CoreTextView.m

/*
     File: CoreTextView.m 
 Abstract: CoreTextView custom NSView subclass to draw text 
 in frames and illustrate CoreText usage. 
  Version: 1.1 
  
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 */
 
 
#import "CoreTextView.h"
 
#define COLUMN_COUNT_MIN 1
#define COLUMN_COUNT_MAX 3
 
 
@implementation CoreTextView
 
@synthesize attributedString = _attributedString;
 
- (id)initWithFrame:(NSRect)frame {
    self = [super initWithFrame:frame];
    if (self) {
        // Initialization code here.
        _columnCount = 1;
        _countIncrement = 1;
    }
    return self;
}
 
- (void)dealloc
{
    self.attributedString = nil;
    
    if(_framesetter != NULL)
        CFRelease(_framesetter);
    
    [super dealloc];
}
 
- (CFArrayRef)newColumns
{
    CGRect bounds = CGRectMake(0, 0, NSWidth([self bounds]), NSHeight([self bounds]));
    
    int column;
    CGRect* columnRects = (CGRect*)calloc(_columnCount, sizeof(*columnRects));
    
    // Start by setting the first column to cover the entire view.
    columnRects[0] = bounds;
    
    // Divide the columns equally across the frame's width.
    CGFloat columnWidth = CGRectGetWidth(bounds) / _columnCount;
    for (column = 0; column < _columnCount - 1; column++) {
        CGRectDivide(columnRects[column], &columnRects[column], &columnRects[column + 1], columnWidth, CGRectMinXEdge);
    }
    
    // Inset all columns by a few pixels of margin.
    for (column = 0; column < _columnCount; column++) {
        columnRects[column] = CGRectInset(columnRects[column], 10.0, 10.0);
    }
    
    CFMutableArrayRef array = CFArrayCreateMutable(kCFAllocatorDefault, _columnCount, &kCFTypeArrayCallBacks);
    for (column = 0; column < _columnCount; column++) {
        CGMutablePathRef path = CGPathCreateMutable();
        CGPathAddRect(path, NULL, columnRects[column]);
        
        CFArrayInsertValueAtIndex(array, column, path);
        CFRelease(path);
    }
    
    free(columnRects);
    
    return array;
}
 
- (void)drawRect:(NSRect)rect {
    // Draw a white background.
    [[NSColor whiteColor] set];
    [NSBezierPath fillRect:[self bounds]];
    
    // Initialize the text matrix to a known value
    CGContextRef context = (CGContextRef)[[NSGraphicsContext currentContext] graphicsPort];
    CGContextSetTextMatrix(context, CGAffineTransformIdentity);
    
    CTFramesetterRef framesetter = [self framesetter];
    CFArrayRef columnPaths = [self newColumns];
    
    CFIndex pathCount = CFArrayGetCount(columnPaths);
    CFIndex startIndex = 0;
    int column;
    for (column = 0; column < pathCount; column++) {
        CGPathRef path = (CGPathRef)CFArrayGetValueAtIndex(columnPaths, column);
        
        // Create a frame for this column and draw it.
        CTFrameRef frame = CTFramesetterCreateFrame(framesetter, CFRangeMake(startIndex, 0), path, NULL);
        CTFrameDraw(frame, context);
        
        // Start the next frame at the first character not visible in this frame.
        CFRange frameRange = CTFrameGetVisibleStringRange(frame);
        startIndex += frameRange.length;
        
        CFRelease(frame);
    }
    
    CFRelease(columnPaths);
}
 
- (void)mouseDown:(NSEvent *)theEvent {
    if (COLUMN_COUNT_MIN == COLUMN_COUNT_MAX) {
        return;
    }
    
    if (_columnCount == COLUMN_COUNT_MIN) {
        _countIncrement = 1;
    }
    else if (_columnCount == COLUMN_COUNT_MAX) {
        _countIncrement = -1;
    }
    
    _columnCount = _columnCount + _countIncrement;
    
    [self setNeedsDisplay:YES];
}
 
- (void)setAttributedString:(NSAttributedString *)attributedString
{
    [_attributedString release];
    _attributedString = [attributedString copy];
    
    if (attributedString)
        // Re-draw the view if the input string changes.
        [self setNeedsDisplay:YES];
}
 
- (CTFramesetterRef)framesetter {
    if (_framesetter == NULL) {
        _framesetter = CTFramesetterCreateWithAttributedString((CFAttributedStringRef)self.attributedString);
    }
    return _framesetter;
}
 
@end