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.annotation.IntRange; 20 import android.annotation.NonNull; 21 import android.annotation.Nullable; 22 import android.graphics.Canvas; 23 import android.graphics.Paint; 24 import android.graphics.Rect; 25 import android.graphics.drawable.Drawable; 26 27 import java.lang.ref.WeakReference; 28 29 /** 30 * Span that replaces the text it's attached to with a {@link Drawable} that can be aligned with 31 * the bottom or with the baseline of the surrounding text. 32 * <p> 33 * For an implementation that constructs the drawable from various sources (<code>Bitmap</code>, 34 * <code>Drawable</code>, resource id or <code>Uri</code>) use {@link ImageSpan}. 35 * <p> 36 * A simple implementation of <code>DynamicDrawableSpan</code> that uses drawables from resources 37 * looks like this: 38 * <pre> 39 * class MyDynamicDrawableSpan extends DynamicDrawableSpan { 40 * 41 * private final Context mContext; 42 * private final int mResourceId; 43 * 44 * public MyDynamicDrawableSpan(Context context, @DrawableRes int resourceId) { 45 * mContext = context; 46 * mResourceId = resourceId; 47 * } 48 * 49 * {@literal @}Override 50 * public Drawable getDrawable() { 51 * Drawable drawable = mContext.getDrawable(mResourceId); 52 * drawable.setBounds(0, 0, drawable.getIntrinsicWidth(), drawable.getIntrinsicHeight()); 53 * return drawable; 54 * } 55 * }</pre> 56 * The class can be used like this: 57 * <pre> 58 * SpannableString string = new SpannableString("Text with a drawable span"); 59 * string.setSpan(new MyDynamicDrawableSpan(context, R.mipmap.ic_launcher), 12, 20, Spanned 60 * .SPAN_EXCLUSIVE_EXCLUSIVE);</pre> 61 * <img src="{@docRoot}reference/android/images/text/style/dynamicdrawablespan.png" /> 62 * <figcaption>Replacing text with a drawable.</figcaption> 63 */ 64 public abstract class DynamicDrawableSpan extends ReplacementSpan { 65 66 /** 67 * A constant indicating that the bottom of this span should be aligned 68 * with the bottom of the surrounding text, i.e., at the same level as the 69 * lowest descender in the text. 70 */ 71 public static final int ALIGN_BOTTOM = 0; 72 73 /** 74 * A constant indicating that the bottom of this span should be aligned 75 * with the baseline of the surrounding text. 76 */ 77 public static final int ALIGN_BASELINE = 1; 78 79 protected final int mVerticalAlignment; 80 81 private WeakReference<Drawable> mDrawableRef; 82 83 /** 84 * Creates a {@link DynamicDrawableSpan}. The default vertical alignment is 85 * {@link #ALIGN_BOTTOM} 86 */ DynamicDrawableSpan()87 public DynamicDrawableSpan() { 88 mVerticalAlignment = ALIGN_BOTTOM; 89 } 90 91 /** 92 * Creates a {@link DynamicDrawableSpan} based on a vertical alignment.\ 93 * 94 * @param verticalAlignment one of {@link #ALIGN_BOTTOM} or {@link #ALIGN_BASELINE} 95 */ DynamicDrawableSpan(int verticalAlignment)96 protected DynamicDrawableSpan(int verticalAlignment) { 97 mVerticalAlignment = verticalAlignment; 98 } 99 100 /** 101 * Returns the vertical alignment of this span, one of {@link #ALIGN_BOTTOM} or 102 * {@link #ALIGN_BASELINE}. 103 */ getVerticalAlignment()104 public int getVerticalAlignment() { 105 return mVerticalAlignment; 106 } 107 108 /** 109 * Your subclass must implement this method to provide the bitmap 110 * to be drawn. The dimensions of the bitmap must be the same 111 * from each call to the next. 112 */ getDrawable()113 public abstract Drawable getDrawable(); 114 115 @Override getSize(@onNull Paint paint, CharSequence text, @IntRange(from = 0) int start, @IntRange(from = 0) int end, @Nullable Paint.FontMetricsInt fm)116 public int getSize(@NonNull Paint paint, CharSequence text, 117 @IntRange(from = 0) int start, @IntRange(from = 0) int end, 118 @Nullable Paint.FontMetricsInt fm) { 119 Drawable d = getCachedDrawable(); 120 Rect rect = d.getBounds(); 121 122 if (fm != null) { 123 fm.ascent = -rect.bottom; 124 fm.descent = 0; 125 126 fm.top = fm.ascent; 127 fm.bottom = 0; 128 } 129 130 return rect.right; 131 } 132 133 @Override draw(@onNull Canvas canvas, CharSequence text, @IntRange(from = 0) int start, @IntRange(from = 0) int end, float x, int top, int y, int bottom, @NonNull Paint paint)134 public void draw(@NonNull Canvas canvas, CharSequence text, 135 @IntRange(from = 0) int start, @IntRange(from = 0) int end, float x, 136 int top, int y, int bottom, @NonNull Paint paint) { 137 Drawable b = getCachedDrawable(); 138 canvas.save(); 139 140 int transY = bottom - b.getBounds().bottom; 141 if (mVerticalAlignment == ALIGN_BASELINE) { 142 transY -= paint.getFontMetricsInt().descent; 143 } 144 145 canvas.translate(x, transY); 146 b.draw(canvas); 147 canvas.restore(); 148 } 149 getCachedDrawable()150 private Drawable getCachedDrawable() { 151 WeakReference<Drawable> wr = mDrawableRef; 152 Drawable d = null; 153 154 if (wr != null) { 155 d = wr.get(); 156 } 157 158 if (d == null) { 159 d = getDrawable(); 160 mDrawableRef = new WeakReference<Drawable>(d); 161 } 162 163 return d; 164 } 165 } 166 167
