xcode 如何在 iPhone 的 UIGraphicsImageContext 中使用属性（特别是描边和填充颜色）绘制文本
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How to draw text with attributes (Specifically Stroke and Fill color) in UIGraphicsImageContext for iPhone
提问by werdsackjon
I am trying to create an image of text to put on top of another image. The text needs to have a white fill and a black stroke outline. I am using objective-C and it is for the iPhone. I can get the text to show up; however, I cannot seam to figure out how to get the stroke and fill color to change.
我正在尝试创建一个文本图像以放置在另一个图像之上。文本需要有白色填充和黑色描边轮廓。我正在使用objective-C，它适用于iPhone。我可以让文字显示出来；但是，我无法弄清楚如何改变笔触和填充颜色。
self.bigImageis a pointer to a UIImage in my xib.
self.bigImage是指向我的 xib 中的 UIImage 的指针。
Here is my code: (This code works... I want it to have a black stroke with white fill however)
这是我的代码：（此代码有效......但是我希望它有一个带有白色填充的黑色描边）
- (IBAction)submitBtn:(id)sender {
UIFont *myfont = [UIFont fontWithName:@"myfont" size:32];
UIImage *textImage = [self imageFromText:@"teststring" font:myfont];
CGSize finalSize = [self.bigImage.image size];
CGSize textSize = [textImage size];
UIGraphicsBeginImageContext(finalSize);
[self.bigImage.image drawInRect:CGRectMake(0,0, finalSize.width, finalSize.height)];
[textImage drawInRect:CGRectMake(0, 0, textSize.width, textSize.height)];
UIImage *newImg = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
self.bigImage.image = newImg;
}
-(UIImage *)imageFromText:(NSString *)text font:(UIFont *)font {
CGSize size = [text sizeWithFont:font];
// check if UIGraphicsBeginImageContextWithOptions is available (iOS is 4.0+)
if (UIGraphicsBeginImageContextWithOptions != NULL)
UIGraphicsBeginImageContextWithOptions(size,NO,0.0);
else
// iOS is < 4.0
UIGraphicsBeginImageContext(size);
[text drawAtPoint:CGPointMake(0.0, 0.0) withFont:font];
// transfer image
UIImage *Image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return Image;
}
I can get it to render one or the other. If I add this code I get a black stroke:
我可以让它渲染一个或另一个。如果我添加此代码，我会得到一个黑色的笔划：
CGContextSetTextDrawingMode(UIGraphicsGetCurrentContext(), kCGTextStroke);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 2);
CGContextSetStrokeColorWithColor(UIGraphicsGetCurrentContext(), [[UIColor blackColor] CGColor]);
If I add this code I get a white font:
如果我添加此代码，我会得到一个白色字体：
CGFloat fontColor[4] = {255,255,255,1};
CGContextSetFillColor(UIGraphicsGetCurrentContext(), fontColor);
But If I add both snipets I get the black stroke but the font color is transparent...
但是，如果我添加两个 snipets，我会得到黑色笔划，但字体颜色是透明的...
Solved:thanks to a little help from 'Brane':
已解决：感谢“Brane”的一点帮助：
I needed to add this bit of code before the drawAtPoint:
我需要在以下代码之前添加这段代码drawAtPoint：
CGFloat fontColor[4] = {255,255,255,1};
CGContextSetFillColor(UIGraphicsGetCurrentContext(), fontColor);
CGContextSetTextDrawingMode(UIGraphicsGetCurrentContext(), kCGTextFillStroke);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 2);
CGContextSetStrokeColorWithColor(UIGraphicsGetCurrentContext(), [[UIColor blackColor] CGColor]);
采纳答案by werdsackjon
I fixed this by modifying Brane's post... I needed to add this snipet of code before drawAtPoint...
我通过修改 Brane 的帖子修复了这个问题......我需要在drawAtPoint......之前添加这段代码......
CGFloat fontColor[4] = {255,255,255,1};
CGContextSetFillColor(UIGraphicsGetCurrentContext(), fontColor);
CGContextSetTextDrawingMode(UIGraphicsGetCurrentContext(), kCGTextFillStroke);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 2);
CGContextSetStrokeColorWithColor(UIGraphicsGetCurrentContext(), [[UIColor blackColor] CGColor]);
回答by Nicola
回答by Brane
Two problems to solve.
两个问题要解决。
First, in order to draw the background, you can't rely on drawAtPoint:withFont:as it does not draw background.
首先，为了绘制背景，您不能依赖drawAtPoint:withFont:它，因为它不绘制背景。
Use CGContextFillRect to draw your background color:
使用 CGContextFillRect 绘制背景颜色：
[[UIColor whiteColor] set];
CGContextFillRect( UIGraphicsGetCurrentContext(), CGRectMake( 0, 0, size.width, size.height )
Second, you need to set the stroke colour using
其次，您需要使用设置笔触颜色
[[UIColor blackColor] set];
prior to calling [text drawAtPoint:CGPointMake(0.0, 0.0) withFont:font];
在打电话之前 [text drawAtPoint:CGPointMake(0.0, 0.0) withFont:font];
