Android example source code file (Texture.java)

This example Android source code file (Texture.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Android by Example" ^TM.

Java - Android tags/keywords

android, buffer, bytebuffer, content, io, ioexception, nio, texture

The Texture.java Android example source code

/*
 * Copyright (C) 2006 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 android.opengl;

import java.io.InputStream;
import java.io.IOException;
import java.nio.Buffer;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;
import javax.microedition.khronos.opengles.GL10;

import android.content.res.AssetManager;

/**
 * {@hide}
 */
public class Texture {

    private int width, height, bpp;
    private ByteBuffer data;
    private int name = -1;

    // Texture maps have the following format.  All integers
    // are 16 bits, high byte first.  Pixels are in 5/6/5
    // RGB format, low byte first.
    //
    // width
    // height
    // pixel (0, 0)
    // pixel (1, 0)
    // ...
    // pixel (width - 1, height - 1)

    private int readInt16(InputStream is) throws IOException {
        return is.read() | (is.read() << 8);
    }

    public Texture(InputStream is) throws IOException {
        this.width  = readInt16(is);
        this.height  = readInt16(is);
        this.bpp = 2;

        int npixels = width*height;
        int nbytes = npixels*bpp;
        byte[] arr = new byte[nbytes];

        int idx = 0;
        while (idx < nbytes) {
            int nread = is.read(arr, idx, nbytes - idx);
            idx += nread;
        }

        if (ByteOrder.nativeOrder() == ByteOrder.BIG_ENDIAN) {
            // Swap pairs of bytes on big-endian platforms
            for (int i = 0; i < npixels; i++) {
                int j = i*2;
                int k = j + 1;

                byte tmp = arr[j];
                arr[j] = arr[k];
                arr[k] = tmp;
            }
        }

        this.data = ByteBuffer.allocateDirect(arr.length);
        this.data.order(ByteOrder.nativeOrder());
        data.put(arr);
        data.position(0);
    }

    private int loadTexture(GL10 gl,
            int textureUnit,
            int minFilter, int magFilter,
            int wrapS, int wrapT,
            int mode,
            int width, int height,
            int dataType,
            Buffer data) {
        int[] texture = new int[1];
        gl.glGenTextures(1, texture, 0);

        gl.glEnable(gl.GL_TEXTURE_2D);
        gl.glClientActiveTexture(textureUnit);
        gl.glBindTexture(gl.GL_TEXTURE_2D, texture[0]);
        gl.glTexParameterf(gl.GL_TEXTURE_2D,
                gl.GL_TEXTURE_MIN_FILTER,
                minFilter);
        gl.glTexParameterf(gl.GL_TEXTURE_2D,
                gl.GL_TEXTURE_MAG_FILTER,
                magFilter);
        gl.glTexParameterf(gl.GL_TEXTURE_2D,
                gl.GL_TEXTURE_WRAP_S,
                wrapS);
        gl.glTexParameterf(gl.GL_TEXTURE_2D,
                gl.GL_TEXTURE_WRAP_T,
                wrapT);
        gl.glTexEnvf(gl.GL_TEXTURE_ENV, gl.GL_TEXTURE_ENV_MODE, mode);

        gl.glTexImage2D(gl.GL_TEXTURE_2D, 0, gl.GL_RGB,
                width, height,
                0, gl.GL_RGB, dataType,
                data);

        return texture[0];
    }

    public void setTextureParameters(GL10 gl) {
        if (name < 0) {
            name = loadTexture(gl,
                    gl.GL_TEXTURE0,
                    gl.GL_NEAREST, gl.GL_NEAREST,
                    gl.GL_REPEAT, gl.GL_REPEAT,
                    gl.GL_MODULATE,
                    width, height,
                    gl.GL_UNSIGNED_SHORT_5_6_5,
                    data);
        }

        gl.glBindTexture(gl.GL_TEXTURE_2D, name);
    }
}