From 588fe293ec28ed240b89a65a377bc6a4b699d1dd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tam=C3=A1s=20B=C3=A1lint=20Misius?= <lbphacker@gmail.com>
Date: Tue, 6 Feb 2024 14:14:00 +0100
Subject: [PATCH] Add panning to ScrollPanel when TouchUI is enabled

---
 android/debug.sh                  |  6 ++++
 src/Misc.h                        |  5 ++++
 src/gui/interface/ScrollPanel.cpp | 47 +++++++++++++++++++++++++++++--
 src/gui/interface/ScrollPanel.h   | 13 ++++++++-
 4 files changed, 68 insertions(+), 3 deletions(-)

diff --git a/android/debug.sh b/android/debug.sh
index 08d8ab1e2..ce8ee01af 100755
--- a/android/debug.sh
+++ b/android/debug.sh
@@ -55,6 +55,7 @@ lldb_server=${LLDB_SERVER:-$default_lldb_server}
 lldb_server_port=${LLDB_SERVER_PORT:-9998}
 jdb_port=${JDB_PORT:-13456}
 lldb_client=${LLDB_CLIENT:-$default_lldb_client}
+meson=${MESON:-meson}
 adb=${ADB:-adb}
 jdb=${JDB:-jdb}
 
@@ -113,6 +114,11 @@ Naturally, replace bagelsbagels with an appropriate password.
 HELP
 		exit 1
 	fi
+	>&2 echo "[+] meson compiling android/$app_exe.apk"
+	if ! $meson compile sign-apk; then
+		>&2 echo "[-]   failed"
+		return 1
+	fi
 	>&2 echo "[+] adb installing android/$app_exe.apk"
 	if ! $adb install android/$app_exe.apk; then
 		>&2 echo "[-]   failed"
diff --git a/src/Misc.h b/src/Misc.h
index 5faa307fb..615cd57a4 100644
--- a/src/Misc.h
+++ b/src/Misc.h
@@ -51,6 +51,11 @@ inline int isign(float i)
 	return 0;
 }
 
+inline int iabs(int i)
+{
+	return i * isign(i);
+}
+
 inline unsigned clamp_flt(float f, float min, float max)
 {
 	if (f<min)
diff --git a/src/gui/interface/ScrollPanel.cpp b/src/gui/interface/ScrollPanel.cpp
index f8b4cff4d..9ad0c728b 100644
--- a/src/gui/interface/ScrollPanel.cpp
+++ b/src/gui/interface/ScrollPanel.cpp
@@ -1,8 +1,9 @@
 #include "ScrollPanel.h"
 #include "Engine.h"
-
 #include "graphics/Graphics.h"
-
+#include "Misc.h"
+#include "PowderToySDL.h"
+#include "Window.h"
 #include <algorithm>
 
 using namespace ui;
@@ -79,6 +80,7 @@ void ScrollPanel::XOnMouseDown(int x, int y, unsigned int button)
 			scrollbarSelected = true;
 			scrollbarInitialYOffset = int(offsetY);
 		}
+		initialOffsetY = offsetY;
 		scrollbarInitialYClick = y - Position.Y;
 		scrollbarClickLocation = 100;
 	}
@@ -87,6 +89,21 @@ void ScrollPanel::XOnMouseDown(int x, int y, unsigned int button)
 void ScrollPanel::XOnMouseUp(int x, int y, unsigned int button)
 {
 	scrollbarSelected = false;
+	panning = false;
+	{
+		auto it = panHistory.end();
+		while (it != panHistory.begin() && *(it - 1))
+		{
+			--it;
+		}
+		if (it < panHistory.end())
+		{
+			auto offsetYDiff = panHistory.back()->offsetY - (*it)->offsetY;
+			auto tickDiff = panHistory.back()->ticks - (*it)->ticks;
+			yScrollVel += offsetYDiff / tickDiff * (1000.f / Engine::Ref().GetFps());
+		}
+	}
+	panHistory = {};
 	isMouseInsideScrollbarArea = false;
 	scrollbarClickLocation = 0;
 }
@@ -116,6 +133,19 @@ void ScrollPanel::XOnMouseMoved(int x, int y, int dx, int dy)
 				offsetY = float(scrollbarInitialYOffset);
 			}
 		}
+		else if (MouseDownInside)
+		{
+			Vec2<int> mouseAt{ x, y };
+			if (Engine::Ref().TouchUI && iabs(scrollbarInitialYClick - mouseAt.Y) > PanOffsetThreshold)
+			{
+				panning = true;
+				for (auto *child : children)
+				{
+					child->MouseDownInside = false;
+				}
+				GetParentWindow()->FocusComponent(NULL);
+			}
+		}
 
 		if (x > (Size.X-scrollBarWidth) && x < (Size.X-scrollBarWidth)+scrollBarWidth)
 		{
@@ -130,6 +160,19 @@ void ScrollPanel::XOnMouseMoved(int x, int y, int dx, int dy)
 
 void ScrollPanel::XTick(float dt)
 {
+	if (panning)
+	{
+		auto scrollY = initialOffsetY + scrollbarInitialYClick - (Engine::Ref().GetMouseY() - GetScreenPos().Y);
+		ViewportPosition.Y = -scrollY;
+		offsetY = float(scrollY);
+		PanPoint p{ offsetY, GetTicks() };
+		if (!(panHistory.back() && panHistory.back()->ticks == p.ticks))
+		{
+			std::copy(panHistory.begin() + 1, panHistory.end(), panHistory.begin());
+			panHistory.back() = p;
+		}
+	}
+
 	if (xScrollVel > 7.0f) xScrollVel = 7.0f;
 	if (xScrollVel < -7.0f) xScrollVel = -7.0f;
 	if (xScrollVel > -0.5f && xScrollVel < 0.5)
diff --git a/src/gui/interface/ScrollPanel.h b/src/gui/interface/ScrollPanel.h
index a1ccb719b..eb41508ab 100644
--- a/src/gui/interface/ScrollPanel.h
+++ b/src/gui/interface/ScrollPanel.h
@@ -1,6 +1,7 @@
 #pragma once
-
 #include "Panel.h"
+#include <optional>
+#include <array>
 
 namespace ui
 {
@@ -19,6 +20,16 @@ namespace ui
 		int scrollbarInitialYOffset;
 		int scrollbarInitialYClick;
 		int scrollbarClickLocation;
+		int initialOffsetY;
+		bool panning = false;
+		static constexpr int PanOffsetThreshold = 10;
+		static constexpr int PanHistorySize = 5;
+		struct PanPoint
+		{
+			float offsetY;
+			unsigned int ticks;
+		};
+		std::array<std::optional<PanPoint>, PanHistorySize> panHistory;
 	public:
 		ScrollPanel(Point position, Point size);