Add scroll_container formspec element (redo) (#9101)

New formspec elements:

 - `scroll_container[<X>,<Y>;<W>,<H>;<scrollbar name>;<orientation>;<scroll factor>]`
 - `scroll_container_end[]`

Other elements can be embedded in this element. Scrollbar must be placed manually.

build/android/jni/Android.mk

@@ -194,6 +194,7 @@ LOCAL_SRC_FILES := \
 		jni/src/gui/guiPasswordChange.cpp         \
 		jni/src/gui/guiPathSelectMenu.cpp         \
 		jni/src/gui/guiScrollBar.cpp              \
+		jni/src/gui/guiScrollContainer.cpp        \
 		jni/src/gui/guiSkin.cpp                   \
 		jni/src/gui/guiTable.cpp                  \
 		jni/src/gui/guiVolumeChange.cpp           \

doc/lua_api.txt

@@ -2102,6 +2102,26 @@ Elements
 * End of a container, following elements are no longer relative to this
   container.
 
+### `scroll_container[<X>,<Y>;<W>,<H>;<scrollbar name>;<orientation>;<scroll factor>]`
+
+* Start of a scroll_container block. All contained elements will ...
+  * take the scroll_container coordinate as position origin,
+  * be additionally moved by the current value of the scrollbar with the name
+    `scrollbar name` times `scroll factor` along the orientation `orientation` and
+  * be clipped to the rectangle defined by `X`, `Y`, `W` and `H`.
+* `orientation`: possible values are `vertical` and `horizontal`.
+* `scroll factor`: optional, defaults to `0.1`.
+* Nesting is possible.
+* Some elements might work a little different if they are in a scroll_container.
+* Note: If you want the scroll_container to actually work, you also need to add a
+  scrollbar element with the specified name. Furthermore, it is highly recommended
+  to use a scrollbaroptions element on this scrollbar.
+
+### `scroll_container_end[]`
+
+* End of a scroll_container, following elements are no longer bound to this
+  container.
+
 ### `list[<inventory location>;<list name>;<X>,<Y>;<W>,<H>;]`
 
 * Show an inventory list if it has been sent to the client. Nothing will

games/minimal/mods/test/formspec.lua

@@ -1,5 +1,35 @@
 local color = minetest.colorize
 
+local hypertext = minetest.formspec_escape([[
+	<global halign=justify valign=center background=#CCF color=#444 actioncolor=darkblue margin=10>
+	<center><bigger>Furnace</bigger></center>
+	<style color=black>Furnaces</style> are <action name="crafting">crafted</action> and used by the player for the purpose of cooking food and <action name="smelting">smelting</action> various items.
+	<item name=default:furnace float=right width=128 rotate=yes>
+	<style color=black>Type:</style> Solid block
+	<style color=black>Drops:</style> Itself
+	<style color=black>Physics:</style> No
+	<style color=black>Luminance:</style> Inactive:No Active:Yes (8)
+	<style color=black>Flammable:</style> No
+	<style color=black>Generated:</style> No
+	<style color=black>Renewable:</style> Yes
+	<style color=black>Stackable:</style> Yes (99)
+	<style color=black>Itemstring:</style> default:furnace default:furnace_active
+	<big>Usage</big>
+	The furnace menu can be accessed by <action name="using">using</action> the furnace.
+	The furnace has 3 <action name="inventory">inventories</action>: An input slot, a fuel slot and 4 output slots. The fire in the furnace will automatically start when there is a smeltable item in the input slot and a fuel in the fuel slot.
+	As long as the fire is on, the furnace will smelt any smeltable item in the input slot, one by one, until it is empty. When the fire goes off, it will smelt the next item until there are no smeltable items and no fuel items left.
+	The current stage of cooking can be seen by <action name="pointing">pointing</action> the furnace or by viewing the furnace menu. In the furnace menu, the flame symbol roughly shows the remaining burning time. The arrow symbol shows the progress of the current smelting process.
+	<big>Renewing</big>
+	Furnaces can be crafted from e.g. <action name="default:cobblestone">cobblestone</action>, a renewable resource.
+	<big>Crafting</big>
+	Sorry no way to display crafting yet in formspec pages.
+	<big>Fuel</big>
+	See <action name="smelting">Smelting</action> for a list of furnace fuels.
+	<big>Recipes</big>
+	See the <action name="smelting">Smelting</action> page.
+]])
+
+
 local clip_fs = [[
 	style_type[label,button,image_button,item_image_button,
 			tabheader,scrollbar,table,animated_image
@@ -188,13 +218,48 @@ Number]
 			animated_image[3,4.25;1,1;;test_animation.png;4;0;3]
 			animated_image[5.5,0.5;5,2;;test_animation.png;4;100]
 			animated_image[5.5,2.75;5,2;;test_animation.jpg;4;100]
-		]]
+		]],
+
+		"formspec_version[3]"..
+		"size[12,12]"..
+		"button[8.5,1;1,1;bla;Bla]"..
+		"box[1,1;8,6;#00aa]"..
+		"scroll_container[1,1;8,6;scrbar;vertical]"..
+			"button[0,1;1,1;lorem;Lorem]"..
+			"button[0,10;1,1;ipsum;Ipsum]"..
+			"pwdfield[2,2;1,1;lorem2;Lorem]"..
+			"list[current_player;main;4,4;1,5;]"..
+			"box[2,5;3,2;#ffff00]"..
+			"image[1,10;3,2;bubble.png]"..
+			"image[3,1;bubble.png]"..
+			"item_image[2,6;3,2;default:mese]"..
+			"label[2,15;bla Bli\nfoo bar]"..
+			"item_image_button[2,3;1,1;default:dirt_with_grass;itemimagebutton;ItemImageButton]"..
+			"tooltip[0,11;3,2;Buz;#f00;#000]"..
+			"box[0,11;3,2;#00ff00]"..
+			"hypertext[3,13;3,3;;" .. hypertext .. "]" ..
+			"container[0,18]"..
+				"box[1,2;3,2;#0a0a]"..
+				"scroll_container[1,2;3,2;scrbar2;horizontal;0.06]"..
+					"button[0,0;6,1;butnest;Nest]"..
+					"label[10,0.5;nest]"..
+				"scroll_container_end[]"..
+				"scrollbar[1,0;3.5,0.3;horizontal;scrbar2;0]"..
+			"container_end[]"..
+			"dropdown[0,6;2;hmdrpdwn;apple,bulb;1]"..
+			"image_button[0,4;2,2;bubble.png;bubblebutton;bbbbtt;false;true;heart.png]"..
+			"box[1,22.5;4,1;#a00a]"..
+		"scroll_container_end[]"..
+		"scrollbaroptions[max=170]".. -- lowest seen pos is: 0.1*170+6=23 (factor*max+height)
+		"scrollbar[7.5,0;0.3,4;vertical;scrbar;0]"..
+		"scrollbar[8,0;0.3,4;vertical;scrbarhmmm;0]"..
+		"dropdown[0,6;2;hmdrpdwnnn;apple,bulb;1]",
 }
 
