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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         public float fontSize;
     35 
     36         public static final float SCALE_ONE = 1.0f;
     37         public static final float SCALE_HALF = 0.5f;
     38         public static final float SCALE_QUARTER = 0.25f;
     39 
     40         public Dimensions() {
     41         }
     42 
     43         public Dimensions(int w, int h, float s) {
     44             this(w, h, s, -1f);
     45         }
     46 
     47         public Dimensions(int width, int height, float scale, float fontSize) {
     48             this.width = width;
     49             this.height = height;
     50             this.scale = scale;
     51             this.fontSize = fontSize;
     52         }
     53 
     54         @Override
     55         public String toString() {
     56             return String.format("Dimens [%d x %d]", width, height);
     57         }
     58     }
     59 
     60     /**
     61      * Draw/composite the given Bitmap corresponding with the key 'id'. It will be sized according
     62      * to whatever {@link #getDesiredDimensions(Object, Dimensions)} reported when the
     63      * decode request was made.
     64      *
     65      * @param decoded an exactly-sized, decoded bitmap to display
     66      * @param key
     67      */
     68     void drawImage(Bitmap decoded, Object key);
     69 
     70     /**
     71      * Reset all state associated with this view so that it can be reused.
     72      */
     73     void reset();
     74 
     75     /**
     76      * Outputs the desired dimensions that the object with key 'id' would like to be drawn to.
     77      *
     78      * @param key
     79      * @param outDim caller-allocated {@link Dimensions} object to house the result
     80      */
     81     void getDesiredDimensions(Object key, Dimensions outDim);
     82 
     83     /**
     84      * Return an arbitrary integer to associate with any asynchronous requests for images that
     85      * currently belong to this canvas. If, later on when results are available, the generation
     86      * that is then reported does not match, the photo manager will assume the image is no longer
     87      * desired and will not offer the image.
     88      * <p>
     89      * Implementors should basically treat this as a counter to increment upon reset() or
     90      * data binding.
     91      */
     92     int getGeneration();
     93 }
     94