ios - 在当前触摸位置添加指示器？

Question

我正在开发颜色选择器并使用圆形渐变和 panGesture 来选择颜色。

我可以在当前触摸位置添加十字准线或其他东西吗？

我需要十字准线可见，但它不应干扰渐变。

这是添加渐变的代码:

- (void)viewDidLoad
{
    [super viewDidLoad];





    CGSize size = CGSizeMake(self.view.bounds.size.width, ((self.view.bounds.size.height)/2));
    UIGraphicsBeginImageContextWithOptions(CGSizeMake(size.width, size.height), YES, 0.0);
    [[UIColor whiteColor] setFill];
    UIRectFill(CGRectMake(0, 0,size.width,size.height));


    int sectors = 180;
    float radius = MIN(size.width, size.height)/2;
    float angle = 2 * M_PI/sectors;
    UIBezierPath *bezierPath;
    for ( int i = 0; i < sectors; i++)
    {
        CGPoint center = CGPointMake(((size.width)/2), ((size.height)/2));
        bezierPath = [UIBezierPath bezierPathWithArcCenter:center radius:radius startAngle:i * angle endAngle:(i + 1) * angle clockwise:YES];
        [bezierPath addLineToPoint:center];
        [bezierPath closePath];
        UIColor *color = [UIColor colorWithHue:((float)i)/sectors saturation:1. brightness:1. alpha:1];
        [color setFill];
        [color setStroke];
        [bezierPath fill];
        [bezierPath stroke];
    }
    img = UIGraphicsGetImageFromCurrentImageContext();
    gradientView = [[UIImageView alloc]initWithImage:img];;
    UIPanGestureRecognizer *panGesture = [[UIPanGestureRecognizer alloc]initWithTarget:self action:@selector(handlePan:)];

    colorView = [[UIView alloc] init];
    colorView.frame = CGRectMake(0, 00, 50, 50);


    rText.textAlignment = NSTextAlignmentCenter;
    gText.textAlignment = NSTextAlignmentCenter;
    bText.textAlignment = NSTextAlignmentCenter;
    saturationText.textAlignment = NSTextAlignmentCenter;
    alphaText.textAlignment = NSTextAlignmentCenter;
    brightnessText.textAlignment = NSTextAlignmentCenter;

    rText.keyboardType = UIKeyboardTypeNumberPad;
    gText.keyboardType = UIKeyboardTypeNumberPad;
    bText.keyboardType = UIKeyboardTypeNumberPad;

    saturationText.keyboardType = UIKeyboardTypeNumberPad;
    alphaText.keyboardType = UIKeyboardTypeNumberPad;
    brightnessText.keyboardType = UIKeyboardTypeNumberPad;



    gradientView.frame = CGRectMake(0,0,size.width,size.height);
    self.view.backgroundColor = [UIColor whiteColor];
    [self.view addSubview:gradientView];
    gradientView.userInteractionEnabled = YES;
    [gradientView addGestureRecognizer: panGesture];

    [self.view addSubview:colorView];





}

handlePan 方法:

    - (IBAction)handlePan:(UIPanGestureRecognizer *)sender
{


    if (sender.numberOfTouches)
        {
            CGSize size = CGSizeMake(self.view.bounds.size.width, (self.view.bounds.size.height)/2);

            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];

            }





        }
}

问题已解决，谢谢。

Answer 1

好吧，您绝对“可以”在当前触摸位置添加十字准线。

我可以告诉您其中一种可行的方法。

实现

 - (IBAction)handlePan:(UIPanGestureRecognizer *)recognizer

Action 处理器。

将十字准线的图像加载到 UIImage(比如 overlayImage)中:

  overlayImage =[UIImage imageNamed:@"crosshair.png"];

并将其设置为 UIView(例如 overlayView)。[这可以在您的 viewDidLoad 方法中完成。]

现在，将以下代码添加到您的 handlePan 方法中:

CGPoint translation = [recognizer translationInView:colorView]; //whichever view you want.
_overlayView.center = CGPointMake(_overlayView.center.x + translation.x,
                                     _overlayView.center.y + translation.y);
[recognizer setTranslation:CGPointMake(0, 0) inView:colorView];

 if (recognizer.state == UIGestureRecognizerStateEnded) {

    CGPoint velocity = [recognizer velocityInView:colorView];
    CGFloat magnitude = sqrtf((velocity.x * velocity.x) + (velocity.y * velocity.y));
    CGFloat slideMult = magnitude / 800;
   // NSLog(@"magnitude: %f, slideMult: %f", magnitude, slideMult);

    float slideFactor = 0.1 * slideMult; // Increase for more of a slide
    CGPoint finalPoint = CGPointMake(_overlayView.center.x + (velocity.x * slideFactor),
                                     _overlayView.center.y + (velocity.y * slideFactor));
    finalPoint.x = MIN(MAX(finalPoint.x, 0), colorView.bounds.size.width);
    finalPoint.y = MIN(MAX(finalPoint.y, 0), colorView.bounds.size.height);

    [UIView animateWithDuration:slideFactor*2 delay:0 options:UIViewAnimationOptionCurveEaseOut animations:^{
        _overlayView.center = finalPoint;
    } completion:nil];

这应该可以解决问题。

您也可以通过实现 touchesBegan 和 touchesMoved 方法来尝试这样做。