Sparrow Forum

1. 

   wbecker
   Member

   i am using this function to create Screenshots of the Stage in my IPAD App:

   - (UIImage *)getImageScreenshot{
   	int WIDTH = 1024;
   	int HEIGHT = 768;
    
   	CGSize size = CGSizeMake(WIDTH,HEIGHT);
   	//Create un buffer for pixels
   	GLuint bufferLenght=size.width*size.height*4;
   	GLubyte *buffer = (GLubyte *) malloc(bufferLenght);
    
   	//Read Pixels from OpenGL
   	glReadPixels(0,0,size.width,size.height,GL_RGBA,GL_UNSIGNED_BYTE,buffer);
   	//Make data provider with data.
   	CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, buffer, bufferLenght, NULL);
    
   	//Configure image
       int bitsPerComponent = 8;
       int bitsPerPixel = 32;
       int bytesPerRow = 4 * size.width;
       CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB();
       CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault;
       CGColorRenderingIntent renderingIntent = kCGRenderingIntentDefault;
   	CGImageRef iref = CGImageCreate(size.width,size.height,bitsPerComponent,bitsPerPixel,bytesPerRow,colorSpaceRef,bitmapInfo,provider,NULL,NO,renderingIntent);
    
   	uint32_t *pixels = (uint32_t *)malloc(bufferLenght);
   	CGContextRef context = CGBitmapContextCreate(pixels, WIDTH, HEIGHT, 8, WIDTH*4, CGImageGetColorSpace(iref), kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
    
   	CGContextTranslateCTM(context,0, size.height);
   	CGContextScaleCTM(context, 1.0, -1.0);
    
   	CGContextDrawImage(context, CGRectMake(0.0, 0.0, size.width, size.height), iref);
   	UIImage* screenshot = [UIImage imageWithCGImage:CGBitmapContextCreateImage(context)];
    
   	UIGraphicsEndImageContext();
    
   	//free memory
   	CGColorSpaceRelease(colorSpaceRef);
   	CGDataProviderRelease(provider);
   	CGImageRelease(iref);
   	CGContextRelease(context);
   	free(buffer);
   	free(pixels);
   	return screenshot;
   }

   The function is declared in a category which extends SPDisplayobject

    @interface SPDisplayObject (ScreenshotFromSPDisplayObject)

   I use it like this from an UIViewController with an SPStage in an SPView:

   	// attach screenshot
   	tempImage = [self.stage getImageScreenshot];
   	screenShot = [[UIImageView alloc] initWithFrame:CGRectMake(0,0,1024,768)];
   	screenShot.image = tempImage;
   	[self.view addSubview:screenShot];
    
   // the dealloc of the UIViewController
   - (void)dealloc
   {
   	[screenShot removeFromSuperview];
   	[screenShot release];
   	[super dealloc];
   }

   Taking Screenshots works like a charm, but with every Screenshot my App is growing around 10 MBs So i can do this around 15 Times till the app crashes.

   Any ideas where to free any memory?

   Thank you for any help with this.

   Wolfgang

   Posted 1 year ago #
2. 

   freerunnering
   Moderator

   Why are you displaying the screenshot rather then saving it to the camera roll or something else?

   Anyway I don't know where the problem is but you could see if this version has less leaks?

   -(void)takeScreenShot{
          SPRectangle *rectangle = [[SPRectangle alloc] initWithX:0 y:0 width:self.stage.width height:self.stage.height];
           int bufferLenght = (rectangle.width*(rectangle.height+30)*4);
    
           int myWidth = rectangle.width;
           int myHeight = rectangle.height;
           int myY = self.stage.height-rectangle.y-rectangle.height;
           int myX = rectangle.x;
    
           unsigned char buffer[bufferLenght];
           glReadPixels(myX, myY, myWidth, myHeight, GL_RGBA, GL_UNSIGNED_BYTE, &buffer);
    
           CGDataProviderRef ref = CGDataProviderCreateWithData(NULL, &buffer, bufferLenght, NULL);
           CGImageRef iref = CGImageCreate(myWidth,myHeight,8,32,myWidth*4,CGColorSpaceCreateDeviceRGB(),
                                                                           kCGBitmapByteOrderDefault,ref,NULL, true, kCGRenderingIntentDefault);
           uint32_t* pixels = (uint32_t *)malloc(bufferLenght);
           CGContextRef context = CGBitmapContextCreate(pixels, myWidth, myHeight, 8, myWidth*4, CGImageGetColorSpace(iref),
                                                                                                    kCGImageAlphaNoneSkipFirst | kCGBitmapByteOrder32Big);
           CGContextTranslateCTM(context, 0.0, myHeight);
           CGContextScaleCTM(context, 1.0, -1.0);
           CGContextDrawImage(context, CGRectMake(0.0, 0.0, myWidth, myHeight), iref);
           CGImageRef outputRef = CGBitmapContextCreateImage(context);
           free(pixels);
    
           UIImageWriteToSavedPhotosAlbum([UIImage imageWithCGImage:outputRef], nil, nil, nil);
           [rectangle release];
   }

   Posted 1 year ago #
3. 

   wbecker
   Member

   To explain why i am displaying the Screenshot:

   My App is an animated Book with a Curleffect between Pages.
   The Pages are UIViews.
   I am using only one SpView with one SPStage which i switch from one UIView to the next during the Curl effect.
   While i am rendering the new Page i display the Screenshot to cover the rendering of the new Scene on the Stage.
   Once the new Page is rendered on Stage i Remove the Screenshot.

   I am doing that because i had problems using Multiple SPStage, in the App (SpImages where rendered like white boxes)

   Thank you for your Version, but it Crashes the app: Program received signal: “EXC_BAD_ACCESS”.
   The Debugger stops after

   unsigned char buffer[bufferLenght];

   I have tried out a similar version from this Forum with the same Error, but could not get it working.

   Posted 1 year ago #
4. 

   wbecker
   Member

   I have the solution:

   In the getImageScreenshot function i did this:

   UIImage* screenshot = [UIImage imageWithCGImage:CGBitmapContextCreateImage(context)];

   which creates a CGImageRef and then creates (autorelease) an UIImage from it.
   What happens here is that this CGImageRef remains alive and is never released, so it's leaking.

   What you should do, instead, is this:

   CGImageRef myCGImage = CGBitmapContextCreateImage(context);
   UIImage* screenshot = [UIImage imageWithCGImage:myCGImage];
   CGImageRelease(myCGImage);

   Posted 1 year ago #
5. 

   Daniel
   Primary Feather

   I'm glad that you found it -- thanks for posting the answer!

   Posted 1 year ago #

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