I have a function:
- (UIImage *) resizeImage:(UIImage *)image width:(CGFloat)resizedWidth height:(CGFloat)resizedHeight shouldCrop:(BOOL)crop
{
CGImageRef imageRef = [image CGImage];
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef bitmap = CGBitmapContextCreate(NULL, resizedWidth, resizedHeight, 8, 4 * resizedWidth, colorSpace, (CGBitmapInfo) kCGImageAlphaPremultipliedFirst);
CGContextDrawImage(bitmap, CGRectMake(0, 0, resizedWidth, resizedHeight), imageRef);
CGImageRef ref = CGBitmapContextCreateImage(bitmap);
if (crop) // for SmallImage (tableviewcell)
{
CGRect cropRect = CGRectMake(0, CGImageGetHeight(ref) * 0.5 - ((float) kIvHeight * 0.5), (float) kIvWidth, (float) kIvHeight);
ref = CGImageCreateWithImageInRect(ref, cropRect);
}
UIImage * result = [UIImage imageWithCGImage:ref];
CGContextRelease(bitmap);
CGImageRelease(ref);
CGImageRelease(imageRef);
return result;
}
The line CGImageRelease(imageRef); causes my app to crash with EXC_BAD_ACCESS
it seems to work when I remove the line - but would this not cause memory leaks?
You don't own the CGImageRef imageRef because you obtain it using [image CGImage] so you don't need to release it.
Take a look at this one as well: How do I release a CGImageRef in iOS
Related
I'm writing this Today Widget, that needs to display an image.
I noticed, that every time the Widget loads, the image is redrawn. This takes about half a second.
After some investigation, I found out, that the culprit is, that the image file is in the Indexed color space.
So: my question is:
How do I convert this file to something that the iPhone can display more efficiently? For instance, an RGB file. I would then save it to a new file, and load that new file in my UIImageView.
I played around a bit with CGImage, since I believe that is the solution direction, but I end up with a white UIImageView.
This is my code:
UIImage * theCartoon = [UIImage imageWithData:imageData];
CGImageRef si = [theCartoon CGImage];
CGDataProviderRef src = CGImageGetDataProvider(si);
CGImageRef imageRef = CGImageCreateWithPNGDataProvider(src, NULL, NO, kCGRenderingIntentDefault);
cartoon.image = [[UIImage alloc] initWithCGImage:imageRef];
Any suggestions on this approach? Some obvious misprogramming?
Try this
// The source image
CGImageRef image = theCartoon.CGImage;
CGSize size = CGSizeMake(CGImageGetWidth(image), CGImageGetHeight(image));
// The result image in RGB color space
CGImageRef result = nil;
// Check color space
CGColorSpaceRef srcColorSpace = CGImageGetColorSpace(image);
if (CGColorSpaceGetModel(srcColorSpace) != kCGColorSpaceModelRGB) {
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(nil, size.width, size.height, 8, 0, colorSpace, kCGImageAlphaNoneSkipLast);
CGRect rect = {CGPointZero, size};
CGContextDrawImage(context, rect, image);
result = CGBitmapContextCreateImage(context);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
}
It's been a while since the question was asked, but for others who might need this, here is my solution:
-(UIImage *) convertIndexedColorSpaceToRGB:(UIImage *) sourceImage {
CGImageRef originalImageRef = sourceImage.CGImage;
const CGBitmapInfo originalBitmapInfo = CGImageGetBitmapInfo(originalImageRef);
// See: http://stackoverflow.com/questions/23723564/which-cgimagealphainfo-should-we-use
const uint32_t alphaInfo = (originalBitmapInfo & kCGBitmapAlphaInfoMask);
CGBitmapInfo bitmapInfo = originalBitmapInfo;
switch (alphaInfo)
{
case kCGImageAlphaNone:
bitmapInfo |= kCGBitmapByteOrder32Big | kCGImageAlphaNoneSkipLast;
break;
case kCGImageAlphaPremultipliedFirst:
case kCGImageAlphaPremultipliedLast:
case kCGImageAlphaNoneSkipFirst:
case kCGImageAlphaNoneSkipLast:
break;
case kCGImageAlphaOnly:
case kCGImageAlphaLast:
case kCGImageAlphaFirst:
{
return sourceImage;
}
break;
}
const CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
const CGSize pixelSize = CGSizeMake(sourceImage.size.width * sourceImage.scale, sourceImage.size.height * sourceImage.scale);
const CGContextRef context = CGBitmapContextCreate(NULL,
pixelSize.width,
pixelSize.height,
CGImageGetBitsPerComponent(originalImageRef),
pixelSize.width*4,
colorSpace,
bitmapInfo
);
CGColorSpaceRelease(colorSpace);
if (!context) return sourceImage;
const CGRect imageRect = CGRectMake(0, 0, pixelSize.width, pixelSize.height);
UIGraphicsPushContext(context);
// Flip coordinate system. See: http://stackoverflow.com/questions/506622/cgcontextdrawimage-draws-image-upside-down-when-passed-uiimage-cgimage
CGContextTranslateCTM(context, 0, pixelSize.height);
CGContextScaleCTM(context, 1.0, -1.0);
[sourceImage drawInRect:imageRect];
UIGraphicsPopContext();
const CGImageRef decompressedImageRef = CGBitmapContextCreateImage(context);
CGContextRelease(context);
UIImage *image = [UIImage imageWithCGImage:decompressedImageRef scale:[UIScreen mainScreen].scale orientation:UIImageOrientationUp];
CGImageRelease(decompressedImageRef);
return image; }
I have one Imageview that contains the Image . And one Mask Shape that contains shape of rabbit.
