src/com/android/gallery3d/ui/NinePatchTexture.java - platform/packages/apps/Gallery2 - Git at Google

 /*
  * Copyright (C) 2010 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 android.content.Context;
 import android.graphics.Bitmap;
 import android.graphics.BitmapFactory;
 import android.graphics.Rect;

 import com.android.gallery3d.common.Utils;

 import java.nio.ByteBuffer;
 import java.nio.ByteOrder;
 import java.nio.FloatBuffer;

 import javax.microedition.khronos.opengles.GL11;

 // NinePatchTexture is a texture backed by a NinePatch resource.
 //
 // getPaddings() returns paddings specified in the NinePatch.
 // getNinePatchChunk() returns the layout data specified in the NinePatch.
 //
 public class NinePatchTexture extends ResourceTexture {
     @SuppressWarnings("unused")
     private static final String TAG = "NinePatchTexture";
     private NinePatchChunk mChunk;
     private SmallCache<NinePatchInstance> mInstanceCache
             = new SmallCache<NinePatchInstance>();

     public NinePatchTexture(Context context, int resId) {
         super(context, resId);
     }

     @Override
     protected Bitmap onGetBitmap() {
         if (mBitmap != null) return mBitmap;

         BitmapFactory.Options options = new BitmapFactory.Options();
         options.inPreferredConfig = Bitmap.Config.ARGB_8888;
         Bitmap bitmap = BitmapFactory.decodeResource(
                 mContext.getResources(), mResId, options);
         mBitmap = bitmap;
         setSize(bitmap.getWidth(), bitmap.getHeight());
         byte[] chunkData = bitmap.getNinePatchChunk();
         mChunk = chunkData == null
                 ? null
                 : NinePatchChunk.deserialize(bitmap.getNinePatchChunk());
         if (mChunk == null) {
             throw new RuntimeException("invalid nine-patch image: " + mResId);
         }
         return bitmap;
     }

     public Rect getPaddings() {
         // get the paddings from nine patch
         if (mChunk == null) onGetBitmap();
         return mChunk.mPaddings;
     }

     public NinePatchChunk getNinePatchChunk() {
         if (mChunk == null) onGetBitmap();
         return mChunk;
     }

     // This is a simple cache for a small number of things. Linear search
     // is used because the cache is small. It also tries to remove less used
     // item when the cache is full by moving the often-used items to the front.
     private static class SmallCache<V> {
         private static final int CACHE_SIZE = 16;
         private static final int CACHE_SIZE_START_MOVE = CACHE_SIZE / 2;
         private int[] mKey = new int[CACHE_SIZE];
         private V[] mValue = (V[]) new Object[CACHE_SIZE];
         private int mCount;  // number of items in this cache

         // Puts a value into the cache. If the cache is full, also returns
         // a less used item, otherwise returns null.
         public V put(int key, V value) {
             if (mCount == CACHE_SIZE) {
                 V old = mValue[CACHE_SIZE - 1];  // remove the last item
                 mKey[CACHE_SIZE - 1] = key;
                 mValue[CACHE_SIZE - 1] = value;
                 return old;
             } else {
                 mKey[mCount] = key;
                 mValue[mCount] = value;
                 mCount++;
                 return null;
             }
         }

         public V get(int key) {
             for (int i = 0; i < mCount; i++) {
                 if (mKey[i] == key) {
                     // Move the accessed item one position to the front, so it
                     // will less likely to be removed when cache is full. Only
                     // do this if the cache is starting to get full.
                     if (mCount > CACHE_SIZE_START_MOVE && i > 0) {
                         int tmpKey = mKey[i];
                         mKey[i] = mKey[i - 1];
                         mKey[i - 1] = tmpKey;

