эта функция у меня сработала.
private void drawDigit(Canvas canvas, int textSize, float cX, float cY, int color, String text) {
Paint tempTextPaint = new Paint();
tempTextPaint.setAntiAlias(true);
tempTextPaint.setStyle(Paint.Style.FILL);
tempTextPaint.setColor(color);
tempTextPaint.setTextSize(textSize);
float textWidth = tempTextPaint.measureText(text);
//if cX and cY are the origin coordinates of the your rectangle
//cX-(textWidth/2) = The x-coordinate of the origin of the text being drawn
//cY+(textSize/2) = The y-coordinate of the origin of the text being drawn
canvas.drawText(text, cX-(textWidth/2), cY+(textSize/2), tempTextPaint);
}