Continuation of 5788: proper alpha blending

Available in files highlighting and editor selection colour

far/changelog

@@ -1,3 +1,9 @@
+--------------------------------------------------------------------------------
+drkns 19.05.2021 00:00:00 +0100 - build 5800
+
+1. Continuation of 5788: proper alpha blending.
+   Available in files highlighting and editor selection colour.
+
 --------------------------------------------------------------------------------
 drkns 16.05.2021 15:31:41 +0100 - build 5799
 

far/colormix.cpp

@@ -57,6 +57,16 @@ enum
 	ConsoleFgShift=0,
 };
 
+static auto to_rgba(COLORREF const Color)
+{
+	return *reinterpret_cast<rgba const*>(&Color);
+}
+
+static auto to_color(rgba const Rgba)
+{
+	return *reinterpret_cast<COLORREF const*>(&Rgba);
+}
+
 namespace colors
 {
 	COLORREF index_value(COLORREF const Colour)
@@ -119,13 +129,47 @@ namespace colors
 		const auto merge_part = [&](COLORREF FarColor::*ColorAccessor, const FARCOLORFLAGS Flag)
 		{
 			const auto TopValue = std::invoke(ColorAccessor, Top);
+
+			// Nothing to apply
 			if (is_transparent(TopValue))
 				return;
 
-			// TODO: proper alpha blending?
-			std::invoke(ColorAccessor, Result) = TopValue;
+			auto& ResultValue = std::invoke(ColorAccessor, Result);
+
+			// Simple case
+			if (is_opaque(TopValue))
+			{
+				ResultValue = TopValue;
+				flags::copy(Result.Flags, Flag, Top.Flags);
+				return;
+			}
 
-			flags::copy(Result.Flags, Flag, Top.Flags);
+			// Alpha blending
+			const auto BottomValue = std::invoke(ColorAccessor, Bottom);
+
+			const auto to_rgba = [](COLORREF const Color, bool const Is4Bit)
+			{
+				return ::to_rgba(Is4Bit ? ConsoleIndexToTrueColor(Color) : Color);
+			};
+
+			const auto TopRGBA = to_rgba(TopValue, (Top.Flags & Flag) != 0);
+			const auto BottomRGBA = to_rgba(BottomValue, (Bottom.Flags & Flag) != 0);
+
+			const auto calc_channel = [&](unsigned char rgba::*Accessor)
+			{
+				return static_cast<unsigned char>((std::invoke(Accessor, TopRGBA) * TopRGBA.a + (0xFF - TopRGBA.a) * std::invoke(Accessor, BottomRGBA)) / 0xFF);
+			};
+
+			rgba const MergedRGBA
+			{
+				calc_channel(&rgba::r),
+				calc_channel(&rgba::g),
+				calc_channel(&rgba::b),
+				static_cast<unsigned char>(BottomRGBA.a | ((0xFF - BottomRGBA.a) * TopRGBA.a / 0xFF))
+			};
+
+			ResultValue = to_color(MergedRGBA);
+			flags::clear(Result.Flags, Flag);
 		};
 
 		merge_part(&FarColor::BackgroundColor, FCF_BG_4BIT);
@@ -174,23 +218,17 @@ namespace colors
 		if (const auto Iterator = Map.find(Color); Iterator != Map.cend())
 			return Iterator->second;
 
-		union color_point
-		{
-			const COLORREF Color;
-			const rgba RGBA;
-		};
-
-		color_point const Point{ Color };
+		const auto PointRGBA = to_rgba(Color);
 
 		const auto distance = [&](COLORREF const PaletteColor)
 		{
-			color_point const PalettePoint{ PaletteColor };
+			const auto PaletteRGBA = to_rgba(PaletteColor);
 
 			const auto distance_part = [&](unsigned char rgba::* const Getter)
 			{
 				return std::abs(
-					int{ std::invoke(Getter, Point.RGBA) } -
-					int{ std::invoke(Getter, PalettePoint.RGBA) }
+					int{ std::invoke(Getter, PointRGBA) } -
+					int{ std::invoke(Getter, PaletteRGBA) }
 				);
 			};
 
