From b4fbbed3794d6c6458beda323c781a78262f38f5 Mon Sep 17 00:00:00 2001
From: Angen <angen@wildfiregames.com>
Date: Sun, 17 Oct 2021 10:58:51 +0000
Subject: [PATCH] There have been quite a bit of number of questions how to
 change scale of the gui, because this option is hidden from the user.

Use dropdown with values. Implement confirmation box with countdown to
revert scale change because buttons can get unable to click.

Differential revision: D3037
Comments by: @vladislavbelov, @Stan, @wraitii, @pieq, @sera
Tested by: @Langbart
This was SVN commit r25966.
---
 .../mods/mod/gui/common/functions_msgbox.js   | 18 ++++++
 .../data/mods/mod/gui/common/utilities.js     | 35 ++++++++++++
 binaries/data/mods/mod/gui/msgbox/msgbox.js   | 34 +----------
 .../mods/mod/gui/page_timedconfirmation.xml   |  8 +++
 .../timedconfirmation/timedconfirmation.js    | 48 ++++++++++++++++
 .../timedconfirmation/timedconfirmation.xml   | 56 +++++++++++++++++++
 .../data/mods/public/gui/options/options.js   | 47 ++++++++++++++++
 .../data/mods/public/gui/options/options.json | 18 ++++++
 .../data/mods/public/gui/options/options.xml  |  1 +
 source/gui/CGUI.cpp                           |  7 ++-
 source/gui/CGUIText.cpp                       | 11 ++--
 source/gui/GUIMatrix.cpp                      |  9 ++-
 source/gui/ObjectTypes/CInput.cpp             | 10 ++--
 source/ps/CConsole.cpp                        |  5 +-
 source/ps/GameSetup/Config.cpp                |  4 --
 source/ps/GameSetup/Config.h                  |  1 -
 source/ps/VideoMode.cpp                       | 16 +++++-
 source/ps/VideoMode.h                         |  9 +++
 source/ps/scripting/JSInterface_ConfigDB.cpp  |  7 +++
 19 files changed, 287 insertions(+), 57 deletions(-)
 create mode 100644 binaries/data/mods/mod/gui/common/utilities.js
 create mode 100644 binaries/data/mods/mod/gui/page_timedconfirmation.xml
 create mode 100644 binaries/data/mods/mod/gui/timedconfirmation/timedconfirmation.js
 create mode 100644 binaries/data/mods/mod/gui/timedconfirmation/timedconfirmation.xml

diff --git a/binaries/data/mods/mod/gui/common/functions_msgbox.js b/binaries/data/mods/mod/gui/common/functions_msgbox.js
index acf524bff3..9f2653b87b 100644
--- a/binaries/data/mods/mod/gui/common/functions_msgbox.js
+++ b/binaries/data/mods/mod/gui/common/functions_msgbox.js
@@ -15,6 +15,24 @@ function messageBox(mbWidth, mbHeight, mbMessage, mbTitle, mbButtonCaptions, mbB
 		});
 }
 
+function timedConfirmation(width, height, message, timeout, title, buttonCaptions, btnCode, callbackArgs)
+{
+	Engine.PushGuiPage(
+		"page_timedconfirmation.xml",
+		{
+			"width": width,
+			"height": height,
+			"message": message,
+			"timeout": timeout,
+			"title": title,
+			"buttonCaptions": buttonCaptions
+		},
+		button => {
+			if (btnCode !== undefined && btnCode[button])
+				btnCode[button](callbackArgs ? callbackArgs[button] : undefined);
+		});
+}
+
 function openURL(url)
 {
 	Engine.OpenURL(url);
diff --git a/binaries/data/mods/mod/gui/common/utilities.js b/binaries/data/mods/mod/gui/common/utilities.js
new file mode 100644
index 0000000000..127c42239a
--- /dev/null
+++ b/binaries/data/mods/mod/gui/common/utilities.js
@@ -0,0 +1,35 @@
+function distributeButtonsHorizontally(button, captions)
+{
+	const y1 = "100%-46";
+	const y2 = "100%-18";
+	switch (captions.length)
+	{
+	case 1:
+		button[0].size = "18 " + y1 + " 100%-18 " + y2;
+		break;
+	case 2:
+		button[0].size = "18 " + y1 + " 50%-5 " + y2;
+		button[1].size = "50%+5 " + y1 + " 100%-18 " + y2;
+		break;
+	case 3:
+		button[0].size = "18 " + y1 + " 33%-5 " + y2;
+		button[1].size = "33%+5 " + y1 + " 66%-5 " + y2;
+		button[2].size = "66%+5 " + y1 + " 100%-18 " + y2;
+		break;
+	}
+}
+
+function setButtonCaptionsAndVisibitily(button, captions, cancelHotkey, name)
+{
+	captions.forEach((caption, i) => {
+		button[i] = Engine.GetGUIObjectByName(name + (i + 1));
+		button[i].caption = caption;
+		button[i].hidden = false;
+		button[i].onPress = () => {
+			Engine.PopGuiPage(i);
+		};
+
+		if (i == 0)
+			cancelHotkey.onPress = button[i].onPress;
+	});
+}
diff --git a/binaries/data/mods/mod/gui/msgbox/msgbox.js b/binaries/data/mods/mod/gui/msgbox/msgbox.js
index 9276a482c6..a52e34e0de 100644
--- a/binaries/data/mods/mod/gui/msgbox/msgbox.js
+++ b/binaries/data/mods/mod/gui/msgbox/msgbox.js
@@ -24,37 +24,7 @@ function init(data)
 
