Capturing ScreenShot of the the Active Window

[Parth Bhatt]

Hi Ranchers,

I am working on a simple application to capture the screen shot of the entire screen and save it in a Disk File. This is what the screen capturing code looks like :

  
    Toolkit toolkit = Toolkit.getDefaultToolkit();
    Dimension screenSize = toolkit.getScreenSize();
    Rectangle screenRect = new Rectangle(screenSize); 
 
    Robot robot = new Robot();
    BufferedImage image = robot.createScreenCapture(screenRect);
 
    ImageIO.write(image, fileType, new File(filePath));

Now i need to add a feature that would capture the screen shot of only the Active Window (& not the entire screen).

Do we have such APIs in java, which my application can use directly ? If not, what could be the ways in which this can be implemented ?

[Ulf Dittmer]

I would think that the way to do it is to pass the rectangle of the currently active window to the createScreenCapture method, instead of the rectangle of the full screen.

[Parth Bhatt]

Exactly Ulf... but is there a way to get the rectangle of the active window.

Specifically, do we have APIs provided by either jdk or other lib that would return the rectangle for the active window...?

[Ulf Dittmer]

Assuming that we're talking about a Java window, look at the getLocationOnScreen method. In conjunction with the getWidth and getHeight methods it should give you the necessary data. The getBounds method may also be helpful.

[Parth Bhatt]

Sorry, for being a little less specific...

Actually, I was referring to the OpenSource project that i started :
GNUSnap

It Presents a very simple GUI that lets the user to capture the screen shot(for now, the snap shot is only of the complete screen) @ the click of a button.

What i wish to add to this is that the user can set an appropriate timeout(say of n secs) and click the button to take the screen shot. After n seconds my app would capture the shot of the Window that is the Active Window(this need not be a window launched my My App, it could be any window belonging to any process in the system).

For Example : Assume i am using Windows. I could configure my app to take a snap shot of the Active Window after 5 secs, minimize the app and launch Notepad. After 5 secs My App would take the snapshot of Notepad(and not the whole screen).

Similarly, if i am on Linux, i would be able to do the same.

If anyone has any idea regarding this, please put it forth...