如何在越狱的 iOS 设备上截取整个屏幕？

Question

我需要对包括状态栏在内的整个屏幕进行截图，我使用CARenderServerRenderDisplay 来实现这一点，它在 iPad 上可以正常工作，但在 iPhone 6 Plus 上就出错了。作为代码中的*标记部分，如果我设置width=screenSize.width*scale和height=screenSize.height*scale，它会导致崩溃，如果我只是将它们更改为：width=screenSize.height*scale和height=screenSize.width*scale，它会起作用，但会产生这样的图像： ，我尝试了很多，但没有找到原因，有人知道吗？我希望我已经描述得够清楚了。

- (void)snapshot
{
    CGFloat scale = [UIScreen mainScreen].scale;
    CGSize screenSize = [UIScreen mainScreen].bounds.size;

    //*********** the place where problem appears        
    size_t width = screenSize.height * scale;
    size_t height = screenSize.width * scale;
    //***********

    size_t bytesPerElement = 4;
    OSType pixelFormat = 'ARGB';
    size_t bytesPerRow = bytesPerElement * width;
    size_t surfaceAllocSize = bytesPerRow * height;

    NSDictionary *properties = [NSDictionary dictionaryWithObjectsAndKeys:
                                [NSNumber numberWithBool:YES], kIOSurfaceIsGlobal,
                                [NSNumber numberWithUnsignedLong:bytesPerElement], kIOSurfaceBytesPerElement,
                                [NSNumber numberWithUnsignedLong:bytesPerRow], kIOSurfaceBytesPerRow,
                                [NSNumber numberWithUnsignedLong:width], kIOSurfaceWidth,
                                [NSNumber numberWithUnsignedLong:height], kIOSurfaceHeight,
                                [NSNumber numberWithUnsignedInt:pixelFormat], kIOSurfacePixelFormat,
                                [NSNumber numberWithUnsignedLong:surfaceAllocSize], kIOSurfaceAllocSize,
                                nil];

    IOSurfaceRef destSurf = IOSurfaceCreate((__bridge CFDictionaryRef)(properties));

    IOSurfaceLock(destSurf, 0, NULL);
    CARenderServerRenderDisplay(0, CFSTR("LCD"), destSurf, 0, 0);
    IOSurfaceUnlock(destSurf, 0, NULL);

    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];
    UIImageWriteToSavedPhotosAlbum(image, nil, nil, nil);
}

Answer 1

如果你在越狱环境中，可以使用私有UIImage方法_UICreateScreenUIImage：

OBJC_EXTERN UIImage *_UICreateScreenUIImage(void);

// ...

- (void)takeScreenshot {
    UIImage *screenImage = _UICreateScreenUIImage();
    // do something with your screenshot
}

此方法使用CARenderServerRenderDisplay 更快地渲染整个设备屏幕。它取代了在 iOS 7 SDK 的 arm64 版本中删除的 UICreateScreenImage 和 UIGetScreenImage 方法。