I have one code that gives the below result.
- (UIImage*)mynewmaskImage:(UIImage *)image withMask:(UIImage *)maskImage {
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGImageRef maskImageRef = [maskImage CGImage];
// create a bitmap graphics context the size of the image
CGContextRef mainViewContentContext = CGBitmapContextCreate (NULL,320, 380, 8, 0, colorSpace,(CGBitmapInfo) kCGImageAlphaPremultipliedLast);
CGColorSpaceRelease(colorSpace);
if (mainViewContentContext==NULL)
return NULL;
CGFloat ratio = 0;
ratio = 320/ image.size.width;
if(ratio * image.size.height < 380) {
ratio = 380/ image.size.height;
}
CGRect rect1 = {{0, 0}, {320,380}};
CGRect rect2 = {{-((image.size.width*ratio)-320)/2 , -((image.size.height*ratio)-380)/2}, {image.size.width*ratio, image.size.height*ratio}};
// CGContextDrawImage(mainViewContentContext, rect2, image.CGImage);
CGContextClipToMask(mainViewContentContext, rect1, maskImageRef);
CGContextDrawImage(mainViewContentContext, rect2, image.CGImage);
CGImageRef newImage = CGBitmapContextCreateImage(mainViewContentContext);
CGContextRelease(mainViewContentContext);
UIImage *theImage = [UIImage imageWithCGImage:newImage];
CGImageRelease(newImage);
// return the image
return theImage;}
The above code gives this result.
But I want the below result (like reverse masking).
How it is possible.Please Help me.
Thanks.
You should look through blendMode. Try smth like this:
[rabbitImage drawInRect:rect
blendMode:kCGBlendModeDestinationOut
alpha:1.0];
My project is automatic reference counting, but when I use CGBitmapContextCreateImage and UIIMage's method imageWithCGImage, something happened. I wrote some testing code, when the code running, the memory increased until the app crashed.
The device:
[16G, iPad2, retina]
The code:
(UIImage*) createImageByImage:(UIImage*)img
{
CGSize imgSize = img.size;
imgSize.width *= [UIScreen mainScreen].scale;
imgSize.height *= [UIScreen mainScreen].scale;
CGColorSpaceRef space = CGColorSpaceCreateDeviceRGB();
CGContextRef ctx = CGBitmapContextCreate(nil, imgSize.width, imgSize.height, 8, imgSize.width * (CGColorSpaceGetNumberOfComponents(space) + 1), space, kCGImageAlphaPremultipliedLast);
CGColorSpaceRelease(space);
CGRect rect;
rect.origin = CGPointMake(0, 0);
rect.size = imgSize;
// here bypass some transformation to the CGContext
CGContextDrawImage(ctx, rect, img.CGImage);
CGImageRef cgImage = CGBitmapContextCreateImage(ctx);
CGContextRelease(ctx);
UIImage* image = [UIImage imageWithCGImage:cgImage scale:[UIScreen mainScreen].scale orientation:UIImageOrientationDown];
CGImageRelease(cgImage);
return image;
}
the caller:
UIImage* baseImg = [UIImage imageNamed:#"corkboard.jpg"]; // any big image,e.g. 1024*768
for (int i = 0; i < 100; i++) {
UIImage* tempImg = [self createImageByImage:baseImg];
tempImg = nil;
}
baseImg = nil;
Is there someone who can explain? Waiting for your help!!!
Another thing: in the code, if I only replace
[UIImage imageWithCGImage:cgImage ....];
with
[UIImage imageWithCGImage:img.CGImage ....];
the error disappeared! But then the function changed, not met the original demand!