 	let captions = data.buttonCaptions || [translate("OK")];
 
-	// Set button captions and visibility
 	let mbButton = [];
-	captions.forEach((caption, i) => {
-		mbButton[i] = Engine.GetGUIObjectByName("mbButton" + (i + 1));
-		mbButton[i].caption = caption;
-		mbButton[i].hidden = false;
-		mbButton[i].onPress = () => {
-			Engine.PopGuiPage(i);
-		};
-
-		// Convention: Cancel is the first button
-		if (i == 0)
-			mbCancelHotkey.onPress = mbButton[i].onPress;
-	});
-
-	// Distribute buttons horizontally
-	let y1 = "100%-46";
-	let y2 = "100%-18";
-	switch (captions.length)
-	{
-	case 1:
-		mbButton[0].size = "18 " + y1 + " 100%-18 " + y2;
-		break;
-	case 2:
-		mbButton[0].size = "18 " + y1 + " 50%-5 " + y2;
-		mbButton[1].size = "50%+5 " + y1 + " 100%-18 " + y2;
-		break;
-	case 3:
-		mbButton[0].size = "18 " + y1 + " 33%-5 " + y2;
-		mbButton[1].size = "33%+5 " + y1 + " 66%-5 " + y2;
-		mbButton[2].size = "66%+5 " + y1 + " 100%-18 " + y2;
-		break;
-	}
+	setButtonCaptionsAndVisibitily(mbButton, captions, mbCancelHotkey, "mbButton");
+	distributeButtonsHorizontally(mbButton, captions);
 }
diff --git a/binaries/data/mods/mod/gui/page_timedconfirmation.xml b/binaries/data/mods/mod/gui/page_timedconfirmation.xml
new file mode 100644
index 0000000000..f006c12219
--- /dev/null
+++ b/binaries/data/mods/mod/gui/page_timedconfirmation.xml
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="utf-8"?>
+<page>
+	<include>common/modern/setup.xml</include>
+	<include>common/modern/styles.xml</include>
+	<include>common/modern/sprites.xml</include>
+
+	<include>timedconfirmation/timedconfirmation.xml</include>
+</page>
diff --git a/binaries/data/mods/mod/gui/timedconfirmation/timedconfirmation.js b/binaries/data/mods/mod/gui/timedconfirmation/timedconfirmation.js
new file mode 100644
index 0000000000..6a8a1f7b11
--- /dev/null
+++ b/binaries/data/mods/mod/gui/timedconfirmation/timedconfirmation.js
@@ -0,0 +1,48 @@
+/**
+ * Currently limited to at most 3 buttons per message box.
+ * The convention is to have "cancel" appear first.
+ */
+function init(data)
+{
+	Engine.GetGUIObjectByName("tmcTitleBar").caption = data.title;
+
+	const textObj = Engine.GetGUIObjectByName("tmcText");
+	textObj.caption = data.message;
+
+	updateDisplayedTimer(data.timeout);
+
+	Engine.GetGUIObjectByName("tmcTimer").caption = data.timeout;
+	if (data.font)
+		textObj.font = data.font;
+
+	const cancelHotkey = Engine.GetGUIObjectByName("tmcCancelHotkey");
+	cancelHotkey.onPress = Engine.PopGuiPage;
+
+	const lRDiff = data.width / 2;
+	const uDDiff = data.height / 2;
+	Engine.GetGUIObjectByName("tmcMain").size = "50%-" + lRDiff + " 50%-" + uDDiff + " 50%+" + lRDiff + " 50%+" + uDDiff;
+
+	const captions = data.buttonCaptions || [translate("OK")];
+
+	// Set button captions and visibility
+	const button = [];
+	setButtonCaptionsAndVisibitily(button, captions, cancelHotkey, "tmcButton");
+	distributeButtonsHorizontally(button, captions);
+}
+
+function onTick()
+{
+	const timerObj = Engine.GetGUIObjectByName("tmcTimer");
+	let time = +timerObj.caption;
+	--time;
+	if (time < 1)
+		Engine.GetGUIObjectByName("tmcButton1").onPress();
+
+	timerObj.caption = time;
