从字节数组的CGImage

问题描述

使用标准图片格式（jpeg，gif，png等）从文件加载CGImage或NSImage非常简单。

Loading a CGImage or NSImage from a file using a standard image format (jpeg, gif, png et.) is all very simple.

但是，现在我需要从使用libfreetype生成的内存中的字节数组中创建一个CGImage。它真的很容易从格式化的字节数组创建OpenGL纹理，我可以看到如何创建一个CGBitmapContext来写。但我似乎找不到一个简单的方法从原始像素数组创建一个CGImage。

However, I now need to create a CGImage from an array in bytes in memory generated using libfreetype. Its really easy to create OpenGL textures from an array of formatted bytes, and I can see how to create a CGBitmapContext to write to. But I can't seem to find an easy way to create a CGImage from a raw pixel array.

推荐答案

CGDataProvider ，让CG从您的提供者请求必要的数据，而不是写入图像缓冲区。

You can create a CGDataProvider, and let CG request the necessary data from your provider, instead of writing to an image buffer.

一个非常简单的例子，生成大小为64x64的黑色 CGImage 。

Here's a very simple example that generates a black CGImage of size 64x64.

CGDataProviderSequentialCallbacks callbacks;
callbacks.getBytes = getBytes;

CGDataProviderRef provider = CGDataProviderCreateSequential(NULL, &callbacks);
CGColorSpaceRef space = CGColorSpaceCreateDeviceRGB();
CGImageRef img = CGImageCreate(64,                         // width
                               64,                         // height
                               8,                          // bitsPerComponent
                               24,                         // bitsPerPixel
                               64*3,                       // bytesPerRow
                               space,                      // colorspace
                               kCGBitmapByteOrderDefault,  // bitmapInfo
                               provider,                   // CGDataProvider
                               NULL,                       // decode array
                               NO,                         // shouldInterpolate
                               kCGRenderingIntentDefault); // intent

CGColorSpaceRelease(space);
CGDataProviderRelease(provider);

// use the created CGImage

CGImageRelease(img);

，getBytes的定义如下：

and getBytes is defined like this:

size_t getBytes(void *info, void *buffer, size_t count) {
    memset(buffer, 0x00, count);
    return count;
}

当然，您将需要实现其他回调（ skipForward ， rewind ， releaseInfo ），并使用适当的结构或对象 info 。

of course, you will want to implement the other callbacks (skipForward, rewind, releaseInfo), and use a proper structure or object for info.

有关详细信息，请查看和参考。

For more information, check out the CGImage and CGDataProvider references.

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