iphone - png 透明度注册触摸事件iphone？

Question

我有三个 png 的“320 x 480px”，我正在将它们加载到单独的 UIImageView 中。 png 的名字是 body 、嘴巴、帽子。通过将图像堆叠在一起，我创建了一个可以轻松更换 body 部位的角色。看照片>

http://www.1976inc.com/dev/iphone/beast.jpg

我的问题是，当您触摸最顶部的 UIImageView 时，整个图像(包括透明度)都会注册触摸事件。我想做的是让触摸事件只注册在 png 的不透明部分。因此，用户可以与所有三个 UIImageView 进行交互。

我确信这很简单，但我是 iPhone 开发新手，我似乎无法弄清楚。

<小时/>

更新所以我意识到完成我想要做的事情的最简单方法是创建循环并为每个 png 创建一个上下文，然后获取发生触摸事件的像素的颜色数据。如果像素代表透明区域，我将移动到下一个图像并尝试相同的操作。这有效，但只是第一次。例如，第一次单击主视图时，我得到此输出

2010-07-26 15:50:06.285 colorTest[21501:207] hat
2010-07-26 15:50:06.286 colorTest[21501:207] offset: 227024 colors: RGB A 0 0 0 0
2010-07-26 15:50:06.293 colorTest[21501:207] mouth
2010-07-26 15:50:06.293 colorTest[21501:207] offset: 227024 colors: RGB A 0 0 0 0
2010-07-26 15:50:06.298 colorTest[21501:207] body
2010-07-26 15:50:06.299 colorTest[21501:207] offset: 227024 colors: RGB A 255 255 255 255

这正是我想看到的。但如果我再次单击同一区域，我就会得到。

2010-07-26 15:51:21.625 colorTest[21501:207] hat
2010-07-26 15:51:21.626 colorTest[21501:207] offset: 283220 colors: RGB A 255 255 255 255
2010-07-26 15:51:21.628 colorTest[21501:207] mouth
2010-07-26 15:51:21.628 colorTest[21501:207] offset: 283220 colors: RGB A 255 255 255 255
2010-07-26 15:51:21.630 colorTest[21501:207] body
2010-07-26 15:51:21.631 colorTest[21501:207] offset: 283220 colors: RGB A 255 255 255 255

这是我正在使用的代码；

触摸事件存在于应用程序的主视图中

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event
{
 NSLog(@"Touched balls");
 UITouch *touch = [touches anyObject];
 CGPoint point = [touch locationInView:self.view];

 UIColor *transparent = [UIColor colorWithRed:0 green:0 blue:0 alpha:0];

 for( viewTest *currentView in imageArray){
  //UIColor *testColor = [self getPixelColorAtLocation:point image:currentView.image];
  [currentView getPixelColorAtLocation:point];

 }

}

它调用扩展 imageView 的自定义类中的方法该函数返回touchEvent下像素的颜色。

- (UIColor*) getPixelColorAtLocation:(CGPoint)point
{
 UIColor *color = nil;
 CGImageRef inImage = self.image.CGImage;

 CGContextRef context = [self createARGBBitmapContextFromImage:inImage];

 if(context == NULL) return nil;

 size_t w = CGImageGetWidth(inImage);
 size_t h = CGImageGetHeight(inImage);
 CGRect rect = {{0,0},{w,h}}; 

 // Draw the image to the bitmap context. Once we draw, the memory
 // allocated for the context for rendering will then contain the
 // raw image data in the specified color space.
 CGContextDrawImage(context, rect, inImage); 

 // Now we can get a pointer to the image data associated with the bitmap
 // context.
 unsigned char* data = CGBitmapContextGetData (context);
 if (data != NULL) {
  //offset locates the pixel in the data from x,y.
  //4 for 4 bytes of data per pixel, w is width of one row of data.
  int offset = 4*((w*round(point.y))+round(point.x));
  int alpha =  data[offset];
  int red = data[offset+1];
  int green = data[offset+2];
  int blue = data[offset+3];
  NSLog(@"%@",name);
  NSLog(@"offset: %i colors: RGB A %i %i %i  %i ",offset,red,green,blue,alpha);
  color = [UIColor colorWithRed:(red/255.0f) green:(green/255.0f) blue:(blue/255.0f) alpha:(alpha/255.0f)];
 }