I have UITableViewCell with image in the right size.
This is how the cell should look like:
And i have the backgound:
And the image placeholder:
And i want to know if there is a way to crop image with the iOS library?
Yes that possible:
UIImage *imageToCrop = ...;
UIGraphicsBeginImageContext();
CGContextRef context = UIGraphicsGetCurrentContext();
[imageToCrop drawAtPoint:CGPointZero];
CGContextAddEllipseInRect(context, CGRectMake(0 ,0, imageToCrop.size.width, imageToCrop.size.height);
CGContextClip(context);
UIImage *croppedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
You can use CoreGraphics to add mask or clip with path. Mask is image with alpha channel which determines what part of image show. Below example how clip with image mask:
- (UIImage *)croppedImage:(UIImage *)sourceImage
{
UIGraphicsBeginImageContextWithOptions(CGSizeMake(width, height), NO, [UIScreen mainScreen].scale);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextClipToMask(context, CGRectMake(0, 0, width, height), [UIImage imageNamed:#"mask"].CGImage);
[sourceImage drawInRect:CGRectMake(0, 0, width, height)];
UIImage *resultImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return resultImage;
}
Then you can write cell.picture = [self croppedImage:sourceImage];
You can use image masking technique to crop this image
Please have a look at this link
https://developer.apple.com/library/mac/documentation/graphicsimaging/conceptual/drawingwithquartz2d/dq_images/dq_images.html#//apple_ref/doc/uid/TP30001066-CH212-CJBHIJEB
I have written some code that may help you out
#interface ImageRenderer : NSObject {
UIImage *image_;
}
#property (nonatomic, retain) UIImage * image;
- (void)cropImageinRect:(CGRect)rect;
- (void)maskImageWithMask:(UIImage *)maskImage;
- (void)imageWithAlpha;
#end
#implementation ImageRenderer
#synthesize image = image_;
- (void)cropImageinRect:(CGRect)rect {
CGImageRef imageRef = CGImageCreateWithImageInRect(image_.CGImage, rect);
image_ = [UIImage imageWithCGImage:imageRef];
CGImageRelease(imageRef);
}
- (void)maskImageWithMask:(UIImage *)maskImage {
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGImageRef maskImageRef = [maskImage CGImage];
// create a bitmap graphics context the size of the image
CGContextRef mainViewContentContext = CGBitmapContextCreate (NULL, maskImage.size.width, maskImage.size.height, 8, 0, colorSpace, kCGImageAlphaPremultipliedLast);
if (mainViewContentContext == NULL){
return;
}
CGFloat ratio = 0;
ratio = maskImage.size.width/ image_.size.width;
if(ratio * image_.size.height < maskImage.size.height) {
ratio = maskImage.size.height/ image_.size.height;
}
CGRect rect1 = {{0, 0}, {maskImage.size.width, maskImage.size.height}};
CGRect rect2 = {{-((image_.size.width*ratio)-maskImage.size.width)/2 , -((image_.size.height*ratio)-maskImage.size.height)/2}, {image_.size.width*ratio, image_.size.height*ratio}};
CGContextClipToMask(mainViewContentContext, rect1, maskImageRef);
CGContextDrawImage(mainViewContentContext, rect2, image_.CGImage);
// Create CGImageRef of the main view bitmap content, and then
// release that bitmap context
CGImageRef newImage = CGBitmapContextCreateImage(mainViewContentContext);
CGContextRelease(mainViewContentContext);
image_ = [UIImage imageWithCGImage:newImage];
CGImageRelease(newImage);
}
- (void)imageWithAlpha {
CGImageRef imageRef = image_.CGImage;
CGFloat width = CGImageGetWidth(imageRef);
CGFloat height = CGImageGetHeight(imageRef);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(nil, width, height, 8, 0, colorSpace, kCGImageAlphaPremultipliedFirst);
CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef);
CGImageRef resultImageRef = CGBitmapContextCreateImage(context);
image_ = [UIImage imageWithCGImage:resultImageRef scale:image_.scale orientation:image_.imageOrientation];
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
CGImageRelease(resultImageRef);
}
#end
In this code you can crop the image out of a bigger one and then you can use a mask image to get your work done.
I'm trying to apply multiple effects to images. I've created a separate file to handle the effects processing that I can send a UIImageView to and receive a modified copy. To save processing time, I first load the image into the separate processing file and store it in memory, rather than load the image every time I want to modify it. The flow is getImageData -> modifyRGB -> displayImage. Everything works till the last step. The returned modified image is displayed on screen for a split second, then Xcode crashes with a EXEC_BAD_ACCESS:code 1 error. I've been over the code repeatedly, and can't find the problem. Any help is greatly appreciated. Thank you!
