacheSize:symbolSize
       forSymbolAtIndex:index];

        return symbolSize;
    } else {
        MPFunctionLayout *layout = [self functionLayoutForFunctionAtIndex:index];
        return [layout sizeOfFunction];
    }
}

#pragma mark Drawing Methods

- (void)drawSymbolAtIndex:(NSUInteger)index
                  atPoint:(NSPoint)point
{
    id symbol = [self.expression symbolAtIndex:index];
    if ([symbol isString]) {
        [self.textStorage setString:symbol];
        NSRange glyphRange = [self.layoutManager glyphRangeForTextContainer:self.textContainer];
        [self.layoutManager drawGlyphsForGlyphRange:glyphRange
                                            atPoint:point];
    } else {
        MPFunctionLayout *layout = [self functionLayoutForFunctionAtIndex:index];
        [layout drawFunctionAtPoint:point];
    }
}

- (void)drawSymbolsInRange:(NSRange)range
                   atPoint:(NSPoint)point
{
    NSSize overallSize = [self sizeForSymbolsInRange:range];
    CGFloat x = point.x;
    for (NSUInteger index = range.location; index < NSMaxRange(range); index++) {
        NSSize symbolSize = [self sizeForSymbolAtIndex:index];
        CGFloat dy = (overallSize.height - symbolSize.height) / 2;
        [self drawSymbolAtIndex:index
                        atPoint:NSMakePoint(x, point.y + dy)];
        x += symbolSize.width;
    }
}

- (void)drawAllSymbolsAtPoint:(NSPoint)point
{
    [self drawSymbolsInRange:NSMakeRange(0, [self.expression numberOfSymbols]) atPoint:point];
}

@end