+	updateDisplayedTimer(time);
+}
+
+function updateDisplayedTimer(time)
+{
+	Engine.GetGUIObjectByName("tmcTimerDisplay").caption = Math.ceil(time / 100);
+}
diff --git a/binaries/data/mods/mod/gui/timedconfirmation/timedconfirmation.xml b/binaries/data/mods/mod/gui/timedconfirmation/timedconfirmation.xml
new file mode 100644
index 0000000000..ba7a9c9811
--- /dev/null
+++ b/binaries/data/mods/mod/gui/timedconfirmation/timedconfirmation.xml
@@ -0,0 +1,56 @@
+<?xml version="1.0" encoding="utf-8"?>
+
+<objects>
+
+	<script directory="gui/common/"/>
+	<script directory="gui/timedconfirmation/"/>
+
+	<!-- Fade out the background because it's non-interactable -->
+	<object sprite="ModernFade" type="image"/>
+	<object name="tmcCancelHotkey" hotkey="cancel" />
+	<object name="tmcMain"
+			style="ModernDialog"
+			type="image"
+	>
+		<action on="Tick">
+			onTick();
+		</action>
+	<object name="tmcTitleBar"
+			style="ModernLabelText"
+			type="text"
+			size="50%-128 -18 50%+128 14"
+	/>
+	<object name="tmcTimerDisplay"
+			type="text"
+			style="ModernLabelText"
+			size="18 28 100%-18 38"
+	/>
+	<object name="tmcText"
+			type="text"
+			style="ModernLabelText"
+			size="18 40 100%-18 100%-64"
+	/>
+	<object name="tmcTimer"
+			type="text"
+			style="ModernLabelText"
+			size="18 18 100%-18 100%-64"
+			hidden="true"
+	/>
+	<!-- The size of the following buttons is set dynamically in timedconfirmation.js -->
+	<object name="tmcButton1"
+			style="ModernButtonRed"
+			type="button"
+			hidden="true"
+	/>
+	<object name="tmcButton2"
+			style="ModernButtonRed"
+			type="button"
+			hidden="true"
+	/>
+	<object name="tmcButton3"
+			style="ModernButtonRed"
+			type="button"
+			hidden="true"
+	/>
+	</object>
+</objects>
diff --git a/binaries/data/mods/public/gui/options/options.js b/binaries/data/mods/public/gui/options/options.js
index 1ce4aa86a7..9cdaaa64e1 100644
--- a/binaries/data/mods/public/gui/options/options.js
+++ b/binaries/data/mods/public/gui/options/options.js
@@ -146,6 +146,35 @@ var g_OptionType = {
 			};
 		}
 	},
+	"dropdownNumber":
+	{
+		"configToValue": value => +value,
+		"valueToGui": (value, control) => {
+			control.selected = control.list_data.indexOf("" + value);
+		},
+		"guiToValue": control => +control.list_data[control.selected],
+		"guiSetter": "onSelectionChange",
+		"initGUI": (option, control) => {
+			control.list = option.list.map(e => e.label);
+			control.list_data = option.list.map(e => e.value);
+			control.onHoverChange = () => {
+				const item = option.list[control.hovered];
+				control.tooltip = item && item.tooltip || option.tooltip;
+			};
+		},
+		"timeout": (option, oldValue, hasChanges, newValue) => {
+			if (!option.timeout)
+				return;
+			timedConfirmation(
+				500, 200,
+				translate("Do you want to keep changes?"),
+				500,
+				translate("Warning"),
+				[translate("No"), translate("Yes")],
+				[() => {this.revertChange(option, +oldValue, hasChanges);}, null]
+			);
+		}
+	},
 	"slider":
 	{
 		"configToValue": value => +value,
@@ -242,14 +271,20 @@ function displayOptions()
 			if (optionType.sanitizeValue)
 				optionType.sanitizeValue(value, control, option);
 
