1/* Copyright (C) 2010 The Android Open Source Project 2 * 3 * Licensed under the Apache License, Version 2.0 (the "License"); 4 * you may not use this file except in compliance with the License. 5 * You may obtain a copy of the License at 6 * 7 * http://www.apache.org/licenses/LICENSE-2.0 8 * 9 * Unless required by applicable law or agreed to in writing, software 10 * distributed under the License is distributed on an "AS IS" BASIS, 11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 12 * See the License for the specific language governing permissions and 13 * limitations under the License. 14 */ 15 16package android.graphics; 17 18import android.content.res.AssetManager; 19 20import java.io.FileDescriptor; 21import java.io.FileInputStream; 22import java.io.IOException; 23import java.io.InputStream; 24 25/** 26 * BitmapRegionDecoder can be used to decode a rectangle region from an image. 27 * BitmapRegionDecoder is particularly useful when an original image is large and 28 * you only need parts of the image. 29 * 30 * <p>To create a BitmapRegionDecoder, call newInstance(...). 31 * Given a BitmapRegionDecoder, users can call decodeRegion() repeatedly 32 * to get a decoded Bitmap of the specified region. 33 * 34 */ 35public final class BitmapRegionDecoder { 36 private long mNativeBitmapRegionDecoder; 37 private boolean mRecycled; 38 // ensures that the native decoder object exists and that only one decode can 39 // occur at a time. 40 private final Object mNativeLock = new Object(); 41 42 /** 43 * Create a BitmapRegionDecoder from the specified byte array. 44 * Currently only the JPEG and PNG formats are supported. 45 * 46 * @param data byte array of compressed image data. 47 * @param offset offset into data for where the decoder should begin 48 * parsing. 49 * @param length the number of bytes, beginning at offset, to parse 50 * @param isShareable If this is true, then the BitmapRegionDecoder may keep a 51 * shallow reference to the input. If this is false, 52 * then the BitmapRegionDecoder will explicitly make a copy of the 53 * input data, and keep that. Even if sharing is allowed, 54 * the implementation may still decide to make a deep 55 * copy of the input data. If an image is progressively encoded, 56 * allowing sharing may degrade the decoding speed. 57 * @return BitmapRegionDecoder, or null if the image data could not be decoded. 58 * @throws IOException if the image format is not supported or can not be decoded. 59 */ 60 public static BitmapRegionDecoder newInstance(byte[] data, 61 int offset, int length, boolean isShareable) throws IOException { 62 if ((offset | length) < 0 || data.length < offset + length) { 63 throw new ArrayIndexOutOfBoundsException(); 64 } 65 return nativeNewInstance(data, offset, length, isShareable); 66 } 67 68 /** 69 * Create a BitmapRegionDecoder from the file descriptor. 70 * The position within the descriptor will not be changed when 71 * this returns, so the descriptor can be used again as is. 72 * Currently only the JPEG and PNG formats are supported. 73 * 74 * @param fd The file descriptor containing the data to decode 75 * @param isShareable If this is true, then the BitmapRegionDecoder may keep a 76 * shallow reference to the input. If this is false, 77 * then the BitmapRegionDecoder will explicitly make a copy of the 78 * input data, and keep that. Even if sharing is allowed, 79 * the implementation may still decide to make a deep 80 * copy of the input data. If an image is progressively encoded, 81 * allowing sharing may degrade the decoding speed. 82 * @return BitmapRegionDecoder, or null if the image data could not be decoded. 83 * @throws IOException if the image format is not supported or can not be decoded. 84 */ 85 public static BitmapRegionDecoder newInstance( 86 FileDescriptor fd, boolean isShareable) throws IOException { 87 return nativeNewInstance(fd, isShareable); 88 } 89 90 /** 91 * Create a BitmapRegionDecoder from an input stream. 92 * The stream's position will be where ever it was after the encoded data 93 * was read. 94 * Currently only the JPEG and PNG formats are supported. 95 * 96 * @param is The input stream that holds the raw data to be decoded into a 97 * BitmapRegionDecoder. 98 * @param isShareable If this is true, then the BitmapRegionDecoder may keep a 99 * shallow reference to the input. If this is false, 100 * then the BitmapRegionDecoder will explicitly make a copy of the 101 * input data, and keep that. Even if sharing is allowed, 102 * the implementation may still decide to make a deep 103 * copy of the input data. If an image is progressively encoded, 104 * allowing sharing may degrade the decoding speed. 105 * @return BitmapRegionDecoder, or null if the image data could not be decoded. 106 * @throws IOException if the image format is not supported or can not be decoded. 107 * 108 * <p class="note">Prior to {@link android.os.Build.VERSION_CODES#KITKAT}, 109 * if {@link InputStream#markSupported is.markSupported()} returns true, 110 * <code>is.mark(1024)</code> would be called. As of 111 * {@link android.os.Build.VERSION_CODES#KITKAT}, this is no longer the case.</p> 112 */ 113 public static BitmapRegionDecoder newInstance(InputStream is, 114 boolean isShareable) throws IOException { 115 if (is instanceof AssetManager.AssetInputStream) { 116 return nativeNewInstance( 117 ((AssetManager.AssetInputStream) is).getNativeAsset(), 118 isShareable); 119 } else { 120 // pass some temp storage down to the native code. 1024 is made up, 121 // but should be large enough to avoid too many small calls back 122 // into is.read(...). 