Android example source code file (ETC1Util.java)

This example Android source code file (ETC1Util.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

bytebuffer, etc1texture, etc1util, gl_rgb, illegalargumentexception, inputstream, io, ioexception, nio, not, outputstream, pkm, unable, unsupported

The ETC1Util.java Android example source code

/*
 *  Copyright 2009 Google Inc.
 *
 * 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.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.nio.Buffer;
import java.nio.ByteBuffer;
import java.nio.ByteOrder;

/**
 * Utility methods for using ETC1 compressed textures.
 *
 */
public class ETC1Util {
    /**
     * Convenience method to load an ETC1 texture whether or not the active OpenGL context
     * supports the ETC1 texture compression format.
     * @param target the texture target.
     * @param level the texture level
     * @param border the border size. Typically 0.
     * @param fallbackFormat the format to use if ETC1 texture compression is not supported.
     * Must be GL_RGB.
     * @param fallbackType the type to use if ETC1 texture compression is not supported.
     * Can be either GL_UNSIGNED_SHORT_5_6_5, which implies 16-bits-per-pixel,
     * or GL_UNSIGNED_BYTE, which implies 24-bits-per-pixel.
     * @param input the input stream containing an ETC1 texture in PKM format.
     * @throws IOException
     */
    public static void loadTexture(int target, int level, int border,
            int fallbackFormat, int fallbackType, InputStream input)
        throws IOException {
        loadTexture(target, level, border, fallbackFormat, fallbackType, createTexture(input));
    }

    /**
     * Convenience method to load an ETC1 texture whether or not the active OpenGL context
     * supports the ETC1 texture compression format.
     * @param target the texture target.
     * @param level the texture level
     * @param border the border size. Typically 0.
     * @param fallbackFormat the format to use if ETC1 texture compression is not supported.
     * Must be GL_RGB.
     * @param fallbackType the type to use if ETC1 texture compression is not supported.
     * Can be either GL_UNSIGNED_SHORT_5_6_5, which implies 16-bits-per-pixel,
     * or GL_UNSIGNED_BYTE, which implies 24-bits-per-pixel.
     * @param texture the ETC1 to load.
     */
    public static void loadTexture(int target, int level, int border,
            int fallbackFormat, int fallbackType, ETC1Texture texture) {
        if (fallbackFormat != GLES10.GL_RGB) {
            throw new IllegalArgumentException("fallbackFormat must be GL_RGB");
        }
        if (! (fallbackType == GLES10.GL_UNSIGNED_SHORT_5_6_5
                || fallbackType == GLES10.GL_UNSIGNED_BYTE)) {
            throw new IllegalArgumentException("Unsupported fallbackType");
        }

        int width = texture.getWidth();
        int height = texture.getHeight();
        Buffer data = texture.getData();
        if (isETC1Supported()) {
            int imageSize = data.remaining();
            GLES10.glCompressedTexImage2D(target, level, ETC1.ETC1_RGB8_OES, width, height,
                    border, imageSize, data);
        } else {
            boolean useShorts = fallbackType != GLES10.GL_UNSIGNED_BYTE;
            int pixelSize = useShorts ? 2 : 3;
            int stride = pixelSize * width;
            ByteBuffer decodedData = ByteBuffer.allocateDirect(stride*height)
                .order(ByteOrder.nativeOrder());
            ETC1.decodeImage(data, decodedData, width, height, pixelSize, stride);
            GLES10.glTexImage2D(target, level, fallbackFormat, width, height, border,
                    fallbackFormat, fallbackType, decodedData);
        }
    }

    /**
     * Check if ETC1 texture compression is supported by the active OpenGL ES context.
     * @return true if the active OpenGL ES context supports ETC1 texture compression.
     */
    public static boolean isETC1Supported() {
        int[] results = new int[20];
        GLES10.glGetIntegerv(GLES10.GL_NUM_COMPRESSED_TEXTURE_FORMATS, results, 0);
        int numFormats = results[0];
        if (numFormats > results.length) {
            results = new int[numFormats];
        }
        GLES10.glGetIntegerv(GLES10.GL_COMPRESSED_TEXTURE_FORMATS, results, 0);
        for (int i = 0; i < numFormats; i++) {
            if (results[i] == ETC1.ETC1_RGB8_OES) {
                return true;
            }
        }
        return false;
    }

    /**
     * A utility class encapsulating a compressed ETC1 texture.
     */
    public static class ETC1Texture {
        public ETC1Texture(int width, int height, ByteBuffer data) {
            mWidth = width;
            mHeight = height;
            mData = data;
        }

