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      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.text.style;
     18 
     19 import android.graphics.Canvas;
     20 import android.graphics.Paint;
     21 import android.graphics.Rect;
     22 import android.graphics.drawable.Drawable;
     23 
     24 import java.lang.ref.WeakReference;
     25 
     26 /**
     27  *
     28  */
     29 public abstract class DynamicDrawableSpan extends ReplacementSpan {
     30     private static final String TAG = "DynamicDrawableSpan";
     31 
     32     /**
     33      * A constant indicating that the bottom of this span should be aligned
     34      * with the bottom of the surrounding text, i.e., at the same level as the
     35      * lowest descender in the text.
     36      */
     37     public static final int ALIGN_BOTTOM = 0;
     38 
     39     /**
     40      * A constant indicating that the bottom of this span should be aligned
     41      * with the baseline of the surrounding text.
     42      */
     43     public static final int ALIGN_BASELINE = 1;
     44 
     45     protected final int mVerticalAlignment;
     46 
     47     public DynamicDrawableSpan() {
     48         mVerticalAlignment = ALIGN_BOTTOM;
     49     }
     50 
     51     /**
     52      * @param verticalAlignment one of {@link #ALIGN_BOTTOM} or {@link #ALIGN_BASELINE}.
     53      */
     54     protected DynamicDrawableSpan(int verticalAlignment) {
     55         mVerticalAlignment = verticalAlignment;
     56     }
     57 
     58     /**
     59      * Returns the vertical alignment of this span, one of {@link #ALIGN_BOTTOM} or
     60      * {@link #ALIGN_BASELINE}.
     61      */
     62     public int getVerticalAlignment() {
     63         return mVerticalAlignment;
     64     }
     65 
     66     /**
     67      * Your subclass must implement this method to provide the bitmap
     68      * to be drawn.  The dimensions of the bitmap must be the same
     69      * from each call to the next.
     70      */
     71     public abstract Drawable getDrawable();
     72 
     73     @Override
     74     public int getSize(Paint paint, CharSequence text,
     75                          int start, int end,
     76                          Paint.FontMetricsInt fm) {
     77         Drawable d = getCachedDrawable();
     78         Rect rect = d.getBounds();
     79 
     80         if (fm != null) {
     81             fm.ascent = -rect.bottom;
     82             fm.descent = 0;
     83 
     84             fm.top = fm.ascent;
     85             fm.bottom = 0;
     86         }
     87 
     88         return rect.right;
     89     }
     90 
     91     @Override
     92     public void draw(Canvas canvas, CharSequence text,
     93                      int start, int end, float x,
     94                      int top, int y, int bottom, Paint paint) {
     95         Drawable b = getCachedDrawable();
     96         canvas.save();
     97 
     98         int transY = bottom - b.getBounds().bottom;
     99         if (mVerticalAlignment == ALIGN_BASELINE) {
    100             transY -= paint.getFontMetricsInt().descent;
    101         }
    102 
    103         canvas.translate(x, transY);
    104         b.draw(canvas);
    105         canvas.restore();
    106     }
    107 
    108     private Drawable getCachedDrawable() {
    109         WeakReference<Drawable> wr = mDrawableRef;
    110         Drawable d = null;
    111 
    112         if (wr != null)
    113             d = wr.get();
    114 
    115         if (d == null) {
    116             d = getDrawable();
    117             mDrawableRef = new WeakReference<Drawable>(d);
    118         }
    119 
    120         return d;
    121     }
    122 
    123     private WeakReference<Drawable> mDrawableRef;
    124 }
    125 
    126