 local function show_test_formspec(pname, page_id)
 	page_id = page_id or 2
 
-	local fs = pages[page_id] .. "tabheader[0,0;6,0.65;maintabs;Real Coord,Styles,Noclip,MiscEle;" .. page_id .. ";false;false]"
+	local fs = pages[page_id] .. "tabheader[0,0;8,0.65;maintabs;Real Coord,Styles,Noclip,MiscEle,Scroll Container;" .. page_id .. ";false;false]"
 
 	minetest.show_formspec(pname, "test:formspec", fs)
 end

src/gui/CMakeLists.txt

@@ -16,6 +16,7 @@ set(gui_SRCS
 	${CMAKE_CURRENT_SOURCE_DIR}/guiPasswordChange.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/guiPathSelectMenu.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/guiScrollBar.cpp
+	${CMAKE_CURRENT_SOURCE_DIR}/guiScrollContainer.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/guiSkin.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/guiTable.cpp
 	${CMAKE_CURRENT_SOURCE_DIR}/guiHyperText.cpp

src/gui/guiFormSpecMenu.cpp

@@ -65,6 +65,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 #include "guiInventoryList.h"
 #include "guiItemImage.h"
 #include "guiScrollBar.h"
+#include "guiScrollContainer.h"
 #include "guiTable.h"
 #include "intlGUIEditBox.h"
 #include "guiHyperText.h"
@@ -143,6 +144,8 @@ GUIFormSpecMenu::~GUIFormSpecMenu()
 		tooltip_rect_it.first->drop();
 	for (auto &clickthrough_it : m_clickthrough_elements)
 		clickthrough_it->drop();
+	for (auto &scroll_container_it : m_scroll_containers)
+		scroll_container_it.second->drop();
 
 	delete m_selected_item;
 	delete m_form_src;
@@ -351,6 +354,102 @@ void GUIFormSpecMenu::parseContainerEnd(parserData* data)
 	}
 }
 