+			const oldValue = optionType.configToValue(Engine.ConfigDB_GetValue("user", option.config));
+
 			control.tooltip = option.tooltip + (optionType.tooltip ? "\n" + optionType.tooltip(value, option) : "");
 
+			const hasChanges = Engine.ConfigDB_HasChanges("user");
 			Engine.ConfigDB_CreateValue("user", option.config, String(value));
 			Engine.ConfigDB_SetChanges("user", true);
 
 			g_ChangedKeys.add(option.config);
 			fireConfigChangeHandlers(new Set([option.config]));
 
+			if (option.timeout)
+				optionType.timeout(option, oldValue, hasChanges, value);
+
 			if (option.function)
 				Engine[option.function](value);
 
@@ -315,6 +350,18 @@ function reallySetDefaults()
 	revertChanges();
 }
 
+function revertChange(option, oldValue, hadChanges)
+{
+	if (!hadChanges)
+		Engine.ConfigDB_SetChanges("user", false);
+
+	Engine.ConfigDB_CreateValue("user", option.config, String(oldValue));
+	if (option.function)
+		Engine[option.function](oldValue);
+
+	displayOptions();
+}
+
 function revertChanges()
 {
 	Engine.ConfigDB_Reload("user");
diff --git a/binaries/data/mods/public/gui/options/options.json b/binaries/data/mods/public/gui/options/options.json
index 500952e0f3..08ecc285c7 100644
--- a/binaries/data/mods/public/gui/options/options.json
+++ b/binaries/data/mods/public/gui/options/options.json
@@ -150,6 +150,24 @@
 				"config": "adaptivefps.session",
 				"min": 20,
 				"max": 100
+			},
+			{
+				"type": "dropdownNumber",
+				"label": "GUI scale",
+				"timeout": 500,
+				"tooltip": "GUI scale",
+				"config": "gui.scale",
+				"function": "SetGUIScale",
+				"list": [
+					{ "value": 0.75, "label": "75%" },
+					{ "value": 1.00, "label": "100%" },
+					{ "value": 1.25, "label": "125%" },
+					{ "value": 1.50, "label": "150%" },
+					{ "value": 1.75, "label": "175%" },
+					{ "value": 2.00, "label": "200%" },
+					{ "value": 2.25, "label": "225%" },
+					{ "value": 2.50, "label": "250%" }
+				]
 			}
 		]
 	},
diff --git a/binaries/data/mods/public/gui/options/options.xml b/binaries/data/mods/public/gui/options/options.xml
index 5d30e227d8..a3e9c34bd1 100644
--- a/binaries/data/mods/public/gui/options/options.xml
+++ b/binaries/data/mods/public/gui/options/options.xml
@@ -33,6 +33,7 @@
 					</object>
 					<object name="option_control_number[n]" size="65% 0 100%-8 100%" type="input" style="ModernInput"/>
 					<object name="option_control_dropdown[n]" size="65% 0 100%-8 100%" type="dropdown" style="ModernDropDown" tooltip_style="tooltipInstant"/>
+					<object name="option_control_dropdownNumber[n]" size="65% 0 100%-8 100%" type="dropdown" style="ModernDropDown" tooltip_style="tooltipInstant"/>
 					<object name="option_control_slider[n]" size="65% 0 100%-8 100%" type="slider" style="ModernSlider"/>
 				</object>
 			</repeat>
diff --git a/source/gui/CGUI.cpp b/source/gui/CGUI.cpp
index 46a6402930..8a33e1e872 100644
--- a/source/gui/CGUI.cpp
+++ b/source/gui/CGUI.cpp
@@ -42,6 +42,7 @@
 #include "ps/Hotkey.h"
 #include "ps/Profile.h"
 #include "ps/Pyrogenesis.h"
+#include "ps/VideoMode.h"
 #include "ps/XML/Xeromyces.h"
 #include "scriptinterface/ScriptContext.h"
 #include "scriptinterface/ScriptInterface.h"
@@ -154,7 +155,7 @@ InReaction CGUI::HandleEvent(const SDL_Event_* ev)
 		// Yes the mouse position is stored as float to avoid
 		//  constant conversions when operating in a
 		//  float-based environment.
-		m_MousePos = CVector2D((float)ev->ev.motion.x / g_GuiScale, (float)ev->ev.motion.y / g_GuiScale);
+		m_MousePos = CVector2D((float)ev->ev.motion.x / g_VideoMode.GetScale(), (float)ev->ev.motion.y / g_VideoMode.GetScale());
 
