ios截图功能 opengl实现

最新推荐文章于 2021-09-13 13:22:00 发布

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最新推荐文章于 2021-09-13 13:22:00 发布

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本文介绍了一个使用OpenGL从屏幕读取像素并进行上下翻转的方法，最终将处理后的图像数据转换为UIImage格式。此过程涉及内存分配、像素读取、数据翻转及Core Graphics图像创建。

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    int width = 352; //视频宽度*3
    int height = 288;//视频宽度*3
    
    NSInteger myDataLength = width * height * 4;
    // allocate array and read pixels into it.
    GLubyte *buffer = (GLubyte *) malloc(myDataLength);
    glReadPixels(0, 0, width, height, GL_RGBA, GL_UNSIGNED_BYTE, buffer);
    // gl renders "upside down" so swap top to bottom into new array.
    // there's gotta be a better way, but this works.
    GLubyte *buffer2 = (GLubyte *) malloc(myDataLength);
    for(int y = 0; y < height; y++) {
        for(int x = 0; x < width* 4; x++) {
            buffer2[(int)((height-1 - y) * width * 4 + x)] = buffer[(int)(y * 4 * width + x)];
        }
    }
    free(buffer);
    // make data provider with data.
    CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, buffer2, myDataLength, NULL);
    // prep the ingredients
    int bitsPerComponent = 8;
    int bitsPerPixel = 32;
    int bytesPerRow = 4 * width;
    CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB();
    CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault;
    CGColorRenderingIntent renderingIntent = kCGRenderingIntentDefault;
    // make the cgimage
    CGImageRef imageRef = CGImageCreate(width , height, bitsPerComponent, bitsPerPixel, bytesPerRow, colorSpaceRef, bitmapInfo, provider, NULL, NO, renderingIntent);
    // then make the uiimage from that
    UIImage *myImage = [UIImage imageWithCGImage:imageRef];
    
    return myImage;