have been struggling with this issue for quite some time now and couldn't find an answer so far. Basically, what I want to do, is capturing the content of my EAGLview and then use it to merge it with other images. Anyway, the mainproblem is, that everything transparent in my EAGLview renders opaque when saving it to the photoalbum or putting it into a UIImageView. Let me share some code with you, I found somewhere else:
- (CGImageRef) glToUIImage {
unsigned char buffer[320*480*4];
glReadPixels(0,0,320,480,GL_RGBA,GL_UNSIGNED_BYTE,&buffer);
CGDataProviderRef ref = CGDataProviderCreateWithData(NULL, &buffer, 320*480*4, NULL);
CGImageRef iref = CGImageCreate(320,480,8,32,320*4,CGColorSpaceCreateDeviceRGB(),kCGBitmapByteOrderDefault,ref,NULL,true,kCGRenderingIntentDefault);
size_t width = CGImageGetWidth(iref);
size_t height = CGImageGetHeight(iref);
size_t length = width*height*4;
uint32_t *pixels = (uint32_t *)malloc(length);
CGContextRef context = CGBitmapContextCreate(pixels, width, height, 8, width*4, CGImageGetColorSpace(iref), kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
CGContextTranslateCTM(context, 0.0, height);
CGContextScaleCTM(context, 1.0, -1.0);
CGContextDrawImage(context, CGRectMake(0.0, 0.0, width, height), iref);
CGImageRef outputRef = CGBitmapContextCreateImage(context);
UIImage *outputImage = [UIImage imageWithCGImage:outputRef];
UIImageWriteToSavedPhotosAlbum(outputImage, nil, nil, nil);
return outputRef;
}
As I already mentioned, this perfectly grabs the content of my EAGLview, but I can not get the image with its alpha values.
Any help appreciated. Thanks!
Two places I can see that you might be losing your transparency:
when you're drawing your scene: does your scene have a transparent background? make sure you're doing a glClear to something like (0,0,0,0) rather than (0,0,0,1).
when you're drawing the image to flip it over: what is the default background color here? Seems likely it's a non-transparent black and you'll end up with that where the transparent parts of your scene used to be.
You could check if #2 is your problem by saving the image before you flip it over, and if it is, you could avoid the flipping over process by flipping the memory in your pixels buffer directly rather than using Core Graphics calls.
Related
I am working on paint app taking reference from GLPaint app. In this app there are two canvas views, one view is moving from left to right (animating) and other view is used as background view (as shown in figure).
I am using CAEAGLLayer for filling colors in both views (using subclassing technique). It is working as expected. Now I have to take screenshot of the complete view (outlines and both OpenGL views), but I am getting screenshot of only one view (either moving view or background view). Code related to screenshot is associated with both views but at a time only one view's content is saved.
Code snippet for screenshot as follows.
- (UIImage*)snapshot:(UIView*)eaglview{
GLint backingWidth, backingHeight;
// Bind the color renderbuffer used to render the OpenGL ES view
// If your application only creates a single color renderbuffer which is already bound at this point,
// this call is redundant, but it is needed if you're dealing with multiple renderbuffers.
// Note, replace "_colorRenderbuffer" with the actual name of the renderbuffer object defined in your class.