+void GUIFormSpecMenu::parseScrollContainer(parserData *data, const std::string &element)
+{
+	std::vector<std::string> parts = split(element, ';');
+
+	if (parts.size() < 4 ||
+			(parts.size() > 5 && m_formspec_version <= FORMSPEC_API_VERSION)) {
+		errorstream << "Invalid scroll_container start element (" << parts.size()
+				<< "): '" << element << "'" << std::endl;
+		return;
+	}
+
+	std::vector<std::string> v_pos  = split(parts[0], ',');
+	std::vector<std::string> v_geom = split(parts[1], ',');
+	std::string scrollbar_name = parts[2];
+	std::string orientation = parts[3];
+	f32 scroll_factor = 0.1f;
+	if (parts.size() >= 5 && !parts[4].empty())
+		scroll_factor = stof(parts[4]);
+
+	MY_CHECKPOS("scroll_container", 0);
+	MY_CHECKGEOM("scroll_container", 1);
+
+	v2s32 pos = getRealCoordinateBasePos(v_pos);
+	v2s32 geom = getRealCoordinateGeometry(v_geom);
+
+	if (orientation == "vertical")
+		scroll_factor *= -imgsize.Y;
+	else if (orientation == "horizontal")
+		scroll_factor *= -imgsize.X;
+	else
+		warningstream << "GUIFormSpecMenu::parseScrollContainer(): "
+				<< "Invalid scroll_container orientation: " << orientation
+				<< std::endl;
+
+	// old parent (at first: this)
+	// ^ is parent of clipper
+	// ^ is parent of mover
+	// ^ is parent of other elements
+
+	// make clipper
+	core::rect<s32> rect_clipper = core::rect<s32>(pos, pos + geom);
+
+	gui::IGUIElement *clipper = new gui::IGUIElement(EGUIET_ELEMENT, Environment,
+			data->current_parent, 0, rect_clipper);
+
+	// make mover
+	FieldSpec spec_mover(
+		"",
+		L"",
+		L"",
+		258 + m_fields.size()
+	);
+
+	core::rect<s32> rect_mover = core::rect<s32>(0, 0, geom.X, geom.Y);
+
+	GUIScrollContainer *mover = new GUIScrollContainer(Environment,
+			clipper, spec_mover.fid, rect_mover, orientation, scroll_factor);
+
+	data->current_parent = mover;
+
+	m_scroll_containers.emplace_back(scrollbar_name, mover);
+
+	m_fields.push_back(spec_mover);
+
+	clipper->drop();
+
+	// remove interferring offset of normal containers
+	container_stack.push(pos_offset);
+	pos_offset.X = 0.0f;
+	pos_offset.Y = 0.0f;
+}
+
+void GUIFormSpecMenu::parseScrollContainerEnd(parserData *data)
+{
+	if (data->current_parent == this || data->current_parent->getParent() == this ||
+			container_stack.empty()) {
+		errorstream << "Invalid scroll_container end element, "
+				<< "no matching scroll_container start element" << std::endl;
+		return;
+	}
+
+	if (pos_offset.getLengthSQ() != 0.0f) {
+		// pos_offset is only set by containers and scroll_containers.
+		// scroll_containers always set it to 0,0 which means that if it is
+		// not 0,0, it is a normal container that was opened last, not a
+		// scroll_container
+		errorstream << "Invalid scroll_container end element, "
+				<< "an inner container was left open" << std::endl;
+		return;
+	}
+
+	data->current_parent = data->current_parent->getParent()->getParent();
+	pos_offset = container_stack.top();
+	container_stack.pop();
+}
+
 void GUIFormSpecMenu::parseList(parserData *data, const std::string &element)
 {
 	if (m_client == 0) {
@@ -443,9 +542,9 @@ void GUIFormSpecMenu::parseList(parserData *data, const std::string &element)
 				pos.X + (geom.X - 1) * slot_spacing.X + imgsize.X,
 				pos.Y + (geom.Y - 1) * slot_spacing.Y + imgsize.Y);
 
-		GUIInventoryList *e = new GUIInventoryList(Environment, this, spec.fid,
+		GUIInventoryList *e = new GUIInventoryList(Environment, data->current_parent,
-				rect, m_invmgr, loc, listname, geom, start_i, imgsize, slot_spacing,
+				spec.fid, rect, m_invmgr, loc, listname, geom, start_i, imgsize,
-				this, data->inventorylist_options, m_font);
+				slot_spacing, this, data->inventorylist_options, m_font);
 
 		m_inventorylists.push_back(e);
 		m_fields.push_back(spec);
@@ -550,8 +649,8 @@ void GUIFormSpecMenu::parseCheckbox(parserData* data, const std::string &element
 
 		spec.ftype = f_CheckBox;
 
-		gui::IGUICheckBox *e = Environment->addCheckBox(fselected, rect, this,
+		gui::IGUICheckBox *e = Environment->addCheckBox(fselected, rect,
-					spec.fid, spec.flabel.c_str());
+				data->current_parent, spec.fid, spec.flabel.c_str());
 
 		auto style = getDefaultStyleForElement("checkbox", name);
 		e->setNotClipped(style.getBool(StyleSpec::NOCLIP, false));
@@ -610,8 +709,8 @@ void GUIFormSpecMenu::parseScrollBar(parserData* data, const std::string &elemen
 
 		spec.ftype = f_ScrollBar;
 		spec.send  = true;
-		GUIScrollBar *e = new GUIScrollBar(Environment, this, spec.fid, rect,
+		GUIScrollBar *e = new GUIScrollBar(Environment, data->current_parent,
-				is_horizontal, true);
+				spec.fid, rect, is_horizontal, true);
 
