Add helpers for creating/using Rectangles in UI contexts (#4734)

* Add MakeRectangle helper to convert from SDL_Rect

* Add Rectangle::inset method for shrinking a rectangle

Turns out some of the other use cases I though this could apply to were actually doing something based on a fixed region

* Simplify initialisation of settings menu rects

Source/DiabloUI/button.cpp

@@ -18,7 +18,7 @@ void RenderButton(UiButton *button)
 	const Surface &out = Surface(DiabloUiSurface());
 	RenderPcxSprite(out, ButtonSprite(button->IsPressed()), { button->m_rect.x, button->m_rect.y });
 
-	Rectangle textRect { { button->m_rect.x, button->m_rect.y }, { button->m_rect.w, button->m_rect.h } };
+	Rectangle textRect = MakeRectangle(button->m_rect);
 	if (!button->IsPressed()) {
 		--textRect.position.y;
 	}

Source/DiabloUI/diabloui.cpp

@@ -802,18 +802,14 @@ namespace {
 
 void Render(const UiText *uiText)
 {
-	Rectangle rect { { uiText->m_rect.x, uiText->m_rect.y }, { uiText->m_rect.w, uiText->m_rect.h } };
-
 	const Surface &out = Surface(DiabloUiSurface());
-	DrawString(out, uiText->GetText(), rect, uiText->GetFlags() | UiFlags::FontSizeDialog);
+	DrawString(out, uiText->GetText(), MakeRectangle(uiText->m_rect), uiText->GetFlags() | UiFlags::FontSizeDialog);
 }
 
 void Render(const UiArtText *uiArtText)
 {
-	Rectangle rect { { uiArtText->m_rect.x, uiArtText->m_rect.y }, { uiArtText->m_rect.w, uiArtText->m_rect.h } };
-
 	const Surface &out = Surface(DiabloUiSurface());
-	DrawString(out, uiArtText->GetText(), rect, uiArtText->GetFlags(), uiArtText->GetSpacing(), uiArtText->GetLineHeight());
+	DrawString(out, uiArtText->GetText(), MakeRectangle(uiArtText->m_rect), uiArtText->GetFlags(), uiArtText->GetSpacing(), uiArtText->GetLineHeight());
 }
 
 void Render(const UiImage *uiImage)
@@ -865,10 +861,8 @@ void Render(const UiImageAnimatedPcx *uiImage)
 
 void Render(const UiArtTextButton *uiButton)
 {
-	Rectangle rect { { uiButton->m_rect.x, uiButton->m_rect.y }, { uiButton->m_rect.w, uiButton->m_rect.h } };
-
 	const Surface &out = Surface(DiabloUiSurface());
-	DrawString(out, uiButton->GetText(), rect, uiButton->GetFlags());
+	DrawString(out, uiButton->GetText(), MakeRectangle(uiButton->m_rect), uiButton->GetFlags());
 }
 
 void Render(const UiList *uiList)
@@ -881,7 +875,7 @@ void Render(const UiList *uiList)
 		if (i == SelectedItem)
 			DrawSelector(rect);
 
-		Rectangle rectangle { { rect.x, rect.y }, { rect.w, rect.h } };
+		Rectangle rectangle = MakeRectangle(rect);
 		if (item->args.empty())
 			DrawString(out, item->m_text, rectangle, uiList->GetFlags() | item->uiFlags, uiList->GetSpacing());
 		else
@@ -928,7 +922,8 @@ void Render(const UiEdit *uiEdit)
 {
 	DrawSelector(uiEdit->m_rect);
 
-	Rectangle rect { { uiEdit->m_rect.x + 43, uiEdit->m_rect.y + 1 }, { uiEdit->m_rect.w - 86, uiEdit->m_rect.h } };
+	// To simulate padding we inset the region used to draw text in an edit control
+	Rectangle rect = MakeRectangle(uiEdit->m_rect).inset({ 43, 1 });
 
 	const Surface &out = Surface(DiabloUiSurface());
 	DrawString(out, uiEdit->m_value, rect, uiEdit->GetFlags() | UiFlags::TextCursor);

Source/DiabloUI/settingsmenu.cpp

@@ -254,8 +254,8 @@ void UiSettingsMenu()
 
 		const Rectangle &uiRectangle = GetUIRectangle();
 
-		rectList = { { uiRectangle.position.x + 50, (uiRectangle.position.y + 204) }, { 540, 208 } };
-		rectDescription = { { uiRectangle.position.x + 24, rectList.position.y + rectList.size.height + 16 }, { 590, 35 } };
+		rectList = { uiRectangle.position + Displacement { 50, 204 }, Size { 540, 208 } };
+		rectDescription = { rectList.position + Displacement { -26, rectList.size.height + 16 }, Size { 590, 35 } };
 
 		optionDescription[0] = '\0';
 

Source/engine/rectangle.hpp

@@ -46,6 +46,19 @@ struct Rectangle {
 	{
 		return position + Displacement(size / 2);
 	}
+
+	/**
+	 * @brief Returns a rectangle with all sides shrunk according to the given displacement
+	 *
+	 * Effectively moves the left/right edges in by deltaX, and the top/bottom edges in by deltaY
+	 */
+	constexpr Rectangle inset(Displacement factor) const
+	{
+		return {
+			position + factor,
+			Size { size.width - factor.deltaX * 2, size.height - factor.deltaY * 2 }
+		};
+	}
 };
 
 } // namespace devilution

Source/panels/spell_book.cpp

@@ -38,16 +38,15 @@ spell_id SpellPages[6][7] = {
 	{ SPL_INVALID, SPL_INVALID, SPL_INVALID, SPL_INVALID, SPL_INVALID, SPL_INVALID, SPL_INVALID }
 };
 
