用Cocoa截取屏幕内容并保存为图片

25MAR

让我们来写一个抓屏程序吧。当然，你知道只要按command+shift+3就可以抓取当前屏幕对吧？本文介绍如何用cocoa程序来实现这一功能。

- (NSImage *) captureScreenImageWithFrame: (NSRect) frame

{

    // 获取屏幕的图形端口

        

    CGrafPtr screenPort = CreateNewPort ();

    Rect screenRect;

    GetPortBounds (screenPort, &screenRect);

        

    // 创建一个临时窗口做为容器

        

    NSWindow *grabWindow = [[NSWindow alloc] initWithContentRect: frame

 

                                                                                              styleMask:NSBorderlessWindowMask

 

                                                                                                   backing:NSBackingStoreRetained

 

                                                                                                     defer: NO

                                                                                                   screen: nil];

    CGrafPtr windowPort = GetWindowPort ([grabWindow windowRef]);

    Rect windowRect;

    GetPortBounds (windowPort, &windowRect);

    SetPort (windowPort);

        

    // 将屏幕内容复制到临时窗口

        

    CopyBits (GetPortBitMapForCopyBits(screenPort),

              GetPortBitMapForCopyBits(windowPort),

              &screenRect,

              &windowRect,

              srcCopy,

              NULL);

        

    // 将窗口内容复制到NSImage中

        

    NSView *grabContentView = [grabWindow contentView];

        

    [grabContentView lockFocus];

    NSBitmapImageRep *screenRep;

    screenRep = [[NSBitmapImageRep alloc] initWithFocusedViewRect: frame];

    [grabContentView unlockFocus];

        

    NSImage *screenImage = [[NSImage alloc] initWithSize: frame.size];

    [screenImage addRepresentation: screenRep];

        

 

    // Clean up

    [grabWindow close];

    DisposePort(screenPort);

        

    return (screenImage);

        

} // captureScreenImageWithFrame