data entry work

How to take an image snapshot of the screen on Mac OS X Lion Q: How do I take an image snapshot of the screen on Mac OS X Lion? A: On Mac OS X Lion, the way to make an image snapshot from the screen is by employing Quartz Display Services. Important: This Q&A describes how to capture static images. If you want to capture real-time videos of screen activity, you should use AV Foundation instead. See How to capture screen activity to a movie file using AV Foundation on OS X 10.7 Lion and later for more information. Make sure you add the ApplicationServices framework in your Xcode project and import the ApplicationServices/ApplicationServices.h header file. Given a display ID (of CGDirectDisplayID type), you can call CGDisplayCreateImage to create a CGImage from the entire screen or CGDisplayCreateImageForRect from a rectangular portion of it. If you always capture from the main display, you may simply pass kCGDirectMainDisplay to either function as shown in Listing 1. It is a shorthand for specifying the current main display. If you might capture from a secondary display, then you can go through the list of active displays returned from CGGetActiveDisplayList and find the one you want to capture. See Listing 2 for an example. Listing 1 Creating an image from the entire main display CGImageRef image = CGDisplayCreateImage(kCGDirectMainDisplay); Listing 2 Creating images from multiple displays CGDisplayCount displayCount; CGDirectDisplayID displays[32]; // grab the active displays CGGetActiveDisplayList(32, displays, &displayCount); // go through the list for (int i=0; i<displayCount; i++) { // make a snapshot of the current display CGImageRef image = CGDisplayCreateImage(displays[i]); // do something with the snapshot image } Check out the dedicated sample code, ScreenSnapshot, for more information. It demonstrates how to use Quartz Display Services to obtain an image containing the contents of any of the connected displays and allows the user to save the image to a file on disk. Document Revision History Date Notes 2011-08-10 Corrected a link. Added information about the ScreenSnapshot sample. 2011-05-13 New document that shows how to take an image snapshot of the screen on Mac OS X Lion