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Only add leading between lines if no absolute line-height set.
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Some first line tricks trying to get closer to how CoreText does it.
Code reindented.
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@odrobnik
odrobnik committed Mar 12, 2012
1 parent 533d5ea commit ab02916
Showing 1 changed file with 49 additions and 66 deletions.
115 changes: 49 additions & 66 deletions Core/Source/DTCoreTextLayoutFrame.m
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Expand Up @@ -8,20 +8,6 @@

#import "DTCoreText.h"
#import "DTCoreTextLayoutFrame.h"
//#import "DTCoreTextConstants.h"
//
//#import "DTCoreTextLayoutFrame.h"
//#import "DTCoreTextLayouter.h"
//#import "DTCoreTextLayoutLine.h"
//#import "DTCoreTextGlyphRun.h"
//
//#import "DTTextAttachment.h"
//#import "UIDevice+DTVersion.h"
//
//#import "NSString+Paragraphs.h"
//#import "DTColor+HTML.h"
//#import "DTImage+HTML.h"


// global flag that shows debug frames
static BOOL _DTCoreTextLayoutFramesShouldDrawDebugFrames = NO;
Expand Down Expand Up @@ -108,7 +94,7 @@ - (void)dealloc
{
CFRelease(_textFrame);
}

if (_framesetter)
{
CFRelease(_framesetter);
Expand All @@ -128,7 +114,7 @@ - (void)_buildLinesWithTypesetter
{
// framesetter keeps internal reference, no need to retain
CTTypesetterRef typesetter = CTFramesetterGetTypesetter(_framesetter);

NSMutableArray *typesetLines = [NSMutableArray array];

CGPoint lineOrigin = _frame.origin;
Expand All @@ -137,7 +123,7 @@ - (void)_buildLinesWithTypesetter

// need the paragraph ranges to know if a line is at the beginning of paragraph
NSMutableArray *paragraphRanges = [[self paragraphRanges] mutableCopy];

NSRange currentParagraphRange = [[paragraphRanges objectAtIndex:0] rangeValue];

// we start out in the requested range, length will be set by the suggested line break function
Expand All @@ -156,15 +142,15 @@ - (void)_buildLinesWithTypesetter
CGFloat leading;
CGFloat trailingWhitespaceWidth;
} lineMetrics;

typedef struct
{
CGFloat paragraphSpacing;
} paragraphMetrics;

paragraphMetrics currentParaMetrics = {0};
paragraphMetrics previousParaMetrics = {0};

lineMetrics currentLineMetrics;
lineMetrics previousLineMetrics;

Expand All @@ -187,7 +173,7 @@ - (void)_buildLinesWithTypesetter

// get the paragraph style at this index
CTParagraphStyleRef paragraphStyle = (__bridge CTParagraphStyleRef)[_attributedStringFragment attribute:(id)kCTParagraphStyleAttributeName atIndex:lineRange.location effectiveRange:NULL];

currentTextBlock = [[_attributedStringFragment attribute:DTTextBlocksAttribute atIndex:lineRange.location effectiveRange:NULL] lastObject];

if (previousTextBlock != currentTextBlock)
Expand Down Expand Up @@ -231,7 +217,7 @@ - (void)_buildLinesWithTypesetter
// at end of paragraph, record the spacing
CTParagraphStyleGetValueForSpecifier(paragraphStyle, kCTParagraphStyleSpecifierParagraphSpacing, sizeof(currentParaMetrics.paragraphSpacing), &currentParaMetrics.paragraphSpacing);
}

// create a line to fit
CTLineRef line = CTTypesetterCreateLine(typesetter, CFRangeMake(lineRange.location, lineRange.length));

Expand Down Expand Up @@ -276,35 +262,36 @@ - (void)_buildLinesWithTypesetter
lineHeight = maxLineHeight;
}
}