 		SGUIMessage msg(GUIM_MOUSE_MOTION);
 		m_BaseObject->RecurseObject(&IGUIObject::IsHiddenOrGhost, &IGUIObject::HandleMessage, msg);
@@ -179,7 +180,7 @@ InReaction CGUI::HandleEvent(const SDL_Event_* ev)
 	CVector2D oldMousePos = m_MousePos;
 	if (ev->ev.type == SDL_MOUSEBUTTONDOWN || ev->ev.type == SDL_MOUSEBUTTONUP)
 	{
-		m_MousePos = CVector2D((float)ev->ev.button.x / g_GuiScale, (float)ev->ev.button.y / g_GuiScale);
+		m_MousePos = CVector2D((float)ev->ev.button.x / g_VideoMode.GetScale(), (float)ev->ev.button.y / g_VideoMode.GetScale());
 	}
 
 	// Allow the focused object to pre-empt regular GUI events.
@@ -420,7 +421,7 @@ IGUIObject* CGUI::FindObjectUnderMouse()
 
 CSize2D CGUI::GetWindowSize() const
 {
-	return CSize2D{static_cast<float>(g_xres) / g_GuiScale, static_cast<float>(g_yres) / g_GuiScale};
+	return CSize2D{static_cast<float>(g_xres) / g_VideoMode.GetScale(), static_cast<float>(g_yres) / g_VideoMode.GetScale() };
 }
 
 void CGUI::SetFocusedObject(IGUIObject* pObject)
diff --git a/source/gui/CGUIText.cpp b/source/gui/CGUIText.cpp
index 47d5804e94..be4cf0c1d3 100644
--- a/source/gui/CGUIText.cpp
+++ b/source/gui/CGUIText.cpp
@@ -26,12 +26,12 @@
 #include "gui/ObjectBases/IGUIObject.h"
 #include "gui/SettingTypes/CGUIString.h"
 #include "ps/CStrInternStatic.h"
+#include "ps/VideoMode.h"
 #include "renderer/Renderer.h"
 
 #include <math.h>
 
 extern int g_xres, g_yres;
-extern float g_GuiScale;
 
 // TODO Gee: CRect => CPoint ?
 void SGenerateTextImage::SetupSpriteCall(
@@ -439,12 +439,13 @@ void CGUIText::Draw(CGUI& pGUI, CCanvas2D& canvas, const CGUIColor& DefaultColor
 		clipping.left = std::ceil(clipping.left);
 		clipping.right = std::floor(clipping.right);
 
+		float scale = g_VideoMode.GetScale();
 		glEnable(GL_SCISSOR_TEST);
 		glScissor(
-			std::ceil(clipping.left * g_GuiScale),
-			std::ceil(g_yres - clipping.bottom * g_GuiScale),
-			std::floor(clipping.GetWidth() * g_GuiScale),
-			std::floor(clipping.GetHeight() * g_GuiScale));
+			std::ceil(clipping.left * scale),
+			std::ceil(g_yres - clipping.bottom * scale),
+			std::floor(clipping.GetWidth() * scale),
+			std::floor(clipping.GetHeight() * scale));
 	}
 
 	CTextRenderer textRenderer;
diff --git a/source/gui/GUIMatrix.cpp b/source/gui/GUIMatrix.cpp
index 0605cbed2c..d8cc7dc913 100644
--- a/source/gui/GUIMatrix.cpp
+++ b/source/gui/GUIMatrix.cpp
@@ -1,4 +1,4 @@
-/* Copyright (C) 2019 Wildfire Games.
+/* Copyright (C) 2021 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -18,16 +18,15 @@
 #include "precompiled.h"
 
