Create an image from a non-visible AWT Component?

Question

I\'m trying to create an image (screen-shot) of a non-visible AWT component. I can\'t use the Robot classes\' screen capture functionality because the component

Answer 1

Excellent question, I've thought about this myself from time to time!

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As you already have written, that rending heavy weight components such as 3D and AWT onto an image is a big problem. These components are (almost) directly transferred to the graphic card so they cannot be re-rendered to an image using the normal paintComponent stuff, you need help from the operative system or doing your own rendering of these components.

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1. Making your own to image renderer

For each component that does not have a to image rendering method you need to create your own. For example using jogl you can take a off-screen screenshot using this method (SO post).

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2. Rendering onto a virtual screen

Prerequisites:

1. Can you start the program/component in a headless environment?
2. Are you using Linux?

Then you can use Xvfb to render the whole program onto a virtual screen and then taking a screenshot from that virtual screen like this:

Xvfb :1 &
DISPLAY=:1 java YourMainClass
xwd -display :1 -root -out image.xwd

Maybe you need to tweek Xvfb a little bit by passing the size of the program you want to render to it (-screen 0 1024x768x24).