// get the correct baseline origin
if (previousLine)
{
if (lineHeight==0)
{
lineHeight = previousLineMetrics.descent + currentLineMetrics.ascent;
lineHeight = previousLineMetrics.descent + currentLineMetrics.ascent + currentLineMetrics.leading;
}

if (isAtBeginOfParagraph)
{
lineHeight += previousParaMetrics.paragraphSpacing;
}

lineHeight += currentLineMetrics.leading;
}
else
{
/*
NOTE: CoreText does weird tricks for the first lines of a layout frame
I don't know why, but somehow it is always shifting the first line slightly higher.
These values seem to work ok.
*/

if (lineHeight>0)
{
if (lineHeight<currentLineMetrics.ascent)
{
// special case, we fake it to look like CoreText
lineHeight -= currentLineMetrics.descent;
}
lineHeight -= currentLineMetrics.descent;
}
else
{
lineHeight = currentLineMetrics.ascent + currentLineMetrics.leading;
lineHeight = currentLineMetrics.ascent + currentLineMetrics.leading - currentLineMetrics.descent/2.0f;
}
}

Expand Down Expand Up @@ -344,7 +331,7 @@ - (void)_buildLinesWithTypesetter
case kCTRightTextAlignment:
{
lineOrigin.x = _frame.origin.x + offset + CTLineGetPenOffsetForFlush(line, 1.0, availableSpace);

break;
}

Expand All @@ -371,7 +358,7 @@ - (void)_buildLinesWithTypesetter
break;
}
}

CGFloat lineBottom = lineOrigin.y + currentLineMetrics.descent;

// abort layout if we left the configured frame
Expand All @@ -380,19 +367,19 @@ - (void)_buildLinesWithTypesetter
// doesn't fit any more
break;
}

// wrap it
DTCoreTextLayoutLine *newLine = [[DTCoreTextLayoutLine alloc] initWithLine:line];
CFRelease(line);

// baseline origin is rounded
lineOrigin.y = roundf(lineOrigin.y);
lineOrigin.y = ceilf(lineOrigin.y);

newLine.baselineOrigin = lineOrigin;

[typesetLines addObject:newLine];
fittingLength += lineRange.length;

lineRange.location += lineRange.length;

previousLine = newLine;
Expand Down Expand Up @@ -459,14 +446,12 @@ - (void)_buildLinesWithStandardFramesetter

[tmpLines addObject:newLine];

NSLog(@"%@ - %f %f %f", newLine, newLine.ascent, newLine.descent, newLine.leading);

lineIndex++;
}
free(origins);

_lines = tmpLines;

// need to get the visible range here
CFRange fittingRange = CTFrameGetStringRange(_textFrame);
_stringRange.location = fittingRange.location;
Expand Down Expand Up @@ -500,7 +485,7 @@ - (void)_buildLines
{
return;
}

// note: building line by line with typesetter
[self _buildLinesWithTypesetter];

Expand All @@ -525,11 +510,11 @@ - (NSArray *)linesVisibleInRect:(CGRect)rect

for (DTCoreTextLayoutLine *oneLine in self.lines)
{
CGRect lineFrame = oneLine.frame;
// CGRectIntersectsRect returns false if the frame has 0 width, which
// lines that consist only of line-breaks have. Set the min-width
// to one to work-around.
lineFrame.size.width = lineFrame.size.width>1?lineFrame.size.width:1;
CGRect lineFrame = oneLine.frame;
// CGRectIntersectsRect returns false if the frame has 0 width, which
// lines that consist only of line-breaks have. Set the min-width
// to one to work-around.
lineFrame.size.width = lineFrame.size.width>1?lineFrame.size.width:1;
if (CGRectIntersectsRect(rect, lineFrame))
{
[tmpArray addObject:oneLine];
Expand Down Expand Up @@ -660,7 +645,7 @@ - (void)drawInContext:(CGContextRef)context drawImages:(BOOL)drawImages
CGFloat dashes[] = {10.0, 2.0};
CGContextSetLineDash(context, 0, dashes, 2);
CGContextStrokeRect(context, self.frame);