 #include "GUIMatrix.h"
-
+#include "ps/VideoMode.h"
 #include "maths/Matrix3D.h"
 
 extern int g_xres, g_yres;
-extern float g_GuiScale;
 
 CMatrix3D GetDefaultGuiMatrix()
 {
-	float xres = g_xres / g_GuiScale;
-	float yres = g_yres / g_GuiScale;
+	float xres = g_xres / g_VideoMode.GetScale();
+	float yres = g_yres / g_VideoMode.GetScale();
 
 	CMatrix3D m;
 	m.SetIdentity();
diff --git a/source/gui/ObjectTypes/CInput.cpp b/source/gui/ObjectTypes/CInput.cpp
index 98debd6adc..0323a3a0a4 100644
--- a/source/gui/ObjectTypes/CInput.cpp
+++ b/source/gui/ObjectTypes/CInput.cpp
@@ -31,6 +31,7 @@
 #include "ps/GameSetup/Config.h"
 #include "ps/Globals.h"
 #include "ps/Hotkey.h"
+#include "ps/VideoMode.h"
 #include "renderer/Renderer.h"
 
 #include <sstream>
@@ -1238,12 +1239,13 @@ void CInput::Draw(CCanvas2D& canvas)
 
 	if (cliparea != CRect())
 	{
+		float scale = g_VideoMode.GetScale();
 		glEnable(GL_SCISSOR_TEST);
 		glScissor(
-			cliparea.left * g_GuiScale,
-			g_yres - cliparea.bottom * g_GuiScale,
-			cliparea.GetWidth() * g_GuiScale,
-			cliparea.GetHeight() * g_GuiScale);
+			cliparea.left * scale,
+			g_yres - cliparea.bottom * scale,
+			cliparea.GetWidth() * scale,
+			cliparea.GetHeight() * scale);
 	}
 
 	// These are useful later.
diff --git a/source/ps/CConsole.cpp b/source/ps/CConsole.cpp
index 1b2e763a69..2fbb8a4815 100644
--- a/source/ps/CConsole.cpp
+++ b/source/ps/CConsole.cpp
@@ -45,6 +45,7 @@
 #include "ps/Hotkey.h"
 #include "ps/Profile.h"
 #include "ps/Pyrogenesis.h"
+#include "ps/VideoMode.h"
 #include "scriptinterface/ScriptInterface.h"
 #include "scriptinterface/JSON.h"
 
@@ -116,8 +117,8 @@ void CConsole::UpdateScreenSize(int w, int h)
 	m_fX = 0;
 	m_fY = 0;
 	float height = h * 0.6f;
-	m_fWidth = w / g_GuiScale;
-	m_fHeight = height / g_GuiScale;
+	m_fWidth = w / g_VideoMode.GetScale();
+	m_fHeight = height / g_VideoMode.GetScale();
 }
 
 void CConsole::ToggleVisible()
diff --git a/source/ps/GameSetup/Config.cpp b/source/ps/GameSetup/Config.cpp
index f207ccccd3..1339b8ab0b 100644
--- a/source/ps/GameSetup/Config.cpp
+++ b/source/ps/GameSetup/Config.cpp
@@ -29,7 +29,6 @@
 bool g_PauseOnFocusLoss = false;
 
 int g_xres, g_yres;
-float g_GuiScale = 1.0f;
 
 bool g_Quickstart = false;
 bool g_DisableAudio = false;
@@ -42,11 +41,8 @@ bool g_DisableAudio = false;
 static void LoadGlobals()
 {
 	CFG_GET_VAL("pauseonfocusloss", g_PauseOnFocusLoss);
-
-	CFG_GET_VAL("gui.scale", g_GuiScale);
 }
 
-
 static void ProcessCommandLineArgs(const CmdLineArgs& args)
 {
 	// TODO: all these options (and the ones processed elsewhere) should
diff --git a/source/ps/GameSetup/Config.h b/source/ps/GameSetup/Config.h
index d3a758fa0a..9ad6e604ec 100644
--- a/source/ps/GameSetup/Config.h
+++ b/source/ps/GameSetup/Config.h
@@ -24,7 +24,6 @@
 extern bool g_PauseOnFocusLoss;
 
 extern int g_xres, g_yres;
-extern float g_GuiScale;
 
