在UIGraphicsBeginImageContextWithOptions中的CGContextDrawImage上忽略了UIEdgeInsets [英] UIEdgeInsets ignored on CGContextDrawImage within a UIGraphicsBeginImageContextWithOptions

问题描述

当绘制到屏幕外缓冲区时，我正在努力让Image Insets工作。

I am struggling getting Image Insets to work when drawing to an off screen buffer.

在UIImage上使用resizableImageWithCapInsets：直接setImage：进入按钮工作正常我：

Using the resizableImageWithCapInsets: on an UIImage directly setImage: into a button works fine for me:

UIImage * base = [UIImage imageNamed:@"button.png"];
UIImage * img = [base resizableImageWithCapInsets:UIEdgeInsetsMake(20,20,20,20)];
[self setImage:img forState:UIControlStateNormal];

如下所示（左边是原始缩放，右边是使用insets缩放）：

As shown below (left is raw scaling, right is scaled with insets):

所以正确的一个很好 - 线条顶部/ botton / left / right等间距。到目前为止一切都那么好。

So the right one is fine - the lines top/botton/left/right are equally spaced. So far so good.

现在，如果我尝试使用绘制的图像进行相同的操作，然后使用以下内容捕获到屏幕外缓冲区：

Now if I try the very same thing with an image that is drawn and then captured to an off screen buffer with:

UIImage * base = [UIImage imageNamed:@"button.png"];
base = [base resizableImageWithCapInsets:UIEdgeInsetsMake(20,20,20,20)];

UIGraphicsBeginImageContextWithOptions(self.bounds.size, NO, 0);
ctx = UIGraphicsGetCurrentContext();

CGContextDrawImage(ctx, CGRectMake(0,0,self.bounds.size.width,
         self.bounds.size.height), [base CGImage]);

img = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext(); 
[self setImage:img forState:UIControlStateNormal];

我得到以下（再次左边是原始缩放，右边是插图）：

I get below (again left is raw scaling, right is with insets):

。

所以这里似乎是插图被忽略了。

So here it seems that the insets are ignored.

有人对这里出了什么问题有任何建议吗？ http://people.apache.org/~dirkx/insetSample.zip <的完整功能示例/ a>以及 http://pastebin.com/rm8h6YFV 上的密钥代码。

Anyone any suggestions as to what is going wrong here ? Fully functional example at http://people.apache.org/~dirkx/insetSample.zip and just the key code at http://pastebin.com/rm8h6YFV.

赞赏任何和所有建议。

Dw

推荐答案

我猜可伸缩的UIImages的处理级别高于Quartz2D，所以使用 CGContextDrawImage 不会起作用。

I would guess that stretchable UIImages are handled at a higher level than Quartz2D and so using CGContextDrawImage is not going to work.

您可以尝试使用 - [UIImage drawInRect] 。这将绘制到当前的UIGraphics上下文，这是您在代码段中创建的位图上下文。

You could try using -[UIImage drawInRect] instead. This will draw to the current UIGraphics context, which is your bitmap context that you create in your code snippet.

相关行是：

[base drawInRect:CGRectMake(0,0,self.bounds.size.width,
                                    self.bounds.size.height)];

这篇关于在UIGraphicsBeginImageContextWithOptions中的CGContextDrawImage上忽略了UIEdgeInsets的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！