(svn r17997) -Codechange: Introduce functions for querying top and bottom of the main view.

src/misc_gui.cpp

@@ -588,13 +588,11 @@ public:
 			return pt;
 		}
 
-		/* Find the screen part between the main toolbar at the top, and the statusbar at the bottom.
+		/* Find the free screen space between the main toolbar at the top, and the statusbar at the bottom.
 		 * Add a fixed distance 20 to make it less cluttered.
 		 */
-		const Window *w = FindWindowById(WC_MAIN_TOOLBAR, 0);
-		int scr_top = ((w != NULL) ? w->top + w->height : 0) + 20;
-		w = FindWindowById(WC_STATUS_BAR, 0);
-		int scr_bot = ((w != NULL) ? w->top : _screen.height) - 20;
+		int scr_top = GetMainViewTop() + 20;
+		int scr_bot = GetMainViewBottom() - 20;
 
 		Point pt = RemapCoords2(this->position.x, this->position.y);
 		const ViewPort *vp = FindWindowById(WC_MAIN_WINDOW, 0)->viewport;
@@ -805,13 +803,11 @@ struct TooltipsWindow : public Window
 
 	virtual Point OnInitialPosition(const WindowDesc *desc, int16 sm_width, int16 sm_height, int window_number)
 	{
-		/* Find the screen part between the main toolbar at the top, and the statusbar at the bottom.
+		/* Find the free screen space between the main toolbar at the top, and the statusbar at the bottom.
 		 * Add a fixed distance 2 so the tooltip floats free from both bars.
 		 */
-		const Window *w = FindWindowById(WC_MAIN_TOOLBAR, 0);
-		int scr_top = ((w != NULL) ? w->top + w->height : 0) + 2;
-		w = FindWindowById(WC_STATUS_BAR, 0);
-		int scr_bot = ((w != NULL) ? w->top : _screen.height) - 2;
+		int scr_top = GetMainViewTop() + 2;
+		int scr_bot = GetMainViewBottom() - 2;
 
 		Point pt;
 

src/widgets/dropdown.cpp

@@ -377,18 +377,13 @@ void ShowDropDownList(Window *w, DropDownList *list, int selected, int button, u
 	int height = list_height;
 
 	/* Check if the status bar is visible, as we don't want to draw over it */
-	Window *w3 = FindWindowById(WC_STATUS_BAR, 0);
-	int screen_bottom = w3 == NULL ? _screen.height : w3->top;
-
+	int screen_bottom = GetMainViewBottom();
 	bool scroll = false;
 
 	/* Check if the dropdown will fully fit below the widget */
 	if (top + height + 4 >= screen_bottom) {
-		w3 = FindWindowById(WC_MAIN_TOOLBAR, 0);
-		int screen_top = w3 == NULL ? 0 : w3->top + w3->height;
-
 		/* If not, check if it will fit above the widget */
-		if (w->top + wi_rect.top - height > screen_top) {
+		if (w->top + wi_rect.top - height > GetMainViewTop()) {
 			top = w->top + wi_rect.top - height - 4;
 		} else {
 			/* ... and lastly if it won't, enable the scroll bar and fit the

src/window.cpp

@@ -1602,6 +1602,26 @@ void ResizeWindow(Window *w, int delta_x, int delta_y)
 	w->SetDirty();
 }
 
+/** Return the top of the main view available for general use.
+ * @return Uppermost vertical coordinate available.
+ * @note Above the upper y coordinate is often the main toolbar.
+ */
+int GetMainViewTop()
+{
+	Window *w = FindWindowById(WC_MAIN_TOOLBAR, 0);
+	return (w == NULL) ? 0 : w->top + w->height;
+}
+
+/** Return the bottom of the main view available for general use.
+ * @return The vertical coordinate of the first unusable row, so 'top + height <= bottom' gives the correct result.
+ * @note At and below the bottom y coordinate is often the status bar.
+ */
+int GetMainViewBottom()
+{
+	Window *w = FindWindowById(WC_STATUS_BAR, 0);
+	return (w == NULL) ? _screen.height : w->top;
+}
+
 /** The minimum number of pixels of the title bar must be visible in both the X or Y direction */
 static const int MIN_VISIBLE_TITLE_BAR = 13;
 

src/window_func.h

@@ -21,6 +21,9 @@ void ChangeWindowOwner(Owner old_owner, Owner new_owner);
 void ResizeWindow(Window *w, int x, int y);
 int PositionMainToolbar(Window *w);
 
+int GetMainViewTop();
+int GetMainViewBottom();
+
 void InitWindowSystem();
 void UnInitWindowSystem();
 void ResetWindowSystem();