Question

我找到了一些很好的代码，它是UIView的子类，用阴影绘制该视图。然后我可以在任何想要放置阴影的地方使用该视图：

-(void) layoutSubviews {
    CGFloat coloredBoxMargin = 40;
    CGFloat coloredBoxHeight = self.frame.size.height;
    _coloredBoxRect = CGRectMake(coloredBoxMargin, 0, 40, coloredBoxHeight);
}

-(void) drawRect:(CGRect)rect {

    CGColorRef lightColor =  [UIColor colorWithRed:105.0f/255.0f green:179.0f/255.0f blue:216.0f/255.0f alpha:0.8].CGColor;
    CGColorRef shadowColor = [UIColor colorWithRed:0.2 green:0.2 blue:0.2 alpha:0.4].CGColor;   

    CGContextRef context = UIGraphicsGetCurrentContext();
    // Draw shadow
    CGContextSaveGState(context);
    CGContextSetFillColorWithColor(context, lightColor);
    CGContextSetShadowWithColor(context, CGSizeMake(-13, 0), 10, shadowColor);

    CGContextFillRect(context, _coloredBoxRect);
    CGContextRestoreGState(context);
}

使用以下内容创建：

UIViewWithShadowRight* verticalLineView2 = [[[UIViewWithShadowRight alloc] initWithFrame:CGRectMake(60, 0, 40 , self.view.frame.size.height)] autorelease];
[verticalLineView2 setBackgroundColor:[UIColor clearColor]];
[verticalLineView2 setAutoresizingMask:UIViewAutoresizingFlexibleHeight];
[verticalLineView2 setClipsToBounds:NO];
[self.view addSubview:verticalLineView2];
[self.view bringSubviewToFront:verticalLineView2];

问题是，阴影是从右到左绘制的，如何将其反转并从左到右绘制？

Answer 1

使13为正而非为负。这是绘制阴影的x偏移量，负值位于原始图形的左侧，正值位于右侧。

Answer 2

尝试更改此CGContextSetShadowWithColor（context，CGSizeMake（-13,0），10，shadowColor）; 将当前x值（-13）替换为右侧的值。

iOS：在UIView中绘制阴影

2 个答案: