如何調用方法上只點擊animage視圖

Question

的可見部分我在應用程序中有UIImageView和我附上一個手勢識別到該圖像視圖。

我的問題是，我只需要觸發其可見區域時才需要調用其操作，而不是在其透明部分出現觸摸時。

我怎樣才能達致這？

Answer 1

的抵達ALPHA看一看github上的OBSHAPED按鈕。它能夠解決您的問題編碼愉快。:)

Answer 2

這些代碼段應該讓你開始。 這第一件是UIView類別（即我某處這樣，但我不記得在哪裏）。 This gets you the color under the touch point.

@interface UIView (ColorOfPoint) 

- (UIColor *) colorOfPoint:(CGPoint)point; 

@end 


- (UIColor *) colorOfPoint:(CGPoint)point 
{ 
    unsigned char pixel[4] = {0}; 
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB(); 
    CGContextRef context = CGBitmapContextCreate(pixel, 1, 1, 8, 4, colorSpace, kCGImageAlphaPremultipliedLast); 

    CGContextTranslateCTM(context, -point.x, -point.y); 

    [self.layer renderInContext:context]; 

    CGContextRelease(context); 
    CGColorSpaceRelease(colorSpace); 
    UIColor *color = [UIColor colorWithRed:pixel[0]/255.0 green:pixel[1]/255.0 blue:pixel[2]/255.0 alpha:pixel[3]/255.0]; 

    return color; 
} 

這第二件顯示瞭如何調用自定義圖像視圖類此方法：

- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event { 
    UITouch *touch = [[event allTouches] anyObject]; 
    CGPoint loc = [touch locationInView:self]; 
    self.pickedColor = [self colorOfPoint:loc]; 
    [[NSNotificationCenter defaultCenter] postNotificationName:@"ColorPicked" object:self userInfo:nil]; 
} 

我用了一個通知，在這裏，因爲我需要讓其他類知道的價值挑選顏色。

Answer 3

U可以用這個觸摸點

 

-(UIColor*) getPixelColorAtLocation:(CGPoint)point 
{ 

    CGImageRef inImage; 
    UIColor *color = nil; 


     inImage = [self.imageView.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; 



      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; 
}