Fix #2657: inability to scroll diagonally with keyboard

Regression from commit ecc0dca665.

Scrolling diagonally requires holding two keys. Now when a key press event
is considered a key press only if there hasn't been a key release in
between, the second key press is no longer considered a key press.

As a workaround, simply activate scrolling on key event even if the event
isn't considered a key press.

src/editor/controller/editor_controller.cpp

@@ -584,7 +584,7 @@ hotkey::ACTION_STATE editor_controller::get_action_state(hotkey::HOTKEY_COMMAND
 	}
 }
 
-bool editor_controller::do_execute_command(const hotkey::hotkey_command& cmd, int index, bool press)
+bool editor_controller::do_execute_command(const hotkey::hotkey_command& cmd, int index, bool press, bool release)
 {
 	hotkey::HOTKEY_COMMAND command = cmd.id;
 	SCOPE_ED;
@@ -592,7 +592,7 @@ bool editor_controller::do_execute_command(const hotkey::hotkey_command& cmd, in
 
 	// nothing here handles release; fall through to base implementation
 	if (!press) {
-		return hotkey::command_executor::do_execute_command(cmd, index, press);
+		return hotkey::command_executor::do_execute_command(cmd, index, press, release);
 	}
 
 	switch (command) {
@@ -988,7 +988,7 @@ bool editor_controller::do_execute_command(const hotkey::hotkey_command& cmd, in
 			return true;
 		}
 		default:
-			return hotkey::command_executor::do_execute_command(cmd, index, press);
+			return hotkey::command_executor::do_execute_command(cmd, index, press, release);
 	}
 }
 

src/editor/controller/editor_controller.hpp

@@ -108,7 +108,7 @@ class editor_controller : public controller_base,
 		hotkey::ACTION_STATE get_action_state(hotkey::HOTKEY_COMMAND command, int index) const override;
 
 		/** command_executor override */
-		bool do_execute_command(const hotkey::hotkey_command& command, int index = -1, bool press=true) override;
+		bool do_execute_command(const hotkey::hotkey_command& command, int index = -1, bool press = true, bool release = false) override;
 
 		/** controller_base override */
 		void show_menu(const std::vector<config>& items_arg, int xloc, int yloc, bool context_menu, display& disp) override;

src/hotkey/command_executor.cpp

@@ -84,10 +84,10 @@ namespace hotkey {
 
 static void event_execute(const SDL_Event& event, command_executor* executor);
 
-bool command_executor::do_execute_command(const hotkey_command&  cmd, int /*index*/, bool press)
+bool command_executor::do_execute_command(const hotkey_command&  cmd, int /*index*/, bool press, bool release)
 {
 	// hotkey release handling
-	if (!press) {
+	if (release) {
 		switch(cmd.id) {
 			// release a scroll key, un-apply scrolling in the given direction
 			case HOTKEY_SCROLL_UP:
@@ -109,20 +109,28 @@ bool command_executor::do_execute_command(const hotkey_command&  cmd, int /*inde
 		return true;
 	}
 
-	// hotkey press handling
+	// handling of hotkeys which activate even on hold events
 	switch(cmd.id) {
 		case HOTKEY_SCROLL_UP:
 			scroll_up(true);
-			break;
+			return true;
 		case HOTKEY_SCROLL_DOWN:
 			scroll_down(true);
-			break;
+			return true;
 		case HOTKEY_SCROLL_LEFT:
 			scroll_left(true);
-			break;
+			return true;
 		case HOTKEY_SCROLL_RIGHT:
 			scroll_right(true);
-			break;
+			return true;
+	}
+
+	if(!press) {
+		return false; // nothing else handles hotkey hold events
+	}
+
+	// hotkey press handling
+	switch(cmd.id) {
 		case HOTKEY_CYCLE_UNITS:
 			cycle_units();
 			break;
@@ -561,6 +569,7 @@ void command_executor::execute_command(const SDL_Event& event, int index)
 		!press_event_sent_;
 	bool press = keypress ||
 		(event.type == SDL_JOYBUTTONDOWN || event.type == SDL_MOUSEBUTTONDOWN);
+	bool release = event.type == SDL_KEYUP;
 	if(press) {
 		LOG_HK << "sending press event (keypress = " <<
 			std::boolalpha << keypress << std::noboolalpha << ")\n";
@@ -570,7 +579,7 @@ void command_executor::execute_command(const SDL_Event& event, int index)
 	}
 
 	if (!can_execute_command(command, index)
-			|| do_execute_command(command, index, press)) {
+			|| do_execute_command(command, index, press, release)) {
 		return;
 	}
 

src/hotkey/command_executor.hpp

@@ -147,7 +147,7 @@ public:
 	}
 
 protected:
-	virtual bool do_execute_command(const hotkey_command& command, int index=-1, bool press=true);
+	virtual bool do_execute_command(const hotkey_command& command, int index=-1, bool press=true, bool release=false);
 
 private:
 	bool press_event_sent_ = false;

src/hotkey/hotkey_handler.cpp

@@ -237,7 +237,7 @@ void play_controller::hotkey_handler::scroll_right(bool on)
 	play_controller_.set_scroll_right(on);
 }
 
-bool play_controller::hotkey_handler::do_execute_command(const hotkey::hotkey_command& cmd, int index, bool press)
+bool play_controller::hotkey_handler::do_execute_command(const hotkey::hotkey_command& cmd, int index, bool press, bool release)
 {
 	hotkey::HOTKEY_COMMAND command = cmd.id;
 	if(index >= 0) {
@@ -259,7 +259,7 @@ bool play_controller::hotkey_handler::do_execute_command(const hotkey::hotkey_co
 
 		return gamestate().get_wml_menu_items().fire_item(name, hex, gamestate().gamedata_, gamestate(), gamestate().board_.units_, !press);
 	}
-	return command_executor::do_execute_command(cmd, index, press);
+	return command_executor::do_execute_command(cmd, index, press, release);
 }
 
 bool play_controller::hotkey_handler::can_execute_command(const hotkey::hotkey_command& cmd, int index) const

src/hotkey/hotkey_handler.hpp

@@ -123,7 +123,7 @@ public:
 	virtual hotkey::ACTION_STATE get_action_state(hotkey::HOTKEY_COMMAND command, int index) const override;
 	/** Check if a command can be executed. */
 	virtual bool can_execute_command(const hotkey::hotkey_command& command, int index=-1) const override;
-	virtual bool do_execute_command(const hotkey::hotkey_command& command, int index=-1, bool press=true) override;
+	virtual bool do_execute_command(const hotkey::hotkey_command& command, int index=-1, bool press=true, bool release=false) override;
 	void show_menu(const std::vector<config>& items_arg, int xloc, int yloc, bool context_menu, display& disp) override;
 
 	/**