Don't automatically scroll listbox when selecting an item in the middle

diff --git a/src/guiFormSpecMenu.cpp b/src/guiFormSpecMenu.cpp
index 79497dca1814ff35d59d4aab0504962fd2af1332..6c34ecc2cbc2bbfb8566ec71cf947cfbea15d25d 100644 (file)
--- a/src/guiFormSpecMenu.cpp
+++ b/src/guiFormSpecMenu.cpp
@@ -184,6 +184,38 @@ bool GUIFormSpecMenu::checkListboxClick(std::wstring wlistboxname,
        return false;
 }
 
+gui::IGUIScrollBar* GUIFormSpecMenu::getListboxScrollbar(
+               gui::IGUIListBox *listbox)
+{
+       // WARNING: BLACK IRRLICHT MAGIC
+       // Ordinarily, due to how formspecs work (recreating the entire GUI
+       // when something changes), when you select an item in a textlist
+       // with more items than fit in the visible area, the newly selected
+       // item is scrolled to the bottom of the visible area. This is
+       // annoying and breaks GUI designs that use double clicks.
+
+       // This function helps fixing this problem by giving direct access
+       // to a listbox's scrollbar. This works because CGUIListBox doesn't
+       // cache the scrollbar position anywhere.
+
+       // If this stops working in a future irrlicht version, consider
+       // maintaining a local copy of irr::gui::CGUIListBox, possibly also
+       // fixing the other reasons why black irrlicht magic is needed.
+
+       core::list<gui::IGUIElement*> children = listbox->getChildren();
+       for(core::list<gui::IGUIElement*>::Iterator it = children.begin();
+                       it != children.end(); ++it) {
+               gui::IGUIElement* child = *it;
+               if (child && child->getType() == gui::EGUIET_SCROLL_BAR) {
+                       return static_cast<gui::IGUIScrollBar*>(child);
+               }
+       }
+
+       verbosestream<<"getListboxScrollbar: WARNING: "
+                       <<"listbox has no scrollbar"<<std::endl;
+       return NULL;
+}
+
 std::vector<std::string> split(const std::string &s, char delim) {
        std::vector<std::string> tokens;
 
@@ -616,6 +648,13 @@ void GUIFormSpecMenu::parseTextList(parserData* data,std::string element) {
                        e->setSelected(data->listbox_selections[fname_w]);
                }
 
+               if (data->listbox_scroll.find(fname_w) != data->listbox_scroll.end()) {
+                       gui::IGUIScrollBar *scrollbar = getListboxScrollbar(e);
+                       if (scrollbar) {
+                               scrollbar->setPos(data->listbox_scroll[fname_w]);
+                       }
+               }
+
                if (str_initial_selection != "")
                        e->setSelected(stoi(str_initial_selection.c_str())-1);
 
@@ -1417,11 +1456,18 @@ void GUIFormSpecMenu::regenerateGui(v2u32 screensize)
 
        //preserve listboxes
        for (unsigned int i = 0; i < m_listboxes.size(); i++) {
-               int selection = m_listboxes[i].second->getSelected();
+               std::wstring listboxname = m_listboxes[i].first.fname;
+               gui::IGUIListBox *listbox = m_listboxes[i].second;
+
+               int selection = listbox->getSelected();
                if (selection != -1) {
-                       std::wstring listboxname = m_listboxes[i].first.fname;
                        mydata.listbox_selections[listboxname] = selection;
                }
+
+               gui::IGUIScrollBar *scrollbar = getListboxScrollbar(listbox);
+               if (scrollbar) {
+                       mydata.listbox_scroll[listboxname] = scrollbar->getPos();
+               }
        }
 
        // Remove children

diff --git a/src/guiFormSpecMenu.h b/src/guiFormSpecMenu.h
index 28f11d2e70390be6f000c227b7f2f5ba3b3c4d68..f8d7ff1fb24136332209e92e040f456c4077c9e1 100644 (file)
--- a/src/guiFormSpecMenu.h
+++ b/src/guiFormSpecMenu.h
@@ -294,6 +294,7 @@ private:
                int bp_set;
                v2u32 screensize;
                std::map<std::wstring,int> listbox_selections;
+               std::map<std::wstring,int> listbox_scroll;
        } parserData;
 
        typedef struct {
@@ -311,6 +312,8 @@ private:
        // (Using some black Irrlicht magic)
        bool checkListboxClick(std::wstring wlistboxname, int eventtype);
 
+       gui::IGUIScrollBar* getListboxScrollbar(gui::IGUIListBox *listbox);
+
        void parseElement(parserData* data,std::string element);
 
        void parseSize(parserData* data,std::string element);