create
PW_SCROLL_NOBAR
When this tag is encountered on creation of the scroll object, then only the arrows will exist, and no scrollbar. In the case, the arrow items may be bigger.
change
PW_SCROLL_CALCSIZE
Set the routine which can be used to calculate the size of the visible area (the bar), to draw the scrollbar. The parameter should be of type "Error (*)(PWObject, pt *)", and should convert the second parameter (which is the size of the canvas), into the size in the metric and type as used as paramter of PW_SCROLL_MINIMUM and PW_SCROLL_MAXIMUM.
PW_SCROLL_CANVAS
Set the canvas to which this scroll object is linked. The parameter should be of type "PWObject" and should be a canvas object.
PW_SCROLL_MINIMUM
Set the minimum value for the scrolling. The parameter is int sized and can be in any chosen metric. The scrollbar will not allow you to scroll further back than this minimum. The metric used should match the metric used as origin of the canvas. The default minimum is 0.
PW_SCROLL_MAXIMUM
Set the maximum value for the scrolling. The parameter is int sized and can be in any chosen metric. The scrollbar will not allow you to scroll further than this minimum. The metric used should match the metric used as origin of the canvas. The default maximum is 0.
PW_SCROLL_MINDIST
Set the distance to scroll when the scroll arrow is activated with a PW_EVENT_HIT. If the maxdist is not set, it will default to this value as well. If the distance is negative, the scrolling distance will be (size+mindist).
PW_SCROLL_MAXDIST
Set the distance to scroll when the scroll arrow is activated with a PW_EVENT_DO. If the mindist is not set, it will default to this value as well. If the distance is negative, the scrolling distance will be (size+maxdist).
PW_SCROLL_SCROLL
Force a scroll without event on the scroll arrows. The scrolling distance is passed as parameter. The direction is right/down for positive, left/up for negative distance. Particularly useful to normalise the scrollbar after a window scale operation (in this case distance=0).

PROGS, Professional & Graphical Software
last edited February 9, 1996