glBindRenderbufferOES(GL_RENDERBUFFER_OES, viewRenderbuffer);
// Get the size of the backing CAEAGLLayer
glGetRenderbufferParameterivOES(GL_RENDERBUFFER_OES, GL_RENDERBUFFER_WIDTH_OES, &backingWidth);
glGetRenderbufferParameterivOES(GL_RENDERBUFFER_OES, GL_RENDERBUFFER_HEIGHT_OES, &backingHeight);
NSInteger x = 0, y = 0, width = backingWidth, height = backingHeight;
NSInteger dataLength = width * height * 4;
GLubyte *data = (GLubyte*)malloc(dataLength * sizeof(GLubyte));
// Read pixel data from the framebuffer
glPixelStorei(GL_PACK_ALIGNMENT, 4);
glReadPixels(x, y, width, height, GL_RGBA, GL_UNSIGNED_BYTE, data);
// Create a CGImage with the pixel data
// If your OpenGL ES content is opaque, use kCGImageAlphaNoneSkipLast to ignore the alpha channel
// otherwise, use kCGImageAlphaPremultipliedLast
CGDataProviderRef ref = CGDataProviderCreateWithData(NULL, data, dataLength, NULL);
CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
CGImageRef iref = CGImageCreate(width, height, 8, 32, width * 4, colorspace, kCGBitmapByteOrder32Big | kCGImageAlphaPremultipliedLast,
ref, NULL, true, kCGRenderingIntentDefault);
// OpenGL ES measures data in PIXELS
// Create a graphics context with the target size measured in POINTS
NSInteger widthInPoints, heightInPoints;
if (NULL != UIGraphicsBeginImageContextWithOptions) {
// On iOS 4 and later, use UIGraphicsBeginImageContextWithOptions to take the scale into consideration
// Set the scale parameter to your OpenGL ES view's contentScaleFactor
// so that you get a high-resolution snapshot when its value is greater than 1.0
CGFloat scale = eaglview.contentScaleFactor;
widthInPoints = width / scale;
heightInPoints = height / scale;
UIGraphicsBeginImageContextWithOptions(CGSizeMake(widthInPoints, heightInPoints), NO, scale);
}
else {
// On iOS prior to 4, fall back to use UIGraphicsBeginImageContext
widthInPoints = width;
heightInPoints = height;
UIGraphicsBeginImageContext(CGSizeMake(widthInPoints, heightInPoints));
}
CGContextRef cgcontext = UIGraphicsGetCurrentContext();
// UIKit coordinate system is upside down to GL/Quartz coordinate system
// Flip the CGImage by rendering it to the flipped bitmap context
// The size of the destination area is measured in POINTS
CGContextSetBlendMode(cgcontext, kCGBlendModeCopy);
CGContextDrawImage(cgcontext, CGRectMake(0.0, 0.0, widthInPoints, heightInPoints), iref);
// Retrieve the UIImage from the current context
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
// Clean up
free(data);
CFRelease(ref);
CFRelease(colorspace);
CGImageRelease(iref);
return image;
}
Is there any way to combine content of both CAEaglelayer views?
Please help.
Thank you very much.
you could create screenshots of each view by separate and then combine them as follows:
UIGraphicsBeginImageContext(canvasSize);
[openGLImage1 drawInRect:CGRectMake(0, 0, canvasSize.width, canvasSize.height)];
[openGLImage2 drawInRect:CGRectMake(0, 0, canvasSize.width, canvasSize.height)];
UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
you should use appropriate canvasSize and frame to draw each generated UIImage, it is just a sample of how you could do it
See here for a much better way of doing this. It basically allows you to capture a larger view that contains all of your OpenGL (and other) views into one, fully composed screenshot that's identical to what you see on the screen.
I’m working on a paint app for iphone. In my code I'm using an imageView which contain outline image on which I am puting CAEAGLLayer for filling colors in outline image. Now I am taking screenshot of OpenGL ES [CAEAGLLayer] rendered content using function:
- (UIImage*)snapshot:(UIView*)eaglview{
GLint backingWidth1, backingHeight1;
// Bind the color renderbuffer used to render the OpenGL ES view
// If your application only creates a single color renderbuffer which is already bound at this point,
// this call is redundant, but it is needed if you're dealing with multiple renderbuffers.
// Note, replace "_colorRenderbuffer" with the actual name of the renderbuffer object defined in your class.
