问题
I am basically creating a custom attribute to draw a rounded rectangle in my text subclassing NSLayoutManager with drawGlyphsForGlyphRange method below. Below works like a charm with ranges that spans one line. However, when the range of text spans in two lines, I am getting a big rectangle which draws the attribute along those two lines. I think I should be using a different approach here, I tried nsbackgroundattribute to draw the highlight but unfortunately I cannot make the highlight rounded rect using that.
I would appreciate any directions.
-(void)drawGlyphsForGlyphRange:(NSRange)glyphsToShow atPoint:(CGPoint)origin {
NSTextStorage *textStorage = self.textStorage;
NSRange glyphRange = glyphsToShow;
while (glyphRange.length > 0) {
NSRange charRange = [self characterRangeForGlyphRange:glyphRange actualGlyphRange:NULL], attributeCharRange, attributeGlyphRange;
id attribute = [textStorage attribute:IKSpecialHighlightAttributeName atIndex:charRange.location longestEffectiveRange:&attributeCharRange inRange:charRange];
attributeGlyphRange = [self glyphRangeForCharacterRange:attributeCharRange actualCharacterRange:NULL];
attributeGlyphRange = NSIntersectionRange(attributeGlyphRange, glyphRange);
if( attribute != nil ) {
NSTextContainer *textContainer = self.textContainers[0];
CGRect boundingRect = [self boundingRectForGlyphRange:attributeGlyphRange inTextContainer:textContainer];
[[UIColor colorWithRed:221.0/255.0 green:255.0/255.0 blue:0.0/255.0 alpha:1] setFill]; // set rounded rect's bg color
boundingRect.origin.x += origin.x-3.0;
boundingRect.origin.y += origin.y+3.0;
boundingRect.size.width += 6.0;
UIBezierPath *roundedRect = [UIBezierPath bezierPathWithRoundedRect:boundingRect cornerRadius: 3.0];
[roundedRect fillWithBlendMode: kCGBlendModeNormal alpha:1.0f];
[super drawGlyphsForGlyphRange:attributeGlyphRange atPoint:origin];
}
else {
[super drawGlyphsForGlyphRange:glyphsToShow atPoint:origin];
}
glyphRange.length = NSMaxRange(glyphRange) - NSMaxRange(attributeGlyphRange);
glyphRange.location = NSMaxRange(attributeGlyphRange);
}
}
来源:https://stackoverflow.com/questions/20689475/textkit-custom-text-attribute-draws-big-rect-when-it-spans-multiple-lines