android - How to put text in a drawable?

Question

I'm trying to create a drawable on the fly to use as a background for a custom linearlayout. It needs to have hash marks and such (no big deal), but also have numbers labeling what the hash marks are (like a ruler). I know I can just create text elements and put them inside the linearlayout and just have the hash marks in the drawable, but I'm hoping to have them inside the drawable as well, so I don't have to do measurement calculations twice.

Answer 1

Here is a brief example of a TextDrawable which works like a normal drawable but lets you specify text as the only constructor variable:

public class TextDrawable extends Drawable {

    private final String text;
    private final Paint paint;

    public TextDrawable(String text) {

        this.text = text;

        this.paint = new Paint();
        paint.setColor(Color.WHITE);
        paint.setTextSize(22f);
        paint.setAntiAlias(true);
        paint.setFakeBoldText(true);
        paint.setShadowLayer(6f, 0, 0, Color.BLACK);
        paint.setStyle(Paint.Style.FILL);
        paint.setTextAlign(Paint.Align.LEFT);
    }

    @Override
    public void draw(Canvas canvas) {
        canvas.drawText(text, 0, 0, paint);
    }

    @Override
    public void setAlpha(int alpha) {
        paint.setAlpha(alpha);
    }

    @Override
    public void setColorFilter(ColorFilter cf) {
        paint.setColorFilter(cf);
    }

    @Override
    public int getOpacity() {
        return PixelFormat.TRANSLUCENT;
    }
}