src/client/gui/components/GuiElementContainer.cpp

@@ -35,6 +35,17 @@ void GuiElementContainer::removeChild( GuiElement* element ) {
 		children.erase(it);
 }
 
+bool GuiElementContainer::containsPointInChildren(int x, int y) const {
+	for (std::vector<GuiElement*>::const_iterator it = children.begin(); it != children.end(); ++it) {
+		GuiElement* child = *it;
+		if (child == NULL || !child->visible) continue;
+		if (child->pointInside(x, y)) return true;
+		const GuiElementContainer* container = dynamic_cast<const GuiElementContainer*>(child);
+		if (container != NULL && container->containsPointInChildren(x, y)) return true;
+	}
+	return false;
+}
+
 void GuiElementContainer::tick( Minecraft* minecraft ) {
 	for(std::vector<GuiElement*>::iterator it = children.begin(); it != children.end(); ++it) {
 		(*it)->tick(minecraft);

src/client/gui/components/GuiElementContainer.h

@@ -13,6 +13,7 @@ public:
 	virtual void setupPositions();
 	virtual void addChild(GuiElement* element);
 	virtual void removeChild(GuiElement* element);
+	bool containsPointInChildren(int x, int y) const;
 
 	virtual void tick( Minecraft* minecraft );
 

src/client/gui/components/OptionsGroup.cpp

@@ -6,14 +6,36 @@
 #include "../../../locale/I18n.h"
 #include "TextOption.h"
 #include "KeyOption.h"
+#include <algorithm>
+#include "../Gui.h"
+#include "../Screen.h"
+#include "../../../platform/input/Mouse.h"
+#include "../../../util/Mth.h"
 
-OptionsGroup::OptionsGroup( std::string labelID )  {
+OptionsGroup::OptionsGroup( std::string labelID )
+: contentHeight(0),
+	scrollOffsetY(0.0f),
+	maxScrollOffsetY(0.0f),
+	trackingScrollGesture(false),
+	scrollingGesture(false),
+	touchDispatched(false),
+	dragStartX(0),
+	dragStartY(0),
+	lastDragY(0),
+	touchStartX(0),
+	touchStartY(0) {
 	label = I18n::get(labelID);
 }
 
 void OptionsGroup::setupPositions() {
+	const int labelHeight = 18;
+	const int bottomPadding = 36;
+	const float requestedScroll = scrollOffsetY;
+	const int scrollOffset = (int)requestedScroll;
+	int curY = y + labelHeight - scrollOffset;
+	const int contentStartY = y + labelHeight;
+
 	// First we write the header and then we add the items
-	int curY = y + 18;
 	for(std::vector<GuiElement*>::iterator it = children.begin(); it != children.end(); ++it) {
 		(*it)->width = width - 5;
 		
@@ -22,16 +44,109 @@ void OptionsGroup::setupPositions() {
 		(*it)->setupPositions();
 		curY += (*it)->height + 3;
 	}
-	height = curY;
+	curY += bottomPadding;
+	contentHeight = std::max(0, curY - contentStartY + scrollOffset);
+	maxScrollOffsetY = std::max(0, contentHeight - (height - labelHeight));
+	const float clampedScroll = Mth::clamp(requestedScroll, 0.0f, maxScrollOffsetY);
+	if (clampedScroll != requestedScroll) {
+		scrollOffsetY = clampedScroll;
+		setupPositions();
+	}
 }
 
 void OptionsGroup::render( Minecraft* minecraft, int xm, int ym ) {
 	float padX = 10.0f;
 	float padY = 5.0f;
+	const int labelHeight = 18;
 	
 	minecraft->font->draw(label, (float)x + padX, (float)y + padY, 0xffffffff, false);
 
