[GEN] Backport left click deselect functionality with Alternate Mouse Setup from Zero Hour

Generals/Code/GameEngine/Include/GameClient/InGameUI.h

@@ -416,6 +416,9 @@ friend class Drawable;	// for selection/deselection transactions
 	virtual void placeBuildAvailable( const ThingTemplate *build, Drawable *buildDrawable );				///< built thing being placed
 	virtual const ThingTemplate *getPendingPlaceType( void );					///< get item we're trying to place
 	virtual const ObjectID getPendingPlaceSourceObjectID( void );			///< get producing object
+			// TheSuperHackers @feature @ShizCalev 04/04/2025 - Backports Zero Hour's alt-mouse mode's left click deselect functionality
+	virtual Bool getPreventLeftClickDeselectionInAlternateMouseModeForOneClick() const { return m_preventLeftClickDeselectionInAlternateMouseModeForOneClick; }
+	virtual void setPreventLeftClickDeselectionInAlternateMouseModeForOneClick( Bool set ) { m_preventLeftClickDeselectionInAlternateMouseModeForOneClick = set; }
 	virtual void setPlacementStart( const ICoord2D *start );					///< placement anchor point (for choosing angles)
 	virtual void setPlacementEnd( const ICoord2D *end );							///< set target placement point (for choosing angles)
 	virtual Bool isPlacementAnchored( void );													///< is placement arrow anchor set
@@ -692,6 +695,7 @@ friend class Drawable;	// for selection/deselection transactions
 	BuildProgress								m_buildProgress[ MAX_BUILD_PROGRESS ];	///< progress for building units
 	const ThingTemplate *				m_pendingPlaceType;											///< type of built thing we're trying to place
 	ObjectID										m_pendingPlaceSourceObjectID;						///< source object of the thing constructing the item
+	Bool										m_preventLeftClickDeselectionInAlternateMouseModeForOneClick; // TheSuperHackers @feature @ShizCalev 04/04/2025 - Backports Zero Hour's alt-mouse mode's left click deselect functionality
 	Drawable **									m_placeIcon;														///< array for drawables to appear at the cursor when building in the world
 	Bool												m_placeAnchorInProgress;								///< is place angle interface for placement active
 	ICoord2D										m_placeAnchorStart;											///< place angle anchor start

Generals/Code/GameEngine/Source/GameClient/InGameUI.cpp

@@ -905,6 +905,7 @@ InGameUI::InGameUI()
 		m_placeIcon[ i ] = NULL;
 	m_pendingPlaceType = NULL;
 	m_pendingPlaceSourceObjectID = INVALID_ID;
+	m_preventLeftClickDeselectionInAlternateMouseModeForOneClick = FALSE; // TheSuperHackers @feature @ShizCalev 04/04/2025 - Backports Zero Hour's alt-mouse mode's left click deselect functionality
 	m_placeAnchorStart.x = m_placeAnchorStart.y = 0;
 	m_placeAnchorEnd.x = m_placeAnchorEnd.y = 0;
 	m_placeAnchorInProgress = FALSE;
@@ -2878,6 +2879,11 @@ void InGameUI::placeBuildAvailable( const ThingTemplate *build, Drawable *buildD
 	// place something, it is overwritten
 	//
 	m_pendingPlaceType = build;
+	// TheSuperHackers @feature @ShizCalev 04/04/2025 - Backports Zero Hour's alt-mouse mode's left click deselect functionality
+
+	//Keep the prev pending place for left click deselection prevention in alternate mouse mode.
+	//We want to keep our dozer selected after initiating construction.
+	setPreventLeftClickDeselectionInAlternateMouseModeForOneClick( m_pendingPlaceSourceObjectID != INVALID_ID );
 	m_pendingPlaceSourceObjectID = INVALID_ID;
 
 	Object *sourceObject = NULL;

Generals/Code/GameEngine/Source/GameClient/MessageStream/GUICommandTranslator.cpp

@@ -492,7 +492,10 @@ GameMessageDisposition GUICommandTranslator::translateGameMessage(const GameMess
 
 				// get out of GUI command mode if we completed the command one way or another
 				if( commandStatus == COMMAND_COMPLETE )
+				{
+					TheInGameUI->setPreventLeftClickDeselectionInAlternateMouseModeForOneClick( TRUE ); // TheSuperHackers @feature @ShizCalev 04/04/2025 - Backports Zero Hour's alt-mouse mode's left click deselect functionality
 					TheInGameUI->setGUICommand( NULL );
+				}
 			}  // end if
 
 			break;

Generals/Code/GameEngine/Source/GameClient/MessageStream/SelectionXlat.cpp

@@ -870,6 +870,31 @@ GameMessageDisposition SelectionTranslator::translateGameMessage(const GameMessa
 				buildRegion( &m_selectFeedbackAnchor, &msg->getArgument(0)->pixel, &selectionRegion );
 				dragMsg->appendPixelRegionArgument( selectionRegion );
 			}
+			// TheSuperHackers @feature @ShizCalev 04/04/2025 - Backports Zero Hour's alt-mouse mode's left click deselect functionality
+			else
+			{
+				// left click behavior (not right drag)
+
+				//Added support to cancel the GUI command without deselecting the unit(s) involved
+				//when you right click.
+				if( !TheInGameUI->getGUICommand() && !TheKeyboard->isShift() && !TheKeyboard->isCtrl() && !TheKeyboard->isAlt() )
+				{
+					//No GUI command mode, so deselect everyone if we're in alternate mouse mode.
+					if( TheGlobalData->m_useAlternateMouse && TheInGameUI->getPendingPlaceSourceObjectID() == INVALID_ID )
+					{
+						if( !TheInGameUI->getPreventLeftClickDeselectionInAlternateMouseModeForOneClick() )
+						{
+							deselectAll();
+						}
+						else
+						{
+							//Prevent deselection of unit if it just issued some type of UI order such as attack move, guard, 
+							//initiating construction of a new structure.
+							TheInGameUI->setPreventLeftClickDeselectionInAlternateMouseModeForOneClick( FALSE );
+						}
+					}
+				}
+			}
 
 			break;
 		}