 		auto style = getDefaultStyleForElement("scrollbar", name);
 		e->setNotClipped(style.getBool(StyleSpec::NOCLIP, false));
@@ -737,7 +836,8 @@ void GUIFormSpecMenu::parseImage(parserData* data, const std::string &element)
 			1
 		);
 		core::rect<s32> rect(pos, pos + geom);
-		gui::IGUIImage *e = Environment->addImage(rect, this, spec.fid, 0, true);
+		gui::IGUIImage *e = Environment->addImage(rect, data->current_parent,
+				spec.fid, 0, true);
 		e->setImage(texture);
 		e->setScaleImage(true);
 		auto style = getDefaultStyleForElement("image", spec.fname);
@@ -774,8 +874,8 @@ void GUIFormSpecMenu::parseImage(parserData* data, const std::string &element)
 			L"",
 			258 + m_fields.size()
 		);
-		gui::IGUIImage *e = Environment->addImage(texture, pos, true, this,
+		gui::IGUIImage *e = Environment->addImage(texture, pos, true,
-				spec.fid, 0);
+				data->current_parent, spec.fid, 0);
 		auto style = getDefaultStyleForElement("image", spec.fname);
 		e->setNotClipped(style.getBool(StyleSpec::NOCLIP, m_formspec_version < 3));
 		m_fields.push_back(spec);
@@ -886,7 +986,7 @@ void GUIFormSpecMenu::parseItemImage(parserData* data, const std::string &elemen
 		);
 		spec.ftype = f_ItemImage;
 
-		GUIItemImage *e = new GUIItemImage(Environment, this, spec.fid,
+		GUIItemImage *e = new GUIItemImage(Environment, data->current_parent, spec.fid,
 				core::rect<s32>(pos, pos + geom), name, m_font, m_client);
 		auto style = getDefaultStyleForElement("item_image", spec.fname);
 		e->setNotClipped(style.getBool(StyleSpec::NOCLIP, false));
@@ -949,8 +1049,8 @@ void GUIFormSpecMenu::parseButton(parserData* data, const std::string &element,
 		if(type == "button_exit")
 			spec.is_exit = true;
 
-		GUIButton *e = GUIButton::addButton(Environment, rect, m_tsrc, this,
+		GUIButton *e = GUIButton::addButton(Environment, rect, m_tsrc,
-				spec.fid, spec.flabel.c_str());
+				data->current_parent, spec.fid, spec.flabel.c_str());
 
 		auto style = getStyleForElement(type, name, (type != "button") ? "button" : "");
 		e->setStyles(style);
@@ -1141,7 +1241,8 @@ void GUIFormSpecMenu::parseTable(parserData* data, const std::string &element)
 		}
 
 		//now really show table
-		GUITable *e = new GUITable(Environment, this, spec.fid, rect, m_tsrc);
+		GUITable *e = new GUITable(Environment, data->current_parent, spec.fid,
+				rect, m_tsrc);
 
 		if (spec.fname == data->focused_fieldname) {
 			Environment->setFocus(e);
@@ -1217,7 +1318,8 @@ void GUIFormSpecMenu::parseTextList(parserData* data, const std::string &element
 		}
 
 		//now really show list
-		GUITable *e = new GUITable(Environment, this, spec.fid, rect, m_tsrc);
+		GUITable *e = new GUITable(Environment, data->current_parent, spec.fid,
+				rect, m_tsrc);
 
 		if (spec.fname == data->focused_fieldname) {
 			Environment->setFocus(e);
@@ -1293,7 +1395,8 @@ void GUIFormSpecMenu::parseDropDown(parserData* data, const std::string &element
 		spec.send = true;
 
 		//now really show list
-		gui::IGUIComboBox *e = Environment->addComboBox(rect, this, spec.fid);
+		gui::IGUIComboBox *e = Environment->addComboBox(rect, data->current_parent,
+				spec.fid);
 
 		if (spec.fname == data->focused_fieldname) {
 			Environment->setFocus(e);
@@ -1379,7 +1482,8 @@ void GUIFormSpecMenu::parsePwdField(parserData* data, const std::string &element
 			);
 
 		spec.send = true;
-		gui::IGUIEditBox * e = Environment->addEditBox(0, rect, true, this, spec.fid);
+		gui::IGUIEditBox *e = Environment->addEditBox(0, rect, true,
+				data->current_parent, spec.fid);
 
 		if (spec.fname == data->focused_fieldname) {
 			Environment->setFocus(e);
@@ -1390,7 +1494,7 @@ void GUIFormSpecMenu::parsePwdField(parserData* data, const std::string &element
 			rect.UpperLeftCorner.Y -= font_height;
 			rect.LowerRightCorner.Y = rect.UpperLeftCorner.Y + font_height;
 			gui::StaticText::add(Environment, spec.flabel.c_str(), rect, false, true,
-				this, 0);
+				data->current_parent, 0);
 		}
 
 		e->setPasswordBox(true,L'*');
@@ -1425,7 +1529,7 @@ void GUIFormSpecMenu::createTextField(parserData *data, FieldSpec &spec,
 	if (!is_editable && !is_multiline) {
 		// spec field id to 0, this stops submit searching for a value that isn't there
 		gui::StaticText::add(Environment, spec.flabel.c_str(), rect, false, true,
-				this, 0);
+				data->current_parent, 0);
 		return;
 	}
 
