Capture screen of GLSurfaceView to bitmap
android, glsurfaceview, java, screen-capture
Solution
`SurfaceView` and `GLSurfaceView` punch holes in their windows to allow their surfaces to be displayed. In other words, they have transparent areas.
So you cannot capture an image by calling `GLSurfaceView.getDrawingCache()`.
If you want to get an image from `GLSurfaceView`, you should invoke `gl.glReadPixels()` in `GLSurfaceView.onDrawFrame()`.
I patched `createBitmapFromGLSurface` method and call it in `onDrawFrame()`.
(The original code might be from skuld's code.)
private Bitmap createBitmapFromGLSurface(int x, int y, int w, int h, GL10 gl)
throws OutOfMemoryError {
int bitmapBuffer[] = new int[w * h];
int bitmapSource[] = new int[w * h];
IntBuffer intBuffer = IntBuffer.wrap(bitmapBuffer);
intBuffer.position(0);
try {
gl.glReadPixels(x, y, w, h, GL10.GL_RGBA, GL10.GL_UNSIGNED_BYTE, intBuffer);
int offset1, offset2;
for (int i = 0; i < h; i++) {
offset1 = i * w;
offset2 = (h - i - 1) * w;
for (int j = 0; j < w; j++) {
int texturePixel = bitmapBuffer[offset1 + j];
int blue = (texturePixel >> 16) & 0xff;
int red = (texturePixel << 16) & 0x00ff0000;
int pixel = (texturePixel & 0xff00ff00) | red | blue;
bitmapSource[offset2 + j] = pixel;
}
}
} catch (GLException e) {
return null;
}
return Bitmap.createBitmap(bitmapSource, w, h, Bitmap.Config.ARGB_8888);
}
Problem
I need to be able to capture an image of a `GLSurfaceView` at certain moment in time. I have the following code: ``` relative.setDrawingCacheEnabled(true); screenshot = Bitmap.createBitmap(relative.getDrawingCache()); relative.setDrawingCacheEnabled(false); Log.v(TAG, "Screenshot height: " + screenshot.getHeight()); image.setImageBitmap(screenshot); ``` The `GLSurfaceView` is contained within a `RelativeLayout`, but I have also tries it straight using the `GLSurfaceView` to try and capture the image. With this I think the screen captures a transparent image, i.e. nothing there. Any help will be appreciated.