我有一个UIButton
子类,我正在使用drawRect:
绘制边界。选择按钮后,我希望更改背景颜色,并删除边框。 (手动绘制边框,因为有时我只需要一边有一个边框)
由于某些原因,当我使用CGContextClearRect
删除已经绘制的边框时,我得到的是黑色背景而不是我设置的颜色:
- (void)setSelected:(BOOL)selected {
[super setSelected:selected];
if (selected) {
self.allOff = YES;
self.backgroundColor = self.selectedColor;
[self setTitleColor:[UIColor whiteColor] forState:UIControlStateSelected];
} else {
self.allOff = NO;
self.backgroundColor = self.defaultColor;
[self setTitleColor:[OTAColors colorWithRed:163 green:163 blue:163] forState:UIControlStateNormal];
}
}
- (void)_setup {
self.opaque = NO;
self.defaultColor = [[UIColor whiteColor] colorWithAlphaComponent:0.99];
self.selectedColor = [[OTAColors colorWithRed:33 green:59 blue:70] colorWithAlphaComponent:0.99];
self.backgroundColor = self.defaultColor;
[self setTitleColor:[OTAColors colorWithRed:163 green:163 blue:163] forState:UIControlStateNormal];
self.titleLabel.font = [UIFont fontWithName:OTAFontPFDinTextCondProMedium size:20];
self.titleLabel.textAlignment = NSTextAlignmentCenter;
}
- (void)drawRect:(CGRect)rect {
CGFloat borderWidth = 0.7f;
CGContextRef ctx = UIGraphicsGetCurrentContext();
CGContextSetLineWidth(ctx, borderWidth);
UIColor *borderColor = self.borderColor ? self.borderColor : [UIColor blackColor];
CGContextSetStrokeColorWithColor(ctx, borderColor.CGColor);
if (!self.allOff) {
// Left
if (self.left) {
CGContextMoveToPoint(ctx, 0, 0);
CGContextAddLineToPoint(ctx, 0,rect.size.height);
CGContextStrokePath(ctx);
}
// Right
if (self.right) {
CGContextMoveToPoint(ctx, rect.size.width, 0);
CGContextAddLineToPoint(ctx, rect.size.width,rect.size.height);
CGContextStrokePath(ctx);
}
// Top
if (self.top) {
CGContextMoveToPoint(ctx, 0, 0);
CGContextAddLineToPoint(ctx, rect.size.width,0);
CGContextStrokePath(ctx);
}
// Bottom
if (self.bottom) {
CGContextMoveToPoint(ctx, 0, rect.size.height);
CGContextAddLineToPoint(ctx, rect.size.width,rect.size.height);
CGContextStrokePath(ctx);
}
} else {
CGContextClearRect(ctx, rect);
}
}
为什么会发生这种情况? CGContextClearRect
似乎导致了这个问题。
答案 0 :(得分:2)
调用clear rect会清除所有内容,因此会恢复为默认的黑色内容。相反,您应首先使用背景颜色填充矩形,然后在此之后为边框绘制相应的线条。