UPDATE WITH MORE INFO
I'm using Xcode 4.3.1 with Automatic Reference Counting
Using Line Breaks, I can verify that the crash happens when the line self.imageView.image = [self.imageManipulation displayImage]; is executed. The image IS updated, but then the program immediately crashes.
Using NSZombie, i get an error -[Not A Type retain]: message sent to deallocated instance 0x2cceaf80
From my viewController I use:
[self.imageManipulation getImageData:self.imageView.image];
[self.imageManipulation modifyRGB];
self.imageView.image = [self.imageManipulation displayImage];
My ImageManipulation file consists of:
#implementation ImageManipulation
static unsigned char *rgbaDataOld;
static unsigned char *rgbaDataNew;
static int width;
static int height;
- (void)getImageData:(UIImage *)image
{
CGImageRef imageRef = [image CGImage];
width = CGImageGetWidth(imageRef);
height = CGImageGetHeight(imageRef);
rgbaDataOld = malloc(height * width * 4);
rgbaDataNew = malloc(height * width * 4);
NSUInteger bytesPerPixel = 4;
NSUInteger bytesPerRow = bytesPerPixel * width;
NSUInteger bitsPerComponent = 8;
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(rgbaDataOld, width, height, bitsPerComponent, bytesPerRow, colorSpace, kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef);
CGColorSpaceRelease(colorSpace);
CGContextRelease(context);
CGImageRelease(imageRef);
}
//modify rgb values
- (void)modifyRGB
{
for (int byteIndex = 0 ; byteIndex < width * height * 4; byteIndex += 4)
{
rgbaDataNew[byteIndex] = (char) (int) (rgbaDataOld[byteIndex] / 3) + 1;
rgbaDataNew[byteIndex+1] = (char) (int) (rgbaDataOld[byteIndex+1] / 3 + 1);
rgbaDataNew[byteIndex+2] = (char) (int) (rgbaDataOld[byteIndex+2] / 3) + 1;
rgbaDataNew[byteIndex+3] = (char) (int) 255;
}
}
//set image
- (UIImage *)displayImage
{
CGContextRef context;
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
context = CGBitmapContextCreate(rgbaDataNew, width, height, 8, 4 * width, colorSpace, kCGImageAlphaPremultipliedLast );
CGImageRef imageRef = CGBitmapContextCreateImage (context);
UIImage *outputImage = [UIImage imageWithCGImage:imageRef];
CGColorSpaceRelease(colorSpace);
CGContextRelease(context);
CGImageRelease(imageRef);
return outputImage;
}
#end
I changed my dispayImage() method to receive a UIImageView property and return VOID. This way, all work is done to the passed UIImageView instead of a localized instance and nothing is returned.
My guess is that the returned UIImage approach I was using before was crashing because the returned reference was deallocated the second the method completed. This also allows me to use CGImageRelease without any ill effects.
Here's the new approach:
- (void)displayImage:(UIImageView *)image
{
CGContextRef context;
CGImageRef imageRef = [image.image CGImage];
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
context = CGBitmapContextCreate(rgbaDataNew, width, height, 8, 4 * width, colorSpace, kCGImageAlphaPremultipliedLast );
imageRef = CGBitmapContextCreateImage (context);
image.image = [UIImage imageWithCGImage:imageRef];
CGColorSpaceRelease(colorSpace);
CGContextRelease(context);
CGImageRelease(imageRef);
image = nil;
}
Thank you to everyone that offered help! I learned a tremendous amount just from your suggestions. This was my first time using bt and NSZombie and now I'm using them religiously! Thanks again!
You're releasing the imageRef, which causes the UIImage to be autoreleased.
Make sure that you retain the UIImage in order to prevent such events from occurring:
- (UIImage *)displayImage
{
CGContextRef context;
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
context = CGBitmapContextCreate(rgbaDataNew, width, height, 8, 4 * width, colorSpace, kCGImageAlphaPremultipliedLast );
CGImageRef imageRef = CGBitmapContextCreateImage (context);
UIImage *outputImage = [[UIImage imageWithCGImage:imageRef] retain];
CGColorSpaceRelease(colorSpace);
CGContextRelease(context);
CGImageRelease(imageRef); //this line would cause outputImage to be released
return outputImage;
}
In displayImage tell the compiler you want to retain the image with __strong:
UIImage __strong *outputImage = [UIImage imageWithCGImage:imageRef];
or if you prefer:
__strong UIImage *outputImage = [UIImage imageWithCGImage:imageRef];