                         V tmpValue = mValue[i];
                         mValue[i] = mValue[i - 1];
                         mValue[i - 1] = tmpValue;
                     }
                     return mValue[i];
                 }
             }
             return null;
         }

         public void clear() {
             for (int i = 0; i < mCount; i++) {
                 mValue[i] = null;  // make sure it's can be garbage-collected.
             }
             mCount = 0;
         }

         public int size() {
             return mCount;
         }

         public V valueAt(int i) {
             return mValue[i];
         }
     }

     private NinePatchInstance findInstance(GLCanvas canvas, int w, int h) {
         int key = w;
         key = (key << 16) | h;
         NinePatchInstance instance = mInstanceCache.get(key);

         if (instance == null) {
             instance = new NinePatchInstance(this, w, h);
             NinePatchInstance removed = mInstanceCache.put(key, instance);
             if (removed != null) {
                 removed.recycle(canvas);
             }
         }

         return instance;
     }

     @Override
     public void draw(GLCanvas canvas, int x, int y, int w, int h) {
         if (!isLoaded()) {
             mInstanceCache.clear();
         }

         if (w != 0 && h != 0) {
             findInstance(canvas, w, h).draw(canvas, this, x, y);
         }
     }

     @Override
     public void recycle() {
         super.recycle();
         GLCanvas canvas = mCanvasRef;
         if (canvas == null) return;
         int n = mInstanceCache.size();
         for (int i = 0; i < n; i++) {
             NinePatchInstance instance = mInstanceCache.valueAt(i);
             instance.recycle(canvas);
         }
         mInstanceCache.clear();
     }
 }

 // This keeps data for a specialization of NinePatchTexture with the size
 // (width, height). We pre-compute the coordinates for efficiency.
 class NinePatchInstance {

     @SuppressWarnings("unused")
     private static final String TAG = "NinePatchInstance";

     // We need 16 vertices for a normal nine-patch image (the 4x4 vertices)
     private static final int VERTEX_BUFFER_SIZE = 16 * 2;

     // We need 22 indices for a normal nine-patch image, plus 2 for each
     // transparent region. Current there are at most 1 transparent region.
     private static final int INDEX_BUFFER_SIZE = 22 + 2;

     private FloatBuffer mXyBuffer;
     private FloatBuffer mUvBuffer;
     private ByteBuffer mIndexBuffer;

     // Names for buffer names: xy, uv, index.
     private int[] mBufferNames;

     private int mIdxCount;

     public NinePatchInstance(NinePatchTexture tex, int width, int height) {
         NinePatchChunk chunk = tex.getNinePatchChunk();

         if (width <= 0 || height <= 0) {
             throw new RuntimeException("invalid dimension");
         }

         // The code should be easily extended to handle the general cases by
         // allocating more space for buffers. But let's just handle the only
         // use case.
         if (chunk.mDivX.length != 2 || chunk.mDivY.length != 2) {
             throw new RuntimeException("unsupported nine patch");
         }

         float divX[] = new float[4];
         float divY[] = new float[4];
         float divU[] = new float[4];
         float divV[] = new float[4];

         int nx = stretch(divX, divU, chunk.mDivX, tex.getWidth(), width);
         int ny = stretch(divY, divV, chunk.mDivY, tex.getHeight(), height);

         prepareVertexData(divX, divY, divU, divV, nx, ny, chunk.mColor);
     }

     /**
      * Stretches the texture according to the nine-patch rules. It will
      * linearly distribute the strechy parts defined in the nine-patch chunk to
      * the target area.
      *
      * <pre>
      *                      source
      *          /--------------^---------------\
      *         u0    u1       u2  u3     u4   u5
      * div ---> |fffff|ssssssss|fff|ssssss|ffff| ---> u
      *          |    div0    div1 div2   div3  |
      *          |     |       /   /      /    /
      *          |     |      /   /     /    /
      *          |     |     /   /    /    /
      *          |fffff|ssss|fff|sss|ffff| ---> x
      *         x0    x1   x2  x3  x4   x5
      *          \----------v------------/
      *                  target
      *
      * f: fixed segment
      * s: stretchy segment
      * </pre>
      *
      * @param div the stretch parts defined in nine-patch chunk
      * @param source the length of the texture
      * @param target the length on the drawing plan
      * @param u output, the positions of these dividers in the texture
      *        coordinate
      * @param x output, the corresponding position of these dividers on the
      *        drawing plan
      * @return the number of these dividers.
      */
     private static int stretch(
             float x[], float u[], int div[], int source, int target) {
         int textureSize = Utils.nextPowerOf2(source);
         float textureBound = (float) source / textureSize;

