summaryrefslogtreecommitdiffstats
path: root/src/com/android/launcher3/AutoExpandTextView.java
blob: ea7ac896eb6d3d5eee25648e88b3d7a1be1ee653 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
/*
 * Copyright (C) 2014 Grantland Chew
 * Copyright (C) 2015 The CyanogenMod Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.android.launcher3;

import android.content.Context;
import android.content.res.Resources;
import android.content.res.TypedArray;
import android.graphics.Color;
import android.text.SpannableString;
import android.text.SpannableStringBuilder;
import android.text.TextPaint;
import android.text.TextUtils;
import android.text.method.TransformationMethod;
import android.text.style.ForegroundColorSpan;
import android.util.AttributeSet;
import android.widget.TextView;

import java.util.ArrayList;

/**
 * A single-line TextView that resizes it's letter spacing to fit the width of the view
 *
 * @author Grantland Chew <grantlandchew@gmail.com>
 * @author Linus Lee <llee@cyngn.com>
 */
public class AutoExpandTextView extends TextView {
    // How precise we want to be when reaching the target textWidth size
    private static final float PRECISION = 0.01f;

    // Attributes
    private float mPrecision;
    private TextPaint mPaint;
    private float[] mPositions;

    public static class HighlightedText {
        public String mText;
        public boolean mHighlight;

        public HighlightedText(String text, boolean highlight) {
            mText = text;
            mHighlight = highlight;
        }
    }

    public AutoExpandTextView(Context context) {
        super(context);
        init(context, null, 0);
    }

    public AutoExpandTextView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(context, attrs, 0);
    }

    public AutoExpandTextView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init(context, attrs, defStyle);
    }

    private void init(Context context, AttributeSet attrs, int defStyle) {
        float precision = PRECISION;

        if (attrs != null) {
            TypedArray ta = context.obtainStyledAttributes(
                    attrs,
                    R.styleable.AutofitTextView,
                    defStyle,
                    0);
            precision = ta.getFloat(R.styleable.AutofitTextView_precision, precision);
        }

        mPaint = new TextPaint();
        setPrecision(precision);
    }

    /**
     * @return the amount of precision used to calculate the correct text size to fit within it's
     * bounds.
     */
    public float getPrecision() {
        return mPrecision;
    }

    /**
     * Set the amount of precision used to calculate the correct text size to fit within it's
     * bounds. Lower precision is more precise and takes more time.
     *
     * @param precision The amount of precision.
     */
    public void setPrecision(float precision) {
        if (precision != mPrecision) {
            mPrecision = precision;
            refitText();
        }
    }

    /**
     * {@inheritDoc}
     */
    @Override
    public void setLines(int lines) {
        super.setLines(1);
        refitText();
    }

    /**
     * Only allow max lines of 1
     */
    @Override
    public void setMaxLines(int maxLines) {
        super.setMaxLines(1);
        refitText();
    }

    /**
     * Re size the font so the specified text fits in the text box assuming the text box is the
     * specified width.
     */
    private void refitText() {
        CharSequence text = getText();

        if (TextUtils.isEmpty(text)) {
            return;
        }

        TransformationMethod method = getTransformationMethod();
        if (method != null) {
            text = method.getTransformation(text, this);
        }
        int targetWidth = getWidth() - getPaddingLeft() - getPaddingRight();
        if (targetWidth > 0) {
            float high = 100;
            float low = 0;

            mPaint.set(getPaint());
            mPaint.setTextSize(getTextSize());
            float letterSpacing = getLetterSpacing(text, mPaint, targetWidth, low, high,
                    mPrecision);
            mPaint.setLetterSpacing(letterSpacing);
            calculateSections(text);

            super.setLetterSpacing(letterSpacing);
        }
    }

    public float getPositionOfSection(int position) {
        if (mPositions == null || position >= mPositions.length) {
            return 0;
        }
        return mPositions[position];
    }

    /**
     * This calculates the different horizontal positions of each character
     */
    private void calculateSections(CharSequence text) {
        mPositions = new float[text.length()];
        for (int i = 0; i < text.length(); i++) {
            if (i == 0) {
                mPositions[0] = mPaint.measureText(text, 0, 1) / 2;
            } else {
                // try to be lazy and just add the width of the newly added char
                mPositions[i] = mPaint.measureText(text, i, i + 1) + mPositions[i - 1];
            }
        }
    }

    /**
     * Sets the list of sections in the text view.  This will take the first character of each
     * and space it out in the text view using letter spacing
     */
    public void setSections(ArrayList<HighlightedText> sections) {
        mPositions = null;
        if (sections == null || sections.size() == 0) {
            setText("");
            return;
        }

        Resources r = getContext().getResources();
        int highlightColor = r.getColor(R.color.app_scrubber_highlight_color);
        int grayColor = r.getColor(R.color.app_scrubber_gray_color);

        SpannableStringBuilder builder = new SpannableStringBuilder();
        for (HighlightedText highlightText : sections) {
            SpannableString spannable = new SpannableString(highlightText.mText.substring(0, 1));
            spannable.setSpan(
                    new ForegroundColorSpan(highlightText.mHighlight ? highlightColor : grayColor),
                    0, spannable.length(), 0);
            builder.append(spannable);
        }

        setText(builder);
    }

    private static float getLetterSpacing(CharSequence text, TextPaint paint, float targetWidth,
                                          float low, float high, float precision) {
        float mid = (low + high) / 2.0f;
        paint.setLetterSpacing(mid);

        float measuredWidth = paint.measureText(text, 0, text.length());

        if (high - low < precision) {
            if (measuredWidth < targetWidth) {
                return mid;
            } else {
                return low;
            }
        } else if (measuredWidth > targetWidth) {
            return getLetterSpacing(text, paint, targetWidth, low, mid, precision);
        } else if (measuredWidth < targetWidth) {
            return getLetterSpacing(text, paint, targetWidth, mid, high, precision);
        } else {
            return mid;
        }
    }

    @Override
    protected void onTextChanged(final CharSequence text, final int start,
                                 final int lengthBefore, final int lengthAfter) {
        super.onTextChanged(text, start, lengthBefore, lengthAfter);
        refitText();
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        if (w != oldw) {
            refitText();
        }
    }
}