/*
 * Copyright (C) 2012 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.gallery3d.ui;

import javax.microedition.khronos.opengles.GL11;
import javax.microedition.khronos.opengles.GL11Ext;

// ExtTexture is a texture whose content comes from a external texture.
// Before drawing, setSize() should be called.
public class ExtTexture extends BasicTexture {

    private static int[] sTextureId = new int[1];
    private static float[] sCropRect = new float[4];
    private int mTarget;

    public ExtTexture(int target) {
        GLId.glGenTextures(1, sTextureId, 0);
        mId = sTextureId[0];
        mTarget = target;
    }

    private void uploadToCanvas(GLCanvas canvas) {
        GL11 gl = canvas.getGLInstance();

        int width = getWidth();
        int height = getHeight();
        // Define a vertically flipped crop rectangle for OES_draw_texture.
        // The four values in sCropRect are: left, bottom, width, and
        // height. Negative value of width or height means flip.
        sCropRect[0] = 0;
        sCropRect[1] = height;
        sCropRect[2] = width;
        sCropRect[3] = -height;

        // Set texture parameters.
        gl.glBindTexture(mTarget, mId);
        gl.glTexParameterfv(mTarget,
                GL11Ext.GL_TEXTURE_CROP_RECT_OES, sCropRect, 0);
        gl.glTexParameteri(mTarget,
                GL11.GL_TEXTURE_WRAP_S, GL11.GL_CLAMP_TO_EDGE);
        gl.glTexParameteri(mTarget,
                GL11.GL_TEXTURE_WRAP_T, GL11.GL_CLAMP_TO_EDGE);
        gl.glTexParameterf(mTarget,
                GL11.GL_TEXTURE_MIN_FILTER, GL11.GL_LINEAR);
        gl.glTexParameterf(mTarget,
                GL11.GL_TEXTURE_MAG_FILTER, GL11.GL_LINEAR);

        setAssociatedCanvas(canvas);
        mState = STATE_LOADED;
    }

    @Override
    protected boolean onBind(GLCanvas canvas) {
        if (!isLoaded()) {
            uploadToCanvas(canvas);
        }

        return true;
    }

    @Override
    public int getTarget() {
        return mTarget;
    }

    @Override
    public boolean isOpaque() {
        return true;
    }

    @Override
    public void yield() {
        // we cannot free the texture because we have no backup.
    }
}