On 24 Sep 2012, at 12:49, jonat...@mugginsoft.com wrote:
>
> On 23 Sep 2012, at 17:33, Kyle Sluder <k...@ksluder.com> wrote:
>>
>> Attributes are specified on a character, rather than glyph, basis. So if
>> you need to draw your characters with a separate color, you should
>> probably override
>> -showCGGlyphs:positions:count:font:matrix:attributes:inContext: to push
>> and pop the foreground color you want before calling super. Should be a
>> really simple override, because the context is already set up for you.
>>
>>
> It turns out that customising NSGlyphGenerator is not necessary as the
> subclass merely calls its delegate, which is the layout manager.
> So an override on NSLayoutManager of -
> insertGlyphs:length:forStartingGlyphAtIndex:characterIndex: is appropriate.
> I cache my substitute glyphs and swap them in as required (a secondary layout
> manager generates the substitute glyphs).
>
> However there are issues.
>
> Colourisation in -
> showCGGlyphs:positions:count:font:matrix:attributes:inContext:
> will necessitate colouring by glyph value. So if a period is used to
> highlight a space then all periods in the text get highlighted regardless.
>
> Secondly, swapping out the tab glyph for another seems to break the tab
> functionality in the NSTextView.
>
> Also, new line and carriage return glyph substitution doesn't seem to work.
> The substitute glyph is not drawn.
> Perhaps its omitted as part of the fragment processing.
>
> I imagine that the second issue is related to the type setter, though that's
> just a guess.
>
I took another look at NSLayoutManager - drawGlyphsForGlyphRange:atPoint: and
decided to try dropping down to CoreText.
NSString -drawAtPoint:withAttributes: seemed to be the source of trouble and
was very inefficient.
I created and cached a CTLineRef for each of my substitute characters thus:
attrString = [[NSAttributedString alloc] initWithString:newLineCharacter
attributes:defAttributes];
textLine =
CFMakeCollectable(CTLineCreateWithAttributedString((CFAttributedStringRef)attrString));
[lineRefs addObject:(id)textLine];
I then used CTLineDraw to draw the required line on demand.
The vertical alignment of the extra glyphs seems fine with this approach.
- (void)drawGlyphsForGlyphRange:(NSRange)glyphRange
atPoint:(NSPoint)containerOrigin
{
if (showInvisibleCharacters ) {
NSPoint pointToDrawAt;
NSRect glyphFragment;
NSString *completeString = [[self textStorage] string];
NSInteger lengthToRedraw = NSMaxRange(glyphRange);
void *gcContext = [[NSGraphicsContext currentContext] graphicsPort];
// if our context is flipped then we need to flip our drawn text too
CGAffineTransform t = {1.0, 0.0, 0.0, -1.0, 0.0, 0.0};
if (![[NSGraphicsContext currentContext] isFlipped]) {
t = CGAffineTransformIdentity;
}
CGContextSetTextMatrix (gcContext, t);
// we may not have any glyphs generated at this stage
for (NSInteger idx = glyphRange.location; idx < lengthToRedraw;
idx++) {
unichar characterToCheck = [completeString
characterAtIndex:idx];
NSUInteger lineRefIndex = 0;
if (characterToCheck == '\t') {
lineRefIndex = 0;
} else if (characterToCheck == ' ') {
lineRefIndex = 1;
} else if (characterToCheck == '\n' || characterToCheck
== '\r') {
lineRefIndex = 2;
} else {
continue;
}
pointToDrawAt = [self locationForGlyphAtIndex:idx];
glyphFragment = [self lineFragmentRectForGlyphAtIndex:idx
effectiveRange:NULL];
pointToDrawAt.x += glyphFragment.origin.x;
pointToDrawAt.y += glyphFragment.origin.y;
// get our text line object
CTLineRef line = (CTLineRef)[lineRefs objectAtIndex:lineRefIndex];
CGContextSetTextPosition(gcContext, pointToDrawAt.x,
pointToDrawAt.y);
CTLineDraw(line, gcContext);
}
}
// the following causes glyph generation to occur if required
[super drawGlyphsForGlyphRange:glyphRange atPoint:containerOrigin];
}
Regards
Jonathan Mitchell
Mugginsoft LLP
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