xcode 从 RGB 数据创建图像？
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Create image from RGB data?
提问by John P
I'm having real trouble with this. I have some raw rgb data, values from 0 to 255, and want to display it as an image on the iphone but can't find out how to do it. Can anyone help? I think i might need to use CGImageCreate but just don't get it. Tried looking at the class reference and am feeling quite stuck.
我真的遇到了这个问题。我有一些原始 rgb 数据，值从 0 到 255，想在 iphone 上将其显示为图像，但不知道如何操作。任何人都可以帮忙吗？我想我可能需要使用 CGImageCreate 但就是不明白。尝试查看课程参考资料，但感觉很卡。
All I want is a 10x10 greyscale image generated from some calculations and if there is an easy way to create a png or something that would be great.
我想要的只是通过一些计算生成的 10x10 灰度图像，如果有一种简单的方法来创建 png 或其他东西会很棒。
回答by justin
a terribly primitive example, similar to Mats' suggestion, but this version uses an external pixel buffer (pixelData):
一个非常原始的例子，类似于 Mats 的建议，但这个版本使用外部像素缓冲区 ( pixelData)：
const size_t Width = 10;
const size_t Height = 10;
const size_t Area = Width * Height;
const size_t ComponentsPerPixel = 4; // rgba
uint8_t pixelData[Area * ComponentsPerPixel];
// fill the pixels with a lovely opaque blue gradient:
for (size_t i=0; i < Area; ++i) {
const size_t offset = i * ComponentsPerPixel;
pixelData[offset] = i;
pixelData[offset+1] = i;
pixelData[offset+2] = i + i; // enhance blue
pixelData[offset+3] = UINT8_MAX; // opaque
}
// create the bitmap context:
const size_t BitsPerComponent = 8;
const size_t BytesPerRow=((BitsPerComponent * Width) / 8) * ComponentsPerPixel;
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef gtx = CGBitmapContextCreate(&pixelData[0], Width, Height, BitsPerComponent, BytesPerRow, colorSpace, kCGImageAlphaPremultipliedLast);
// create the image:
CGImageRef toCGImage = CGBitmapContextCreateImage(gtx);
UIImage * uiimage = [[UIImage alloc] initWithCGImage:toCGImage];
NSData * png = UIImagePNGRepresentation(uiimage);
// remember to cleanup your resources! :)
回答by Mats
Use CGBitmapContextCreate()to create a memory based bitmap for yourself. Then call CGBitmapContextGetData()to get a pointer for your drawing code. Then CGBitmapContextCreateImage()to create a CGImageRef.
使用CGBitmapContextCreate()创建基于内存位图自己。然后调用CGBitmapContextGetData()以获取您的绘图代码的指针。然后CGBitmapContextCreateImage()创建一个CGImageRef.
I hope this is sufficient to get you started.
我希望这足以让你开始。
回答by w-m
On Mac OS you could do it with an NSBitmapImageRep. For iOS it seems to be a bit more complicated. I found this blog post though:
在 Mac OS 上，您可以使用 NSBitmapImageRep 来完成。对于iOS，它似乎有点复杂。不过我发现了这篇博文：
http://paulsolt.com/2010/09/ios-converting-uiimage-to-rgba8-bitmaps-and-back/
http://paulsolt.com/2010/09/ios-converting-uiimage-to-rgba8-bitmaps-and-back/
