code snippet for drawing font metric lines

gistfile1.java

Typeface SANS_SERIF = createFromAsset(getContext(), "NotoSansCJKsc-Regular.otf", Typeface.SANS_SERIF);

@Override
protected void onDraw(Canvas canvas) {
    drawText(canvas, 300, Typeface.DEFAULT, Color.RED, "Android Default");
    drawText(canvas, 900, SANS_SERIF, Color.BLUE, "Source Han Sans SC Regular");
}

private void drawText(Canvas canvas, float y, Typeface typeface, int color, String name) {
    String str = "你好 aloha";
    float textSize = 120;

    TextPaint paint = new TextPaint();
    paint.setDither(true);
    paint.setAntiAlias(true);
    paint.setTypeface(typeface);
    paint.setColor(color);
    paint.setTextSize(40);
    canvas.drawText(name, 0, y - 260, paint);

    paint.setTextSize(textSize);
    canvas.drawText(str, 100, y, paint);

    Paint.FontMetrics metrics = paint.getFontMetrics();
    drawLine(canvas, y, "baseline", color);
    drawLine(canvas, y + metrics.ascent, "ascent", color);
    drawLine(canvas, y + metrics.top , "top", color);
    drawLine(canvas, y + metrics.bottom, "bottom", color);
    drawLine(canvas, y + metrics.descent, "descent", color);

    paint.setTextSize(30);
    canvas.drawText(String.format("textSize=%.2f", textSize),
            0, y + metrics.bottom + 100, paint);
    canvas.drawText(String.format("ascent=%.2f, descent=%.2f", metrics.ascent, metrics.descent),
            0, y + metrics.bottom + 140, paint);
    canvas.drawText(String.format("top=%.2f, bottom=%.2f", metrics.top, metrics.bottom),
            0, y + metrics.bottom + 180, paint);
    canvas.drawText(String.format("leading=%.2f", metrics.leading),
            0, y + metrics.bottom + 220, paint);
}

private void drawLine(Canvas canvas, float y, String name, int color) {
    Paint paint = new Paint();
    paint.setColor(color);

    canvas.drawLine(0, y, 1000, y, paint);
    canvas.drawText(name, 0, y, paint);
}