glBindRenderbufferOES(GL_RENDERBUFFER_OES, viewRenderbuffer);
// Get the size of the backing CAEAGLLayer
glGetRenderbufferParameterivOES(GL_RENDERBUFFER_OES, GL_RENDERBUFFER_WIDTH_OES, &backingWidth1);
glGetRenderbufferParameterivOES(GL_RENDERBUFFER_OES, GL_RENDERBUFFER_HEIGHT_OES, &backingHeight1);
NSInteger x = 0, y = 0, width = backingWidth1, height = backingHeight1;
NSInteger dataLength = width * height * 4;
GLubyte *data = (GLubyte*)malloc(dataLength * sizeof(GLubyte));
// Read pixel data from the framebuffer
glPixelStorei(GL_PACK_ALIGNMENT, 4);
glReadPixels(x, y, width, height, GL_RGBA, GL_UNSIGNED_BYTE, data);
// Create a CGImage with the pixel data
// If your OpenGL ES content is opaque, use kCGImageAlphaNoneSkipLast to ignore the alpha channel
// otherwise, use kCGImageAlphaPremultipliedLast
CGDataProviderRef ref = CGDataProviderCreateWithData(NULL, data, dataLength, NULL);
CGColorSpaceRef colorspace = CGColorSpaceCreateDeviceRGB();
CGImageRef iref = CGImageCreate(width, height, 8, 32, width * 4, colorspace, kCGBitmapByteOrder32Big | kCGImageAlphaPremultipliedLast,
ref, NULL, true, kCGRenderingIntentDefault);
// OpenGL ES measures data in PIXELS
// Create a graphics context with the target size measured in POINTS
NSInteger widthInPoints, heightInPoints;
if (NULL != UIGraphicsBeginImageContextWithOptions) {
// On iOS 4 and later, use UIGraphicsBeginImageContextWithOptions to take the scale into consideration
// Set the scale parameter to your OpenGL ES view's contentScaleFactor
// so that you get a high-resolution snapshot when its value is greater than 1.0
CGFloat scale = eaglview.contentScaleFactor;
widthInPoints = width / scale;
heightInPoints = height / scale;
UIGraphicsBeginImageContextWithOptions(CGSizeMake(widthInPoints, heightInPoints), NO, scale);
}
else {
// On iOS prior to 4, fall back to use UIGraphicsBeginImageContext
widthInPoints = width;
heightInPoints = height;
UIGraphicsBeginImageContext(CGSizeMake(widthInPoints, heightInPoints));
}
CGContextRef cgcontext = UIGraphicsGetCurrentContext();
// UIKit coordinate system is upside down to GL/Quartz coordinate system
// Flip the CGImage by rendering it to the flipped bitmap context
// The size of the destination area is measured in POINTS
CGContextSetBlendMode(cgcontext, kCGBlendModeCopy);
CGContextDrawImage(cgcontext, CGRectMake(0.0, 0.0, widthInPoints, heightInPoints), iref);
// Retrieve the UIImage from the current context
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
// Clean up
free(data);
CFRelease(ref);
CFRelease(colorspace);
CGImageRelease(iref);
return image;}
combining this screenshot with outline image using function:
- (void)Combine:(UIImage *)Back{
UIImage *Front =backgroundImageView.image;
//UIGraphicsBeginImageContext(Back.size);
UIGraphicsBeginImageContext(CGSizeMake(640,960));
// Draw image1
[Back drawInRect:CGRectMake(0, 0, Back.size.width*2, Back.size.height*2)];
// Draw image2
[Front drawInRect:CGRectMake(0, 0, Front.size.width*2, Front.size.height*2)];
UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();
UIImageWriteToSavedPhotosAlbum(resultingImage, nil, nil, nil);
UIGraphicsEndImageContext();
}
Save this image to photoalbum using function
-(void)captureToPhotoAlbum {
[self Combine:[self snapshot:self]];
UIAlertView *alert = [[UIAlertView alloc] initWithTitle:#"Success" message:#"Image saved to Photo Album" delegate:nil cancelButtonTitle:#"OK" otherButtonTitles:nil];
[alert show];
[alert release]; }
Above Code is working but the image quality of screenshot is poor. On the outlines of the brush, there is a grayish outline. I have uploaded a screenshot of my app which is combination of opengles content & UIImage.
Is there any way to get retina display screenshot of opengles-CAEaglelayer content.
Thank you in advance!
I don't believe that resolution is your issue here. If you aren't seeing the grayish outlines on your drawing when it appears on the screen, odds are that you're observing a compression artifact in the saving process. Your image is probably being saved as a lower-quality JPEG image, where artifacts will appear on sharp edges, like the ones in your drawing.
To work around this, Ben Weiss's answer here provides the following code for forcing your image to be saved to the photo library as a PNG:
UIImage* im = [UIImage imageWithCGImage:myCGRef]; // make image from CGRef
NSData* imdata = UIImagePNGRepresentation ( im ); // get PNG representation
UIImage* im2 = [UIImage imageWithData:imdata]; // wrap UIImage around PNG representation
UIImageWriteToSavedPhotosAlbum(im2, nil, nil, nil); // save to photo album
While this is probably the easiest way to address your problem here, you could also try employing multisample antialiasing, as Apple describes in the "Using Multisampling to Improve Image Quality" section of the OpenGL ES Programming Guide for iOS. Depending on how fill-rate limited you are, MSAA might lead to a little bit of slowdown in your application.
