It should be about the average size of graphics in the QwSpriteField. Chunks too small increase the amount of calculation required when drawing. Chunks too large increase the amount of drawing that is needed. If the QwSpriteField has a large number of small, dispersed graphics, this should be about that number. The more clusters the slower the redraw, but also the bigger clusters are the slower the redraw, so a balance is needed.
Testing reveals that a large number of clusters is almost always best.
Does not destroy QwSpriteFieldGraphic objects in the field. This method adds an element to the list of QwSpriteFieldGraphic objects in this QwSpriteField. The QwSpriteFieldGraphic class calls this, so you should not need it. This method adds a QwSpriteFieldGraphic to the list of those which need to be drawn if the given chunk is redrawn. This method adds a QwSpriteFieldGraphic to the list of those which need to be drawn if the chunk containing the given pixel is redrawn.