 extern bool g_Quickstart;
 extern bool g_DisableAudio;
diff --git a/source/ps/VideoMode.cpp b/source/ps/VideoMode.cpp
index 19b59e726a..2f5c448a05 100644
--- a/source/ps/VideoMode.cpp
+++ b/source/ps/VideoMode.cpp
@@ -178,7 +178,7 @@ void CVideoMode::CCursor::SetCursor(const CStrW& name)
 		LOGERROR("Can't create surface for cursor: %s", SDL_GetError());
 		return;
 	}
-	const float scale = g_GuiScale;
+	const float scale = g_VideoMode.GetScale();
 	if (scale != 1.0)
 	{
 		SDL_Surface* scaledSurface = SDL_CreateRGBSurface(0,
@@ -223,6 +223,8 @@ void CVideoMode::ReadConfig()
 	CFG_GET_VAL("windowed", windowed);
 	m_ConfigFullscreen = !windowed;
 
+	CFG_GET_VAL("gui.scale", m_Scale);
+
 	CFG_GET_VAL("xres", m_ConfigW);
 	CFG_GET_VAL("yres", m_ConfigH);
 	CFG_GET_VAL("bpp", m_ConfigBPP);
@@ -516,6 +518,18 @@ bool CVideoMode::ResizeWindow(int w, int h)
 	return true;
 }
 
+void CVideoMode::Rescale(float scale)
+{
+	ENSURE(m_IsInitialised);
+	m_Scale = scale;
+	UpdateRenderer(m_CurrentW, m_CurrentH);
+}
+
+float CVideoMode::GetScale() const
+{
+	return m_Scale;
+}
+
 bool CVideoMode::SetFullscreen(bool fullscreen)
 {
 	// This might get called before initialisation by psDisplayError;
diff --git a/source/ps/VideoMode.h b/source/ps/VideoMode.h
index f8f1b49167..b4e14cc61a 100644
--- a/source/ps/VideoMode.h
+++ b/source/ps/VideoMode.h
@@ -51,6 +51,11 @@ public:
 	 */
 	bool ResizeWindow(int w, int h);
 
+	/**
+	 * Set scale and tell dependent compoenent to recompute sizes.
+	 */
+	void Rescale(float scale);
+
 	/**
 	 * Switch to fullscreen or windowed mode.
 	 */
@@ -89,6 +94,8 @@ public:
 	int GetDesktopBPP() const;
 	int GetDesktopFreq() const;
 
+	float GetScale() const;
+
 	SDL_Window* GetWindow();
 
 	void SetWindowIcon();
@@ -117,6 +124,8 @@ private:
 	int m_PreferredBPP = 0;
 	int m_PreferredFreq = 0;
 
+	float m_Scale = 1.0f;
+
 	// Config file settings (0 if unspecified)
 	int m_ConfigW = 0;
 	int m_ConfigH = 0;
diff --git a/source/ps/scripting/JSInterface_ConfigDB.cpp b/source/ps/scripting/JSInterface_ConfigDB.cpp
index 34303829eb..c7d6d1562b 100644
--- a/source/ps/scripting/JSInterface_ConfigDB.cpp
+++ b/source/ps/scripting/JSInterface_ConfigDB.cpp
@@ -21,6 +21,7 @@
 
 #include "ps/ConfigDB.h"
 #include "ps/CLogger.h"
+#include "ps/VideoMode.h"
 #include "scriptinterface/FunctionWrapper.h"
 #include "scriptinterface/ScriptRequest.h"
 
@@ -193,6 +194,11 @@ void PauseOnFocusLoss(bool pause)
 	g_PauseOnFocusLoss = pause;
 }
 
+void SetGUIScale(float scale)
+{
+	g_VideoMode.Rescale(scale);
+}
+
 void RegisterScriptFunctions(const ScriptRequest& rq)
 {
 	ScriptFunction::Register<&HasChanges>(rq, "ConfigDB_HasChanges");
@@ -207,5 +213,6 @@ void RegisterScriptFunctions(const ScriptRequest& rq)
 	ScriptFunction::Register<&SetFile>(rq, "ConfigDB_SetFile");
 	ScriptFunction::Register<&Reload>(rq, "ConfigDB_Reload");
 	ScriptFunction::Register<&PauseOnFocusLoss>(rq, "PauseOnFocusLoss");
+	ScriptFunction::Register<&SetGUIScale>(rq, "SetGUIScale");
 }
 }