        /**
         * Get the width of the texture in pixels.
         * @return the width of the texture in pixels.
         */
        public int getWidth() { return mWidth; }

        /**
         * Get the height of the texture in pixels.
         * @return the width of the texture in pixels.
         */
        public int getHeight() { return mHeight; }

        /**
         * Get the compressed data of the texture.
         * @return the texture data.
         */
        public ByteBuffer getData() { return mData; }

        private int mWidth;
        private int mHeight;
        private ByteBuffer mData;
    }

    /**
     * Create a new ETC1Texture from an input stream containing a PKM formatted compressed texture.
     * @param input an input stream containing a PKM formatted compressed texture.
     * @return an ETC1Texture read from the input stream.
     * @throws IOException
     */
    public static ETC1Texture createTexture(InputStream input) throws IOException {
        int width = 0;
        int height = 0;
        byte[] ioBuffer = new byte[4096];
        {
            if (input.read(ioBuffer, 0, ETC1.ETC_PKM_HEADER_SIZE) != ETC1.ETC_PKM_HEADER_SIZE) {
                throw new IOException("Unable to read PKM file header.");
            }
            ByteBuffer headerBuffer = ByteBuffer.allocateDirect(ETC1.ETC_PKM_HEADER_SIZE)
                .order(ByteOrder.nativeOrder());
            headerBuffer.put(ioBuffer, 0, ETC1.ETC_PKM_HEADER_SIZE).position(0);
            if (!ETC1.isValid(headerBuffer)) {
                throw new IOException("Not a PKM file.");
            }
            width = ETC1.getWidth(headerBuffer);
            height = ETC1.getHeight(headerBuffer);
        }
        int encodedSize = ETC1.getEncodedDataSize(width, height);
        ByteBuffer dataBuffer = ByteBuffer.allocateDirect(encodedSize).order(ByteOrder.nativeOrder());
        for (int i = 0; i < encodedSize; ) {
            int chunkSize = Math.min(ioBuffer.length, encodedSize - i);
            if (input.read(ioBuffer, 0, chunkSize) != chunkSize) {
                throw new IOException("Unable to read PKM file data.");
            }
            dataBuffer.put(ioBuffer, 0, chunkSize);
            i += chunkSize;
        }
        dataBuffer.position(0);
        return new ETC1Texture(width, height, dataBuffer);
    }

    /**
     * Helper function that compresses an image into an ETC1Texture.
     * @param input a native order direct buffer containing the image data
     * @param width the width of the image in pixels
     * @param height the height of the image in pixels
     * @param pixelSize the size of a pixel in bytes (2 or 3)
     * @param stride the width of a line of the image in bytes
     * @return the ETC1 texture.
     */
    public static ETC1Texture compressTexture(Buffer input, int width, int height, int pixelSize, int stride){
        int encodedImageSize = ETC1.getEncodedDataSize(width, height);
        ByteBuffer compressedImage = ByteBuffer.allocateDirect(encodedImageSize).
            order(ByteOrder.nativeOrder());
        ETC1.encodeImage(input, width, height, 3, stride, compressedImage);
        return new ETC1Texture(width, height, compressedImage);
    }

    /**
     * Helper function that writes an ETC1Texture to an output stream formatted as a PKM file.
     * @param texture the input texture.
     * @param output the stream to write the formatted texture data to.
     * @throws IOException
     */
    public static void writeTexture(ETC1Texture texture, OutputStream output) throws IOException {
        ByteBuffer dataBuffer = texture.getData();
        int originalPosition = dataBuffer.position();
        try {
            int width = texture.getWidth();
            int height = texture.getHeight();
            ByteBuffer header = ByteBuffer.allocateDirect(ETC1.ETC_PKM_HEADER_SIZE).order(ByteOrder.nativeOrder());
            ETC1.formatHeader(header, width, height);
            byte[] ioBuffer = new byte[4096];
            header.get(ioBuffer, 0, ETC1.ETC_PKM_HEADER_SIZE);
            output.write(ioBuffer, 0, ETC1.ETC_PKM_HEADER_SIZE);
            int encodedSize = ETC1.getEncodedDataSize(width, height);
            for (int i = 0; i < encodedSize; ) {
                int chunkSize = Math.min(ioBuffer.length, encodedSize - i);
                dataBuffer.get(ioBuffer, 0, chunkSize);
                output.write(ioBuffer, 0, chunkSize);
                i += chunkSize;
            }
        } finally {
            dataBuffer.position(originalPosition);
        }
    }
}