UI: Support status-bar hiding

Just like the top-bar, the status-bar can now be hidden/collapsed by dragging
its edge. We display a small line with the editor outline color then, so there
is something that can be dragged up to un-collapse the area again.
This collapsed state is not written to files yet.

3 files changed, 29 insertions, 7 deletions

diff --git a/source/blender/editors/screen/area.c b/source/blender/editors/screen/area.c
index e96580855d3..207047c2ad3 100644
--- a/source/blender/editors/screen/area.c
+++ b/source/blender/editors/screen/area.c
@@ -421,6 +421,17 @@ void ED_area_do_msg_notify_tag_refresh(
 	ED_area_tag_refresh(sa);
 }
 
+/**
+ * Although there's no general support for minimizing areas, the status-bar can
+ * be snapped to be only a few pixels high. A few pixels rather than 0 so it
+ * can be un-minimized again. We consider it pseudo-minimalized and don't draw
+ * it then.
+ */
+static bool area_is_pseudo_minimized(const ScrArea *area)
+{
+	return (area->winx < 3) || (area->winy < 3);
+}
+
 /* only exported for WM */
 void ED_region_do_layout(bContext *C, ARegion *ar)
 {
@@ -432,7 +443,7 @@ void ED_region_do_layout(bContext *C, ARegion *ar)
 		return;
 	}
 
-	if (at->do_lock) {
+	if (at->do_lock || (sa && area_is_pseudo_minimized(sa))) {
 		return;
 	}
 
@@ -462,8 +473,13 @@ void ED_region_do_draw(bContext *C, ARegion *ar)
 
 	UI_SetTheme(sa ? sa->spacetype : 0, at->regionid);
 
+	if (sa && area_is_pseudo_minimized(sa)) {
+		UI_ThemeClearColor(TH_EDITOR_OUTLINE);
+		glClear(GL_COLOR_BUFFER_BIT);
+		return;
+	}
 	/* optional header info instead? */
-	if (ar->headerstr) {
+	else if (ar->headerstr) {
 		UI_ThemeClearColor(TH_HEADER);
 		glClear(GL_COLOR_BUFFER_BIT);
 
diff --git a/source/blender/editors/screen/screen_edit.c b/source/blender/editors/screen/screen_edit.c
index 1b2908104f5..6bc8a6c10cf 100644
--- a/source/blender/editors/screen/screen_edit.c
+++ b/source/blender/editors/screen/screen_edit.c
@@ -787,7 +787,7 @@ static void screen_global_statusbar_area_create(wmWindow *win)
 	BLI_rcti_init(&rect, 0, WM_window_pixels_x(win) - 1, 0, WM_window_pixels_y(win) - 1);
 	rect.ymax = rect.ymin + size_y;
 
-	screen_global_area_create(win, SPACE_STATUSBAR, GLOBAL_AREA_ALIGN_BOTTOM, &rect, size_y, size_y, size_y);
+	screen_global_area_create(win, SPACE_STATUSBAR, GLOBAL_AREA_ALIGN_BOTTOM, &rect, size_y, 0, size_y);
 }
 
 void ED_screen_global_areas_create(wmWindow *win)
diff --git a/source/blender/editors/screen/screen_ops.c b/source/blender/editors/screen/screen_ops.c
index 0c124f6c9a4..ad64018929c 100644
--- a/source/blender/editors/screen/screen_ops.c
+++ b/source/blender/editors/screen/screen_ops.c
@@ -1235,8 +1235,11 @@ static void area_move_set_limits(
 	if (use_bigger_smaller_snap != NULL) {
 		*use_bigger_smaller_snap = false;
 		for (ScrArea *area = win->global_areas.areabase.first; area; area = area->next) {
-			const int size_min = ED_area_global_min_size_y(area) - 1;
-			const int size_max = ED_area_global_max_size_y(area) - 1;
+			int size_min = ED_area_global_min_size_y(area) - 1;
+			int size_max = ED_area_global_max_size_y(area) - 1;
+
+			size_min = MAX2(size_min, 0);
+			BLI_assert(size_min < size_max);
 
 			/* logic here is only tested for lower edge :) */
 			/* left edge */
@@ -1412,7 +1415,8 @@ static int area_snap_calc_location(
 			break;
 	}
 
-	BLI_assert(IN_RANGE_INCL(final_loc, origval - smaller, origval + bigger));
+	BLI_assert(ELEM(snap_type, SNAP_BIGGER_SMALLER_ONLY) ||
+	           IN_RANGE_INCL(final_loc, origval - smaller, origval + bigger));
 
 	return final_loc;
 }
@@ -1429,7 +1433,9 @@ static void area_move_apply_do(
 	short final_loc = -1;
 	bool doredraw = false;
 
-	CLAMP(delta, -smaller, bigger);
+	if (snap_type != SNAP_BIGGER_SMALLER_ONLY) {
+		CLAMP(delta, -smaller, bigger);
+	}
 
 	if (snap_type == SNAP_NONE) {
 		final_loc = origval + delta;