以编程方式从 UILabel 创建图像 [英] Programmatically create image from UILabel

问题描述

我想使用 UILabel 以编程方式(在运行时)创建字节图像表示的 RGBA 流.

I want to use a UILabel to create an RGBA stream of bytes image representation programmatically (at runtime).

例如，我想创建一个特定字体和特定文本的 UILabel，将其转换为 RGBA 无符号字节的 NSData，然后我可以轻松地将其转换为 OpenGL 纹理并显示它但是我想要.

For example, I want to create a UILabel in a specific font and with specific text, turn this in to an NSData of RGBA unsigned bytes, and then from that point I can easily turn it in to an OpenGL texture and display it however I want.

知道生成图像的尺寸很重要，但如果绝对必要，我可以创建一个非常宽的空白"画布来渲染它，然后在运行时通过检查字节自己检测宽度和高度.

It's important that I can know the dimensions of the resulting image, although if absolutely necessary I can create a very wide "blank" canvas to render this in to, and then at runtime detect the width and height myself by checking the bytes.

如果我可以通过 UIImage/CG 实现这一点，那绝对是一个优势 - 具有多个渲染目标的解决方案是不合理/不理想的.

If I can achieve this through UIImage/CG it's a definite plus - and a solution with multiple render targets isn't reasonable/desired.

悬赏；我最初是从 meronix 那里得到这个好看的答案，但现在我有时间尝试一下，但它不能正常工作.我在昨天"需要这个工作并且非常沮丧.这里有一些细微差别，比我更了解 Cocoa 绘图状态的人肯定能捕捉到.

Placed a bounty; I had originally gotten this good-looking answer below from meronix, but now I got time to try it out and it does not work properly. I need this working "yesterday" and am quite frustrated. There's some nuance here, that someone who knows Cocoa drawing state better than me can surely catch.

推荐答案

CGFloat scale  = [[[view window] screen] scale];
CGRect  bounds = [view bounds];

CGColorSpaceRef space = CGColorSpaceCreateDeviceRGB();
CGContextRef ctx = CGBitmapContextCreate(NULL, CGRectGetWidth(bounds) * scale, CGRectGetHeight(bounds) * scale, 8, CGRectGetWidth(bounds) *
scale * 4, space, kCGImageAlphaPremultipliedLast);
CGContextTranslateCTM(ctx, 0.0, CGRectGetHeight(bounds) * scale);
CGContextScaleCTM(ctx, scale, -scale);
[[view layer] renderInContext:ctx];

然后，通过 CGBitmapContextGetData(myContext) 使用字节.没有理由为 UIImage 烦恼

Then, use the bytes via CGBitmapContextGetData(myContext). No reason to bother with a UIImage

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