Support handling touch state as part of the client update

So the touch state can be handled by gameclient components independently from their rendering, so touch inputs are not skipped when frames are.

Also store the time when touch fingers are first pressed down.

src/engine/client/input.cpp

@@ -301,6 +301,14 @@ const std::vector<IInput::CTouchFingerState> &CInput::TouchFingerStates() const
 	return m_vTouchFingerStates;
 }
 
+void CInput::ClearTouchDeltas()
+{
+	for(CTouchFingerState &TouchFingerState : m_vTouchFingerStates)
+	{
+		TouchFingerState.m_Delta = vec2(0.0f, 0.0f);
+	}
+}
+
 std::string CInput::GetClipboardText()
 {
 	char *pClipboardText = SDL_GetClipboardText();
@@ -348,10 +356,7 @@ void CInput::Clear()
 	mem_zero(m_aInputState, sizeof(m_aInputState));
 	mem_zero(m_aInputCount, sizeof(m_aInputCount));
 	m_vInputEvents.clear();
-	for(CTouchFingerState &TouchFingerState : m_vTouchFingerStates)
-	{
-		TouchFingerState.m_Delta = vec2(0.0f, 0.0f);
-	}
+	ClearTouchDeltas();
 }
 
 float CInput::GetUpdateTime() const
@@ -565,6 +570,7 @@ void CInput::HandleTouchDownEvent(const SDL_TouchFingerEvent &Event)
 	TouchFingerState.m_Finger.m_FingerId = Event.fingerId;
 	TouchFingerState.m_Position = vec2(Event.x, Event.y);
 	TouchFingerState.m_Delta = vec2(Event.dx, Event.dy);
+	TouchFingerState.m_PressTime = time_get_nanoseconds();
 	m_vTouchFingerStates.emplace_back(TouchFingerState);
 }
 

src/engine/client/input.h

@@ -146,6 +146,7 @@ class CInput : public IEngineInput
 	bool NativeMousePressed(int Index) const override;
 
 	const std::vector<CTouchFingerState> &TouchFingerStates() const override;
+	void ClearTouchDeltas() override;
 
 	std::string GetClipboardText() override;
 	void SetClipboardText(const char *pText) override;

src/engine/input.h

@@ -8,6 +8,7 @@
 #include <base/types.h>
 #include <base/vmath.h>
 
+#include <chrono>
 #include <cstdint>
 #include <functional>
 #include <string>
@@ -128,6 +129,10 @@ class IInput : public IInterface
 		 * @remark This is reset to zero at the end of each frame.
 		 */
 		vec2 m_Delta;
+		/**
+		 * The time when this finger was first pressed down.
+		 */
+		std::chrono::nanoseconds m_PressTime;
 	};
 	/**
 	 * Returns a vector of the states of all touch fingers currently being pressed down on touch devices.
@@ -137,6 +142,12 @@ class IInput : public IInterface
 	 * @return vector of all touch finger states
 	 */
 	virtual const std::vector<CTouchFingerState> &TouchFingerStates() const = 0;
+	/**
+	 * Must be called after the touch finger states have been used during the client update to ensure that
+	 * touch deltas are only accumulated until the next update. If the touch states are only used during
+	 * rendering, i.e. for user interfaces, then this is called automatically by calling @link Clear @endlink.
+	 */
+	virtual void ClearTouchDeltas() = 0;
 
 	// clipboard
 	virtual std::string GetClipboardText() = 0;

src/game/client/component.h

@@ -212,6 +212,14 @@ class CComponent
 	 * @param Event The input event.
 	 */
 	virtual bool OnInput(const IInput::CEvent &Event) { return false; }
+	/**
+	 * Called with all current touch finger states.
+	 *
+	 * @param vTouchFingerStates The touch finger states to be handled.
+	 *
+	 * @return `true` if the component used the touch events, `false` otherwise
+	 */
+	virtual bool OnTouchState(const std::vector<IInput::CTouchFingerState> &vTouchFingerStates) { return false; }
 };
 
 #endif

src/game/client/gameclient.cpp

@@ -444,6 +444,23 @@ void CGameClient::OnUpdate()
 		}
 	}
 
+	// handle touch events
+	const std::vector<IInput::CTouchFingerState> &vTouchFingerStates = Input()->TouchFingerStates();
+	bool TouchHandled = false;
+	for(auto &pComponent : m_vpInput)
+	{
+		if(TouchHandled)
+		{
+			// Also update inactive components so they can handle touch fingers being released.
+			pComponent->OnTouchState({});
+		}
+		else if(pComponent->OnTouchState(vTouchFingerStates))
+		{
+			Input()->ClearTouchDeltas();
+			TouchHandled = true;
+		}
+	}
+
 	// handle key presses
 	Input()->ConsumeEvents([&](const IInput::CEvent &Event) {
 		for(auto &pComponent : m_vpInput)