@@ -1443,14 +1547,14 @@ void GUIFormSpecMenu::createTextField(parserData *data, FieldSpec &spec,
 
 	if (use_intl_edit_box && g_settings->getBool("freetype")) {
 		e = new gui::intlGUIEditBox(spec.fdefault.c_str(), true, Environment,
-				this, spec.fid, rect, is_editable, is_multiline);
+				data->current_parent, spec.fid, rect, is_editable, is_multiline);
 	} else {
 		if (is_multiline) {
-			e = new GUIEditBoxWithScrollBar(spec.fdefault.c_str(), true,
+			e = new GUIEditBoxWithScrollBar(spec.fdefault.c_str(), true, Environment,
-					Environment, this, spec.fid, rect, is_editable, true);
+					data->current_parent, spec.fid, rect, is_editable, true);
 		} else if (is_editable) {
-			e = Environment->addEditBox(spec.fdefault.c_str(), rect, true, this,
+			e = Environment->addEditBox(spec.fdefault.c_str(), rect, true,
-					spec.fid);
+					data->current_parent, spec.fid);
 			e->grab();
 		}
 	}
@@ -1491,7 +1595,7 @@ void GUIFormSpecMenu::createTextField(parserData *data, FieldSpec &spec,
 		rect.UpperLeftCorner.Y -= font_height;
 		rect.LowerRightCorner.Y = rect.UpperLeftCorner.Y + font_height;
 		IGUIElement *t = gui::StaticText::add(Environment, spec.flabel.c_str(),
-				rect, false, true, this, 0);
+				rect, false, true, data->current_parent, 0);
 
 		if (t)
 			t->setNotClipped(style.getBool(StyleSpec::NOCLIP, false));
@@ -1671,8 +1775,8 @@ void GUIFormSpecMenu::parseHyperText(parserData *data, const std::string &elemen
 	);
 
 	spec.ftype = f_HyperText;
-	GUIHyperText *e = new GUIHyperText(spec.flabel.c_str(), Environment, this,
+	GUIHyperText *e = new GUIHyperText(spec.flabel.c_str(), Environment,
-			spec.fid, rect, m_client, m_tsrc);
+			data->current_parent, spec.fid, rect, m_client, m_tsrc);
 	e->drop();
 
 	m_fields.push_back(spec);
@@ -1750,7 +1854,8 @@ void GUIFormSpecMenu::parseLabel(parserData* data, const std::string &element)
 				4
 			);
 			gui::IGUIStaticText *e = gui::StaticText::add(Environment,
-					spec.flabel.c_str(), rect, false, false, this, spec.fid);
+					spec.flabel.c_str(), rect, false, false, data->current_parent,
+					spec.fid);
 			e->setTextAlignment(gui::EGUIA_UPPERLEFT, gui::EGUIA_CENTER);
 
 			auto style = getDefaultStyleForElement("label", spec.fname);
@@ -1830,7 +1935,7 @@ void GUIFormSpecMenu::parseVertLabel(parserData* data, const std::string &elemen
 			258 + m_fields.size()
 		);
 		gui::IGUIStaticText *e = gui::StaticText::add(Environment, spec.flabel.c_str(),
-				rect, false, false, this, spec.fid);
+				rect, false, false, data->current_parent, spec.fid);
 		e->setTextAlignment(gui::EGUIA_CENTER, gui::EGUIA_CENTER);
 
 		auto style = getDefaultStyleForElement("vertlabel", spec.fname, "label");
@@ -1904,7 +2009,7 @@ void GUIFormSpecMenu::parseImageButton(parserData* data, const std::string &elem
 			spec.is_exit = true;
 
 		GUIButtonImage *e = GUIButtonImage::addButton(Environment, rect, m_tsrc,
-				this, spec.fid, spec.flabel.c_str());
+				data->current_parent, spec.fid, spec.flabel.c_str());
 
 		if (spec.fname == data->focused_fieldname) {
 			Environment->setFocus(e);
@@ -2010,8 +2115,8 @@ void GUIFormSpecMenu::parseTabHeader(parserData* data, const std::string &elemen
 		core::rect<s32> rect = core::rect<s32>(pos.X, pos.Y, pos.X+geom.X,
 				pos.Y+geom.Y);
 
-		gui::IGUITabControl *e = Environment->addTabControl(rect, this,
+		gui::IGUITabControl *e = Environment->addTabControl(rect,
-				show_background, show_border, spec.fid);
+				data->current_parent, show_background, show_border, spec.fid);
 		e->setAlignment(irr::gui::EGUIA_UPPERLEFT, irr::gui::EGUIA_UPPERLEFT,
 				irr::gui::EGUIA_UPPERLEFT, irr::gui::EGUIA_LOWERRIGHT);
 		e->setTabHeight(geom.Y);
@@ -2046,7 +2151,6 @@ void GUIFormSpecMenu::parseTabHeader(parserData* data, const std::string &elemen
 
 void GUIFormSpecMenu::parseItemImageButton(parserData* data, const std::string &element)
 {
-
 	if (m_client == 0) {
 		warningstream << "invalid use of item_image_button with m_client==0"
 			<< std::endl;
@@ -2106,7 +2210,7 @@ void GUIFormSpecMenu::parseItemImageButton(parserData* data, const std::string &
 		);
 
