我有一个在ImageView内呈现圆形渐变的函数，我有一个panGestureRecognizer作为颜色选择器。
如何限制用户的触摸输入仅在他的触摸位于ImageView边界内时应用？
我在没有结果的情况下尝试了这段代码：
@interface testViewController ()
@end
@implementation testViewController
- (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:)];
[self.view addGestureRecognizer: panGesture];
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;
[self.view addSubview:gradientView];
[self.view addSubview:colorView];
gradientView.frame = CGRectMake(0,0,size.width,size.height);
}
- (void)didReceiveMemoryWarning {
[super didReceiveMemoryWarning];
// Dispose of any resources that can be recreated.
}
- (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];
}
}
}
-(void)blueSlider:(id)sender {
bSlider = (UISlider *)sender;
bText.text = [NSString stringWithFormat:@"%.0f",bSlider.value];
bSlider.value = bText.text.floatValue;
UIColor *newColor = [UIColor colorWithRed:rSlider.value green:gSlider.value blue:bSlider.value alpha:alphaSlider.value];
colorView.backgroundColor = newColor;
}
-(void)greenSlider:(id)sender {
gSlider = (UISlider *)sender;
gText.text = [NSString stringWithFormat:@"%.0f",gSlider.value];
gSlider.value = gText.text.floatValue;
UIColor *newColor = [UIColor colorWithRed:rSlider.value green:gSlider.value blue:bSlider.value alpha:alphaSlider.value];
colorView.backgroundColor = newColor;
}
-(void)redSlider:(id)sender {
rSlider = (UISlider *)sender;
rText.text = [NSString stringWithFormat:@"%.0f",rSlider.value];
rSlider.value = rText.text.floatValue;
UIColor *newColor = [UIColor colorWithRed:rSlider.value green:gSlider.value blue:bSlider.value alpha:alphaSlider.value];
colorView.backgroundColor = newColor;
}
-(void)saturate:(id)sender {
saturationSlider = (UISlider *)sender;
UIColor *currentColor = colorView.backgroundColor;
CGFloat hue, saturation, brightness, alpha;
BOOL success = [currentColor getHue:&hue saturation:&saturation brightness:&brightness alpha:&alpha];
UIColor *newColor = [UIColor colorWithHue:hue saturation:saturationSlider.value brightness:hellSlider.value alpha:alphaSlider.value];
colorView.backgroundColor = newColor;
alphaText.text = [NSString stringWithFormat:@"%.2f",alphaSlider.value];
brightnessText.text = [NSString stringWithFormat:@"%.2f",hellSlider.value];
saturationText.text = [NSString stringWithFormat:@"%.2f",saturationSlider.value];
}
- (void)changeOpacity:(id)sender {
alphaSlider = (UISlider *)sender;
float red = r;
float green = g;
float blue = b;
UIColor *color2 = [UIColor colorWithRed:red green:green blue:blue alpha: alphaSlider.value];
colorView.backgroundColor = color2;
alphaText.text = [NSString stringWithFormat:@"%.2f",alphaSlider.value];
brightnessText.text = [NSString stringWithFormat:@"%.2f",hellSlider.value];
saturationText.text = [NSString stringWithFormat:@"%.2f",saturationSlider.value];
}
- (void)changeBrightness:(id)sender {
hellSlider = (UISlider *)sender;
UIColor *currentColor = colorView.backgroundColor;
CGFloat hue, saturation, brightness, alpha;
BOOL success = [currentColor getHue:&hue saturation:&saturation brightness:&brightness alpha:&alpha];
brightness = hellSlider.value;
UIColor *newColor = [UIColor colorWithHue:hue saturation:saturationSlider.value brightness:hellSlider.value alpha:alphaSlider.value];
colorView.backgroundColor = newColor;
alphaText.text = [NSString stringWithFormat:@"%.2f",alphaSlider.value];
brightnessText.text = [NSString stringWithFormat:@"%.2f",hellSlider.value];
saturationText.text = [NSString stringWithFormat:@"%.2f",saturationSlider.value];
}
@end
答案 0 :(得分：2)
替换此行
[self.view addGestureRecognizer: panGesture];
用这个
[gradientView addGestureRecognizer:panGesture];