Reduce redrawing on resize events.

[rrace.git] / src / motif_ui.c

diff --git a/src/motif_ui.c b/src/motif_ui.c
index 726e24fd06033691f60d7f2af4fedd0045d0a4e2..4559ff664e6e6461f50dff86a5f90b22113b5274 100644 (file)
--- a/src/motif_ui.c
+++ b/src/motif_ui.c
@@ -205,18 +205,6 @@ construct_menu(const struct ui_menuitem *root, Widget parent, unsigned i)
        }
 }
 
-static void game_resize(Widget w, void *data, void *cb_data)
-{
-       if (XtIsRealized(w))
-               x11_redraw_game(data, -1);
-}
-
-static void goal_resize(Widget w, void *data, void *cb_data)
-{
-       if (XtIsRealized(w))
-               x11_redraw_goal(data, -1);
-}
-
 /* Figure out which tiles intersect a rectangle. */
 static uint_fast32_t
 expose_mask(int rect_x, int rect_y, int rect_w, int rect_h,
@@ -228,6 +216,57 @@ expose_mask(int rect_x, int rect_y, int rect_w, int rect_h,
             & board_left((rect_x + rect_w - 1) / tile_w);
 }
 
+/*
+ * Calculate which tiles need to be redrawn after resizing.  This is the
+ * tiles which (at the new size) are fully contained in the previous area.
+ *
+ * When shrinking, this is all tiles, but when enlarging, the generated
+ * expose events will trigger drawing of the new area.
+ */
+static uint_fast32_t resize_helper(Widget w, Dimension *oldsz, int gridsz)
+{
+       Dimension new_w, new_h, common_w, common_h;
+
+       if (!XtIsRealized(w))
+               return 0;
+
+       XtVaGetValues(w, XmNwidth, &new_w, XmNheight, &new_h, (char *)NULL);
+       common_w = MIN(new_w, oldsz[0]);
+       common_h = MIN(new_h, oldsz[1]);
+       oldsz[0] = new_w;
+       oldsz[1] = new_h;
+       new_w /= gridsz;
+       new_h /= gridsz;
+
+       /* Round down to multiple of tile dimensions */
+       common_w = common_w / new_w * new_w;
+       common_h = common_h / new_h * new_h;
+
+       if (new_w > 0 && new_h > 0)
+               return expose_mask(0, 0, common_w, common_h, new_w, new_h);
+       return 0;
+}
+
+static void game_resize(Widget w, void *data, void *cb_data)
+{
+       struct app_state *state = data;
+       uint_fast32_t mask;
+
+       mask = resize_helper(w, state->game_sz, 5);
+       if (mask)
+               x11_redraw_game(data, mask);
+}
+
+static void goal_resize(Widget w, void *data, void *cb_data)
+{
+       struct app_state *state = data;
+       uint_fast32_t mask;
+
+       mask = resize_helper(w, state->goal_sz, 3);
+       if (mask)
+               x11_redraw_goal(data, mask);
+}
+
 static void game_expose(Widget w, void *data, void *cb_data)
 {
        XmDrawingAreaCallbackStruct *cbs = cb_data;
@@ -271,8 +310,16 @@ void ui_initialize(struct app_state *state, Widget shell)
        XtVaSetValues(menubar, XmNmenuHelpWidget, help, (char *)NULL);
 
        configure_mainwin(state, XtNameToWidget(shell, "*game"));
+
+       XtVaGetValues(state->game, XmNwidth, &state->game_sz[0],
+                                  XmNheight, &state->game_sz[1],
+                                  (char *)NULL);
        XtAddCallback(state->game, XmNresizeCallback, game_resize, state);
        XtAddCallback(state->game, XmNexposeCallback, game_expose, state);
+
+       XtVaGetValues(state->game, XmNwidth, &state->goal_sz[0],
+                                  XmNheight, &state->goal_sz[1],
+                                  (char *)NULL);
        XtAddCallback(state->goal, XmNresizeCallback, goal_resize, state);
        XtAddCallback(state->goal, XmNexposeCallback, goal_expose, state);
 }