Add 9-slice background support to button formspec elements (#9290)

doc/lua_api.txt

@@ -2573,6 +2573,8 @@ Some types may inherit styles from parent types.
     * bgcolor_pressed - color when pressed. Defaults to a darker bgcolor when not provided.
     * bgimg - standard background image. Defaults to none.
     * bgimg_hovered - background image when hovered. Defaults to bgimg when not provided.
+    * bgimg_middle - Makes the bgimg textures render in 9-sliced mode and defines the middle rect.
+                     See background9[] documentation for more details
     * bgimg_pressed - background image when pressed. Defaults to bgimg when not provided.
     * border - boolean, draw border. Set to false to hide the bevelled button pane. Default true.
     * noclip - boolean, set to true to allow the element to exceed formspec bounds.

games/minimal/mods/test/formspec.lua

@@ -78,6 +78,9 @@ local style_fs = [[
 	style[one_btn15;border=false;bgimg=test_bg.png;bgimg_hovered=test_bg_hovered.png;bgimg_pressed=test_bg_pressed.png]
 	item_image_button[1.25,9.6;1,1;default:sword_steel;one_btn15;Bg]
 
+	style[one_btn16;border=false;bgimg=test_bg_9slice.png;bgimg_hovered=test_bg_9slice_hovered.png;bgimg_pressed=test_bg_9slice_pressed.png;bgimg_middle=4,6]
+	button[2.5,9.6;2,1;one_btn16;9-Slice Bg]
+
 
 
 	container[2.75,0]

src/gui/StyleSpec.h

@@ -37,6 +37,7 @@ public:
 		BORDER,
 		BGIMG,
 		BGIMG_HOVERED,
+		BGIMG_MIDDLE,
 		BGIMG_PRESSED,
 		FGIMG,
 		FGIMG_HOVERED,
@@ -69,6 +70,8 @@ public:
 			return BGIMG;
 		} else if (name == "bgimg_hovered") {
 			return BGIMG_HOVERED;
+		} else if (name == "bgimg_middle") {
+			return BGIMG_MIDDLE;
 		} else if (name == "bgimg_pressed") {
 			return BGIMG_PRESSED;
 		} else if (name == "fgimg") {
@@ -117,6 +120,29 @@ public:
 		return color;
 	}
 
+	irr::core::rect<s32> getRect(Property prop, irr::core::rect<s32> def) const
+	{
+		const auto &val = properties[prop];
+		if (val.empty())
+			return def;
+
+		irr::core::rect<s32> rect;
+		if (!parseRect(val, &rect))
+			return def;
+
+		return rect;
+	}
+
+	irr::core::rect<s32> getRect(Property prop) const
+	{
+		const auto &val = properties[prop];
+		FATAL_ERROR_IF(val.empty(), "Unexpected missing property");
+
+		irr::core::rect<s32> rect;
+		parseRect(val, &rect);
+		return rect;
+	}
+
 	video::ITexture *getTexture(Property prop, ISimpleTextureSource *tsrc,
 			video::ITexture *def) const
 	{
@@ -175,4 +201,36 @@ public:
 		newspec |= other;
 		return newspec;
 	}
+
+private:
+	bool parseRect(const std::string &value, irr::core::rect<s32> *parsed_rect) const
+	{
+		irr::core::rect<s32> rect;
+		std::vector<std::string> v_rect = split(value, ',');
+
+		if (v_rect.size() == 1) {
+			s32 x = stoi(v_rect[0]);
+			rect.UpperLeftCorner = irr::core::vector2di(x, x);
+			rect.LowerRightCorner = irr::core::vector2di(-x, -x);
+		} else if (v_rect.size() == 2) {
+			s32 x = stoi(v_rect[0]);
+			s32 y =	stoi(v_rect[1]);
+			rect.UpperLeftCorner = irr::core::vector2di(x, y);
+			rect.LowerRightCorner = irr::core::vector2di(-x, -y);
+			// `-x` is interpreted as `w - x`
+		} else if (v_rect.size() == 4) {
+			rect.UpperLeftCorner = irr::core::vector2di(
+					stoi(v_rect[0]), stoi(v_rect[1]));
+			rect.LowerRightCorner = irr::core::vector2di(
+					stoi(v_rect[2]), stoi(v_rect[3]));
+		} else {
+			warningstream << "Invalid rectangle string format: \"" << value
+					<< "\"" << std::endl;
+			return false;
+		}
+
+		*parsed_rect = rect;
+
+		return true;
+	}
 };

src/gui/guiButton.cpp

@@ -307,10 +307,25 @@ void GUIButton::draw()
 			}
 		}
 
-		driver->draw2DImage(ButtonImages[(u32)imageState].Texture,
-				ScaleImage? AbsoluteRect : core::rect<s32>(pos, sourceRect.getSize()),
-				sourceRect, &AbsoluteClippingRect,
-				0, UseAlphaChannel);
+		// PATCH
+		video::ITexture* texture = ButtonImages[(u32)imageState].Texture;
+		if (BgMiddle.getArea() == 0) {
+			driver->draw2DImage(texture,
+					ScaleImage? AbsoluteRect : core::rect<s32>(pos, sourceRect.getSize()),
+					sourceRect, &AbsoluteClippingRect,
+					0, UseAlphaChannel);
+		} else {
+			core::rect<s32> middle = BgMiddle;
+			// `-x` is interpreted as `w - x`
+			if (middle.LowerRightCorner.X < 0)
+				middle.LowerRightCorner.X += texture->getOriginalSize().Width;
+			if (middle.LowerRightCorner.Y < 0)
+				middle.LowerRightCorner.Y += texture->getOriginalSize().Height;
+			draw2DImage9Slice(driver, texture,
+					ScaleImage ? AbsoluteRect : core::rect<s32>(pos, sourceRect.getSize()),
+					middle, &AbsoluteClippingRect);
+		}
+		// END PATCH
 	}
 
 	if (SpriteBank)
@@ -804,5 +819,6 @@ void GUIButton::setFromStyle(const StyleSpec& style, ISimpleTextureSource *tsrc)
 					Environment->getVideoDriver(), pressed_texture, geom.X, geom.Y));
 		setScaleImage(true);
 	}
+	BgMiddle = style.getRect(StyleSpec::BGIMG_MIDDLE, BgMiddle);
 }
 // END PATCH

src/gui/guiButton.h

@@ -330,5 +330,7 @@ private:
 	video::SColor PressedColors[4];
 
 	gui::IGUIStaticText *StaticText;
+
+	core::rect<s32> BgMiddle;
 	// END PATCH
 };

util/travis/clang-format-whitelist.txt

@@ -196,6 +196,7 @@ src/gui/mainmenumanager.h
 src/gui/modalMenu.h
 src/guiscalingfilter.cpp
 src/guiscalingfilter.h
+src/gui/StyleSpec.h
 src/gui/touchscreengui.cpp
 src/httpfetch.cpp
 src/hud.cpp