 // When finished, release the context
 CGContextRelease(context);

 // Free image data memory for the context
 if (data) { free(data); }

 return color;
}

- (CGContextRef) createARGBBitmapContextFromImage:(CGImageRef) inImage {

 CGContextRef    context = NULL;
 CGColorSpaceRef colorSpace;
 void *          bitmapData;
 int             bitmapByteCount;
 int             bitmapBytesPerRow;

 // Get image width, height. We'll use the entire image.
 size_t pixelsWide = CGImageGetWidth(inImage);
 size_t pixelsHigh = CGImageGetHeight(inImage);

 // Declare the number of bytes per row. Each pixel in the bitmap in this
 // example is represented by 4 bytes; 8 bits each of red, green, blue, and
 // alpha.
 bitmapBytesPerRow   = (pixelsWide * 4);
 bitmapByteCount     = (bitmapBytesPerRow * pixelsHigh);

 // Use the generic RGB color space.
 colorSpace = CGColorSpaceCreateDeviceRGB();//CGColorSpaceCreateWithName(kCGColorSpaceGenericRGB);
 if (colorSpace == NULL)
 {
  fprintf(stderr, "Error allocating color space\n");
  return NULL;
 }

 // Allocate memory for image data. This is the destination in memory
 // where any drawing to the bitmap context will be rendered.
 bitmapData = malloc( bitmapByteCount );
 if (bitmapData == NULL)
 {
  fprintf (stderr, "Memory not allocated!");
  CGColorSpaceRelease( colorSpace );
  return NULL;
 }

 // Create the bitmap context. We want pre-multiplied ARGB, 8-bits
 // per component. Regardless of what the source image format is
 // (CMYK, Grayscale, and so on) it will be converted over to the format
 // specified here by CGBitmapContextCreate.
 context = CGBitmapContextCreate (bitmapData,
          pixelsWide,
          pixelsHigh,
          8,      // bits per component
          bitmapBytesPerRow,
          colorSpace,
          kCGImageAlphaPremultipliedFirst);
 if (context == NULL)
 {
  free (bitmapData);
  fprintf (stderr, "Context not created!");
 }

 // Make sure and release colorspace before returning
 CGColorSpaceRelease( colorSpace );

 return context;
}

<小时/>

更新2感谢您及时的回复。我不确定我是否关注你。如果我将隐藏更改为 true，则 UIImageView“层”将被隐藏。我想要的是 png 的透明部分不注册触摸事件。例如，如果您查看我在帖子中包含的图片。如果您单击蠕虫、茎或叶“它们都是同一个 png 的一部分”，则该 ImageView 会触发触摸事件，但如果您触摸圆圈，则该 ImageView 会触发触摸事件。顺便说一句，这是我用来将它们放置在 View 中的代码。

UIView *tempView = [[UIView alloc] init];
[self.view addSubview:tempView];


UIImageView *imageView1 = [[UIImageView alloc] initWithImage:[UIImage  imageNamed:@"body.png"] ];
[imageView1 setUserInteractionEnabled:YES];
UIImageView *imageView2 = [[UIImageView alloc] initWithImage:[UIImage  imageNamed:@"mouth.png"] ];
[imageView2 setUserInteractionEnabled:YES];
UIImageView *imageView3 = [[UIImageView alloc] initWithImage:[UIImage  imageNamed:@"hat.png"] ];
[imageView3 setUserInteractionEnabled:YES];

[tempView addSubview:imageView1];
[tempView addSubview:imageView2];
[tempView addSubview:imageView3];

[self.view addSubview:tempView];

Answer 1

首先:

您可以使用透明度，但隐藏图像可能会满足您的需求。

您可以使用以下命令隐藏图像:[myImage setHidden:YES]; 或 myImage.hidden = YES;

if (CGRectContainsPoint(myImage.frame, touchPosition)==true && myImage.hidden==NO) 
{
}

这可以确保您的图像在点击时不透明，因为 myImage.hidden==NO 检查图像是否隐藏。