You're using kCGImageAlphaPremultipliedLast when you create the CG bitmap context. Although I can't see your OpenGL code, it seems unlikely to me that your OpenGL context is rendering premultiplied alpha. Unfortunately, IIRC, it's not possible to create a non-premultiplied CG bitmap context on iOS (it would be using kCGImageAlphaLast, but I think that'll just make the creation call fail), so you may need to premultiply the data by hand between getting it from OpenGL and making the CG context.
On the other hand, is there a reason your OpenGL context has an alpha channel? Could you just make it opaque white then use kCGImageAlphaNoneSkipLast?
I'm trying to write an iPhone app that takes PNG tilesets and displays segments of them on-screen, and I'm trying to get it to refresh the whole screen at 20fps. Currently I'm managing about 3 or 4fps on the simulator, and 0.5 - 2fps on the device (an iPhone 3G), depending on how much stuff is on the screen.
I'm using Core Graphics at the moment and currently trying to find ways to avoid biting the bullet and refactoring in OpenGL. I've done a Shark time profile analysis on the code and about 70-80% of everything that's going on is boiling down to a function called copyImageBlockSetPNG, which is being called from within CGContextDrawImage, which itself is calling all sorts of other functions with PNG in the name. Inflate is also in there, accounting for 37% of it.
Question is, I already loaded the image into memory from a UIImage, so why does the code still care that it was a PNG? Does it not decompress into a native uncompressed format on load? Can I convert it myself? The analysis implies that it's decompressing the image every time I draw a section from it, which ends up being 30 or more times a frame.
Solution
-(CGImageRef)inflate:(CGImageRef)compressedImage
{
size_t width = CGImageGetWidth(compressedImage);
size_t height = CGImageGetHeight(compressedImage);
CGContextRef context = NULL;
CGColorSpaceRef colorSpace;
int bitmapByteCount;
int bitmapBytesPerRow;
bitmapBytesPerRow = (width * 4);
bitmapByteCount = (bitmapBytesPerRow * height);
colorSpace = CGColorSpaceCreateDeviceRGB();
context = CGBitmapContextCreate (NULL,
width,
height,
8,
bitmapBytesPerRow,
colorSpace,
kCGImageAlphaPremultipliedLast);
CGColorSpaceRelease( colorSpace );
CGContextDrawImage(context, CGRectMake(0, 0, width, height), compressedImage);
CGImageRef result = CGBitmapContextCreateImage(context);
CFRelease(context);
return result;
}
It's based on zneak's code (so he gets the big tick) but I've changed some of the parameters to CGBitmapContextCreate to stop it crashing when I feed it my PNG images.
To answer your last questions, your empirical case seems to prove they're not uncompressed once loaded.
To convert them into uncompressed data, you can draw them (once) in a CGBitmapContext and get a CGImage out of it. It should be well enough uncompressed.
Off my head, this should do it:
CGImageRef Inflate(CGImageRef compressedImage)
{
size_t width = CGImageGetWidth(compressedImage);
size_t height = CGImageGetHeight(compressedImage);
CGContextRef context = CGBitmapContextCreate(
NULL,
width,
height,
CGImageGetBitsPerComponent(compressedImage),
CGImageGetBytesPerRow(compressedImage),
CGImageGetColorSpace(compressedImage),
CGImageGetBitmapInfo(compressedImage)
);
CGContextDrawImage(context, CGRectMake(0, 0, width, height), compressedImage);
CGImageRef result = CGBitmapContextCreateImage(context);
CFRelease(context);
return result;
}
Don't forget to release the CGImage you get once you're done with it.
This question totally saved my day! thanks!! I was having this problem although I wasn't sure where the problem was. Speed up UIImage creation from SpriteSheet
I would like to add that there is another way to load the image directly decompressed, qithout having to write to a context.
