Question

我已经尝试过这段代码，但却出现了错误的数字。有时它会点击透明部分并返回值，有时它会点击没有值的彩色部分。

-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event
{
    UITouch *touch = [[event allTouches] anyObject];
    CGPoint location = [touch locationInView:touch.view];
    UIColor *color = [self colorAtPosition: location];

    const CGFloat* components = CGColorGetComponents(color.CGColor);
    NSLog(@"Red: %f", components[0]);
    NSLog(@"Green: %f", components[1]);
    NSLog(@"Blue: %f", components[2]);
    NSLog(@"Alpha: %f", CGColorGetAlpha(color.CGColor));
    NSLog(@"x:%f y:%f",location.x,location.y);
}

- (UIColor *)colorAtPosition:(CGPoint)position {

    CGRect sourceRect = CGRectMake(position.x, position.y, 1.f, 1.f);
    CGImageRef imageRef = CGImageCreateWithImageInRect(self.image.CGImage, sourceRect);

    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    unsigned char *buffer = malloc(4);
    CGBitmapInfo bitmapInfo = kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big;
    CGContextRef context = CGBitmapContextCreate(buffer, 1, 1, 8, 4, colorSpace, bitmapInfo);
    CGColorSpaceRelease(colorSpace);
    CGContextDrawImage(context, CGRectMake(0.f, 0.f, 1.f, 1.f), imageRef);
    CGImageRelease(imageRef);
    CGContextRelease(context);

    CGFloat r = buffer[0] / 255.f;
    CGFloat g = buffer[1] / 255.f;
    CGFloat b = buffer[2] / 255.f;
    CGFloat a = buffer[3] / 255.f;

    free(buffer);

    return [UIColor colorWithRed:r green:g blue:b alpha:a];
}

Answer 1

我已经使用了你的代码，它可以解决一些变化：D！（但我用的是长按手势）

- (void)didRecognizeLogPressGesture:(UILongPressGestureRecognizer*)gesture
{    
    if (gesture.state == UIGestureRecognizerStateChanged)
    {
        CGPoint point = [gesture locationInView:self.imageView];
        point.x = point.x*self.imageView.image.size.width/self.imageView.bounds.size.width;
        point.y = point.y*self.imageView.image.size.height/self.imageView.bounds.size.height;


        CGRect sourceRect   = CGRectMake(point.x, point.y, 1.f, 1.f);
        CGImageRef imageRef = CGImageCreateWithImageInRect(self.imageView.image.CGImage, sourceRect);

        CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
        unsigned char *buffer = malloc(4);
        CGBitmapInfo bitmapInfo = kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big;
        CGContextRef context = CGBitmapContextCreate(buffer, 1, 1, 8, 4, colorSpace, bitmapInfo);
        CGColorSpaceRelease(colorSpace);
        CGContextDrawImage(context, CGRectMake(0, 0, 1, 1), imageRef);

        CGFloat r = buffer[0] / 255.f;
        CGFloat g = buffer[1] / 255.f;
        CGFloat b = buffer[2] / 255.f;
        CGFloat a = buffer[3] / 255.f;

        free(buffer);

        self.viewColor.backgroundColor = [UIColor colorWithRed:r green:g blue:b alpha:a];
    }
}

主要变化是：

    point.x = point.x*self.imageView.image.size.width/self.imageView.bounds.size.width;
    point.y = point.y*self.imageView.image.size.height/self.imageView.bounds.size.height;

使用它，您将转换相对于实际图像大小的坐标。

尝试从UIView上的触摸点检索颜色

1 个答案: