iOS -OPenGL的屏幕截图

1.初始化。

CAEAGLLayer *eaglLayer = (CAEAGLLayer *) self.layer;  eaglLayer.drawableProperties = @{      kEAGLDrawablePropertyRetainedBacking: [NSNumber numberWithBool:YES],      kEAGLDrawablePropertyColorFormat: kEAGLColorFormatRGBA8  };

2.声明方法。

- (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 "viewRenderbuffer" 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;}

3.使用

调用上述的方法即可。

- (UIImage*)snapshot:(UIView*)eaglview