Merge #4267

4267: Add DoTooltip r=def- a=edg-l

Related to #4212

Example rendering a label:

![image](https://user-images.githubusercontent.com/15859336/139472955-65c00603-9f37-484a-9552-adde9ef99822.png)

![image](https://user-images.githubusercontent.com/15859336/139472972-b1fc2fe7-a84e-4eb5-aaa7-8e9522ec6b8a.png)


## Checklist

- [x] Tested the change ingame
- [ ] Provided screenshots if it is a visual change
- [ ] Tested in combination with possibly related configuration options
- [ ] Written a unit test if it works standalone, system.c especially
- [ ] Considered possible null pointers and out of bounds array indexing
- [ ] Changed no physics that affect existing maps
- [ ] Tested the change with [ASan+UBSan or valgrind's memcheck](https://github.com/ddnet/ddnet/#using-addresssanitizer--undefinedbehavioursanitizer-or-valgrinds-memcheck) (optional)


Co-authored-by: Edgar Luque <git@edgarluque.com>

src/game/client/components/menus.cpp

@@ -2833,3 +2833,63 @@ bool CMenus::HandleListInputs(const CUIRect &View, float &ScrollValue, const flo
 
 	return NewIndex != -1;
 }
+
+void CMenus::DoToolTip(const void *pID, const CUIRect *pNearRect, const char *pText, float WidthHint)
+{
+	static int64_t HoverTime = -1;
+
+	if(!UI()->MouseInside(pNearRect))
+	{
+		if(pID == UI()->ActiveTooltipItem())
+			HoverTime = -1;
+		return;
+	}
+
+	UI()->SetActiveTooltipItem(pID);
+
+	if(HoverTime == -1)
+		HoverTime = time_get();
+
+	// Delay tooltip until 1 second passed.
+	if(HoverTime > time_get() - time_freq())
+		return;
+
+	const float MARGIN = 5.0f;
+
+	CUIRect Rect;
+	Rect.w = WidthHint;
+	if(WidthHint < 0.0f)
+		Rect.w = TextRender()->TextWidth(0, 14.0f, pText, -1, -1.0f) + 4.0f;
+	Rect.h = 30.0f;
+
+	CUIRect *pScreen = UI()->Screen();
+
+	// Try the top side.
+	if(pNearRect->y - Rect.h - MARGIN > pScreen->y)
+	{
+		Rect.x = clamp(UI()->MouseX() - Rect.w / 2.0f, MARGIN, pScreen->w - Rect.w - MARGIN);
+		Rect.y = pNearRect->y - Rect.h - MARGIN;
+	}
+	// Try the bottom side.
+	else if(pNearRect->y + pNearRect->h + MARGIN < pScreen->h)
+	{
+		Rect.x = clamp(UI()->MouseX() - Rect.w / 2.0f, MARGIN, pScreen->w - Rect.w - MARGIN);
+		Rect.y = pNearRect->y + pNearRect->h + MARGIN;
+	}
+	// Try the right side.
+	else if(pNearRect->x + pNearRect->w + MARGIN + Rect.w < pScreen->w)
+	{
+		Rect.x = pNearRect->x + pNearRect->w + MARGIN;
+		Rect.y = clamp(UI()->MouseY() - Rect.h / 2.0f, MARGIN, pScreen->h - Rect.h - MARGIN);
+	}
+	// Try the left side.
+	else if(pNearRect->x - Rect.w - MARGIN > pScreen->x)
+	{
+		Rect.x = pNearRect->x - Rect.w - MARGIN;
+		Rect.y = clamp(UI()->MouseY() - Rect.h / 2.0f, MARGIN, pScreen->h - Rect.h - MARGIN);
+	}
+
+	RenderTools()->DrawUIRect(&Rect, ColorRGBA(0.2, 0.2, 0.2, 0.80f), CUI::CORNER_ALL, 5.0f);
+	Rect.Margin(2.0f, &Rect);
+	UI()->DoLabel(&Rect, pText, 14.0f, TEXTALIGN_LEFT);
+}

src/game/client/components/menus.h

@@ -205,6 +205,15 @@ class CMenus : public CComponent
 
 	int UiLogicGetCurrentClickedItem();
 
+	/**
+	 * Places and renders a tooltip near pNearRect.
+	 * For now only works correctly with single line tooltips, since Text width calculation gets broken when there are multiple lines.
+	 *
+	 * @param pID The ID of the tooltip. Usually a reference to some g_Config value.
+	 * @param pNearTo Place the tooltip near this rect.
+	 * @param pText The text to display in the tooltip
+	 */
+	void DoToolTip(const void *pID, const CUIRect *pNearRect, const char *pText, float WidthHint = -1.0f);
 	// menus_settings_assets.cpp
 public:
 	struct SCustomItem

src/game/client/components/menus_settings.cpp

@@ -530,6 +530,7 @@ void CMenus::RenderSettingsTee(CUIRect MainView)
 	{
 		m_Dummy ^= 1;
 	}
+	DoToolTip(&m_Dummy, &DummyLabel, Localize("Toggle to edit your dummy settings."));
 
 	Dummy.HSplitTop(20.0f, &DummyLabel, &Dummy);
 
@@ -1264,6 +1265,7 @@ void CMenus::RenderSettingsGraphics(CUIRect MainView)
 	MainView.HSplitTop(20.0f, &Button, &MainView);
 	if(DoButton_CheckBox(&g_Config.m_GfxHighDetail, Localize("High Detail"), g_Config.m_GfxHighDetail, &Button))
 		g_Config.m_GfxHighDetail ^= 1;
+	DoToolTip(&g_Config.m_GfxHighDetail, &Button, Localize("Allows maps to render with more detail."));
 
 	MainView.HSplitTop(20.0f, &Button, &MainView);
 	if(DoButton_CheckBox(&g_Config.m_GfxHighdpi, Localize("Use high DPI"), g_Config.m_GfxHighdpi, &Button))

src/game/client/ui.cpp

@@ -57,6 +57,7 @@ CUI::CUI()
 	m_pActiveItem = 0;
 	m_pLastActiveItem = 0;
 	m_pBecomingHotItem = 0;
+	m_pActiveTooltipItem = 0;
 
 	m_MouseX = 0;
 	m_MouseY = 0;

src/game/client/ui.h

@@ -194,6 +194,7 @@ class CUI
 	const void *m_pActiveItem;
 	const void *m_pLastActiveItem;
 	const void *m_pBecomingHotItem;
+	const void *m_pActiveTooltipItem;
 	float m_MouseX, m_MouseY; // in gui space
 	float m_MouseDeltaX, m_MouseDeltaY; // in gui space
 	float m_MouseWorldX, m_MouseWorldY; // in world space
@@ -261,10 +262,12 @@ public:
 		if(pID)
 			m_pLastActiveItem = pID;
 	}
+	void SetActiveTooltipItem(const void *pID) { m_pActiveTooltipItem = pID; }
 	void ClearLastActiveItem() { m_pLastActiveItem = 0; }
 	const void *HotItem() const { return m_pHotItem; }
 	const void *NextHotItem() const { return m_pBecomingHotItem; }
 	const void *ActiveItem() const { return m_pActiveItem; }
+	const void *ActiveTooltipItem() const { return m_pActiveTooltipItem; }
 	const void *LastActiveItem() const { return m_pLastActiveItem; }
 
 	bool MouseInside(const CUIRect *pRect) const;