网站上有几个类似的问题,但我正在寻找一些特定且略微不同的东西。
我遵循了这里给出的指示:http://www.cimgf.com/2010/01/28/fun-with-uibuttons-and-core-animation-layers/,通过对UIButton进行子类化来创建一个通用类,可以在其中指定渐变颜色,而不是尝试使用静态图像。
我遇到了一个问题,即按钮层上的setMasksToBounds要么允许 A)显示投影,但同时也允许渐变层在圆角之外显示 要么 B)让渐变层剪切到圆角,但不允许显示投影
我解决问题的方法似乎很笨拙(尽管它有效),我想知道是否有人知道更好和/或更清晰的方法来完成相同的事情。以下是我的代码:
CSGradientButton.h
#import <UIKit/UIKit.h>
@interface CSGradientButton : UIButton {
UIColor *_highColor;
UIColor *_lowColor;
CAGradientLayer *gradientLayer;
CALayer *wrapperLayer;
CGColorRef _borderColor;
}
@property (nonatomic, retain) UIColor *_highColor;
@property (nonatomic, retain) UIColor *_lowColor;
@property (nonatomic) CGColorRef _borderColor;
@property (nonatomic, retain) CALayer *wrapperLayer;
@property (nonatomic, retain) CAGradientLayer *gradientLayer;
- (void)setHighColor:(UIColor*)color;
- (void)setLowColor:(UIColor*)color;
- (void)setBorderColor:(CGColorRef)color;
- (void)setCornerRadius:(float)radius;
@end
CSGradient.m(仅涉及有趣的部分)
#import "CSGradientButton.h"
@implementation CSGradientButton
...
- (void)awakeFromNib
{
// Initialize the gradient wrapper layer
wrapperLayer = [[CALayer alloc] init];
// Set its bounds to be the same of its parent
[wrapperLayer setBounds:[self bounds]];
// Center the layer inside the parent layer
[wrapperLayer setPosition:
CGPointMake([self bounds].size.width/2,
[self bounds].size.height/2)];
// Initialize the gradient layer
gradientLayer = [[CAGradientLayer alloc] init];
// Set its bounds to be the same of its parent
[gradientLayer setBounds:[self bounds]];
// Center the layer inside the parent layer
[gradientLayer setPosition: CGPointMake([self bounds].size.width/2,
[self bounds].size.height/2)];
// Insert the layer at position zero to make sure the
// text of the button is not obscured
[wrapperLayer insertSublayer:gradientLayer atIndex:0];
[[self layer] insertSublayer:wrapperLayer atIndex:0];
// Set the layer's corner radius
[[self layer] setCornerRadius:0.0f];
[wrapperLayer setCornerRadius:0.0f];
// Turn on masking
[wrapperLayer setMasksToBounds:YES];
// Display a border around the button
// with a 1.0 pixel width
[[self layer] setBorderWidth:1.0f];
}
- (void)drawRect:(CGRect)rect
{
if (_highColor && _lowColor)
{
// Set the colors for the gradient to the
// two colors specified for high and low
[gradientLayer setColors:
[NSArray arrayWithObjects:
(id)[_highColor CGColor],
(id)[_lowColor CGColor], nil]];
}
[super drawRect:rect];
}
- (void)setCornerRadius:(float)radius
{
[[self layer] setCornerRadius:radius];
// and get the wrapper for the gradient layer too
[wrapperLayer setCornerRadius:radius];
}
- (void)setHighColor:(UIColor*)color
{
// Set the high color and repaint
[self set_highColor:color];
[[self layer] setNeedsDisplay];
}
- (void)setLowColor:(UIColor*)color
{
// Set the low color and repaint
[self set_lowColor:color];
[[self layer] setNeedsDisplay];
}
- (void)setBorderColor:(CGColorRef)color
{
[[self layer] setBorderColor:color];
[[self layer] setNeedsDisplay];
}
@end
可以看出,我添加了一个“包装”层,梯度图层可以安全地进行遮盖,而按钮视图的顶层CALayer在添加阴影时可以安全地设置masksToBounds = NO。 我添加了一个setCornerRadius:方法,允许顶层和“包装”都进行调整。
所以,与其像这样做:[[myCustomButton layer] setCornerRadius:3.0f];
,我只需这样说:[myCustomButton setCornerRadius:3.0f];
可以看出,这可能不是我希望的那么简洁。
有更好的方法吗?