Question

相应于滚动视图上下文中的一些UIColor值我想要更改之后要覆盖的几个UIImages的像素rgb值。至少我有4个我想要叠加的图像，一个静态的背景图像和3层图像，其像素信息我想在重叠之前改变它们。我正在努力解决的问题是UIImages的颜色不正确。我记得在某个地方我读过有关线程问题的困难。但是我不确定我的代码中是否存在同样的问题：

scrollViewDidEndDecelerating委托方法获取3层图像并将它们传递给为像素进行颜色更改的方法。

- (void)scrollViewDidEndDecelerating:(UIScrollView *)scrollView
{
 MyViewController *controller = [scrollViewControllers objectAtIndex:currentScrollViewPage];
 int color1 = [self getIntFromUIColor:controller.view1.backgroundColor];
 int color2 = [self getIntFromUIColor:controller.view2.backgroundColor];
 int color3 = [self getIntFromUIColor:controller.view3.backgroundColor];
 UIImage *bgImage = [UIImage imageName:@"bg.png"];


    //pass the overlay images to the coloring method 
    //I suppose my problem to be here
 UIImage *layer1 = [self convertImage:[UIImage imageName:@"layer1.png"] withColor:color1];
 UIImage *layer2 = [self convertImage:[UIImage imageName:@"layer2.png"] withColor:color2];
 UIImage *layer3 = [self convertImage:[UIImage imageName:@"layer3.png"] withColor:color3];

 CGSize sizeBG = bgImage.size;

 CGRect bgBoundingBox = CGRectMake (0, 0, sizeBG.width,sizeBG.height);

 CGContextRef myBitmapContext = [self createBitmapContextOfSize:sizeBG];

    //here I'd like to overlay the images
    CGContextDrawImage(myBitmapContext, bgBoundingBox, bgImage.CGImage);
 CGContextDrawImage(myBitmapContext, bgBoundingBox, layer1.CGImage);
 CGContextDrawImage(myBitmapContext, bgBoundingBox, layer2.CGImage);
 CGContextDrawImage(myBitmapContext, bgBoundingBox, layer3.CGImage);

 UIImage *result = [UIImage imageWithCGImage: CGBitmapContextCreateImage (myBitmapContext)];

 CGContextRelease (myBitmapContext);
    //finally paint the result on the imageView
 imageView.image = result;

}

以下方法获取UIImage和颜色：

-(void) convertImage:(UIImage *)src_img withColor:(int)color
{
 [src_img retain];

  CGColorSpaceRef d_colorSpace = CGColorSpaceCreateDeviceRGB();
  /*
   * Note we specify 4 bytes per pixel here even though we ignore the
   * alpha value; you can't specify 3 bytes per-pixel.
   */
  int height = src_img.size.height;
  size_t d_bytesPerRow = src_img.size.width * 4; 
  unsigned int * imgData = (unsigned int*)malloc(src_img.size.height*d_bytesPerRow);

  CGContextRef context =  CGBitmapContextCreate(imgData, src_img.size.width, 
               src_img.size.height, 
               8, d_bytesPerRow, 
               d_colorSpace, 
               kCGImageAlphaPremultipliedLast);

  UIGraphicsPushContext(context);
  // These next two lines 'flip' the drawing so it doesn't appear upside-down.
  CGContextTranslateCTM(context, 0.0, src_img.size.height);
  CGContextScaleCTM(context, 1.0, -1.0);
  // Use UIImage's drawInRect: instead of the CGContextDrawImage function, otherwise you'll have issues when the source image is in portrait orientation.
  [src_img drawInRect:CGRectMake(0.0, 0.0, src_img.size.width, src_img.size.height)];
  UIGraphicsPopContext();

  //swap colors
  int red = (color & 0xff0000) >> 16;
  int green = (color & 0xff00) >> 8;
  int blue = (color & 0xff);
  int colorShifted = (blue << 16) + (green << 8) + red;

            //in this function the pixels are manipulated
  colorChanger((int *)imgData,(src_img.size.height * src_img.size.width),colorShifted);

  // After we've processed the raw data, turn it back into a UIImage instance.
  CGImageRef new_img = CGBitmapContextCreateImage(context);
  UIImage * convertedImage = [[[UIImage alloc] initWithCGImage:
          new_img] autorelease];


  CGImageRelease(new_img);
  CGContextRelease(context);
  CGColorSpaceRelease(d_colorSpace);
  free(imgData);
  [src_img release];

            return convertedImage;

}

任何帮助将不胜感激。 changeColor函数运行安静。当我只改变一个单层的颜色时，结果看起来很好。但是同时改变所有3层的颜色，主要是layer2和layer3用color3绘制，layer1用color2绘制。谢谢你的帮助...

Answer 1

与此同时，我通过更改绘图顺序来解决问题：

 CGContextDrawImage(myBitmapContext, bgBoundingBox, bgImage.CGImage);
 CGContextDrawImage(myBitmapContext, bgBoundingBox, layer1.CGImage);
 CGContextDrawImage(myBitmapContext, bgBoundingBox, layer2.CGImage);
 CGContextDrawImage(myBitmapContext, bgBoundingBox, layer3.CGImage);

到

 CGContextDrawImage(myBitmapContext, bgBoundingBox, bgImage.CGImage);
 CGContextDrawImage(myBitmapContext, bgBoundingBox, layer3.CGImage);
 CGContextDrawImage(myBitmapContext, bgBoundingBox, layer2.CGImage);
 CGContextDrawImage(myBitmapContext, bgBoundingBox, layer1.CGImage);

但这根本不适合我，因为当我使用另一个绘图订单时，我没有看到关于绘图顺序和颜色不匹配的连接......

覆盖不同UIImages的问题

1 个答案: