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实现不规则形状的按钮

分类: IT文章 • 2022-05-12 16:43:51

用到了四个文件：

UIImage+ColorAtPixel.h UIImage+ColorAtPixel.m OBShapedButton.h OBShapedButton.m

作者：Ole Begemann

 1 /*
 2  Copyright (c) 2009 Ole Begemann
 3  
 4  Permission is hereby granted, free of charge, to any person obtaining a copy
 5  of this software and associated documentation files (the "Software"), to deal
 6  in the Software without restriction, including without limitation the rights
 7  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 8  copies of the Software, and to permit persons to whom the Software is
 9  furnished to do so, subject to the following conditions:
10  
11  The above copyright notice and this permission notice shall be included in
12  all copies or substantial portions of the Software.
13  
14  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
17  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
18  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
19  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
20  THE SOFTWARE.
21  */
22 
23 /*
24  UIImage+ColorAtPixel.h
25 
26  Created by Ole Begemann
27  October, 2009
28  */
29  
30 #import <UIKit/UIKit.h>
31 
32 /*
33  A category on UIImage that enables you to query the color value of arbitrary 
34  pixels of the image.
35  */
36 @interface UIImage (ColorAtPixel)
37 
38 - (UIColor *)colorAtPixel:(CGPoint)point;
39 
40 @end
View Code 
 1 /*
 2  Copyright (c) 2009 Ole Begemann
 3  
 4  Permission is hereby granted, free of charge, to any person obtaining a copy
 5  of this software and associated documentation files (the "Software"), to deal
 6  in the Software without restriction, including without limitation the rights
 7  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 8  copies of the Software, and to permit persons to whom the Software is
 9  furnished to do so, subject to the following conditions:
10  
11  The above copyright notice and this permission notice shall be included in
12  all copies or substantial portions of the Software.
13  
14  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
17  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
18  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
19  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
20  THE SOFTWARE.
21  */
22 
23 /*
24  UIImage+ColorAtPixel.m
25  
26  Created by Ole Begemann
27  October, 2009
28  */
29 
30 #import <CoreGraphics/CoreGraphics.h>
31 
32 #import "UIImage+ColorAtPixel.h"
33 
34 
35 @implementation UIImage (ColorAtPixel)
36 
37 /*
38  Returns the color of the image pixel at point. Returns nil if point lies outside the image bounds.
39  If the point coordinates contain decimal parts, they will be truncated.
40  
41  To get at the pixel data, this method must draw the image into a bitmap context.
42  For minimal memory usage and optimum performance, only the specific requested
43  pixel is drawn.
44  If you need to query pixel colors for the same image repeatedly (e.g., in a loop),
45  this approach is probably less efficient than drawing the entire image into memory
46  once and caching it.
47  */
48 - (UIColor *)colorAtPixel:(CGPoint)point {
49     // Cancel if point is outside image coordinates
50     if (!CGRectContainsPoint(CGRectMake(0.0f, 0.0f, self.size.width, self.size.height), point)) {
51         return nil;
52     }
53     
54     
55     // Create a 1x1 pixel byte array and bitmap context to draw the pixel into.
56     // Reference: http://stackoverflow.com/questions/1042830/retrieving-a-pixel-alpha-value-for-a-uiimage
57     NSInteger pointX = trunc(point.x);
58     NSInteger pointY = trunc(point.y);
59     CGImageRef cgImage = self.CGImage;
60     NSUInteger width = self.size.width;
61     NSUInteger height = self.size.height;
62     CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
63     int bytesPerPixel = 4;
64     int bytesPerRow = bytesPerPixel * 1;
65     NSUInteger bitsPerComponent = 8;
66     unsigned char pixelData[4] = { 0, 0, 0, 0 };
67     CGContextRef context = CGBitmapContextCreate(pixelData, 
68                                                  1,
69                                                  1,
70                                                  bitsPerComponent, 
71                                                  bytesPerRow, 
