First off, apologies if my terminology is all wrong, I'm only a couple of days
into exploring Quartz Composer.
I've created a simple composition which has a defined image output. In my Cocoa
project I've managed to display the image properly using a
QCQuartzCompositionLayer but ideally I'd like to be able to grab the image on
demand without rendering it to screen. I therefore started looking into
QCRenderer but am now struggling to get things working.
My initial attempt was as follows:
NSString* compName = @"ScreenImages";
NSString* compositionPath = [[NSBundle mainBundle] pathForResource:compName
ofType:@"qtz"];
@try
{
CGColorSpaceRef colorSpace =
CGColorSpaceCreateWithName(kCGColorSpaceGenericRGB);
QCRenderer *renderer = [[QCRenderer alloc] initWithComposition:composition
colorSpace:colorSpace];
[renderer renderAtTime:0.0 arguments:nil];
NSLog(@"%@", [renderer outputKeys]);
NSImage *image = [renderer valueForOutputKey:@"Screenshot"];
if (image) {
BOOL success = [[image
TIFFRepresentationUsingCompression:NSTIFFCompressionLZW factor:1.0]
writeToFile:@"/Users/Simon/Desktop/ImageTest.tiff" atomically:YES];
if(success == NO) {
NSLog(@"Failed");
}
}
[renderer release];
CGColorSpaceRelease(colorSpace);
}
@catch(id exception)
{
NSLog(@"Error running Quartz Composition '%s': %@", compName, exception);
}
This keels over when I try to create the renderer with:
Error running Quartz Composition '‡CÅpˇ': -[QCRenderer
initWithComposition:colorSpace:]: Inconsistent state
My second attempt is based on the code at http://developer.casgrain.com/?p=4.
This never managed to retrieve an NSImage from the composition:
CGImageRef resultImage = NULL;
NSString* compName = @"ScreenImages";
NSString* compositionPath = [[NSBundle mainBundle] pathForResource:compName
ofType:@"qtz"];
NSOpenGLPixelFormatAttribute attributes[] = {NSOpenGLPFAAccelerated,
NSOpenGLPFANoRecovery, (NSOpenGLPixelFormatAttribute)0};
NSOpenGLPixelFormat* format = [[NSOpenGLPixelFormat alloc]
initWithAttributes:attributes];
NSOpenGLContext* context = [[NSOpenGLContext alloc] initWithFormat:format
shareContext:nil];
@try
{
QCRenderer* renderer = [[QCRenderer alloc] initWithOpenGLContext:context
pixelFormat:format file:compositionPath];
[renderer renderAtTime:0.0 arguments:nil];
NSImage* image = [renderer valueForOutputKey:@"Screenshot"];
if (image) {
BOOL success = [[image
TIFFRepresentationUsingCompression:NSTIFFCompressionLZW factor:1.0]
writeToFile:@"/Users/Simon/Desktop/ImageTest.tiff" atomically:YES];
if(success == NO) {
NSLog(@"Failed");
}
}
[renderer release];
}
@catch(id exception)
{
NSLog(@"Error running Quartz Composition '%s': %@", compName, exception);
}
// Done, clean up
[context release];
[format release];
So, does anyone have any idea what I'm doing wrong or can anyone give me some
advice about retrieving an image from a composition in a QCRenderer.
Here's hoping and thanks for reading.
Simon Wolf _______________________________________________
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