CGImage functions
CGImage functions
- Subject: CGImage functions
- From: "koen gogne" <email@hidden>
- Date: Tue, 15 Nov 2005 08:17:26 +0100
> Hi all,
>
> I'm trying to integrate the new core functionality available in 10.4 in our application.
> One of the functions I use now is CGImageSourceCreateThumbnailAtIndex.
> You'll find a code sample below.
>
> However I find it strange that I can't set a resolution in the thumbnail created.
> I can set kCGImageSourceThumbnailMaxPixelSize,
> and leaving out this setting will make the thumbnail the same size as the original.
> But the resulting thumbnail is always 72 dpi (screen resolution).
>
> Is there a way to set the resolution higher ?
> Is there another function available we can use for this purpose ?
>
> The idea being:
> we have an original image,
> for which we want to make previews at a given resolution.
>
> Kind regards,
> Koen Gogne
>
>
>
>
>
> ### CODE SAMPLE ###
> int main (int argc, const char *argv[])
> {
> NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init];
> NSLog([[NSString alloc] initWithFormat:@"Processing file '%s' to '%s' for thumbtype '%s'.",argv[1], argv[2], argv[3]]);
>
> NSString *inpath;
> NSString *outpath;
>
> inpath = [[[NSString alloc] initWithFormat:@"%s",argv[1]] stringByExpandingTildeInPath];
> NSURL * url = [NSURL fileURLWithPath:inpath];
> CGImageSourceRef source = CGImageSourceCreateWithURL((CFURLRef)url, NULL);
>
> if (source)
> {
> // image thumbnail options
> //NSDictionary* thumbOpts = [NSDictionary dictionaryWithObjectsAndKeys:
> // (id)kCFBooleanTrue, (id)kCGImageSourceCreateThumbnailWithTransform,
> // (id)kCFBooleanTrue, (id)kCGImageSourceCreateThumbnailFromImageIfAbsent,
> // [NSNumber numberWithInt:128], (id)kCGImageSourceThumbnailMaxPixelSize,
> // nil];
> NSDictionary* thumbOpts = [NSDictionary dictionaryWithObjectsAndKeys:
> (id)kCFBooleanTrue, (id)kCGImageSourceCreateThumbnailWithTransform,
> (id)kCFBooleanTrue, (id)kCGImageSourceCreateThumbnailFromImageIfAbsent,
> nil];
>
> CGImageRef image = CGImageSourceCreateThumbnailAtIndex(source, 0, (CFDictionaryRef)thumbOpts);
>
> outpath = [[[NSString alloc] initWithFormat:@"%s.jpg",argv[2]] stringByExpandingTildeInPath];
> NSURL * outurl = [NSURL fileURLWithPath: outpath];
> CGImageDestinationRef ref = CGImageDestinationCreateWithURL((CFURLRef)outurl, (CFStringRef)@"public.jpeg", 1, NULL);
>
> // add image to the ImageIO destination (specify the image we want to save)
> CGImageDestinationAddImage(ref, image, NULL);
>
> if (!CGImageDestinationFinalize(ref))
> {
> NSLog([[NSString alloc] initWithString:@"Error writing JPEG file\n"]);
> }
>
> CFRelease(ref);
> CGImageRelease(image);
> }
> else // couldn't make image source for image, so display nothing
> {
> NSLog([[NSString alloc] initWithString:@"Error reading source file\n"]);
> }
>
> [pool release];
> return 1;
> }
> ### CODE SAMPLE ###
>
>
>
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