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      1 /*
      2  * Copyright (C) 2013 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 com.android.mail.ui;
     18 
     19 import android.graphics.Bitmap;
     20 
     21 /**
     22  * A canvas to draw loaded photos.
     23  */
     24 public interface ImageCanvas {
     25 
     26     /**
     27      * Dimensions holds the desired width, height, and scale for a bitmap being
     28      * placed in the ImageCanvas.
     29      */
     30     public static class Dimensions {
     31         public int width;
     32         public int height;
     33         public float scale;
     34 
     35         public static final float SCALE_ONE = 1.0f;
     36         public static final float SCALE_HALF = 0.5f;
     37         public static final float SCALE_QUARTER = 0.25f;
     38 
     39         public Dimensions() {
     40         }
     41 
     42         public Dimensions(int w, int h, float s) {
     43             width = w;
     44             height = h;
     45             scale = s;
     46         }
     47 
     48         @Override
     49         public String toString() {
     50             return String.format("Dimens [%d x %d]", width, height);
     51         }
     52     }
     53 
     54     /**
     55      * Draw/composite the given Bitmap corresponding with the key 'id'. It will be sized according
     56      * to whatever {@link #getDesiredDimensions(Object, Dimensions)} reported when the
     57      * decode request was made.
     58      *
     59      * @param decoded an exactly-sized, decoded bitmap to display
     60      * @param key
     61      */
     62     void drawImage(Bitmap decoded, Object key);
     63 
     64     /**
     65      * Reset all state associated with this view so that it can be reused.
     66      */
     67     void reset();
     68 
     69     /**
     70      * Outputs the desired dimensions that the object with key 'id' would like to be drawn to.
     71      *
     72      * @param key
     73      * @param outDim caller-allocated {@link Dimensions} object to house the result
     74      */
     75     void getDesiredDimensions(Object key, Dimensions outDim);
     76 
     77     /**
     78      * Return an arbitrary integer to associate with any asynchronous requests for images that
     79      * currently belong to this canvas. If, later on when results are available, the generation
     80      * that is then reported does not match, the photo manager will assume the image is no longer
     81      * desired and will not offer the image.
     82      * <p>
     83      * Implementors should basically treat this as a counter to increment upon reset() or
     84      * data binding.
     85      */
     86     int getGeneration();
     87 }
     88