Home | History | Annotate | Download | only in graphics 
      1 /*
      2  * Copyright (C) 2006 The Android Open Source Project
      3  *
      4  * Licensed under the Apache License, Version 2.0 (the "License");
      5  * you may not use this file except in compliance with the License.
      6  * You may obtain a copy of the License at
      7  *
      8  *      http://www.apache.org/licenses/LICENSE-2.0
      9  *
     10  * Unless required by applicable law or agreed to in writing, software
     11  * distributed under the License is distributed on an "AS IS" BASIS,
     12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
     13  * See the License for the specific language governing permissions and
     14  * limitations under the License.
     15  */
     16 
     17 package android.graphics;
     18 
     19 import android.os.Parcel;
     20 import android.os.Parcelable;
     21 import android.util.DisplayMetrics;
     22 
     23 import java.io.OutputStream;
     24 import java.nio.Buffer;
     25 import java.nio.ByteBuffer;
     26 import java.nio.IntBuffer;
     27 import java.nio.ShortBuffer;
     28 
     29 /**
     30  * LargeBitmap can be used to decode a rectangle region from an image.
     31  * LargeBimap is particularly useful when an original image is large and
     32  * you only need parts of the image.
     33  *
     34  * To create a LargeBitmap, call BitmapFactory.createLargeBitmap().
     35  * Given a LargeBitmap, users can call decodeRegion() repeatedly
     36  * to get a decoded Bitmap of the specified region.
     37  * @hide
     38  */
     39 public final class LargeBitmap {
     40     private int mNativeLargeBitmap;
     41     private boolean mRecycled;
     42 
     43     /*  Private constructor that must received an already allocated native
     44         large bitmap int (pointer).
     45 
     46         This can be called from JNI code.
     47     */
     48     private LargeBitmap(int lbm) {
     49         mNativeLargeBitmap = lbm;
     50         mRecycled = false;
     51     }
     52 
     53     /**
     54      * Decodes a rectangle region in the image specified by rect.
     55      *
     56      * @param rect The rectangle that specified the region to be decode.
     57      * @param opts null-ok; Options that control downsampling.
     58      *             inPurgeable is not supported.
     59      * @return The decoded bitmap, or null if the image data could not be
     60      *         decoded.
     61      */
     62     public Bitmap decodeRegion(Rect rect, BitmapFactory.Options options) {
     63         checkRecycled("decodeRegion called on recycled large bitmap");
     64         if (rect.left < 0 || rect.top < 0 || rect.right > getWidth() || rect.bottom > getHeight())
     65             throw new IllegalArgumentException("rectangle is not inside the image");
     66         return nativeDecodeRegion(mNativeLargeBitmap, rect.left, rect.top,
     67                 rect.right - rect.left, rect.bottom - rect.top, options);
     68     }
     69 
     70     /** Returns the original image's width */
     71     public int getWidth() {
     72         checkRecycled("getWidth called on recycled large bitmap");
     73         return nativeGetWidth(mNativeLargeBitmap);
     74     }
     75 
     76     /** Returns the original image's height */
     77     public int getHeight() {
     78         checkRecycled("getHeight called on recycled large bitmap");
     79         return nativeGetHeight(mNativeLargeBitmap);
     80     }
     81 
     82     /**
     83      * Frees up the memory associated with this large bitmap, and mark the
     84      * large bitmap as "dead", meaning it will throw an exception if decodeRegion(),
     85      * getWidth() or getHeight() is called.
     86      * This operation cannot be reversed, so it should only be called if you are
     87      * sure there are no further uses for the large bitmap. This is an advanced call,
     88      * and normally need not be called, since the normal GC process will free up this
     89      * memory when there are no more references to this bitmap.
     90      */
     91     public void recycle() {
     92         if (!mRecycled) {
     93             nativeClean(mNativeLargeBitmap);
     94             mRecycled = true;
     95         }
     96     }
     97 
     98     /**
     99      * Returns true if this large bitmap has been recycled.
    100      * If so, then it is an error to try use its method.
    101      *
    102      * @return true if the large bitmap has been recycled
    103      */
    104     public final boolean isRecycled() {
    105         return mRecycled;
    106     }
    107 
    108     /**
    109      * Called by methods that want to throw an exception if the bitmap
    110      * has already been recycled.
    111      */
    112     private void checkRecycled(String errorMessage) {
    113         if (mRecycled) {
    114             throw new IllegalStateException(errorMessage);
    115         }
    116     }
    117 
    118     protected void finalize() {
    119         recycle();
    120     }
    121 
    122     private static native Bitmap nativeDecodeRegion(int lbm,
    123             int start_x, int start_y, int width, int height,
    124             BitmapFactory.Options options);
    125     private static native int nativeGetWidth(int lbm);
    126     private static native int nativeGetHeight(int lbm);
    127     private static native void nativeClean(int lbm);
    128 }
    129