 		GUIButtonItemImage *e_btn = GUIButtonItemImage::addButton(Environment,
-				rect, m_tsrc, this, spec_btn.fid, spec_btn.flabel.c_str(),
+				rect, m_tsrc, data->current_parent, spec_btn.fid, spec_btn.flabel.c_str(),
 				item_name, m_client);
 
 		auto style = getStyleForElement("item_image_button", spec_btn.fname, "image_button");
@@ -2164,7 +2268,8 @@ void GUIFormSpecMenu::parseBox(parserData* data, const std::string &element)
 
 			core::rect<s32> rect(pos, pos + geom);
 
-			GUIBox *e = new GUIBox(Environment, this, spec.fid, rect, tmp_color);
+			GUIBox *e = new GUIBox(Environment, data->current_parent, spec.fid,
+					rect, tmp_color);
 
 			auto style = getDefaultStyleForElement("box", spec.fname);
 			e->setNotClipped(style.getBool(StyleSpec::NOCLIP, m_formspec_version < 3));
@@ -2316,7 +2421,7 @@ void GUIFormSpecMenu::parseTooltip(parserData* data, const std::string &element)
 		core::rect<s32> rect(pos, pos + geom);
 
 		gui::IGUIElement *e = new gui::IGUIElement(EGUIET_ELEMENT, Environment,
-				this, fieldspec.fid, rect);
+				data->current_parent, fieldspec.fid, rect);
 
 		// the element the rect tooltip is bound to should not block mouse-clicks
 		e->setVisible(false);
@@ -2775,6 +2880,16 @@ void GUIFormSpecMenu::parseElement(parserData* data, const std::string &element)
 		return;
 	}
 
+	if (type == "scroll_container") {
+		parseScrollContainer(data, description);
+		return;
+	}
+
+	if (type == "scroll_container_end") {
+		parseScrollContainerEnd(data);
+		return;
+	}
+
 	// Ignore others
 	infostream << "Unknown DrawSpec: type=" << type << ", data=\"" << description << "\""
 			<< std::endl;
@@ -2831,8 +2946,10 @@ void GUIFormSpecMenu::regenerateGui(v2u32 screensize)
 		tooltip_rect_it.first->drop();
 	for (auto &clickthrough_it : m_clickthrough_elements)
 		clickthrough_it->drop();
+	for (auto &scroll_container_it : m_scroll_containers)
+		scroll_container_it.second->drop();
 
-	mydata.size= v2s32(100,100);
+	mydata.size = v2s32(100, 100);
 	mydata.screensize = screensize;
 	mydata.offset = v2f32(0.5f, 0.5f);
 	mydata.anchor = v2f32(0.5f, 0.5f);
@@ -2841,6 +2958,9 @@ void GUIFormSpecMenu::regenerateGui(v2u32 screensize)
 	// Base position of contents of form
 	mydata.basepos = getBasePos();
 
+	// the parent for the parsed elements
+	mydata.current_parent = this;
+
 	m_inventorylists.clear();
 	m_backgrounds.clear();
 	m_tables.clear();
@@ -2851,6 +2971,7 @@ void GUIFormSpecMenu::regenerateGui(v2u32 screensize)
 	m_tooltip_rects.clear();
 	m_inventory_rings.clear();
 	m_dropdowns.clear();
+	m_scroll_containers.clear();
 	theme_by_name.clear();
 	theme_by_type.clear();
 	m_clickthrough_elements.clear();
@@ -3117,11 +3238,24 @@ void GUIFormSpecMenu::regenerateGui(v2u32 screensize)
 		parseElement(&mydata, elements[i]);
 	}
 
-	if (!container_stack.empty()) {
+	if (mydata.current_parent != this) {
+		errorstream << "Invalid formspec string: scroll_container was never closed!"
+			<< std::endl;
+	} else if (!container_stack.empty()) {
 		errorstream << "Invalid formspec string: container was never closed!"
 			<< std::endl;
 	}
 
+	// get the scrollbar elements for scroll_containers
+	for (const std::pair<std::string, GUIScrollContainer *> &c : m_scroll_containers) {
+		for (const std::pair<FieldSpec, GUIScrollBar *> &b : m_scrollbars) {
+			if (c.first == b.first.fname) {
+				c.second->setScrollBar(b.second);
+				break;
+			}
+		}
+	}
+
 	// If there are fields without explicit size[], add a "Proceed"
 	// button and adjust size to fit all the fields.
 	if (mydata.simple_field_count > 0 && !mydata.explicit_size) {
@@ -4418,6 +4552,12 @@ bool GUIFormSpecMenu::OnEvent(const SEvent& event)
 			}
 		}
 
