Question

我使用的是在图像视图中绘制的圆形渐变，作为我的颜色选择器的色轮。我想将平移手势识别器的shouldReceiveTouch:限制为渐变的位置，以便视图的其余部分不受平移手势识别器的影响。

如何指定与渐变半径匹配的圆形边界？

编辑：我尝试了以下代码但没有效果：

if (sender.numberOfTouches)
    {
        CGSize size = CGSizeMake(self.view.bounds.size.width, self.view.bounds.size.height/3);

        float radius = MIN(size.width, size.height)/2;

        [alphaSlider addTarget:self action:@selector(changeOpacity:) forControlEvents:UIControlEventValueChanged];
        [hellSlider addTarget:self action:@selector(changeBrightness:) forControlEvents:UIControlEventValueChanged];
        [saturationSlider addTarget:self action:@selector(saturate:) forControlEvents:UIControlEventValueChanged];
        [rSlider addTarget:self action:@selector(redSlider:) forControlEvents:UIControlEventValueChanged];
        [gSlider addTarget:self action:@selector(greenSlider:) forControlEvents:UIControlEventValueChanged];
        [bSlider addTarget:self action:@selector(blueSlider:) forControlEvents:UIControlEventValueChanged];




        CGPoint lastPoint = [sender locationOfTouch: sender.numberOfTouches - 1 inView: gradientView];
        CGPoint center = CGPointMake((size.width/2), (size.height /2));
        CGPoint delta = CGPointMake(lastPoint.x - center.x,  lastPoint.y - center.y);
        CGFloat angle = (delta.y == 0 ? delta.x >= 0 ? 0 : M_PI : atan2(delta.y, delta.x));
        angle = fmod(angle,  M_PI * 2.0);
        angle += angle >= 0 ? 0 : M_PI * 2.0;
        if((lastPoint.x - center.x) + (lastPoint.y - center.y)/2 < radius)
        {
            UIColor *color = [UIColor colorWithHue: angle / (M_PI * 2.0) saturation:saturationSlider.value brightness:hellSlider.value alpha:alphaSlider.value];
            if ([color getRed: &r green: &g blue:&b alpha: &a])
            {
                NSLog(@"Color value - R : %g G : %g : B %g", r*255, g*255, b*255);
            }
            float red = r;
            float green = g;
            float blue = b;
            rText.text = [NSString stringWithFormat:@"%.0f",rSlider.value];
            gText.text = [NSString stringWithFormat:@"%.0f",green*255];
            bText.text = [NSString stringWithFormat:@"%.0f",blue*255];


            colorView.backgroundColor = [UIColor colorWithRed:(rText.text.floatValue/255) green:(gText.text.floatValue/255) blue:(bText.text.floatValue/255) alpha:alphaSlider.value];
            rSlider.value = red*255;
            gSlider.value = green*255;
            bSlider.value = blue*255;
            alphaText.text = [NSString stringWithFormat:@"%.2f",alphaSlider.value];
            brightnessText.text = [NSString stringWithFormat:@"%.2f",hellSlider.value];
            saturationText.text = [NSString stringWithFormat:@"%.2f",saturationSlider.value];

        }





    }

}

它似乎在渐变的右侧工作并退出接收颜色更新，左侧和下侧仍在更新。我需要适当限制panGesture，以便它停止干扰我的UISliders。

有什么想法吗？

Answer 1

您只需要点击测试触摸事件，看它是否在圆圈区域内。要做到这一点，您需要知道圆的中心点及其半径。

这个现有问题涵盖了这样做的一般方程式：

Equation for testing if a point is inside a circle

将平移手势识别器限制为特定的圆圈

1 个答案: