Custom rotated EditText view with working selection, cursor location, etc

Question

What I want to do

I want to make a rotated and flipped EditText view that has all of the properties of a normal EditText view.

My problem

I have

Answer 1

Update

I ended up developing a vertical script MongolEditText from scratch. It is available as a part of mongol-library.

Here it is being used with two different third party keyboards.

Old answer

This is still a work in progress so I won't mark this as solved yet, but let me post what I have so far. It does most of what I wanted to do. Basically, I'm using TextView rather than EditText because EditText was doing to many strange things when rotated.

I have an unblinking cursor that responds to touch events but highlighting is still not supported. Here is the code:

public class MongolTextView extends TextView {

    private TextPaint textPaint;
    private Paint cursorPaint = new Paint();
    private boolean mCursorIsVisible;
    private CursorTouchLocationListener listener;

    // Naming is based on pre-rotated/mirrored values
    private float mCursorBaseY;
    private float mCursorBottomY;
    private float mCursorAscentY; // This is a negative number
    private float mCursorX;
    
    private static final float CURSOR_THICKNESS = 2f; 

    // Constructors
    public MongolTextView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init();
    }

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

    public MongolTextView(Context context) {
        super(context);
        init();
    }

    // This class requires the mirrored Mongolian font to be in the assets/fonts folder
    private void init() {
        //Typeface tf = Typeface.createFromAsset(getContext().getAssets(),
        //      "fonts/ChimeeWhiteMirrored.ttf");
        //setTypeface(tf);
        
        // Use the above commented code is using a single font in another application 
        Typeface tf = FontCache.get(SettingsActivity.FONT_DEFAULT, getContext());
        if(tf != null) {
            setTypeface(tf);
        }

        this.mCursorIsVisible = true;

        cursorPaint.setStrokeWidth(CURSOR_THICKNESS);
        cursorPaint.setColor(Color.BLACK); // TODO should be same as text color
        
    }

    // This interface may be deleted if touch functionality is not needed
    public interface CursorTouchLocationListener {

        /**
         * Returns the touch location to be used for the cursor so you can update the insert
         * location in a text string.
         * 
         * @param glyphIndex
         *            You will need to translate glyphIndex into a Unicode index if you are using a
         *            Unicode string.
         */
        public void onCursorTouchLocationChanged(int glyphIndex);

    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        // swap the height and width
        super.onMeasure(heightMeasureSpec, widthMeasureSpec);
        setMeasuredDimension(getMeasuredHeight(), getMeasuredWidth());
    }

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

        canvas.save();

        // flip and rotate the canvas
        canvas.translate(getWidth(), 0);
        canvas.rotate(90);
        canvas.translate(0, getWidth());
        canvas.scale(1, -1);
        canvas.translate(getCompoundPaddingLeft(), getExtendedPaddingTop());

        // draw the cursor
        if (mCursorIsVisible) {
            canvas.drawLine(mCursorX, mCursorBottomY, mCursorX, mCursorBaseY + mCursorAscentY,
                    cursorPaint);
        }

        getLayout().draw(canvas);

        canvas.restore();
    }

    public void showCursor(boolean visible) {
        mCursorIsVisible = visible;
        this.invalidate();
        // TODO make the cursor blink
    }
    
    public void setCursorColor(int color) {
        cursorPaint.setColor(color);
    }

    public void setCursorLocation(int characterOffset) {
        
        Layout layout = this.getLayout();
        
        if (layout!=null){
            
            try {
                // This method is giving a lot of crashes so just surrounding with 
                // try catch for now
                
                int line = layout.getLineForOffset(characterOffset);
                mCursorX = layout.getPrimaryHorizontal(characterOffset);
                mCursorBaseY = layout.getLineBaseline(line);
                mCursorBottomY = layout.getLineBottom(line);
                mCursorAscentY = layout.getLineAscent(line);
                
                this.invalidate();
            } catch (Exception e) {
                e.printStackTrace();
            }
        }

    }

    public class InputWindowTouchListener implements OnTouchListener {
        @Override
        public boolean onTouch(View view, MotionEvent event) {

            Layout layout = ((TextView) view).getLayout();

            // swapping x and y for touch events
            int y = (int) event.getX();
            int x = (int) event.getY();

            if (layout != null) {

                int line = layout.getLineForVertical(y);
                int offset = layout.getOffsetForHorizontal(line, x);

                mCursorX = layout.getPrimaryHorizontal(offset);
                mCursorBaseY = layout.getLineBaseline(line);
                mCursorBottomY = layout.getLineBottom(line);
                mCursorAscentY = layout.getLineAscent(line);
                //mCursorHeightY = layout.getLineTop(line);

                view.invalidate();
                
                switch (event.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    //handler.postDelayed(mLongPressed, 1000);
                    listener.onCursorTouchLocationChanged(offset);
                    break;
                case MotionEvent.ACTION_UP:
                    //handler.removeCallbacks(mLongPressed);
                    // notify the host activity of the new cursor location
                    
                    break;
                }

            }

            return false;
        }
        
    }
    
    public void setCursorTouchLocationListener(CursorTouchLocationListener listener) {
        this.listener = listener;
    }
}

Feel free to add your own answer if you have something better or make a comment if you have something to add for improving this (adding highlighting, getting the cursor to blink, etc.). The most recent version of this code should be on github.