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Re: Drawing Core Image into a PDF Context

Subject: Re: Drawing Core Image into a PDF Context
From: Scott Thompson <email@hidden>
Date: Tue, 21 Jun 2005 20:39:42 -0700
Delivered-to: email@hidden
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On Jun 20, 2005, at 11:21 AM, John Harper wrote:
On Jun 18, 2005, at 1:13 AM, Scott Thompson wrote:
Upon trying to draw a CIImage into a PDF context, I was surprised to see that area of the context show up completely black.

Is it the case that you can only render a CIImage into a pixel- based context?

No, it should work with any context, what kind of CIImage are you using?

John

OK... I put my code that tries to draw a CIImage into a PDF context back together again and I'm getting the same result. The resulting PDF is black where the image is supposed to be. The same CIImage drawn to a window works just fine.

I'll put my code in below.

The original application was a carbon application using Core Image (that's why there's an explicit autorelease pool for example.

There's really nothing remarkable (that I know of) about the Beach image. It's just a picture that I took with my digital camera and exported at 640x480. If I adjust the application so that it draws in a Carbon window (inside of an HIView's kEventControlDraw handler into the context passed to me by the OS), the same DrawBlurredImage routine draws a blurry version of my image.

If you have any thoughts about why I can't dump the image into a PDF context. Please let me know.

I'll also put together a bug report and sample app.

Scott

--- begin included code ---

CGImageRef CreateSourceImage() { CFURLRef sourceImageURL = CFBundleCopyResourceURL (CFBundleGetMainBundle(), CFSTR("Beach"), CFSTR("jpg"), NULL); CGImageSourceRef imageSource = CGImageSourceCreateWithURL (sourceImageURL, 0); CFRelease(sourceImageURL); sourceImageURL = NULL;

CGImageRef sourceCGImage = CGImageSourceCreateImageAtIndex (imageSource,0,0); CFRelease(imageSource); imageSource = NULL;

    return sourceCGImage;
}

void DrawBlurredImage(CGContextRef outputContext, const CGRect &viewBounds) { // Create an autorelease pool to catch stray objects NSAutoreleasePool *autoreleasePool = [[NSAutoreleasePool alloc] init];

// Obtain the source image and create a CIImage with that set of pixels CGImageRef sourceCGImage = CreateSourceImage(); CIImage *sourceCIImage = [CIImage imageWithCGImage: sourceCGImage];

CGRect sourceBounds = CGRectMake(0, 0, CGImageGetWidth (sourceCGImage), CGImageGetHeight(sourceCGImage));

    // We've done with the source image.
    CFRelease(sourceCGImage);
    sourceCGImage = NULL;

// Create a filter and assign the parameters CIFilter *gaussianBlur = [CIFilter filterWithName: @"CIGaussianBlur"]; [gaussianBlur setDefaults];

[gaussianBlur setValue: sourceCIImage forKey: @"inputImage"]; [gaussianBlur setValue: [NSNumber numberWithFloat: 10] forKey: @"inputRadius"];

    // extract the resulting CIImage from the blur filter.
    CIImage *result = [gaussianBlur valueForKey: @"outputImage"];

// Create a CIContext on our graphics context and render the image into it. CIContext *outputCIContext = [CIContext contextWithCGContext: outputContext options: NULL]; [outputCIContext drawImage: result inRect: viewBounds fromRect: sourceBounds];

    // release the autorelase pool
    [autoreleasePool release];
    autoreleasePool = NULL;
}

void DrawPDFVersion() { CGRect mediaRect = CGRectMake(0, 0, 640, 480); CFURLRef destinationURL = CFURLCreateWithFileSystemPath(NULL, CFSTR("/Users/scott/Desktop/BlurredBeach.pdf"), kCFURLPOSIXPathStyle, false);

CGContextRef outputContext = CGPDFContextCreateWithURL ( destinationURL, &mediaRect, NULL); CGContextBeginPage(outputContext, &mediaRect);

    DrawBlurredImage(outputContext, mediaRect);

    CGContextEndPage(outputContext);
    CFRelease(outputContext);
    CFRelease(destinationURL);
}

int main(int argc, char* argv[])
{

    DrawPDFVersion();


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Follow-Ups:
- Re: Drawing Core Image into a PDF Context
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References:
	>Drawing Core Image into a PDF Context (From: Scott Thompson <email@hidden>)
	>Re: Drawing Core Image into a PDF Context (From: John Harper <email@hidden>)
	>Re: Drawing Core Image into a PDF Context (From: Scott Thompson <email@hidden>)

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