Vertical (rotated) label in Android

Question

I need 2 ways of showing vertical label in Android:

1. Horizontal label turned 90 degrees counterclockwise (letters on the side)
2. Horizontal label with letters one under the other (like a store sign)

Do I need to develop custom widgets for both cases (one case), can I make TextView to render that way, and what would be a good way to do something like that if I need to go completely custom?

Answer 1

Here is my elegant and simple vertical text implementation, extending TextView. This means that all standard styles of TextView may be used, because it is extended TextView.

public class VerticalTextView extends TextView{
   final boolean topDown;

   public VerticalTextView(Context context, AttributeSet attrs){
      super(context, attrs);
      final int gravity = getGravity();
      if(Gravity.isVertical(gravity) && (gravity&Gravity.VERTICAL_GRAVITY_MASK) == Gravity.BOTTOM) {
         setGravity((gravity&Gravity.HORIZONTAL_GRAVITY_MASK) | Gravity.TOP);
         topDown = false;
      }else
         topDown = true;
   }

   @Override
   protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
      super.onMeasure(heightMeasureSpec, widthMeasureSpec);
      setMeasuredDimension(getMeasuredHeight(), getMeasuredWidth());
   }

   @Override
   protected boolean setFrame(int l, int t, int r, int b){
      return super.setFrame(l, t, l+(b-t), t+(r-l));
   }

   @Override
   public void draw(Canvas canvas){
      if(topDown){
         canvas.translate(getHeight(), 0);
         canvas.rotate(90);
      }else {
         canvas.translate(0, getWidth());
         canvas.rotate(-90);
      }
      canvas.clipRect(0, 0, getWidth(), getHeight(), android.graphics.Region.Op.REPLACE);
      super.draw(canvas);
   }
}

By default, rotated text is from top to bottom. If you set android:gravity="bottom", then it's drawn from bottom to top.

Technically, it fools underlying TextView to think that it's normal rotation (swapping width/height in few places), while drawing it rotated. It works fine also when used in an xml layout.

EDIT: posting another version, above has problems with animations. This new version works better, but loses some TextView features, such as marquee and similar specialties.

public class VerticalTextView extends TextView{
   final boolean topDown;

   public VerticalTextView(Context context, AttributeSet attrs){
      super(context, attrs);
      final int gravity = getGravity();
      if(Gravity.isVertical(gravity) && (gravity&Gravity.VERTICAL_GRAVITY_MASK) == Gravity.BOTTOM) {
         setGravity((gravity&Gravity.HORIZONTAL_GRAVITY_MASK) | Gravity.TOP);
         topDown = false;
      }else
         topDown = true;
   }

   @Override
   protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec){
      super.onMeasure(heightMeasureSpec, widthMeasureSpec);
      setMeasuredDimension(getMeasuredHeight(), getMeasuredWidth());
   }

   @Override
   protected void onDraw(Canvas canvas){
      TextPaint textPaint = getPaint(); 
      textPaint.setColor(getCurrentTextColor());
      textPaint.drawableState = getDrawableState();

      canvas.save();

      if(topDown){
         canvas.translate(getWidth(), 0);
         canvas.rotate(90);
      }else {
         canvas.translate(0, getHeight());
         canvas.rotate(-90);
      }


      canvas.translate(getCompoundPaddingLeft(), getExtendedPaddingTop());

      getLayout().draw(canvas);
      canvas.restore();
  }
}

EDIT Kotlin version:

import android.content.Context
import android.graphics.Canvas
import android.text.BoringLayout
import android.text.Layout
import android.text.TextUtils.TruncateAt
import android.util.AttributeSet
import android.view.Gravity
import androidx.appcompat.widget.AppCompatTextView
import androidx.core.graphics.withSave

class VerticalTextView(context: Context, attrs: AttributeSet) : AppCompatTextView(context, attrs) {
    private val topDown = gravity.let { g ->
        !(Gravity.isVertical(g) && g.and(Gravity.VERTICAL_GRAVITY_MASK) == Gravity.BOTTOM)
    }
    private val metrics = BoringLayout.Metrics()
    private var padLeft = 0
    private var padTop = 0

    private var layout1: Layout? = null

    override fun setText(text: CharSequence, type: BufferType) {
        super.setText(text, type)
        layout1 = null
    }

    private fun makeLayout(): Layout {
        if (layout1 == null) {
            metrics.width = height
            paint.color = currentTextColor
            paint.drawableState = drawableState
            layout1 = BoringLayout.make(text, paint, metrics.width, Layout.Alignment.ALIGN_NORMAL, 2f, 0f, metrics, false, TruncateAt.END, height - compoundPaddingLeft - compoundPaddingRight)
            padLeft = compoundPaddingLeft
            padTop = extendedPaddingTop
        }
        return layout1!!
    }

    override fun onDraw(c: Canvas) {
        //      c.drawColor(0xffffff80); // TEST
        if (layout == null)
            return
        c.withSave {
            if (topDown) {
                val fm = paint.fontMetrics
                translate(textSize - (fm.bottom + fm.descent), 0f)
                rotate(90f)
            } else {
                translate(textSize, height.toFloat())
                rotate(-90f)
            }
            translate(padLeft.toFloat(), padTop.toFloat())
            makeLayout().draw(this)
        }
    }
}