public int tileXToX(int tx) {
        return tx*tileWidth + tileGridXOffset;
    }
Converts a horizontal tile index into the X coordinate of its
upper left pixel.  This is a convenience method.  No attempt is made
to detect out-of-range indices.

@param tx the horizontal index of a tile.
@return the X coordinate of the tile's upper left pixel.
plugins/svg-plugin/batik-codec-fix/src/main/java/org/apache/batik/ext/awt/image/codec/util/SimpleRenderedImage.java