123 byte [] tempStorage = new byte[16 * 1024]; 124 return nativeNewInstance(is, tempStorage, isShareable); 125 } 126 } 127 128 /** 129 * Create a BitmapRegionDecoder from a file path. 130 * Currently only the JPEG and PNG formats are supported. 131 * 132 * @param pathName complete path name for the file to be decoded. 133 * @param isShareable If this is true, then the BitmapRegionDecoder may keep a 134 * shallow reference to the input. If this is false, 135 * then the BitmapRegionDecoder will explicitly make a copy of the 136 * input data, and keep that. Even if sharing is allowed, 137 * the implementation may still decide to make a deep 138 * copy of the input data. If an image is progressively encoded, 139 * allowing sharing may degrade the decoding speed. 140 * @return BitmapRegionDecoder, or null if the image data could not be decoded. 141 * @throws IOException if the image format is not supported or can not be decoded. 142 */ 143 public static BitmapRegionDecoder newInstance(String pathName, 144 boolean isShareable) throws IOException { 145 BitmapRegionDecoder decoder = null; 146 InputStream stream = null; 147 148 try { 149 stream = new FileInputStream(pathName); 150 decoder = newInstance(stream, isShareable); 151 } finally { 152 if (stream != null) { 153 try { 154 stream.close(); 155 } catch (IOException e) { 156 // do nothing here 157 } 158 } 159 } 160 return decoder; 161 } 162 163 /* Private constructor that must receive an already allocated native 164 region decoder int (pointer). 165 166 This can be called from JNI code. 167 */ 168 private BitmapRegionDecoder(long decoder) { 169 mNativeBitmapRegionDecoder = decoder; 170 mRecycled = false; 171 } 172 173 /** 174 * Decodes a rectangle region in the image specified by rect. 175 * 176 * @param rect The rectangle that specified the region to be decode. 177 * @param options null-ok; Options that control downsampling. 178 * inPurgeable is not supported. 179 * @return The decoded bitmap, or null if the image data could not be 180 * decoded. 181 * @throws IllegalArgumentException if {@link BitmapFactory.Options#inPreferredConfig} 182 * is {@link android.graphics.Bitmap.Config#HARDWARE} 183 * and {@link BitmapFactory.Options#inMutable} is set, if the specified color space 184 * is not {@link ColorSpace.Model#RGB RGB}, or if the specified color space's transfer 185 * function is not an {@link ColorSpace.Rgb.TransferParameters ICC parametric curve} 186 */ 187 public Bitmap decodeRegion(Rect rect, BitmapFactory.Options options) { 188 BitmapFactory.Options.validate(options); 189 synchronized (mNativeLock) { 190 checkRecycled("decodeRegion called on recycled region decoder"); 191 if (rect.right <= 0 || rect.bottom <= 0 || rect.left >= getWidth() 192 || rect.top >= getHeight()) 193 throw new IllegalArgumentException("rectangle is outside the image"); 194 return nativeDecodeRegion(mNativeBitmapRegionDecoder, rect.left, rect.top, 195 rect.right - rect.left, rect.bottom - rect.top, options); 196 } 197 } 198 199 /** Returns the original image's width */ 200 public int getWidth() { 201 synchronized (mNativeLock) { 202 checkRecycled("getWidth called on recycled region decoder"); 203 return nativeGetWidth(mNativeBitmapRegionDecoder); 204 } 205 } 206 207 /** Returns the original image's height */ 208 public int getHeight() { 209 synchronized (mNativeLock) { 210 checkRecycled("getHeight called on recycled region decoder"); 211 return nativeGetHeight(mNativeBitmapRegionDecoder); 212 } 213 } 214 215 /** 216 * Frees up the memory associated with this region decoder, and mark the 217 * region decoder as "dead", meaning it will throw an exception if decodeRegion(), 218 * getWidth() or getHeight() is called. 219 * 220 * <p>This operation cannot be reversed, so it should only be called if you are 221 * sure there are no further uses for the region decoder. This is an advanced call, 222 * and normally need not be called, since the normal GC process will free up this 223 * memory when there are no more references to this region decoder. 224 */ 225 public void recycle() { 226 synchronized (mNativeLock) { 227 if (!mRecycled) { 228 nativeClean(mNativeBitmapRegionDecoder); 229 mRecycled = true; 230 } 231 } 232 } 233 234 /** 235 * Returns true if this region decoder has been recycled. 236 * If so, then it is an error to try use its method. 237 * 238 * @return true if the region decoder has been recycled 239 */ 240 public final boolean isRecycled() { 241 return mRecycled; 242 } 243 244 /** 245 * Called by methods that want to throw an exception if the region decoder 246 * has already been recycled. 247 */ 248 private void checkRecycled(String errorMessage) { 249 if (mRecycled) { 250 throw new IllegalStateException(errorMessage); 251 } 252 } 253 254 @Override 255 protected void finalize() throws Throwable { 256 try { 257 recycle(); 258 } finally { 259 super.finalize(); 260 } 261 } 262 263 private static native Bitmap nativeDecodeRegion(long lbm, 264 int start_x, int start_y, int width, int height, 265 BitmapFactory.Options options); 266 private static native int nativeGetWidth(long lbm); 267 private static native int nativeGetHeight(long lbm); 268 private static native void nativeClean(long lbm); 269 270 private static native BitmapRegionDecoder nativeNewInstance( 271 byte[] data, int offset, int length, boolean isShareable); 272 private static native BitmapRegionDecoder nativeNewInstance( 273 FileDescriptor fd, boolean isShareable); 274 private static native BitmapRegionDecoder nativeNewInstance( 275 InputStream is, byte[] storage, boolean isShareable); 276 private static native BitmapRegionDecoder nativeNewInstance( 277 long asset, boolean isShareable); 278} 279