HI
I'm trying to use NSImage's CGImageForProposedRect method to scale an image but
it's not doing it. I gat back an image the same size as the original. I've
double-checked all my math and that seems to be right. Here's how it's being
used anyone see where I'm going wrong?
- (BOOL) createThumbnail:(NSString *) inSource
maxDimension:(int) inMax
saveTo:(NSString *) inDest
{
NSImage *img = [[NSImage alloc] initWithContentsOfFile: inSource];
BOOL result = NO;
//NSLog(@"img: %@", img);
if (img != nil)
{
float width = [img size].width,
height = [img size].height,
scaledWidth = (width < height) ? inMax * (width /
height) : inMax ,
scaledHeight = (width < height) ? inMax : inMax *
(height / width);
// tried both with and without next two lines, no difference in
output size
[img setScalesWhenResized: YES];
[img setSize: NSMakeSize(scaledWidth, scaledHeight)];
NSRect scaledRect = NSMakeRect(0, 0, scaledWidth,
scaledHeight);
//NSLog(@"scaledRect: %@", [NSValue valueWithRect: scaledRect]);
// Ultimately I want to write the scaled image to a file.
Should I set a context here? If so, which one and how?
CGImageRef imgRef = [img CGImageForProposedRect:
&scaledRect
context: NULL
hints: NULL];
if (imgRef != NULL)
{
NSURL *destURL = [NSURL fileURLWithPath:
inDest];
NSDictionary *options = [NSDictionary
dictionaryWithObjectsAndKeys:
[NSNumber numberWithInt: 72], kCGImagePropertyDPIHeight,
[NSNumber numberWithInt: 72], kCGImagePropertyDPIWidth,
nil];
CGImageDestinationRef destRef =
CGImageDestinationCreateWithURL((CFURLRef) destURL,
kUTTypeJPEG, 1, NULL);
if (destRef != NULL)
{
// create the image
CGImageDestinationAddImage(destRef, imgRef,
(CFDictionaryRef) options);
CGImageDestinationFinalize(destRef);
CFRelease(destRef);
if ([[NSFileManager defaultManager]
fileExistsAtPath: inDest])
result = YES;
}
else
NSLog(@"Error: Failed to create image
destination for: %@", inSource);
CFRelease(imgRef);
}
else
NSLog(@"Error: Failed to create image ref for: %@",
inSource);
[img release];
}
else
NSLog(@"Error: Failed to load image: %@", inSource);
return result;
}
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