         float stretch = 0;
         for (int i = 0, n = div.length; i < n; i += 2) {
             stretch += div[i + 1] - div[i];
         }

         float remaining = target - source + stretch;

         float lastX = 0;
         float lastU = 0;

         x[0] = 0;
         u[0] = 0;
         for (int i = 0, n = div.length; i < n; i += 2) {
             // Make the stretchy segment a little smaller to prevent sampling
             // on neighboring fixed segments.
             // fixed segment
             x[i + 1] = lastX + (div[i] - lastU) + 0.5f;
             u[i + 1] = Math.min((div[i] + 0.5f) / textureSize, textureBound);

             // stretchy segment
             float partU = div[i + 1] - div[i];
             float partX = remaining * partU / stretch;
             remaining -= partX;
             stretch -= partU;

             lastX = x[i + 1] + partX;
             lastU = div[i + 1];
             x[i + 2] = lastX - 0.5f;
             u[i + 2] = Math.min((lastU - 0.5f)/ textureSize, textureBound);
         }
         // the last fixed segment
         x[div.length + 1] = target;
         u[div.length + 1] = textureBound;

         // remove segments with length 0.
         int last = 0;
         for (int i = 1, n = div.length + 2; i < n; ++i) {
             if ((x[i] - x[last]) < 1f) continue;
             x[++last] = x[i];
             u[last] = u[i];
         }
         return last + 1;
     }

     private void prepareVertexData(float x[], float y[], float u[], float v[],
             int nx, int ny, int[] color) {
         /*
          * Given a 3x3 nine-patch image, the vertex order is defined as the
          * following graph:
          *
          * (0) (1) (2) (3)
          *  |  /|  /|  /|
          *  | / | / | / |
          * (4) (5) (6) (7)
          *  | \ | \ | \ |
          *  |  \|  \|  \|
          * (8) (9) (A) (B)
          *  |  /|  /|  /|
          *  | / | / | / |
          * (C) (D) (E) (F)
          *
          * And we draw the triangle strip in the following index order:
          *
          * index: 04152637B6A5948C9DAEBF
          */
         int pntCount = 0;
         float xy[] = new float[VERTEX_BUFFER_SIZE];
         float uv[] = new float[VERTEX_BUFFER_SIZE];
         for (int j = 0; j < ny; ++j) {
             for (int i = 0; i < nx; ++i) {
                 int xIndex = (pntCount++) << 1;
                 int yIndex = xIndex + 1;
                 xy[xIndex] = x[i];
                 xy[yIndex] = y[j];
                 uv[xIndex] = u[i];
                 uv[yIndex] = v[j];
             }
         }

         int idxCount = 1;
         boolean isForward = false;
         byte index[] = new byte[INDEX_BUFFER_SIZE];
         for (int row = 0; row < ny - 1; row++) {
             --idxCount;
             isForward = !isForward;

             int start, end, inc;
             if (isForward) {
                 start = 0;
                 end = nx;
                 inc = 1;
             } else {
                 start = nx - 1;
                 end = -1;
                 inc = -1;
             }

             for (int col = start; col != end; col += inc) {
                 int k = row * nx + col;
                 if (col != start) {
                     int colorIdx = row * (nx - 1) + col;
                     if (isForward) colorIdx--;
                     if (color[colorIdx] == NinePatchChunk.TRANSPARENT_COLOR) {
                         index[idxCount] = index[idxCount - 1];
                         ++idxCount;
                         index[idxCount++] = (byte) k;
                     }
                 }

                 index[idxCount++] = (byte) k;
                 index[idxCount++] = (byte) (k + nx);
             }
         }

         mIdxCount = idxCount;

         int size = (pntCount * 2) * (Float.SIZE / Byte.SIZE);
         mXyBuffer = allocateDirectNativeOrderBuffer(size).asFloatBuffer();
         mUvBuffer = allocateDirectNativeOrderBuffer(size).asFloatBuffer();
         mIndexBuffer = allocateDirectNativeOrderBuffer(mIdxCount);

         mXyBuffer.put(xy, 0, pntCount * 2).position(0);
         mUvBuffer.put(uv, 0, pntCount * 2).position(0);
         mIndexBuffer.put(index, 0, idxCount).position(0);
     }

