如何绘制背景具有 alpha 值但前景正常的自定义按钮

发布于 2024-10-12 04:56:52 字数 721 浏览 0 评论 0原文

我正在尝试创建一个具有半透明背景和不透明前景的自定义按钮。我使用以下代码为自定义按钮创建背景图像：

UIImage *buttonBg = [UIImage imageNamed:@"ButtonBG_35"];
buttonBg = [buttonBg stretchableImageWithLeftCapWidth:14.0 topCapHeight:0];

CGSize size = self.button1.bounds.size;

UIGraphicsBeginImageContext( size );

[buttonBg drawInRect:CGRectMake( 0, 0, size.width, size.height ) blendMode:kCGBlendModeNormal alpha:0.33];
UIImage *button1BgImage = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

[self.button1 setBackgroundImage:button1BgImage forState:UIControlStateNormal];

这正如我在按钮中放置文本时所期望的那样工作。但是，如果我将图像放置在按钮前景中，则该图像也是半透明的。如何阻止前景图像变得透明。

我尝试使用 alpha:1.0 将图像绘制到按钮中，但这没有执行任何操作。

感谢您的任何帮助。

原文

I am trying to create a custom button with a semi-transparent background and a non-transparent foreground. I am using the following code to create a background image for the custom button:

UIImage *buttonBg = [UIImage imageNamed:@"ButtonBG_35"];
buttonBg = [buttonBg stretchableImageWithLeftCapWidth:14.0 topCapHeight:0];

CGSize size = self.button1.bounds.size;

UIGraphicsBeginImageContext( size );

[buttonBg drawInRect:CGRectMake( 0, 0, size.width, size.height ) blendMode:kCGBlendModeNormal alpha:0.33];
UIImage *button1BgImage = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();

[self.button1 setBackgroundImage:button1BgImage forState:UIControlStateNormal];

This works as I expect when placing text in the button. However, if I place an image in the button foreground then that image is also semi-transparent. How do I stop the foreground image from being transparent.

I tried to draw the image into the button using an alpha:1.0 but that didn't do anything.

Thanks for any help.

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