Fix garbage pixels on the right of the board

The extra pixel that is requested in sizing the board window back to
an available size because we ofte get one less pixel than we ask for
can lead to a line of garbage pixels next to the board. This is combatted
by limiting expose events to the true board area, remembering that in the
Graph Option rather than the actual window size, and suppressing resizing
when the latter only exceeds the stored width by more than 1 pixel.

diff --git a/xoptions.c b/xoptions.c
index e9cc0c4..bf1ff10 100644 (file)
--- a/xoptions.c
+++ b/xoptions.c
@@ -551,23 +551,26 @@ GraphEventProc(Widget widget, caddr_t client_data, XEvent *event)
            XtSetArg(args[j], XtNwidth, &w); j++;
            XtSetArg(args[j], XtNheight, &h); j++;
            XtGetValues(widget, args, j);
-           sizing = ((w != graph->max || h != graph->value) && ((XExposeEvent*)event)->count >= 0);
-           graph->max = w; graph->value = h;
+           if(w < graph->max || w > graph->max + 1 || h != graph->value) { // use width fudge of 1 pixel
+               sizing = (((XExposeEvent*)event)->count >= 0); // suppress sizing on ordered redraw in response to sizing.
+               graph->max = w; graph->value = h; // note: old values are kept if we we don't exceed width fudge
+           }
            if(sizing && ((XExposeEvent*)event)->count > 0) { graph->max = 0; return; } // don't bother if further exposure is pending during resize
            if(!graph->textValue || sizing) { // create surfaces of new size for display widget
                if(graph->textValue) cairo_surface_destroy((cairo_surface_t *)graph->textValue);
                graph->textValue = (char*) cairo_xlib_surface_create(xDisplay, XtWindow(widget), DefaultVisual(xDisplay, 0), w, h);
            }
            if(sizing) { // the memory buffer was already created in GenericPopup(),
-                        // to give drawing routines opportunity to use it befor first expose event
+                        // to give drawing routines opportunity to use it before first expose event
                         // (which are only processed when main gets to the event loop, so after all init!)
                         // so only change when size is no longer good
                if(graph->choice) cairo_surface_destroy((cairo_surface_t *) graph->choice);
                graph->choice = (char**) cairo_image_surface_create (CAIRO_FORMAT_ARGB32, w, h);
                break;
            }
-           ExposeRedraw(graph, ((XExposeEvent*)event)->x, ((XExposeEvent*)event)->y,
-                               ((XExposeEvent*)event)->width, ((XExposeEvent*)event)->height);
+           w = ((XExposeEvent*)event)->width;
+           if(((XExposeEvent*)event)->x + w > graph->max) w--; // cut off fudge pixel
+           if(w) ExposeRedraw(graph, ((XExposeEvent*)event)->x, ((XExposeEvent*)event)->y, w, ((XExposeEvent*)event)->height);
            return;
        case MotionNotify:
            f = 0;