NSDictionary *dict = [NSDictionary dictionaryWithObject:[NSNumber numberWithBool:YES]
forKey:(id)kCGImageSourceShouldCache];
NSData *imageData = [NSData dataWithContentsOfFile:#"path/to/image.png"]];
CGImageSourceRef source = CGImageSourceCreateWithData((__bridge CFDataRef)(imageData), NULL);
CGImageRef atlasCGI = CGImageSourceCreateImageAtIndex(source, 0, (__bridge CFDictionaryRef)dict);
CFRelease(source);
I believe it is a little bit faster this way. Hope it helps!
Alright what I am trying to do is:
given an image where there is a circle within that image that is "blank". I want to take an existing image from user library and then mask it so that only a certain part of that image is shown on the "blank" image..
I have tried a few masking code but they all seem to work the other way around ... any tips on how to tackle this?
Unfortunately you can't use CoreAnimation to do this (which would make it rather easy).
Looking at Apple's CoreAnimation documentation:
iOS Note: As a performance consideration, iOS does not support the mask property.
Therefore the next best way to do this is to use Quartz 2D (as answered here):
CGContextRef mainViewContentContext;
CGColorSpaceRef colorSpace;
colorSpace = CGColorSpaceCreateDeviceRGB();
// create a bitmap graphics context the size of the image
mainViewContentContext = CGBitmapContextCreate (NULL, targetSize.width, targetSize.height, 8, 0, colorSpace, kCGImageAlphaPremultipliedLast);
// free the rgb colorspace
CGColorSpaceRelease(colorSpace);
if (mainViewContentContext==NULL)
return NULL;
CGImageRef maskImage = [[UIImage imageNamed:#"mask.png"] CGImage];
CGContextClipToMask(mainViewContentContext, CGRectMake(0, 0, targetSize.width, targetSize.height), maskImage);
CGContextDrawImage(mainViewContentContext, CGRectMake(thumbnailPoint.x, thumbnailPoint.y, scaledWidth, scaledHeight), self.CGImage);
// Create CGImageRef of the main view bitmap content, and then
// release that bitmap context
CGImageRef mainViewContentBitmapContext = CGBitmapContextCreateImage(mainViewContentContext);
CGContextRelease(mainViewContentContext);
// convert the finished resized image to a UIImage
UIImage *theImage = [UIImage imageWithCGImage:mainViewContentBitmapContext];
// image is retained by the property setting above, so we can
// release the original
CGImageRelease(mainViewContentBitmapContext);
// return the image
return theImage;
finally I choose to devote some time to find a way/implementation to
mask text inside UITextView/UIWebView.
By now what I'm able to do is:
- add some custom background
- add a uitextview/uiwebview with some text
- add an UIImageView (with a covering png) or a CAGradientLayer to
create a simple mask effect (*)
Of course this is not a magic bullet and require at least one more
layer (the one pointed out with *).
Furthermore it's not so good when you have a full transparent
background 'cause everyone can recognize the extra view/layer used to
fade away the text.
I searched all over google but still not found a good solution (I've
found about mask an image, blah blah)...
Any tips?
Thanks in advance,
marcio
PS maybe a screenshot will be more straightforward, here you're!
http://grab.by/KzS
Yes! I finally got it. I don't know if it's the Apple's way but it works. Maybe they have the opportunity to employ some private apis. Anyway this is a sort of pseudo-algorithm on how I got it works:
1) get a screenshot of the window
2) crop the desired rect with CGImageCreateWithImageInRect
3) apply a gradient mask (stolen from Apple' sample code on Reflections)
4) create an UIImageView with the freshly created image
I also noted that it doesn't affect the performances even on the lowest devices.
Hope it will be helpful!
And this is a crop of the result (link text)
I've promised to myself to implement a category just to make it better. Until now the code is quite spread in different classes.
