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/*
* Copyright (C) 2009 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.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, pixelSize, 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);
}
}
}
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