1 /*
2  * Copyright (C) 2024 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;
18 
19 import android.annotation.ColorInt;
20 import android.annotation.Nullable;
21 import android.graphics.Color;
22 import android.text.style.CharacterStyle;
23 
24 /**
25  * Finds the foreground text color for the given Spanned text so you can iterate through each color
26  * change.
27  *
28  * @hide
29  */
30 public class SpanColors {
31     public static final @ColorInt int NO_COLOR_FOUND = Color.TRANSPARENT;
32 
33     private final SpanSet<CharacterStyle> mCharacterStyleSpanSet =
34             new SpanSet<>(CharacterStyle.class);
35     @Nullable private TextPaint mWorkPaint;
36 
SpanColors()37     public SpanColors() {}
38 
39     /**
40      * Init for the given text
41      *
42      * @param workPaint A temporary TextPaint object that will be used to calculate the colors. The
43      *                  paint properties will be mutated on calls to {@link #getColorAt(int)} so
44      *                  make sure to reset it before you use it for something else.
45      * @param spanned the text to examine
46      * @param start index to start at
47      * @param end index of the end
48      */
init(TextPaint workPaint, Spanned spanned, int start, int end)49     public void init(TextPaint workPaint, Spanned spanned, int start, int end) {
50         mWorkPaint = workPaint;
51         mCharacterStyleSpanSet.init(spanned, start, end);
52     }
53 
54     /**
55      * Removes all internal references to the spans to avoid memory leaks.
56      */
recycle()57     public void recycle() {
58         mWorkPaint = null;
59         mCharacterStyleSpanSet.recycle();
60     }
61 
62     /**
63      * Calculates the foreground color of the text at the given character index.
64      *
65      * <p>You must call {@link #init(TextPaint, Spanned, int, int)} before calling this
66      */
getColorAt(int index)67     public @ColorInt int getColorAt(int index) {
68         var finalColor = NO_COLOR_FOUND;
69         // Reset the paint so if we get a CharacterStyle that doesn't actually specify color,
70         // (like UnderlineSpan), we still return no color found.
71         mWorkPaint.setColor(finalColor);
72         for (int k = 0; k < mCharacterStyleSpanSet.numberOfSpans; k++) {
73             if ((index >= mCharacterStyleSpanSet.spanStarts[k])
74                     && (index <= mCharacterStyleSpanSet.spanEnds[k])) {
75                 final CharacterStyle span = mCharacterStyleSpanSet.spans[k];
76                 span.updateDrawState(mWorkPaint);
77 
78                 finalColor = calculateFinalColor(mWorkPaint);
79             }
80         }
81         return finalColor;
82     }
83 
calculateFinalColor(TextPaint workPaint)84     private @ColorInt int calculateFinalColor(TextPaint workPaint) {
85         // TODO: can we figure out what the getColorFilter() will do?
86         //  if so, we also need to reset colorFilter before the loop in getColorAt()
87         return workPaint.getColor();
88     }
89 }
90