+		if (event.GUIEvent.EventType == gui::EGET_SCROLL_BAR_CHANGED) {
+			// move scroll_containers
+			for (const std::pair<std::string, GUIScrollContainer *> &c : m_scroll_containers)
+				c.second->onScrollEvent(event.GUIEvent.Caller);
+		}
+
 		if (event.GUIEvent.EventType == gui::EGET_EDITBOX_ENTER) {
 			if (event.GUIEvent.Caller->getID() > 257) {
 				bool close_on_enter = true;

src/gui/guiFormSpecMenu.h

@@ -39,6 +39,7 @@ class ISimpleTextureSource;
 class Client;
 class GUIScrollBar;
 class TexturePool;
+class GUIScrollContainer;
 
 typedef enum {
 	f_Button,
@@ -310,6 +311,7 @@ protected:
 	std::vector<std::pair<FieldSpec, GUIScrollBar *>> m_scrollbars;
 	std::vector<std::pair<FieldSpec, std::vector<std::string>>> m_dropdowns;
 	std::vector<gui::IGUIElement *> m_clickthrough_elements;
+	std::vector<std::pair<std::string, GUIScrollContainer *>> m_scroll_containers;
 
 	GUIInventoryList::ItemSpec *m_selected_item = nullptr;
 	u16 m_selected_amount = 0;
@@ -359,6 +361,7 @@ private:
 		std::string focused_fieldname;
 		GUITable::TableOptions table_options;
 		GUITable::TableColumns table_columns;
+		gui::IGUIElement *current_parent = nullptr;
 
 		GUIInventoryList::Options inventorylist_options;
 
@@ -391,6 +394,8 @@ private:
 	void parseSize(parserData* data, const std::string &element);
 	void parseContainer(parserData* data, const std::string &element);
 	void parseContainerEnd(parserData* data);
+	void parseScrollContainer(parserData *data, const std::string &element);
+	void parseScrollContainerEnd(parserData *data);
 	void parseList(parserData* data, const std::string &element);
 	void parseListRing(parserData* data, const std::string &element);
 	void parseCheckbox(parserData* data, const std::string &element);

src/gui/guiHyperText.cpp

@@ -917,20 +917,20 @@ void TextDrawer::place(const core::rect<s32> &dest_rect)
 
 // Draw text in a rectangle with a given offset. Items are actually placed in
 // relative (to upper left corner) coordinates.
-void TextDrawer::draw(const core::rect<s32> &dest_rect,
+void TextDrawer::draw(const core::rect<s32> &clip_rect,
 		const core::position2d<s32> &dest_offset)
 {
 	irr::video::IVideoDriver *driver = m_environment->getVideoDriver();
-	core::position2d<s32> offset = dest_rect.UpperLeftCorner + dest_offset;
+	core::position2d<s32> offset = dest_offset;
 	offset.Y += m_voffset;
 
 	if (m_text.background_type == ParsedText::BACKGROUND_COLOR)
-		driver->draw2DRectangle(m_text.background_color, dest_rect);
+		driver->draw2DRectangle(m_text.background_color, clip_rect);
 
 	for (auto &p : m_text.m_paragraphs) {
 		for (auto &el : p.elements) {
 			core::rect<s32> rect(el.pos + offset, el.dim);
-			if (!rect.isRectCollided(dest_rect))
+			if (!rect.isRectCollided(clip_rect))
 				continue;
 
 			switch (el.type) {
@@ -947,7 +947,7 @@ void TextDrawer::draw(const core::rect<s32> &dest_rect,
 
 				if (el.type == ParsedText::ELEMENT_TEXT)
 					el.font->draw(el.text, rect, color, false, true,
-							&dest_rect);
+							&clip_rect);
 
 				if (el.underline &&  el.drawwidth) {
 					s32 linepos = el.pos.Y + offset.Y +
@@ -958,7 +958,7 @@ void TextDrawer::draw(const core::rect<s32> &dest_rect,
 							el.pos.X + offset.X + el.drawwidth,
 							linepos + (el.baseline >> 3));
 
-					driver->draw2DRectangle(color, linerect, &dest_rect);
+					driver->draw2DRectangle(color, linerect, &clip_rect);
 				}
 			} break;
 
@@ -972,7 +972,7 @@ void TextDrawer::draw(const core::rect<s32> &dest_rect,
 							irr::core::rect<s32>(
 									core::position2d<s32>(0, 0),
 									texture->getOriginalSize()),
-							&dest_rect, 0, true);
+							&clip_rect, 0, true);
 			} break;
 
 			case ParsedText::ELEMENT_ITEM: {
@@ -982,7 +982,7 @@ void TextDrawer::draw(const core::rect<s32> &dest_rect,
 
 				drawItemStack(
 						m_environment->getVideoDriver(),
-						g_fontengine->getFont(), item, rect, &dest_rect,
+						g_fontengine->getFont(), item, rect, &clip_rect,
 						m_client, IT_ROT_OTHER, el.angle, el.rotation
 				);
 			} break;
@@ -1094,6 +1094,7 @@ bool GUIHyperText::OnEvent(const SEvent &event)
 			m_text_scrollpos.Y = -m_vscrollbar->getPos();
 			m_drawer.draw(m_display_text_rect, m_text_scrollpos);
 			checkHover(event.MouseInput.X, event.MouseInput.Y);
+			return true;
 
