CODEWITHSUNDEEP
objective-cipadios5core-graphicscore-image
DZenBot
DZenBot

Reputation: 4878

Core Graphics effect: works on simulator but not in device

I have done a simple but effective emboss effect with Core Graphics. It works great! But only in simulator... Here is the result:

1st image

What I do is the following: - From a picked image, I take the alpha out if it has and I fill it with white. - I transform this RGB image to Grayscale - I invert colors of this image

I then call a custom method to create the effect with parameters:

2nd image

The method then makes a simple mask, applies shadows and oppacity and returns a brand new UIImage. I can't understand why in the simulator it does work, nor the device. While running in the device, I get a non-null UIImage tho... Please help!

Here is the code:

- (UIImage *)stampImage:(UIImage *)canvasImg withMask:(UIImage *)maskImg withOpacity:(CGFloat)opacity
{
//Creating the mask Image
CGContextRef mainViewContentContext;
CGColorSpaceRef colorSpace;
colorSpace = CGColorSpaceCreateDeviceRGB();
mainViewContentContext = CGBitmapContextCreate(NULL, maskImg.size.width, maskImg.size.height, 8, 0, colorSpace, kCGImageAlphaPremultipliedLast);
CGColorSpaceRelease(colorSpace);

if (mainViewContentContext == NULL) return NULL;

CGContextClipToMask(mainViewContentContext, CGRectMake(0, 0, maskImg.size.width, maskImg.size.height), maskImg.CGImage);
CGContextDrawImage(mainViewContentContext, CGRectMake(0, 0, maskImg.size.width, maskImg.size.height), canvasImg.CGImage);
CGContextSetAllowsAntialiasing(mainViewContentContext, true);
CGContextSetShouldAntialias(mainViewContentContext, true);
CGImageRef mainViewContentBitmapContext = CGBitmapContextCreateImage(mainViewContentContext);
CGContextRelease(mainViewContentContext);
UIImage *maskedImage = [UIImage imageWithCGImage:mainViewContentBitmapContext];
CGImageRelease(mainViewContentBitmapContext);

//Giving some Drop shadows
CGColorSpaceRef colourSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef shadowContext = CGBitmapContextCreate(NULL, maskedImage.size.width + 10, maskedImage.size.height + 10,
                                                   CGImageGetBitsPerComponent(maskedImage.CGImage), 0, 
                                                   colourSpace, kCGImageAlphaPremultipliedLast);
CGColorSpaceRelease(colourSpace);
CGContextSetShadowWithColor(shadowContext, CGSizeMake(0, -1), 1, [UIColor colorWithWhite:1.0 alpha:0.3].CGColor);
CGContextSetAllowsAntialiasing(shadowContext, true);
CGContextSetShouldAntialias(shadowContext, true);
CGContextDrawImage(shadowContext, CGRectMake(0, 10, maskedImage.size.width, maskedImage.size.height), maskedImage.CGImage);
CGImageRef shadowedCGImage = CGBitmapContextCreateImage(shadowContext);
CGContextRelease(shadowContext);

UIImage *stampImg = [UIImage imageWithCGImage:shadowedCGImage];
CGImageRelease(shadowedCGImage);

return stampImg;

}

Upvotes: 0

Views: 659

Answers (1)

jstevenco
jstevenco

Reputation: 2953

Also be aware of the memory limitations of the device vs the simulator. I've had CG logic that would build and run fine on the simulator; the same logic will build and run emitting no errors on the device, but the visual result is not the desired one. I'd suggest trying your logic on a considerably smaller image to verify that it works on the device. I had to abandon some very cool image masking stuff that I'd come up with because the device didn't have the horsepower to pull it off for larger images.

Upvotes: 1

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