1 package com.davemorrissey.labs.subscaleview.decoder; 2 3 import android.content.Context; 4 import android.graphics.Bitmap; 5 import android.graphics.Point; 6 import android.graphics.Rect; 7 import android.net.Uri; 8 9 /** 10 * Interface for image decoding classes, allowing the default {@link android.graphics.BitmapRegionDecoder} 11 * based on the Skia library to be replaced with a custom class. 12 */ 13 public interface ImageRegionDecoder { 14 15 /** 16 * Initialise the decoder. When possible, perform initial setup work once in this method. The 17 * dimensions of the image must be returned. The URI can be in one of the following formats: 18 * <br> 19 * File: <code>file:///scard/picture.jpg</code> 20 * <br> 21 * Asset: <code>file:///android_asset/picture.png</code> 22 * <br> 23 * Resource: <code>android.resource://com.example.app/drawable/picture</code> 24 * @param context Application context. A reference may be held, but must be cleared on recycle. 25 * @param uri URI of the image. 26 * @return Dimensions of the image. 27 * @throws Exception if initialisation fails. 28 */ 29 Point init(Context context, Uri uri) throws Exception; 30 31 /** 32 * <p> 33 * Decode a region of the image with the given sample size. This method is called off the UI 34 * thread so it can safely load the image on the current thread. It is called from 35 * {@link android.os.AsyncTask}s running in an executor that may have multiple threads, so 36 * implementations must be thread safe. Adding <code>synchronized</code> to the method signature 37 * is the simplest way to achieve this, but bear in mind the {@link #recycle()} method can be 38 * called concurrently. 39 * </p><p> 40 * See {@link SkiaImageRegionDecoder} and {@link SkiaPooledImageRegionDecoder} for examples of 41 * internal locking and synchronization. 42 * </p> 43 * @param sRect Source image rectangle to decode. 44 * @param sampleSize Sample size. 45 * @return The decoded region. It is safe to return null if decoding fails. 46 */ 47 Bitmap decodeRegion(Rect sRect, int sampleSize); 48 49 /** 50 * Status check. Should return false before initialisation and after recycle. 51 * @return true if the decoder is ready to be used. 52 */ 53 boolean isReady(); 54 55 /** 56 * This method will be called when the decoder is no longer required. It should clean up any resources still in use. 57 */ 58 void recycle(); 59 60 } 61