72                                                  colorSpace,
73                                                  kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
74     CGColorSpaceRelease(colorSpace);
75     CGContextSetBlendMode(context, kCGBlendModeCopy);
76 
77     // Draw the pixel we are interested in onto the bitmap context
78     CGContextTranslateCTM(context, -pointX, pointY-(CGFloat)height);
79     CGContextDrawImage(context, CGRectMake(0.0f, 0.0f, (CGFloat)width, (CGFloat)height), cgImage);
80     CGContextRelease(context);
81     
82     // Convert color values [0..255] to floats [0.0..1.0]
83     CGFloat red   = (CGFloat)pixelData[0] / 255.0f;
84     CGFloat green = (CGFloat)pixelData[1] / 255.0f;
85     CGFloat blue  = (CGFloat)pixelData[2] / 255.0f;
86     CGFloat alpha = (CGFloat)pixelData[3] / 255.0f;
87     return [UIColor colorWithRed:red green:green blue:blue alpha:alpha];
88 }
89 
90 @end
View Code 
 1 /*
 2  Copyright (c) 2009 Ole Begemann
 3  
 4  Permission is hereby granted, free of charge, to any person obtaining a copy
 5  of this software and associated documentation files (the "Software"), to deal
 6  in the Software without restriction, including without limitation the rights
 7  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 8  copies of the Software, and to permit persons to whom the Software is
 9  furnished to do so, subject to the following conditions:
10  
11  The above copyright notice and this permission notice shall be included in
12  all copies or substantial portions of the Software.
13  
14  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
15  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
17  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
18  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
19  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
20  THE SOFTWARE.
21  */
22 
23 /*
24  OBShapedButton.h
25  
26  Created by Ole Begemann
27  October, 2009
28  */
29 
30 #import <UIKit/UIKit.h>
31 
32 
33 /*
34  OBShapedButton is a UIButton subclass optimized for non-rectangular button shapes.
35  Instances of OBShapedButton respond to touches only in areas where the image that is
36  assigned to the button for UIControlStateNormal is non-transparent.
37  
38  Usage:
39  - Add OBShapedButton.h, OBShapedButton.m, UIImage+ColorAtPixel.h, and UIImage+ColorAtPixel.m
40    to your Xcode project.
41  - Design your UI in Interface Builder with UIButtons as usual. Set the Button type to Custom
42    and provide transparent PNG images for the different control states as needed.
43  - In the Identity Inspector in Interface Builder, set the Class of the button to OBShapedButton.
44    That's it! Your button will now only respond to touches where the PNG image for the normal
45    control state is non-transparent.
46  */
47 
48 
49 
50 // -[UIView hitTest:withEvent: ignores views that an alpha level less than 0.1.
51 // So we will do the same and treat pixels with alpha < 0.1 as transparent.
52 #define kAlphaVisibleThreshold (0.1f)
53 
54 
55 @interface OBShapedButton : UIButton {
56     // Our class interface is empty. OBShapedButton only overwrites one method of UIView.
57     // It has no attributes of its own.
58 }
59 
60 @end
View Code 
  1 /*
  2  Copyright (c) 2009 Ole Begemann
  3  
  4  Permission is hereby granted, free of charge, to any person obtaining a copy
  5  of this software and associated documentation files (the "Software"), to deal
  6  in the Software without restriction, including without limitation the rights
  7  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  8  copies of the Software, and to permit persons to whom the Software is
  9  furnished to do so, subject to the following conditions:
 10  
 11  The above copyright notice and this permission notice shall be included in
 12  all copies or substantial portions of the Software.
 13  
 14  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 15  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 16  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 17  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 18  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 19  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 20  THE SOFTWARE.
 21  */
 22 
 23 /*
 24  OBShapedButton.m
 25  
 26  Created by Ole Begemann
 27  October, 2009
