Calling external methods from within openGL class

Question

Hey Guys,

I'm attempting to call a method which is outside the class I'm working in from an openGL thread but I'm getting a Can't create handler inside thread that has not called Looper.prepare() runtime exception. Does anyone know of a way around this without putting the method in the same class?

Program breaks @ Extract cam = new Extract();

        public void onDrawFrame(GL10 gl) {
    onDrawFrameCounter++;
    gl.glEnable(GL10.GL_TEXTURE_2D);
    gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);

    bindCameraTexture(gl);
    System.out.println(Global.bearing);
    float bear = Global.bearing;
    gl.glLoadIdentity();
    gl.glNormal3f(0,0,1);
    System.out.println("ARRAY!: " + GLCamTest.array.length);
    p = 0;
    gl.glRotatef(bear, 1, 0, 0);
    int q = 0;
    int e = 0;  
    if(q < Global.cubes){

                Extract cam = new Extract();
                Bitmap image = cam.extractimage(q);
                final int TILE_WIDTH = 512;
                final int TILE_HEIGHT = 512;
                final int TILE_SIZE = TILE_WIDTH * TILE_HEIGHT;

                int[] pixels = new int[TILE_WIDTH];

                short[] rgb_565 = new short[TILE_SIZE];

                // Convert 8888 to 565, and swap red and green channel position:

                int i = 0;
                for (int y = 0; y < TILE_HEIGHT; y++) {
                    image.getPixels(pixels, 0, TILE_WIDTH, 0, y, TILE_WIDTH,
        1);
                    for (int x = 0; x < TILE_WIDTH; x++) {
                        int argb = pixels[x];
                        int r = 0x1f & (argb >> 19); // Take 5 bits from23..19
                        int g = 0x3f & (argb >> 10); // Take 6 bits from15..10
                        int b = 0x1f & (argb >> 3); // Take 5 bits from  7.. 3
                        int rgb = (r << 11) | (g << 5) | b;
                        rgb_565[i] = (short) rgb;
                        ++i;
                    }
                }
                ShortBuffer textureBuffer = ShortBuffer.wrap (rgb_565, 0,
        TILE_SIZE);
                gl.glTexImage2D(GL10.GL_TEXTURE_2D, 0, GL10.GL_RGB, 48, 48, 0,
                        GL10.GL_RGB, GL10.GL_UNSIGNED_SHORT_5_6_5,
        textureBuffer);

    gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, e, 4);
    e = e + 4;
    gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, e, 4);
    e = e + 4;
    gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, e, 4);
    e = e + 4;
    gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, e, 4);
    e = e + 4;
    gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, e, 4);
    e = e + 4;
    gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, e, 4);
    e = e + 4;
    q++;
    }

}

Answer 1

The error indicates that you are calling some code that expects to be called from the UI thread, but is not. The gl onDrawFrame is not called from the UI thread, hence the error.

From the code this looks to be happening in the Extract class' constructor. What is the class full name?

Assuming the Extract method loads an image from the camera or similar. I would move the code doing the "extracting" out of the gl thread, you likely dont want to limit your fps by doing this conversion on the gl thread anyway :-) Its better doing this "as fast as possible" on a separate thread, and have the gl draw the latest.

If you do need to make this work here, use http://developer.android.com/intl/zh-TW/reference/android/os/Handler.html