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      1 /*
      2  * Copyright (C) 2016 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.deskclock.widget;
     18 
     19 import android.text.Layout;
     20 import android.text.TextPaint;
     21 import android.util.TypedValue;
     22 import android.view.View;
     23 import android.widget.TextView;
     24 
     25 import static java.lang.Integer.MAX_VALUE;
     26 
     27 /**
     28  * A TextView which automatically re-sizes its text to fit within its boundaries.
     29  */
     30 public final class TextSizeHelper {
     31 
     32     // The text view whose size this class controls.
     33     private final TextView mTextView;
     34 
     35     // Text paint used for measuring.
     36     private final TextPaint mMeasurePaint = new TextPaint();
     37 
     38     // The maximum size the text is allowed to be (in pixels).
     39     private float mMaxTextSize;
     40 
     41     // The maximum width the text is allowed to be (in pixels).
     42     private int mWidthConstraint = MAX_VALUE;
     43 
     44     // The maximum height the text is allowed to be (in pixels).
     45     private int mHeightConstraint = MAX_VALUE;
     46 
     47     // When {@code true} calls to {@link #requestLayout()} should be ignored.
     48     private boolean mIgnoreRequestLayout;
     49 
     50     public TextSizeHelper(TextView view) {
     51         mTextView = view;
     52         mMaxTextSize = view.getTextSize();
     53     }
     54 
     55     public void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
     56         int widthConstraint = MAX_VALUE;
     57         if (View.MeasureSpec.getMode(widthMeasureSpec) != View.MeasureSpec.UNSPECIFIED) {
     58             widthConstraint = View.MeasureSpec.getSize(widthMeasureSpec)
     59                     - mTextView.getCompoundPaddingLeft() - mTextView.getCompoundPaddingRight();
     60         }
     61 
     62         int heightConstraint = MAX_VALUE;
     63         if (View.MeasureSpec.getMode(heightMeasureSpec) != View.MeasureSpec.UNSPECIFIED) {
     64             heightConstraint = View.MeasureSpec.getSize(heightMeasureSpec)
     65                     - mTextView.getCompoundPaddingTop() - mTextView.getCompoundPaddingBottom();
     66         }
     67 
     68         if (mTextView.isLayoutRequested() || mWidthConstraint != widthConstraint
     69                 || mHeightConstraint != heightConstraint) {
     70             mWidthConstraint = widthConstraint;
     71             mHeightConstraint = heightConstraint;
     72 
     73             adjustTextSize();
     74         }
     75     }
     76 
     77     public void onTextChanged(int lengthBefore, int lengthAfter) {
     78         // The length of the text has changed, request layout to recalculate the current text
     79         // size. This is necessary to workaround an optimization in TextView#checkForRelayout()
     80         // which will avoid re-layout when the view has a fixed layout width.
     81         if (lengthBefore != lengthAfter) {
     82             mTextView.requestLayout();
     83         }
     84     }
     85 
     86     public boolean shouldIgnoreRequestLayout() {
     87         return mIgnoreRequestLayout;
     88     }
     89 
     90     private void adjustTextSize() {
     91         final CharSequence text = mTextView.getText();
     92         float textSize = mMaxTextSize;
     93         if (text.length() > 0 && (mWidthConstraint < MAX_VALUE || mHeightConstraint < MAX_VALUE)) {
     94             mMeasurePaint.set(mTextView.getPaint());
     95 
     96             float minTextSize = 1f;
     97             float maxTextSize = mMaxTextSize;
     98             while (maxTextSize >= minTextSize) {
     99                 final float midTextSize = Math.round((maxTextSize + minTextSize) / 2f);
    100                 mMeasurePaint.setTextSize(midTextSize);
    101 
    102                 final float width = Layout.getDesiredWidth(text, mMeasurePaint);
    103                 final float height = mMeasurePaint.getFontMetricsInt(null);
    104                 if (width > mWidthConstraint || height > mHeightConstraint) {
    105                     maxTextSize = midTextSize - 1f;
    106                 } else {
    107                     textSize = midTextSize;
    108                     minTextSize = midTextSize + 1f;
    109                 }
    110             }
    111         }
    112 
    113         if (mTextView.getTextSize() != textSize) {
    114             mIgnoreRequestLayout = true;
    115             mTextView.setTextSize(TypedValue.COMPLEX_UNIT_PX, textSize);
    116             mIgnoreRequestLayout = false;
    117         }
    118     }
    119 }