+	glEnable2(GL_SCISSOR_TEST);
+	glScissor(
+		Gui::GuiScale * x,
+		minecraft->height - Gui::GuiScale * (y + height),
+		Gui::GuiScale * width,
+		Gui::GuiScale * (height - labelHeight)
+	);
+
 	super::render(minecraft, xm, ym);
+	glDisable2(GL_SCISSOR_TEST);
+}
+
+void OptionsGroup::tick(Minecraft* minecraft) {
+	int xm = Mouse::getX();
+	int ym = Mouse::getY();
+	if (minecraft->screen != NULL) {
+		minecraft->screen->toGUICoordinate(xm, ym);
+	}
+
+	bool leftDown = Mouse::isButtonDown(MouseAction::ACTION_LEFT);
+
+	if (trackingScrollGesture && leftDown) {
+		int dy = ym - lastDragY;
+		int dx = xm - dragStartX;
+		if (!scrollingGesture) {
+			int totalDx = xm - dragStartX;
+			int totalDy = ym - dragStartY;
+			if (std::abs(totalDx) >= ScrollStartThreshold || std::abs(totalDy) >= ScrollStartThreshold) {
+				if (std::abs(totalDy) >= std::abs(totalDx)) {
+					scrollingGesture = true;
+				} else if (!touchDispatched) {
+					super::mouseClicked(minecraft, touchStartX, touchStartY, MouseAction::ACTION_LEFT);
+					touchDispatched = true;
+				}
+			}
+		}
+		if (scrollingGesture && dy != 0) {
+			scrollByPixels((float)dy);
+		}
+		lastDragY = ym;
+	}
+	super::tick(minecraft);
+}
+
+void OptionsGroup::mouseClicked(Minecraft* minecraft, int x, int y, int buttonNum) {
+	trackingScrollGesture = false;
+	scrollingGesture = false;
+	touchDispatched = false;
+
+	if (buttonNum == MouseAction::ACTION_LEFT && pointInside(x, y)) {
+		trackingScrollGesture = true;
+		dragStartX = x;
+		dragStartY = y;
+		lastDragY = y;
+		touchStartX = x;
+		touchStartY = y;
+		return;
+	}
+
+	super::mouseClicked(minecraft, x, y, buttonNum);
+}
+
+void OptionsGroup::mouseReleased(Minecraft* minecraft, int x, int y, int buttonNum) {
+	bool wasScrolling = scrollingGesture;
+	bool wasTracking = trackingScrollGesture;
+	trackingScrollGesture = false;
+	scrollingGesture = false;
+	if (buttonNum == MouseAction::ACTION_LEFT && wasTracking && !touchDispatched && pointInside(touchStartX, touchStartY)) {
+		super::mouseClicked(minecraft, touchStartX, touchStartY, buttonNum);
+		touchDispatched = true;
+	}
+
+	if (!wasScrolling) {
+		super::mouseReleased(minecraft, x, y, buttonNum);
+	}
+}
+
+void OptionsGroup::scrollByPixels(float deltaY) {
+	if (deltaY == 0.0f || maxScrollOffsetY <= 0.0f) return;
+
+	scrollOffsetY = Mth::clamp(scrollOffsetY - deltaY, 0.0f, maxScrollOffsetY);
+	setupPositions();
+}
+
+bool OptionsGroup::isScrollingGestureActive() const {
+	return trackingScrollGesture || scrollingGesture;
 }
 
 OptionsGroup& OptionsGroup::addOptionItem(OptionId optId, Minecraft* minecraft ) {

src/client/gui/components/OptionsGroup.h

@@ -17,7 +17,12 @@ public:
 	OptionsGroup(std::string labelID);
 	virtual void setupPositions();
 	virtual void render(Minecraft* minecraft, int xm, int ym);
+	virtual void tick(Minecraft* minecraft);
+	virtual void mouseClicked(Minecraft* minecraft, int x, int y, int buttonNum);
+	virtual void mouseReleased(Minecraft* minecraft, int x, int y, int buttonNum);
 	OptionsGroup& addOptionItem(OptionId optId, Minecraft* minecraft);
+	void scrollByPixels(float deltaY);
+	bool isScrollingGestureActive() const;
 protected:
 
 	void createToggle(OptionId optId, Minecraft* minecraft);
@@ -27,6 +32,18 @@ protected:
 	void createKey(OptionId optId, Minecraft* minecraft);
 
 	std::string label;
+	int contentHeight;
+	float scrollOffsetY;
+	float maxScrollOffsetY;
+	bool trackingScrollGesture;
+	bool scrollingGesture;
+	bool touchDispatched;
+	int dragStartX;
+	int dragStartY;
+	int lastDragY;
+	int touchStartX;
+	int touchStartY;
+	static const int ScrollStartThreshold = 5;
 };
 
 #endif /*NET_MINECRAFT_CLIENT_GUI_COMPONENTS__OptionsGroup_H__*/

src/client/gui/screens/OptionsScreen.cpp

@@ -121,6 +121,7 @@ void OptionsScreen::setupPositions() {
 			(*it)->x = categoryButtons[0]->width;
 			(*it)->y = bHeader->height;
 			(*it)->width = width - categoryButtons[0]->width;
+			(*it)->height = height - bHeader->height;
 
 			(*it)->setupPositions();
 		}
@@ -253,6 +254,12 @@ void OptionsScreen::mouseReleased(int x, int y, int buttonNum) {
 	super::mouseReleased(x, y, buttonNum);
 }
 
+void OptionsScreen::mouseWheel(int dx, int dy, int xm, int ym) {
+	if (currentOptionsGroup != NULL && currentOptionsGroup->pointInside(xm, ym) && dy != 0) {
+		currentOptionsGroup->scrollByPixels((float)dy * 18.0f);
+	}
+}
+
 void OptionsScreen::keyPressed(int eventKey) {
 	if (currentOptionsGroup != NULL)
 		currentOptionsGroup->keyPressed(minecraft, eventKey);

src/client/gui/screens/OptionsScreen.h

@@ -27,6 +27,7 @@ public:
 
 	virtual void mouseClicked(int x, int y, int buttonNum);
 	virtual void mouseReleased(int x, int y, int buttonNum);
+	virtual void mouseWheel(int dx, int dy, int xm, int ym);
 	virtual void keyPressed(int eventKey);
 	virtual void charPressed(char inputChar);