在高通openGL中take a screenshot

- (BOOL)presentFramebuffer

{

    if (takePhoto)

    {

        [self glToUIImage];

        takePhoto = NO;

    }

 

....remaining code ...

}

- (UIImage*) glToUIImage

{

    GLint backingWidth, backingHeight;

    glGetRenderbufferParameterivOES(GL_RENDERBUFFER_OES, GL_RENDERBUFFER_WIDTH_OES, &backingWidth);

    glGetRenderbufferParameterivOES(GL_RENDERBUFFER_OES, GL_RENDERBUFFER_HEIGHT_OES, &backingHeight);

    

    CGRect s = CGRectMake(0, 0, backingWidth, backingHeight);

    

    uint8_t *buffer = (uint8_t *) malloc(s.size.width * s.size.height * 4);

    glReadPixels(0, 0, s.size.width, s.size.height, GL_RGBA, GL_UNSIGNED_BYTE, buffer);

    CGDataProviderRef ref = CGDataProviderCreateWithData(NULL, buffer, s.size.width * s.size.height * 4, NULL);

    CGImageRef iref = CGImageCreate(s.size.width, s.size.height, 8, 32, s.size.width * 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 cgcontext = CGBitmapContextCreate(pixels, width, height, 8, width * 4,

                                                 CGImageGetColorSpace(iref), kCGImageAlphaNoneSkipFirst | kCGBitmapByteOrder32Big);

    

    CGAffineTransform transform = CGAffineTransformIdentity;

    transform = CGAffineTransformMakeTranslation(0.0f, height);

    transform = CGAffineTransformScale(transform, 1.0, -1.0);

    CGContextConcatCTM(cgcontext, transform);

    CGContextDrawImage(cgcontext, CGRectMake(0.0f, 0.0f, width, height), iref);

    CGImageRef outputRef = CGBitmapContextCreateImage(cgcontext);

    

    UIImage* outputImage = [UIImage imageWithCGImage:outputRef];

    UIImageWriteToSavedPhotosAlbum(outputImage, self, @selector(image:didFinishSavingWithError:contextInfo:), nil);

    

    CGDataProviderRelease(ref);

    CGImageRelease(iref);

    CGContextRelease(cgcontext);

    CGImageRelease(outputRef);

    

    free(pixels);

    free(buffer);

    

    NSLog(@"Screenshot size: %d, %d", (int)[outputImage size].width, (int)[outputImage size].height);

    

    return outputImage;

}

// callback for UIImageWriteToSavedPhotosAlbum

- (void)image:(UIImage *)image didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo {

    

    if (error) {

        NSLog(@"Photo save error");

    }

    else {

        NSLog(@"Photo saved");

    }

}