WidthResizeTextView.java

import android.content.Context;
import android.graphics.Canvas;
import android.util.AttributeSet;
import android.widget.TextView;

/**
 * Width resizing text view
 *
 * @author cab404
 */

public class WidthResizeTextView extends TextView {
    public WidthResizeTextView(Context context) {
        super(context);
    }

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

    public WidthResizeTextView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
    }

    {
        setSingleLine();
    }

    float lastWidth, lastCalculatedSize;

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);

        int viewWidth = getWidth();
        float top = viewWidth, bottom = 0, width = 0, current = 0;
        int spec = MeasureSpec.makeMeasureSpec(1000000, MeasureSpec.AT_MOST);
        int steps = 300;

        if (viewWidth != lastWidth) {
            while (Math.abs(width - viewWidth) > 5f && steps-- > 0) {
                current = (top + bottom) / 2;

                setTextSize(current);
                measure(spec, spec);
                width = getMeasuredWidth();

                if (width - viewWidth < 0)
                    bottom = (top - bottom) / 2 + bottom;
                if (width - viewWidth > 0)
                    top = top - (top - bottom) / 2;

            }
            lastWidth = viewWidth;
            lastCalculatedSize = current;
        } else {
            current = lastCalculatedSize;
        }

        setTextSize(current);
    }

}