     private static ByteBuffer allocateDirectNativeOrderBuffer(int size) {
         return ByteBuffer.allocateDirect(size).order(ByteOrder.nativeOrder());
     }

     private void prepareBuffers(GLCanvas canvas) {
         mBufferNames = new int[3];
         GL11 gl = canvas.getGLInstance();
         GLId.glGenBuffers(3, mBufferNames, 0);

         gl.glBindBuffer(GL11.GL_ARRAY_BUFFER, mBufferNames[0]);
         gl.glBufferData(GL11.GL_ARRAY_BUFFER,
                 mXyBuffer.capacity() * (Float.SIZE / Byte.SIZE),
                 mXyBuffer, GL11.GL_STATIC_DRAW);

         gl.glBindBuffer(GL11.GL_ARRAY_BUFFER, mBufferNames[1]);
         gl.glBufferData(GL11.GL_ARRAY_BUFFER,
                 mUvBuffer.capacity() * (Float.SIZE / Byte.SIZE),
                 mUvBuffer, GL11.GL_STATIC_DRAW);

         gl.glBindBuffer(GL11.GL_ELEMENT_ARRAY_BUFFER, mBufferNames[2]);
         gl.glBufferData(GL11.GL_ELEMENT_ARRAY_BUFFER,
                 mIndexBuffer.capacity(),
                 mIndexBuffer, GL11.GL_STATIC_DRAW);

         // These buffers are never used again.
         mXyBuffer = null;
         mUvBuffer = null;
         mIndexBuffer = null;
     }

     public void draw(GLCanvas canvas, NinePatchTexture tex, int x, int y) {
         if (mBufferNames == null) {
             prepareBuffers(canvas);
         }
         canvas.drawMesh(tex, x, y, mBufferNames[0], mBufferNames[1],
                 mBufferNames[2], mIdxCount);
     }

     public void recycle(GLCanvas canvas) {
         if (mBufferNames != null) {
             canvas.deleteBuffer(mBufferNames[0]);
             canvas.deleteBuffer(mBufferNames[1]);
             canvas.deleteBuffer(mBufferNames[2]);
             mBufferNames = null;
         }
     }
 }
	/*
	* Copyright (C) 2010 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 android.content.Context;
	import android.graphics.Bitmap;
	import android.graphics.BitmapFactory;
	import android.graphics.Rect;

	import com.android.gallery3d.common.Utils;

	import java.nio.ByteBuffer;
	import java.nio.ByteOrder;
	import java.nio.FloatBuffer;

	import javax.microedition.khronos.opengles.GL11;

	// NinePatchTexture is a texture backed by a NinePatch resource.
	//
	// getPaddings() returns paddings specified in the NinePatch.
	// getNinePatchChunk() returns the layout data specified in the NinePatch.
	//
	public class NinePatchTexture extends ResourceTexture {
	@SuppressWarnings("unused")
	private static final String TAG = "NinePatchTexture";
	private NinePatchChunk mChunk;
	private SmallCache<NinePatchInstance> mInstanceCache
	= new SmallCache<NinePatchInstance>();

	public NinePatchTexture(Context context, int resId) {
	super(context, resId);
	}

	@Override
	protected Bitmap onGetBitmap() {
	if (mBitmap != null) return mBitmap;

	BitmapFactory.Options options = new BitmapFactory.Options();
	options.inPreferredConfig = Bitmap.Config.ARGB_8888;
	Bitmap bitmap = BitmapFactory.decodeResource(
	mContext.getResources(), mResId, options);
	mBitmap = bitmap;
	setSize(bitmap.getWidth(), bitmap.getHeight());
	byte[] chunkData = bitmap.getNinePatchChunk();
	mChunk = chunkData == null
	? null
	: NinePatchChunk.deserialize(bitmap.getNinePatchChunk());
	if (mChunk == null) {
	throw new RuntimeException("invalid nine-patch image: " + mResId);
	}
	return bitmap;
	}

	public Rect getPaddings() {
	// get the paddings from nine patch
	if (mChunk == null) onGetBitmap();
	return mChunk.mPaddings;
	}

	public NinePatchChunk getNinePatchChunk() {
	if (mChunk == null) onGetBitmap();
	return mChunk;
	}

