imagesettile() sets the tile
image to be used by all region filling functions (such as
imagefill() and
imagefilledpolygon()) when filling with the special
color IMG_COLOR_TILED.
A tile is an image used to fill an area with a repeated
pattern.
Any GD image can be used as a tile, and by setting
the transparent color index of the tile image with
imagecolortransparent(), a tile allows certain parts
of the underlying area to shine through can be created.
注: You need not take special action when you are finished with a tile, but if you destroy the tile image, you must not use the IMG_COLOR_TILED color until you have set a new tile image!
注: This function was added in PHP 4.0.6