// draw center line
CGContextMoveToPoint(context, CGRectGetMidX(self.frame), self.frame.origin.y);
CGContextAddLineToPoint(context, CGRectGetMidX(self.frame), CGRectGetMaxY(self.frame));
Expand All @@ -679,13 +664,13 @@ - (void)drawInContext:(CGContextRef)context drawImages:(BOOL)drawImages
// text block handling
if (_textBlockHandler)
{
// DTCoreTextLayoutLine *firstLine = [visibleLines objectAtIndex:0];
// DTCoreTextLayoutLine *lastLine = [visibleLines lastObject];
//
// // find visible range
// NSUInteger startIndex = firstLine.stringRange.location;
// NSUInteger endIndex = NSMaxRange(lastLine.stringRange);
// NSRange visibleRange = NSMakeRange(startIndex, endIndex - startIndex);
// DTCoreTextLayoutLine *firstLine = [visibleLines objectAtIndex:0];
// DTCoreTextLayoutLine *lastLine = [visibleLines lastObject];
//
// // find visible range
// NSUInteger startIndex = firstLine.stringRange.location;
// NSUInteger endIndex = NSMaxRange(lastLine.stringRange);
// NSRange visibleRange = NSMakeRange(startIndex, endIndex - startIndex);

__block NSMutableSet *handledBlocks = [NSMutableSet set];

Expand All @@ -702,7 +687,7 @@ - (void)drawInContext:(CGContextRef)context drawImages:(BOOL)drawImages
BOOL shouldDrawStandardBackground = YES;
if (_textBlockHandler)
{
_textBlockHandler(oneBlock, frame, context, &shouldDrawStandardBackground);
_textBlockHandler(oneBlock, frame, context, &shouldDrawStandardBackground);
}

// draw standard background if necessary
Expand Down Expand Up @@ -979,7 +964,7 @@ - (NSArray *)textAttachments

_textAttachments = [[NSArray alloc] initWithArray:tmpAttachments];
}


return _textAttachments;
}
Expand Down Expand Up @@ -1144,9 +1129,9 @@ - (CGPoint)baselineOriginToPositionLine:(DTCoreTextLayoutLine *)line afterLine:(
NSInteger lineStartIndex = line.stringRange.location;

CTParagraphStyleRef lineParagraphStyle = (__bridge CTParagraphStyleRef)[_attributedStringFragment
attribute:(id)kCTParagraphStyleAttributeName
atIndex:lineStartIndex effectiveRange:NULL];

attribute:(id)kCTParagraphStyleAttributeName
atIndex:lineStartIndex effectiveRange:NULL];
// get line height in px if it is specified for this line
CGFloat lineHeight = 0;
CGFloat minLineHeight = 0;
Expand Down Expand Up @@ -1188,19 +1173,19 @@ - (CGPoint)baselineOriginToPositionLine:(DTCoreTextLayoutLine *)line afterLine:(
}
}

// get the correct baseline origin
// is absolute line height set?
if (lineHeight==0)
{
lineHeight = previousLine.descent + line.ascent;
lineHeight = previousLine.descent + line.ascent + usedLeading;
}

if ([self isLineLastInParagraph:previousLine])
{
// need to get paragraph spacing
CTParagraphStyleRef previousLineParagraphStyle = (__bridge CTParagraphStyleRef)[_attributedStringFragment
attribute:(id)kCTParagraphStyleAttributeName
atIndex:previousLine.stringRange.location effectiveRange:NULL];

attribute:(id)kCTParagraphStyleAttributeName
atIndex:previousLine.stringRange.location effectiveRange:NULL];
CGFloat paraSpacing;

if (CTParagraphStyleGetValueForSpecifier(previousLineParagraphStyle, kCTParagraphStyleSpecifierParagraphSpacing, sizeof(paraSpacing), &paraSpacing))
Expand All @@ -1210,15 +1195,13 @@ - (CGPoint)baselineOriginToPositionLine:(DTCoreTextLayoutLine *)line afterLine:(

}

lineHeight += usedLeading;

lineOrigin.y += lineHeight;

// preserve own baseline x
lineOrigin.x = line.baselineOrigin.x;

// origins are rounded
lineOrigin.y = roundf(lineOrigin.y);
lineOrigin.y = ceilf(lineOrigin.y);

return lineOrigin;
}
Expand Down

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