	// This is a simple cache for a small number of things. Linear search
	// is used because the cache is small. It also tries to remove less used
	// item when the cache is full by moving the often-used items to the front.
	private static class SmallCache<V> {
	private static final int CACHE_SIZE = 16;
	private static final int CACHE_SIZE_START_MOVE = CACHE_SIZE / 2;
	private int[] mKey = new int[CACHE_SIZE];
	private V[] mValue = (V[]) new Object[CACHE_SIZE];
	private int mCount; // number of items in this cache

	// Puts a value into the cache. If the cache is full, also returns
	// a less used item, otherwise returns null.
	public V put(int key, V value) {
	if (mCount == CACHE_SIZE) {
	V old = mValue[CACHE_SIZE - 1]; // remove the last item
	mKey[CACHE_SIZE - 1] = key;
	mValue[CACHE_SIZE - 1] = value;
	return old;
	} else {
	mKey[mCount] = key;
	mValue[mCount] = value;
	mCount++;
	return null;
	}
	}

	public V get(int key) {
	for (int i = 0; i < mCount; i++) {
	if (mKey[i] == key) {
	// Move the accessed item one position to the front, so it
	// will less likely to be removed when cache is full. Only
	// do this if the cache is starting to get full.
	if (mCount > CACHE_SIZE_START_MOVE && i > 0) {
	int tmpKey = mKey[i];
	mKey[i] = mKey[i - 1];
	mKey[i - 1] = tmpKey;

	V tmpValue = mValue[i];
	mValue[i] = mValue[i - 1];
	mValue[i - 1] = tmpValue;
	}
	return mValue[i];
	}
	}
	return null;
	}

	public void clear() {
	for (int i = 0; i < mCount; i++) {
	mValue[i] = null; // make sure it's can be garbage-collected.
	}
	mCount = 0;
	}

	public int size() {
	return mCount;
	}

	public V valueAt(int i) {
	return mValue[i];
	}
	}

	private NinePatchInstance findInstance(GLCanvas canvas, int w, int h) {
	int key = w;
	key = (key << 16) \| h;
	NinePatchInstance instance = mInstanceCache.get(key);

	if (instance == null) {
	instance = new NinePatchInstance(this, w, h);
	NinePatchInstance removed = mInstanceCache.put(key, instance);
	if (removed != null) {
	removed.recycle(canvas);
	}
	}

	return instance;
	}

	@Override
	public void draw(GLCanvas canvas, int x, int y, int w, int h) {
	if (!isLoaded()) {
	mInstanceCache.clear();
	}

	if (w != 0 && h != 0) {
	findInstance(canvas, w, h).draw(canvas, this, x, y);
	}
	}

	@Override
	public void recycle() {
	super.recycle();
	GLCanvas canvas = mCanvasRef;
	if (canvas == null) return;
	int n = mInstanceCache.size();
	for (int i = 0; i < n; i++) {
	NinePatchInstance instance = mInstanceCache.valueAt(i);
	instance.recycle(canvas);
	}
	mInstanceCache.clear();
	}
	}

	// This keeps data for a specialization of NinePatchTexture with the size
	// (width, height). We pre-compute the coordinates for efficiency.
	class NinePatchInstance {

	@SuppressWarnings("unused")
	private static final String TAG = "NinePatchInstance";

	// We need 16 vertices for a normal nine-patch image (the 4x4 vertices)
	private static final int VERTEX_BUFFER_SIZE = 16 * 2;

	// We need 22 indices for a normal nine-patch image, plus 2 for each
	// transparent region. Current there are at most 1 transparent region.
	private static final int INDEX_BUFFER_SIZE = 22 + 2;

	private FloatBuffer mXyBuffer;
	private FloatBuffer mUvBuffer;
	private ByteBuffer mIndexBuffer;

	// Names for buffer names: xy, uv, index.
	private int[] mBufferNames;

	private int mIdxCount;

	public NinePatchInstance(NinePatchTexture tex, int width, int height) {
	NinePatchChunk chunk = tex.getNinePatchChunk();

	if (width <= 0 \|\| height <= 0) {
	throw new RuntimeException("invalid dimension");
	}