@@ -292,9 +330,9 @@ FarColor ConsoleColorToFarColor(WORD Color)
 	};
 }
 
-COLORREF ConsoleIndexToTrueColor(size_t Index)
+COLORREF ConsoleIndexToTrueColor(COLORREF const Color)
 {
-	return opaque(console_palette()[Index & ConsoleMask]);
+	return alpha_value(Color) | console_palette()[Color & ConsoleMask];
 }
 
 const FarColor& PaletteColorToFarColor(PaletteColors ColorIndex)
@@ -402,6 +440,28 @@ TEST_CASE("colors.COLORREF")
 	}
 }
 
+TEST_CASE("colors.merge")
+{
+	static const struct
+	{
+		FarColor Bottom, Top, Merged;
+	}
+	Tests[]
+	{
+		{ { 0, {0x00000000}, {0x00000000} }, { 0, {0x00000000}, {0x00000000} }, { 0, {0x00000000}, {0x00000000} } },
+		{ { 0, {0xFF123456}, {0xFF654321} }, { 0, {0xFFABCDEF}, {0xFFFEDCBA} }, { 0, {0xFFABCDEF}, {0xFFFEDCBA} } },
+		{ { 0, {0x80000000}, {0xFF000000} }, { 0, {0x80000000}, {0x01000000} }, { 0, {0xBF000000}, {0xFF000000} } },
+		{ { 0, {0xFFFFFFFF}, {0xFF000000} }, { 0, {0x80000000}, {0x80FFFFFF} }, { 0, {0xFF7F7F7F}, {0xFF808080} } },
+		{ { 0, {0xFF00D5FF}, {0xFFBB5B00} }, { 0, {0x800000FF}, {0x80000000} }, { 0, {0xFF006AFF}, {0xFF5D2D00} } },
+	};
+
+	for (const auto& i: Tests)
+	{
+		const auto Color = colors::merge(i.Bottom, i.Top);
+		REQUIRE(Color == i.Merged);
+	}
+}
+
 TEST_CASE("colors.parser")
 {
 	static const struct

far/colormix.hpp

@@ -67,7 +67,7 @@ namespace colors
 	FarColor merge(const FarColor& Bottom, const FarColor& Top);
 	WORD FarColorToConsoleColor(const FarColor& Color);
 	FarColor ConsoleColorToFarColor(WORD Color);
-	COLORREF ConsoleIndexToTrueColor(size_t Index);
+	COLORREF ConsoleIndexToTrueColor(COLORREF Color);
 	const FarColor& PaletteColorToFarColor(PaletteColors ColorIndex);
 	const FarColor* StoreColor(const FarColor& Value);
 	COLORREF ARGB2ABGR(int Color);

far/dialog.cpp

@@ -1988,8 +1988,8 @@ void Dialog::ShowDialog(size_t ID)
 					int startx = m_Where.left + CX1 + (Item.Flags&DIF_NOBRACKETS? 0 : 2);
 					Global->ScrBuf->ApplyColor(
 						{ startx, m_Where.top + CY1, startx + 1, m_Where.top + CY1 },
-						colors::ConsoleColorToFarColor(B_YELLOW | F_LIGHTBLUE),
-						ScreenBuf::apply_mode::all);
+						colors::ConsoleColorToFarColor(B_YELLOW | F_LIGHTBLUE)
+					);
 				}
 				break;
 			}

far/edit.cpp

@@ -345,7 +345,7 @@ void Edit::FastShow(const ShowInfo* Info)
 	{
 		if (m_Flags.Check(FEDITLINE_CLEARFLAG))
 		{
-			Global->ScrBuf->ApplyColor(m_Where, GetUnchangedColor(), ScreenBuf::apply_mode::all);
+			Global->ScrBuf->ApplyColor(m_Where, GetUnchangedColor());
 		}
 	}
 	else
@@ -358,7 +358,7 @@ void Edit::FastShow(const ShowInfo* Info)
 
 		if (m_Flags.Check(FEDITLINE_DROPDOWNBOX))
 		{
-			Global->ScrBuf->ApplyColor(m_Where, GetSelectedColor(), ScreenBuf::apply_mode::color);
+			Global->ScrBuf->ApplyColor(m_Where, GetSelectedColor());
 		}
 		else
 		{
@@ -369,8 +369,7 @@ void Edit::FastShow(const ShowInfo* Info)
 					std::min(m_Where.left + TabSelEnd - 1, static_cast<int>(m_Where.right)),
 					m_Where.top
 				},
-				GetSelectedColor(),
-				ScreenBuf::apply_mode::color
+				GetSelectedColor()
 			);
 		}
 	}
@@ -2204,7 +2203,7 @@ void Edit::ApplyColor(const FarColor& SelColor, int XPos, int FocusedLeftPos)
 		// Раскрашиваем элемент, если есть что раскрашивать
 		if (End >= Start)
 		{
-			Global->ScrBuf->ApplyColor({ m_Where.left + Start, m_Where.top, m_Where.left + End, m_Where.top }, CurItem.GetColor(), ScreenBuf::apply_mode::all);
+			Global->ScrBuf->ApplyColor({ m_Where.left + Start, m_Where.top, m_Where.left + End, m_Where.top }, CurItem.GetColor());
 		}
 	}
 }