-constexpr int SpellBookDescriptionWidth = 250;
-constexpr int SpellBookDescriptionHeight = 43;
-constexpr int SpellBookDescriptionPaddingLeft = 2;
-constexpr int SpellBookDescriptionPaddingRight = 2;
+constexpr Size SpellBookDescription { 250, 43 };
+constexpr int SpellBookDescriptionPaddingHorizontal = 2;
 
 void PrintSBookStr(const Surface &out, Point position, string_view text, UiFlags flags = UiFlags::None)
 {
 	DrawString(out, text,
-	    { GetPanelPosition(UiPanels::Spell, { SPLICONLENGTH + SpellBookDescriptionPaddingLeft + position.x, position.y }),
-	        { SpellBookDescriptionWidth - SpellBookDescriptionPaddingLeft - SpellBookDescriptionPaddingRight, 0 } },
+	    Rectangle(GetPanelPosition(UiPanels::Spell, position + Displacement { SPLICONLENGTH, 0 }),
+	        SpellBookDescription)
+	        .inset({ SpellBookDescriptionPaddingHorizontal, 0 }),
 	    UiFlags::ColorWhite | flags);
 }
 
@@ -140,7 +139,7 @@ void DrawSpellBook(const Surface &out)
 		if (sn != SPL_INVALID && (spl & GetSpellBitmask(sn)) != 0) {
 			spell_type st = GetSBookTrans(sn, true);
 			SetSpellTrans(st);
-			const Point spellCellPosition = GetPanelPosition(UiPanels::Spell, { 11, yp + SpellBookDescriptionHeight });
+			const Point spellCellPosition = GetPanelPosition(UiPanels::Spell, { 11, yp + SpellBookDescription.height });
 			DrawSpellCel(out, spellCellPosition, *pSBkIconCels, SpellITbl[sn]);
 			if (sn == player._pRSpell && st == player._pRSplType) {
 				SetSpellTrans(RSPLTYPE_SKILL);
@@ -184,16 +183,19 @@ void DrawSpellBook(const Surface &out)
 			} break;
 			}
 		}
-		yp += SpellBookDescriptionHeight;
+		yp += SpellBookDescription.height;
 	}
 }
 
 void CheckSBook()
 {
-	Rectangle iconArea = { GetPanelPosition(UiPanels::Spell, { 11, 18 }), { 48 - 11, 314 - 18 } };
-	Rectangle tabArea = { GetPanelPosition(UiPanels::Spell, { 7, 320 }), { 311 - 7, 349 - 320 } };
+	// Icons are drawn in a column near the left side of the panel and aligned with the spell book description entries
+	// Spell icons/buttons are 37x38 pixels, laid out from 11,18 with a 5 pixel margin between each icon. This is close
+	// enough to the height of the space given to spell descriptions that we can reuse that value and subtract the
+	// padding from the end of the area.
+	Rectangle iconArea = { GetPanelPosition(UiPanels::Spell, { 11, 18 }), Size { 37, SpellBookDescription.height * 7 - 5 } };
 	if (iconArea.Contains(MousePosition)) {
-		spell_id sn = SpellPages[sbooktab][(MousePosition.y - GetRightPanel().position.y - 18) / 43];
+		spell_id sn = SpellPages[sbooktab][(MousePosition.y - iconArea.position.y) / SpellBookDescription.height];
 		Player &player = *MyPlayer;
 		uint64_t spl = player._pMemSpells | player._pISpells | player._pAblSpells;
 		if (sn != SPL_INVALID && (spl & GetSpellBitmask(sn)) != 0) {
@@ -208,9 +210,23 @@ void CheckSBook()
 			player._pRSplType = st;
 			force_redraw = 255;
 		}
+		return;
 	}
+
+	// The width of the panel excluding the border is 305 pixels. This does not cleanly divide by 4 meaning Diablo tabs
+	// end up with an extra pixel somewhere around the buttons. Vanilla Diablo had the buttons left-aligned, devilutionX
+	// instead justifies the buttons and puts the gap between buttons 2/3. See DrawSpellBook
+	const int TabWidth = gbIsHellfire ? 61 : 76;
+	// Tabs are drawn in a row near the bottom of the panel
+	Rectangle tabArea = { GetPanelPosition(UiPanels::Spell, { 7, 320 }), Size { 305, 29 } };
 	if (tabArea.Contains(MousePosition)) {
-		sbooktab = (MousePosition.x - (GetRightPanel().position.x + 7)) / (gbIsHellfire ? 61 : 76);
+		int hitColumn = MousePosition.x - tabArea.position.x;
+		// Clicking on the gutter currently activates tab 3. Could make it do nothing by checking for == here and return early.
+		if (!gbIsHellfire && hitColumn > TabWidth * 2) {
+			// Subtract 1 pixel to account for the gutter between buttons 2/3
+			hitColumn--;
+		}
+		sbooktab = hitColumn / TabWidth;
 	}
 }
 

Source/utils/sdl_geometry.h

@@ -31,4 +31,8 @@ inline SDL_Rect MakeSdlRect(Rectangle rect)
 	return MakeSdlRect(rect.position.x, rect.position.y, rect.size.width, rect.size.height);
 }
 
+constexpr Rectangle MakeRectangle(SDL_Rect sdlRect)
+{
+	return { Point { sdlRect.x, sdlRect.y }, Size { sdlRect.w, sdlRect.h } };
+}
 } // namespace devilution