 		} else if (event.MouseInput.Event == EMIE_LMOUSE_PRESSED_DOWN) {
 			ParsedText::Element *element = getElementAt(
@@ -1151,7 +1152,8 @@ void GUIHyperText::draw()
 		m_vscrollbar->setPos(0);
 		m_vscrollbar->setVisible(false);
 	}
-	m_drawer.draw(m_display_text_rect, m_text_scrollpos);
+	m_drawer.draw(AbsoluteClippingRect,
+			m_display_text_rect.UpperLeftCorner + m_text_scrollpos);
 
 	// draw children
 	IGUIElement::draw();

src/gui/guiHyperText.h

@@ -174,7 +174,7 @@ public:
 
 	void place(const core::rect<s32> &dest_rect);
 	inline s32 getHeight() { return m_height; };
-	void draw(const core::rect<s32> &dest_rect,
+	void draw(const core::rect<s32> &clip_rect,
 			const core::position2d<s32> &dest_offset);
 	ParsedText::Element *getElementAt(core::position2d<s32> pos);
 	ParsedText::Tag *m_hovertag;

src/gui/guiScrollContainer.cpp

@@ -0,0 +1,70 @@
+/*
+Minetest
+Copyright (C) 2020 DS
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#include "guiScrollContainer.h"
+
+GUIScrollContainer::GUIScrollContainer(gui::IGUIEnvironment *env,
+		gui::IGUIElement *parent, s32 id, const core::rect<s32> &rectangle,
+		const std::string &orientation, f32 scrollfactor) :
+		gui::IGUIElement(gui::EGUIET_ELEMENT, env, parent, id, rectangle),
+		m_scrollbar(nullptr), m_scrollfactor(scrollfactor)
+{
+	if (orientation == "vertical")
+		m_orientation = VERTICAL;
+	else if (orientation == "horizontal")
+		m_orientation = HORIZONTAL;
+	else
+		m_orientation = UNDEFINED;
+}
+
+bool GUIScrollContainer::OnEvent(const SEvent &event)
+{
+	if (event.EventType == EET_MOUSE_INPUT_EVENT &&
+			event.MouseInput.Event == EMIE_MOUSE_WHEEL &&
+			!event.MouseInput.isLeftPressed() && m_scrollbar) {
+		Environment->setFocus(m_scrollbar);
+		bool retval = m_scrollbar->OnEvent(event);
+
+		// a hacky fix for updating the hovering and co.
+		IGUIElement *hovered_elem = getElementFromPoint(core::position2d<s32>(
+				event.MouseInput.X, event.MouseInput.Y));
+		SEvent mov_event = event;
+		mov_event.MouseInput.Event = EMIE_MOUSE_MOVED;
+		Environment->postEventFromUser(mov_event);
+		if (hovered_elem)
+			hovered_elem->OnEvent(mov_event);
+
+		return retval;
+	}
+
+	return IGUIElement::OnEvent(event);
+}
+
+void GUIScrollContainer::updateScrolling()
+{
+	s32 pos = m_scrollbar->getPos();
+	core::rect<s32> rect = getRelativePosition();
+
+	if (m_orientation == VERTICAL)
+		rect.UpperLeftCorner.Y = pos * m_scrollfactor;
+	else if (m_orientation == HORIZONTAL)
+		rect.UpperLeftCorner.X = pos * m_scrollfactor;
+
+	setRelativePosition(rect);
+}

src/gui/guiScrollContainer.h

@@ -0,0 +1,56 @@
+/*
+Minetest
+Copyright (C) 2020 DS
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU Lesser General Public License as published by
+the Free Software Foundation; either version 2.1 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU Lesser General Public License for more details.
+
+You should have received a copy of the GNU Lesser General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+*/
+
+#pragma once
+
+#include "irrlichttypes_extrabloated.h"
+#include "util/string.h"
+#include "guiScrollBar.h"
+
+class GUIScrollContainer : public gui::IGUIElement
+{
+public:
+	GUIScrollContainer(gui::IGUIEnvironment *env, gui::IGUIElement *parent, s32 id,
+			const core::rect<s32> &rectangle, const std::string &orientation,
+			f32 scrollfactor);
+
+	virtual bool OnEvent(const SEvent &event) override;
+
+	inline void onScrollEvent(gui::IGUIElement *caller)
+	{
+		if (caller == m_scrollbar)
+			updateScrolling();
+	}
+
+	inline void setScrollBar(GUIScrollBar *scrollbar) { m_scrollbar = scrollbar; }
+
+private:
+	enum OrientationEnum
+	{
+		VERTICAL,
+		HORIZONTAL,
+		UNDEFINED
+	};
+
+	GUIScrollBar *m_scrollbar;
+	OrientationEnum m_orientation;
+	f32 m_scrollfactor;
+
+	void updateScrolling();
+};

src/network/networkprotocol.h

@@ -237,6 +237,7 @@ with this program; if not, write to the Free Software Foundation, Inc.,
 		Formspec elements are drawn in the order of definition
 		bgcolor[]: use 3 parameters (bgcolor, formspec (now an enum), fbgcolor)
 		box[] and image[] elements enable clipping by default
+		new element: scroll_container[]
 */
 #define FORMSPEC_API_VERSION 3