String width via fontmetrics calculation is very slow if there are arabic or persian letters in text

Question

I have a problem. My application interface works much slower if i use eastern languages there. Especially i felt it in components such as JList, JCombobox, JTable.

Answer 1

I use a cache when calculating the string widths. It don't solve the internal calls that javas own classes do but it solved my performance issues with persian letters (I use a lot of own renders and so on). The Pair class is just a typed bean of two objects...

public class GuiUtils {
private static final Map>, Integer> stringWidthCache = new HashMap>, Integer>();

public static int getStringWidth(FontMetrics fm, String text){
    return getStringWidth(null, fm, text);
}

public static int getStringWidth(Graphics g, FontMetrics fm, String text){
    if(text == null || text.equals("")) {
        return 0;
    }
    Pair> cacheKey = 
            new Pair>(g != null, new Pair(fm, text));
    if (!stringWidthCache.containsKey(cacheKey)) {
        stringWidthCache.put(
                cacheKey, 
                g != null ? 
                        (int)Math.ceil(fm.getStringBounds(text, g).getWidth()) :
                            fm.stringWidth(text));
    }
    return stringWidthCache.get(cacheKey);
}

}