	// The code should be easily extended to handle the general cases by
	// allocating more space for buffers. But let's just handle the only
	// use case.
	if (chunk.mDivX.length != 2 \|\| chunk.mDivY.length != 2) {
	throw new RuntimeException("unsupported nine patch");
	}

	float divX[] = new float[4];
	float divY[] = new float[4];
	float divU[] = new float[4];
	float divV[] = new float[4];

	int nx = stretch(divX, divU, chunk.mDivX, tex.getWidth(), width);
	int ny = stretch(divY, divV, chunk.mDivY, tex.getHeight(), height);

	prepareVertexData(divX, divY, divU, divV, nx, ny, chunk.mColor);
	}

	/**
	* Stretches the texture according to the nine-patch rules. It will
	* linearly distribute the strechy parts defined in the nine-patch chunk to
	* the target area.
	*
	* <pre>
	* source
	* /--------------^---------------\
	* u0 u1 u2 u3 u4 u5
	* div ---> \|fffff\|ssssssss\|fff\|ssssss\|ffff\| ---> u
	* \| div0 div1 div2 div3 \|
	* \| \| / / / /
	* \| \| / / / /
	* \| \| / / / /
	* \|fffff\|ssss\|fff\|sss\|ffff\| ---> x
	* x0 x1 x2 x3 x4 x5
	* \----------v------------/
	* target
	*
	* f: fixed segment
	* s: stretchy segment
	* </pre>
	*
	* @param div the stretch parts defined in nine-patch chunk
	* @param source the length of the texture
	* @param target the length on the drawing plan
	* @param u output, the positions of these dividers in the texture
	* coordinate
	* @param x output, the corresponding position of these dividers on the
	* drawing plan
	* @return the number of these dividers.
	*/
	private static int stretch(
	float x[], float u[], int div[], int source, int target) {
	int textureSize = Utils.nextPowerOf2(source);
	float textureBound = (float) source / textureSize;

	float stretch = 0;
	for (int i = 0, n = div.length; i < n; i += 2) {
	stretch += div[i + 1] - div[i];
	}

	float remaining = target - source + stretch;

	float lastX = 0;
	float lastU = 0;

	x[0] = 0;
	u[0] = 0;
	for (int i = 0, n = div.length; i < n; i += 2) {
	// Make the stretchy segment a little smaller to prevent sampling
	// on neighboring fixed segments.
	// fixed segment
	x[i + 1] = lastX + (div[i] - lastU) + 0.5f;
	u[i + 1] = Math.min((div[i] + 0.5f) / textureSize, textureBound);

	// stretchy segment
	float partU = div[i + 1] - div[i];
	float partX = remaining * partU / stretch;
	remaining -= partX;
	stretch -= partU;

	lastX = x[i + 1] + partX;
	lastU = div[i + 1];
	x[i + 2] = lastX - 0.5f;
	u[i + 2] = Math.min((lastU - 0.5f)/ textureSize, textureBound);
	}
	// the last fixed segment
	x[div.length + 1] = target;
	u[div.length + 1] = textureBound;

	// remove segments with length 0.
	int last = 0;
	for (int i = 1, n = div.length + 2; i < n; ++i) {
	if ((x[i] - x[last]) < 1f) continue;
	x[++last] = x[i];
	u[last] = u[i];
	}
	return last + 1;
	}

	private void prepareVertexData(float x[], float y[], float u[], float v[],
	int nx, int ny, int[] color) {
	/*
	* Given a 3x3 nine-patch image, the vertex order is defined as the
	* following graph:
	*
	* (0) (1) (2) (3)
	* \| /\| /\| /\|
	* \| / \| / \| / \|
	* (4) (5) (6) (7)
	* \| \ \| \ \| \ \|
	* \| \\| \\| \\|
	* (8) (9) (A) (B)
	* \| /\| /\| /\|
	* \| / \| / \| / \|
	* (C) (D) (E) (F)
	*
	* And we draw the triangle strip in the following index order:
	*
	* index: 04152637B6A5948C9DAEBF
	*/
	int pntCount = 0;
	float xy[] = new float[VERTEX_BUFFER_SIZE];
	float uv[] = new float[VERTEX_BUFFER_SIZE];
	for (int j = 0; j < ny; ++j) {
	for (int i = 0; i < nx; ++i) {
	int xIndex = (pntCount++) << 1;
	int yIndex = xIndex + 1;
	xy[xIndex] = x[i];
	xy[yIndex] = y[j];
	uv[xIndex] = u[i];
	uv[yIndex] = v[j];
	}
	}

