FontFitTextView.java

/*
 * RapidPro Android Channel - Relay SMS messages where MNO connections aren't practical.
 * Copyright (C) 2014 Nyaruka, UNICEF
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

package io.rapidpro.androidchannel.ui;
import android.content.Context;
import android.graphics.Paint;
import android.graphics.Rect;
import android.util.AttributeSet;
import android.util.TypedValue;
import android.widget.TextView;
import io.rapidpro.androidchannel.RapidPro;

public class FontFitTextView extends TextView {

    public FontFitTextView(Context context) {
        super(context);
        initialise();
    }

    public FontFitTextView(Context context, AttributeSet attrs) {
        super(context, attrs);
        initialise();
    }

    private void initialise() {
        mTestPaint = new Paint();
        mTestPaint.set(this.getPaint());
        //max size defaults to the initially specified text size unless it is too small
    }

    /*
     * Re size the font so the specified text fits in the text box
     * assuming the text box is the specified width.
     */
    private void refitText(String text, int textWidth, int textHeight){
        if (textWidth <= 0){
            return;
        }

        int targetWidth = textWidth - this.getPaddingLeft() - this.getPaddingRight();
        int targetHeight = (int)((textHeight - this.getPaddingTop() - this.getPaddingBottom()) * .75);

        float hi = 80;
        float lo = 2;

        mTestPaint.set(this.getPaint());
        Rect bounds = new Rect();
        float size = hi;

        do {
            size -= 2;
            mTestPaint.setTextSize(size);
            mTestPaint.getTextBounds(text, 0, text.length(), bounds);
        } while ((bounds.width() >= targetWidth || bounds.height() >= targetHeight) && (size > lo));

        this.setTextSize(TypedValue.COMPLEX_UNIT_PX, size);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        int parentWidth = MeasureSpec.getSize(widthMeasureSpec);
        int height = getMeasuredHeight();
        refitText(this.getText().toString(), parentWidth, height);
        this.setMeasuredDimension(parentWidth, height);
    }

    @Override
    protected void onTextChanged(final CharSequence text, final int start, final int before, final int after) {
        refitText(text.toString(), this.getWidth(), this.getHeight());
    }

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

    private Paint mTestPaint;
}