ios - 从 ios 表面创建图像并保存

Question

我正在尝试获取与 ios 设备主屏幕关联的表面，从中创建图像并保存。这与这个问题有关 - Taking Screenshots from iOS app - emulating Display recorder (query on the internals) .
代码如下:

    IOMobileFramebufferConnection connect;
    kern_return_t result;

    io_service_t framebufferService = IOServiceGetMatchingService(kIOMasterPortDefault, IOServiceMatching("AppleH1CLCD"));
    if(!framebufferService)
        framebufferService = IOServiceGetMatchingService(kIOMasterPortDefault, IOServiceMatching("AppleM2CLCD"));
    if(!framebufferService)
        framebufferService = IOServiceGetMatchingService(kIOMasterPortDefault, IOServiceMatching("AppleCLCD"));

    result = IOMobileFramebufferOpen(framebufferService, mach_task_self(), 0, &connect);

    result = IOMobileFramebufferGetLayerDefaultSurface(connect, 0, &screenSurface);

    uint32_t aseed;
    IOSurfaceLock(screenSurface, kIOSurfaceLockReadOnly, &aseed);
    uint32_t width = IOSurfaceGetWidth(screenSurface);
    uint32_t height = IOSurfaceGetHeight(screenSurface);

    CFMutableDictionaryRef dict;
    int pitch = width*4, size = 4*width*height;
    int bPE=4;
    char pixelFormat[4] = {'A','R','G','B'};
    dict = CFDictionaryCreateMutable(kCFAllocatorDefault, 0, &kCFTypeDictionaryKeyCallBacks, &kCFTypeDictionaryValueCallBacks);
    CFDictionarySetValue(dict, kIOSurfaceIsGlobal, kCFBooleanTrue);
    CFDictionarySetValue(dict, kIOSurfaceBytesPerRow, CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt32Type, &pitch));
    CFDictionarySetValue(dict, kIOSurfaceBytesPerElement, CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt32Type, &bPE));
    CFDictionarySetValue(dict, kIOSurfaceWidth, CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt32Type, &width));
    CFDictionarySetValue(dict, kIOSurfaceHeight, CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt32Type, &height));
    CFDictionarySetValue(dict, kIOSurfacePixelFormat, CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt32Type, pixelFormat));
    CFDictionarySetValue(dict, kIOSurfaceAllocSize, CFNumberCreate(kCFAllocatorDefault, kCFNumberSInt32Type, &size));

    IOSurfaceRef destSurf = IOSurfaceCreate(dict);
    IOSurfaceAcceleratorRef outAcc;
    IOSurfaceAcceleratorCreate(NULL, 0, &outAcc);

    CFDictionaryRef ed = (__bridge CFDictionaryRef)[NSDictionary dictionaryWithObjectsAndKeys: nil];
    IOSurfaceAcceleratorTransferSurface(outAcc, screenSurface, destSurf, ed, NULL);

    IOSurfaceUnlock(screenSurface, kIOSurfaceLockReadOnly, &aseed);

    CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, IOSurfaceGetBaseAddress(destSurf), (width*height*4), NULL);
    CGImageRef cgImage=CGImageCreate(width, height, 8, 8*4, IOSurfaceGetBytesPerRow(destSurf), CGColorSpaceCreateDeviceRGB(), kCGImageAlphaNoneSkipFirst | kCGBitmapByteOrder32Little, provider, NULL, YES, kCGRenderingIntentDefault);
    UIImage *image = [UIImage imageWithCGImage: cgImage];
    CGImageRelease(cgImage);
    UIImageWriteToSavedPhotosAlbum(image, self, nil, nil);

但我得到的只是一张保存在我的照片文件夹中的空白图像。请帮助我哪里出错了。谢谢。

Answer 1

我记得前段时间看到过关于这个主题的东西(后台截图)。我找不到我看到的确切位置和代码。我留给自己的唯一笔记是 createScreenIOSurface 的用法

我用谷歌搜索了一下，发现了一些提及:

Get a screenshot while App is in background? (Private APIs allowed)

https://github.com/rpetrich/FastBlurredNotificationCenter/blob/master/Tweak.x

http://pastie.org/pastes/3734430

我记得代码比你展示的更紧凑。