Just to make a sample (supported only landscape orientation, see the transform below, supported only top mask). In this case I overrided didMoveToWindow of the table that needs to be masked:
- (void)didMoveToWindow {
if (self.window) {
UIImageView *reflected = (UIImageView *)[self.superview viewWithTag:TABLE_SHADOW_TOP];
if (!reflected) {
UIImage *image = [UIImage screenshot:self.window];
//
CGRect croppedRect = CGRectMake(480-self.frame.size.height, self.frame.origin.x, 16, self.frame.size.width);
CGImageRef cropImage = CGImageCreateWithImageInRect(image.CGImage, croppedRect);
UIImage *reflectedImage = [UIImage imageMaskedWithGradient:cropImage];
CGImageRelease(cropImage);
UIImageView *reflected = [[UIImageView alloc] initWithImage:reflectedImage];
reflected.transform = CGAffineTransformMakeRotation(-(M_PI/2));
reflected.tag = TABLE_SHADOW_TOP;
CGRect adjusted = reflected.frame;
adjusted.origin = self.frame.origin;
reflected.frame = adjusted;
[self.superview addSubview:reflected];
[reflected release];
}
}
}
and this is the uiimage category:
CGImageRef CreateGradientImage(int pixelsWide, int pixelsHigh)
{
CGImageRef theCGImage = NULL;
// gradient is always black-white and the mask must be in the gray colorspace
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceGray();
// create the bitmap context
CGContextRef gradientBitmapContext = CGBitmapContextCreate(NULL, pixelsWide, pixelsHigh,
8, 0, colorSpace, kCGImageAlphaNone);
// define the start and end grayscale values (with the alpha, even though
// our bitmap context doesn't support alpha the gradient requires it)
CGFloat colors[] = {0.0, 1.0, 1.0, 1.0};
// create the CGGradient and then release the gray color space
CGGradientRef grayScaleGradient = CGGradientCreateWithColorComponents(colorSpace, colors, NULL, 2);
CGColorSpaceRelease(colorSpace);
// create the start and end points for the gradient vector (straight down)
CGPoint gradientStartPoint = CGPointZero;
// CGPoint gradientStartPoint = CGPointMake(0, pixelsHigh);
CGPoint gradientEndPoint = CGPointMake(pixelsWide/1.75, 0);
// draw the gradient into the gray bitmap context
CGContextDrawLinearGradient(gradientBitmapContext, grayScaleGradient, gradientStartPoint,
gradientEndPoint, kCGGradientDrawsAfterEndLocation);
CGGradientRelease(grayScaleGradient);
// convert the context into a CGImageRef and release the context
theCGImage = CGBitmapContextCreateImage(gradientBitmapContext);
CGContextRelease(gradientBitmapContext);
// return the imageref containing the gradient
return theCGImage;
}
CGContextRef MyCreateBitmapContext(int pixelsWide, int pixelsHigh)
{
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
// create the bitmap context
CGContextRef bitmapContext = CGBitmapContextCreate (NULL, pixelsWide, pixelsHigh, 8,
0, colorSpace,
// this will give us an optimal BGRA format for the device:
(kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedFirst));
CGColorSpaceRelease(colorSpace);
return bitmapContext;
}
+ (UIImage *)imageMaskedWithGradient:(CGImageRef)image {
UIDeviceOrientation deviceOrientation = [UIDevice currentDevice].orientation;
DEBUG(#"need to support deviceOrientation: %i", deviceOrientation);
float width = CGImageGetWidth(image);
float height = CGImageGetHeight(image);
// create a bitmap graphics context the size of the image
CGContextRef mainViewContentContext = MyCreateBitmapContext(width, height);
// create a 2 bit CGImage containing a gradient that will be used for masking the
// main view content to create the 'fade' of the reflection. The CGImageCreateWithMask
// function will stretch the bitmap image as required, so we can create a 1 pixel wide gradient
CGImageRef gradientMaskImage = CreateGradientImage(width, 1);
// create an image by masking the bitmap of the mainView content with the gradient view
// then release the pre-masked content bitmap and the gradient bitmap
CGContextClipToMask(mainViewContentContext, CGRectMake(0.0, 0.0, width, height), gradientMaskImage);
CGImageRelease(gradientMaskImage);
// draw the image into the bitmap context
CGContextDrawImage(mainViewContentContext, CGRectMake(0, 0, width, height), image);
// create CGImageRef of the main view bitmap content, and then release that bitmap context
CGImageRef reflectionImage = CGBitmapContextCreateImage(mainViewContentContext);
CGContextRelease(mainViewContentContext);
// convert the finished reflection image to a UIImage
UIImage *theImage = [UIImage imageWithCGImage:reflectionImage];
// image is retained by the property setting above, so we can release the original
CGImageRelease(reflectionImage);
return theImage;
}
Hope it helps.