Very quickly. Are you locking your contexts before rendering to them?
Both qc gl context and cgbitmaps? Webkit uses gl/core animation to
render things, so you may be drawing to or from the " wrong context"
sobriety speak. Try throwing some cgllockcontexts() around? No idea if
that's it though!
Sent from my iPhone
On Jan 17, 2010, at 2:21 PM, Adrian Ward
<[email protected]> wrote:
Hello all,
I'm trying to build a plugin that makes it possible to generate
images with attributed strings (ie. support for bold, italic, etc).
Ultimately I'd like this to be a drop-in replacement for Image With
String, but that could accept HTML markup, using a CSS stylesheet etc.
The technique I'm attempting is:
1. Allocate a bitmap buffer
2. Create a CGContextRef for it
3. Create an NSAttributedString with some suitable formatting
4. Render it into the CGContext using a CTFramesetter (as per
Apple's Core Text Programming Guide)
5. Make a QCPlugInOutputImageProvider using [qccontext
outputImageProviderFromBufferWithPixelFormat:...]
<Untitled Image.png>
As you can see, this technique seems to be working - albeit with
some weirdness, hacks and bugs - however, when I try implementing
step 3 like so:
NSData* htmldata = [self.inputString
dataUsingEncoding:NSUnicodeStringEncoding];
NSAttributedString* attrString = [[NSAttributedString alloc]
initWithHTML:htmldata baseURL:[qccontext compositionURL]
documentAttributes:nil];
This does work, but Quartz Composer's OpenGL view seems to become
corrupted, and subsequent drawing goes wildly wrong. Sprites with
width 1 suddenly and rapidly render at double their size, and the
corruption gets worse each frame, quickly causing QC to render
nonsense. There's no crashing, just garbage being rendered.
I know that initWithHTML:... causes WebKit to load internally, and
this probably requires all sorts of graphics state changes, and am
guessing that this is causing the problem. However, I'm not sure
what I should be looking at to get around the problem and would
appreciate some tips.
Solutions/workarounds I've tried:
- blindly experimenting with CGContextSaveGState, glLoadIdentity,
etc in attempts to avoid corrupt graphics states (makes no difference)
- using NSAttributedString's initWithPath:@"/test.html" instead
(same problem)
- using NSAttributedString's initWithPath:@"/test.docx" instead
(works perfectly! ...but isn't what I want to achieve)
- manually building my NSAttributedString instead of using
initWithHTML: (problem goes away, but I lose the convenience of
HTML, CSS etc)
Would anyone with a bit more experience be able to make some kind
suggestions?
Thanks and all the best,
Ade.
- (BOOL) execute:(id<QCPlugInContext>)qccontext atTime:
(NSTimeInterval)time withArguments:(NSDictionary*)arguments
{
// CGLContextObj ctl_ctx = [qccontext CGLContextObj];
// Make the backing buffer
NSUInteger width = self.inputWidth;
NSUInteger height = self.inputHeight;
NSUInteger bytesPerRow = width * 4; // FIXME: This must be modulo
16 - what if width isn't a nice number?
char* buffer = valloc(height * bytesPerRow); // FIXME: What if the
memory wasn't allocated?
// Clear the buffer
memset(buffer, 0, height * bytesPerRow);
// Make a CGContextRef around it FIXME: What if we're running on a
non-Intel platform, where the format wouldn't be ARGB but BGRA?
CGColorSpaceRef cgcolorspace = CGColorSpaceCreateDeviceRGB();
CGContextRef cgcontext = CGBitmapContextCreate(buffer, width,
height, 8, bytesPerRow, cgcolorspace,
kCGImageAlphaPremultipliedFirst); // FIXME: What if the CGContextRef
wasn't created?
// Create attributed string FIXME: This corrupts QC's graphics
state???
NSData* htmldata = [self.inputString
dataUsingEncoding:NSUnicodeStringEncoding];
NSAttributedString* attrString = [[NSAttributedString alloc]
initWithHTML:htmldata baseURL:[qccontext compositionURL]
documentAttributes:nil]; // FIXME: What if attrString wasn't created?
// Draw a string using a typesetter
// Initialize a rectangular path.
CGMutablePathRef path = CGPathCreateMutable();
CGRect bounds = CGRectMake(0, 0, width, height);
CGPathAddRect(path, NULL, bounds);
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Quartzcomposer-dev mailing list ([email protected]
)
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/quartzcomposer-dev/doktorp%40mac.com
This email sent to [email protected]
_______________________________________________
Do not post admin requests to the list. They will be ignored.
Quartzcomposer-dev mailing list ([email protected])
Help/Unsubscribe/Update your Subscription:
http://lists.apple.com/mailman/options/quartzcomposer-dev/archive%40mail-archive.com
This email sent to [email protected]
