从 ios 表面创建图像并保存

问题描述

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 - 从 iOS 应用程序截屏 - 模拟显示记录器(内部查询).
代码如下:

I am trying to acquire the surface associated with the main screen of the ios device, create an image out of it and save it. This is in relevance to this question - Taking Screenshots from iOS app - emulating Display recorder (query on the internals).
The code is as follows:

    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);

但我得到的只是保存在我的照片文件夹中的空白图像.请帮忙看看我哪里出错了.谢谢.

But all I get is a blank image saved in my photos folder. Please help on what part am I going wrong. Thanks.

推荐答案

我记得我前段时间看到了一些关于这个主题的东西(在后台截屏).我无法找到我看到的确切位置和代码.我给自己留下的唯一笔记是 createScreenIOSurface 的用法

I remember I saw something on this subject (taking screenshots in the background) some time ago. I wasn't able find exact place and code which I saw. The only note which I left for myself was usage of createScreenIOSurface

我用谷歌搜索了一下，发现有几个提到:

I googled a little bit and found couple of mentions:

在应用运行时获取屏幕截图背景?(允许私有 API)

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

http://pastie.org/pastes/3734430

我记得代码比你展示的要紧凑.

As I remember the code was way more compact then what you showed.

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