 28  */
 29 
 30 #import "OBShapedButton.h"
 31 #import "UIImage+ColorAtPixel.h"
 32 
 33 
 34 @interface OBShapedButton ()
 35 
 36 @property (nonatomic, assign) CGPoint previousTouchPoint;
 37 @property (nonatomic, assign) BOOL previousTouchHitTestResponse;
 38 
 39 - (void)resetHitTestCache;
 40 
 41 @end
 42 
 43 
 44 @implementation OBShapedButton
 45 
 46 @synthesize previousTouchPoint = _previousTouchPoint;
 47 @synthesize previousTouchHitTestResponse = _previousTouchHitTestResponse;
 48 
 49 - (id)initWithFrame:(CGRect)frame
 50 {
 51     self = [super initWithFrame:frame];
 52     if (self) {
 53         [self resetHitTestCache];
 54     }
 55     return self;
 56 }
 57 
 58 - (id)initWithCoder:(NSCoder *)decoder
 59 {
 60     self = [super initWithCoder:decoder];
 61     if (self) {
 62         [self resetHitTestCache];
 63     }
 64     return self;
 65 }
 66 
 67 
 68 #pragma mark - Hit testing
 69 
 70 - (BOOL)isAlphaVisibleAtPoint:(CGPoint)point forImage:(UIImage *)image
 71 {
 72     // Correct point to take into account that the image does not have to be the same size
 73     // as the button. See https://github.com/ole/OBShapedButton/issues/1
 74     CGSize iSize = image.size;
 75     CGSize bSize = self.bounds.size;
 76     point.x *= (bSize.width != 0) ? (iSize.width / bSize.width) : 1;
 77     point.y *= (bSize.height != 0) ? (iSize.height / bSize.height) : 1;
 78 
 79     CGColorRef pixelColor = [[image colorAtPixel:point] CGColor];
 80     CGFloat alpha = CGColorGetAlpha(pixelColor);
 81     return alpha >= kAlphaVisibleThreshold;
 82 }
 83 
 84 
 85 // UIView uses this method in hitTest:withEvent: to determine which subview should receive a touch event.
 86 // If pointInside:withEvent: returns YES, then the subview’s hierarchy is traversed; otherwise, its branch
 87 // of the view hierarchy is ignored.
 88 - (BOOL)pointInside:(CGPoint)point withEvent:(UIEvent *)event 
 89 {
 90     // Return NO if even super returns NO (i.e., if point lies outside our bounds)
 91     BOOL superResult = [super pointInside:point withEvent:event];
 92     if (!superResult) {
 93         return superResult;
 94     }
 95 
 96     // Don't check again if we just queried the same point
 97     // (because pointInside:withEvent: gets often called multiple times)
 98     if (CGPointEqualToPoint(point, self.previousTouchPoint)) {
 99         return self.previousTouchHitTestResponse;
100     } else {
101         self.previousTouchPoint = point;
102     }
103     
104     // We can't test the image's alpha channel if the button has no image. Fall back to super.
105     UIImage *buttonImage = [self imageForState:UIControlStateNormal];
106     UIImage *buttonBackground = [self backgroundImageForState:UIControlStateNormal];
107 
108     BOOL response = NO;
109     
110     if (buttonImage == nil && buttonBackground == nil) {
111         response = YES;
112     }
113     else if (buttonImage != nil && buttonBackground == nil) {
114         response = [self isAlphaVisibleAtPoint:point forImage:buttonImage];
115     }
116     else if (buttonImage == nil && buttonBackground != nil) {
117         response = [self isAlphaVisibleAtPoint:point forImage:buttonBackground];
118     }
119     else {
120         if ([self isAlphaVisibleAtPoint:point forImage:buttonImage]) {
121             response = YES;
122         } else {
123             response = [self isAlphaVisibleAtPoint:point forImage:buttonBackground];
124         }
125     }
126     
127     self.previousTouchHitTestResponse = response;
128     return response;
129 }
130 
131 
132 // Reset the Hit Test Cache when a new image is assigned to the button
133 - (void)setImage:(UIImage *)image forState:(UIControlState)state
134 {
135     [super setImage:image forState:state];
136     [self resetHitTestCache];
137 }
138 
139 - (void)setBackgroundImage:(UIImage *)image forState:(UIControlState)state
140 {
141     [super setBackgroundImage:image forState:state];
142     [self resetHitTestCache];
143 }
144 
145 - (void)resetHitTestCache
146 {
147     self.previousTouchPoint = CGPointMake(CGFLOAT_MIN, CGFLOAT_MIN);
148     self.previousTouchHitTestResponse = NO;
149 }
150 
151 @end
View Code

使用：

使用IB，添加一个UIButton，把关联类选择为OBShapedButton，把Button的Type修改为Custom，添加一个异形的Image，然后编译运行即可看到效果。

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