Use sizes from AOSP LetterTileDrawable instead

app/src/main/java/de/kuschku/quasseldroid/util/ui/TextDrawable.java

@@ -114,7 +114,7 @@ public class TextDrawable extends ShapeDrawable {
     // draw text
     int width = this.width < 0 ? r.width() : this.width;
     int height = this.height < 0 ? r.height() : this.height;
-    int fontSize = this.fontSize < 0 ? (Math.min(width, height) / 2) : this.fontSize;
+    int fontSize = this.fontSize < 0 ? (int) (Math.min(width, height) * 0.67) : this.fontSize;
     textPaint.setTextSize(fontSize);
     canvas.drawText(text, width / 2, height / 2 - ((textPaint.descent() + textPaint.ascent()) / 2), textPaint);