[Search for users]
[Overall Top Noters]
[List of all Conferences]
[Download this site]
| Title: | DECWINDOWS 26-JAN-89 to 29-NOV-90 |
| Notice: | See 1639.0 for VMS V5.3 kit; 2043.0 for 5.4 IFT kit |
| Moderator: | STAR::VATNE |
|
| Created: | Mon Oct 30 1989 |
| Last Modified: | Mon Dec 31 1990 |
| Last Successful Update: | Fri Jun 06 1997 |
| Number of topics: | 3726 |
| Total number of notes: | 19516 |
2692.0. "Xlib region routines and clipping" by KAORSC::K_BURECHAILO () Tue May 01 1990 10:14
I have a question about use of the X region routines and clipping. I have a
case where X sometimes seems to handle clipping, but at other times complains
loudly. This particular application displays maps. The maps are created by
passing a set of points to the XPolygonRegion routine. Smaller regions are then
subtracted from the main region using XSubtractRegion. Finally the clip mask of
a graphics context is associated with the main region. The desired result is
that a portion of the map should be displayed in a window somewhat smaller than
the main region. Different areas of the map can be viewed by adjusting the
coordinates of the points that are passed. Sometimes this seems to work. Other
times it fails for various reasons, usually on one of the X region calls. This
seems to be dependant on the coordinates of points that are passed. It is
difficult to determine why or at what point this breaks. It is not clear if it
is the value of the points(ie. the size of the image) or the complexity. A
simple rectangle seems to be handled properly regardless of the size. This
leads to the questions: Should I expect Xlib to handle clipping in this way?
Would it be better for the application to do the clipping?