	int idxCount = 1;
	boolean isForward = false;
	byte index[] = new byte[INDEX_BUFFER_SIZE];
	for (int row = 0; row < ny - 1; row++) {
	--idxCount;
	isForward = !isForward;

	int start, end, inc;
	if (isForward) {
	start = 0;
	end = nx;
	inc = 1;
	} else {
	start = nx - 1;
	end = -1;
	inc = -1;
	}

	for (int col = start; col != end; col += inc) {
	int k = row * nx + col;
	if (col != start) {
	int colorIdx = row * (nx - 1) + col;
	if (isForward) colorIdx--;
	if (color[colorIdx] == NinePatchChunk.TRANSPARENT_COLOR) {
	index[idxCount] = index[idxCount - 1];
	++idxCount;
	index[idxCount++] = (byte) k;
	}
	}

	index[idxCount++] = (byte) k;
	index[idxCount++] = (byte) (k + nx);
	}
	}

	mIdxCount = idxCount;

	int size = (pntCount * 2) * (Float.SIZE / Byte.SIZE);
	mXyBuffer = allocateDirectNativeOrderBuffer(size).asFloatBuffer();
	mUvBuffer = allocateDirectNativeOrderBuffer(size).asFloatBuffer();
	mIndexBuffer = allocateDirectNativeOrderBuffer(mIdxCount);

	mXyBuffer.put(xy, 0, pntCount * 2).position(0);
	mUvBuffer.put(uv, 0, pntCount * 2).position(0);
	mIndexBuffer.put(index, 0, idxCount).position(0);
	}

	private static ByteBuffer allocateDirectNativeOrderBuffer(int size) {
	return ByteBuffer.allocateDirect(size).order(ByteOrder.nativeOrder());
	}

	private void prepareBuffers(GLCanvas canvas) {
	mBufferNames = new int[3];
	GL11 gl = canvas.getGLInstance();
	GLId.glGenBuffers(3, mBufferNames, 0);

	gl.glBindBuffer(GL11.GL_ARRAY_BUFFER, mBufferNames[0]);
	gl.glBufferData(GL11.GL_ARRAY_BUFFER,
	mXyBuffer.capacity() * (Float.SIZE / Byte.SIZE),
	mXyBuffer, GL11.GL_STATIC_DRAW);

	gl.glBindBuffer(GL11.GL_ARRAY_BUFFER, mBufferNames[1]);
	gl.glBufferData(GL11.GL_ARRAY_BUFFER,
	mUvBuffer.capacity() * (Float.SIZE / Byte.SIZE),
	mUvBuffer, GL11.GL_STATIC_DRAW);

	gl.glBindBuffer(GL11.GL_ELEMENT_ARRAY_BUFFER, mBufferNames[2]);
	gl.glBufferData(GL11.GL_ELEMENT_ARRAY_BUFFER,
	mIndexBuffer.capacity(),
	mIndexBuffer, GL11.GL_STATIC_DRAW);

	// These buffers are never used again.
	mXyBuffer = null;
	mUvBuffer = null;
	mIndexBuffer = null;
	}

	public void draw(GLCanvas canvas, NinePatchTexture tex, int x, int y) {
	if (mBufferNames == null) {
	prepareBuffers(canvas);
	}
	canvas.drawMesh(tex, x, y, mBufferNames[0], mBufferNames[1],
	mBufferNames[2], mIdxCount);
	}

	public void recycle(GLCanvas canvas) {
	if (mBufferNames != null) {
	canvas.deleteBuffer(mBufferNames[0]);
	canvas.deleteBuffer(mBufferNames[1]);
	canvas.deleteBuffer(mBufferNames[2]);
	mBufferNames = null;
	}
	}
	}