far/editor.cpp

@@ -360,7 +360,7 @@ void Editor::ShowEditor()
 						BlockX2=XX2;
 
 					if (BlockX1 <= XX2 && BlockX2 >= m_Where.left)
-						Global->ScrBuf->ApplyColor({ BlockX1, Y, BlockX2, Y }, colors::PaletteColorToFarColor(COL_EDITORSELECTEDTEXT), ScreenBuf::apply_mode::color);
+						Global->ScrBuf->ApplyColor({ BlockX1, Y, BlockX2, Y }, colors::PaletteColorToFarColor(COL_EDITORSELECTEDTEXT));
 				}
 
 				++CurPtr;

far/farlang.templ.m4

@@ -18754,6 +18754,22 @@ MSetColorBackground
 "&Фон:"
 "&Fonas:"
 
+MSetColorForeAARRGGBB
+l:
+l:// 8 characters max
+"AARRGGBB"
+"AARRGGBB"
+"AARRGGBB"
+"AARRGGBB"
+"AARRGGBB"
+"AARRGGBB"
+"AARRGGBB"
+"AARRGGBB"
+"AARRGGBB"
+"AARRGGBB"
+"AARRGGBB"
+"AARRGGBB"
+
 MSetColorForeRGB
 l:
 l:// 3 characters max
@@ -18770,6 +18786,22 @@ l:// 3 characters max
 "&RGB…"
 "&RGB…"
 
+MSetColorBackAARRGGBB
+l:
+l:// 8 characters max
+"AARRGGBB"
+"AARRGGBB"
+"AARRGGBB"
+"AARRGGBB"
+"AARRGGBB"
+"AARRGGBB"
+"AARRGGBB"
+"AARRGGBB"
+"AARRGGBB"
+"AARRGGBB"
+"AARRGGBB"
+"AARRGGBB"
+
 MSetColorBackRGB
 l:
 l:// 3 characters max

far/scrbuf.cpp

@@ -206,31 +206,9 @@ void ScreenBuf::ApplyColor(rectangle Where, const FarColor& Color, apply_mode co
 
 	fix_coordinates(Where);
 
-	const auto
-		DoForeground = ApplyMode & apply_mode::foreground && !colors::is_transparent(Color.ForegroundColor),
-		DoBackground = ApplyMode & apply_mode::background && !colors::is_transparent(Color.BackgroundColor),
-		DoStyle = ApplyMode & apply_mode::style && !(Color.BackgroundColor & FCF_IGNORE_STYLE);
-
 	for_submatrix(Buf, Where, [&](FAR_CHAR_INFO& Element)
 	{
-		auto& DstColor = Element.Attributes;
-
-		if (DoForeground)
-		{
-			DstColor.ForegroundColor = Color.ForegroundColor;
-			flags::copy(DstColor.Flags, FCF_FG_4BIT, Color.Flags);
-		}
-
-		if (DoBackground)
-		{
-			DstColor.BackgroundColor = Color.BackgroundColor;
-			flags::copy(DstColor.Flags, FCF_BG_4BIT, Color.Flags);
-		}
-
-		if (DoStyle)
-		{
-			flags::copy(DstColor.Flags, FCF_STYLEMASK, Color.Flags);
-		}
+		Element.Attributes = colors::merge(Element.Attributes, Color);
 	});
 
 	debug_flush();

far/scrbuf.hpp

@@ -111,7 +111,7 @@ class ScreenBuf: noncopyable
 		all        = color | style
 	};
 
-	void ApplyColor(rectangle Where, const FarColor& Color, apply_mode ApplyMode);
+	void ApplyColor(rectangle Where, const FarColor& Color, apply_mode ApplyMode = apply_mode::all);
 	void FillRect(rectangle Where, const FAR_CHAR_INFO& Info);
 
 	void Scroll(size_t Count);