Add: {PUSH_COLOUR} and {POP_COLOUR} control codes to handle switching colours. (#6737)

This replaces the internal SCC_PREVIOUS_COLOUR swap.

src/gfx_layout.cpp

@@ -594,8 +594,10 @@ static inline void GetLayouter(Layouter::LineCacheItem &line, const char *&str,
 			break;
 		} else if (c >= SCC_BLUE && c <= SCC_BLACK) {
 			state.SetColour((TextColour)(c - SCC_BLUE));
-		} else if (c == SCC_PREVIOUS_COLOUR) { // Revert to the previous colour.
-			state.SetPreviousColour();
+		} else if (c == SCC_PUSH_COLOUR) {
+			state.PushColour();
+		} else if (c == SCC_POP_COLOUR) {
+			state.PopColour();
 		} else if (c >= SCC_FIRST_FONT && c <= SCC_LAST_FONT) {
 			state.SetFontSize((FontSize)(c - SCC_FIRST_FONT));
 		} else {

src/gfx_layout.h

@@ -18,6 +18,7 @@
 
 #include <map>
 #include <string>
+#include <stack>
 
 #ifdef WITH_ICU_LAYOUT
 #include "layout/ParagraphLayout.h"
@@ -33,10 +34,11 @@
 struct FontState {
 	FontSize fontsize;       ///< Current font size.
 	TextColour cur_colour;   ///< Current text colour.
-	TextColour prev_colour;  ///< Text colour from before the last colour switch.
 
-	FontState() : fontsize(FS_END), cur_colour(TC_INVALID), prev_colour(TC_INVALID) {}
-	FontState(TextColour colour, FontSize fontsize) : fontsize(fontsize), cur_colour(colour), prev_colour(colour) {}
+	std::stack<TextColour> colour_stack; ///< Stack of colours to assist with colour switching.
+
+	FontState() : fontsize(FS_END), cur_colour(TC_INVALID) {}
+	FontState(TextColour colour, FontSize fontsize) : fontsize(fontsize), cur_colour(colour) {}
 
 	/**
 	 * Switch to new colour \a c.
@@ -45,14 +47,25 @@ struct FontState {
 	inline void SetColour(TextColour c)
 	{
 		assert(c >= TC_BLUE && c <= TC_BLACK);
-		this->prev_colour = this->cur_colour;
 		this->cur_colour = c;
 	}
 
-	/** Switch to previous colour. */
-	inline void SetPreviousColour()
+	/**
+	 * Switch to and pop the last saved colour on the stack.
+	 */
+	inline void PopColour()
 	{
-		Swap(this->cur_colour, this->prev_colour);
+		if (colour_stack.empty()) return;
+		SetColour(colour_stack.top());
+		colour_stack.pop();
+	}
+
+	/**
+	 * Push the current colour on to the stack.
+	 */
+	inline void PushColour()
+	{
+		colour_stack.push(this->cur_colour);
 	}
 
 	/**
@@ -149,7 +162,7 @@ class Layouter : public AutoDeleteSmallVector<const ParagraphLayouter::Line *, 4
 		{
 			if (this->state_before.fontsize != other.state_before.fontsize) return this->state_before.fontsize < other.state_before.fontsize;
 			if (this->state_before.cur_colour != other.state_before.cur_colour) return this->state_before.cur_colour < other.state_before.cur_colour;
-			if (this->state_before.prev_colour != other.state_before.prev_colour) return this->state_before.prev_colour < other.state_before.prev_colour;
+			if (this->state_before.colour_stack != other.state_before.colour_stack) return this->state_before.colour_stack < other.state_before.colour_stack;
 			return this->str < other.str;
 		}
 	};

src/strings.cpp

@@ -449,6 +449,8 @@ static char *FormatGenericCurrency(char *buff, const CurrencySpec *spec, Money n
 
 	/* convert from negative */
 	if (number < 0) {
+		if (buff + Utf8CharLen(SCC_PUSH_COLOUR) > last) return buff;
+		buff += Utf8Encode(buff, SCC_PUSH_COLOUR);
 		if (buff + Utf8CharLen(SCC_RED) > last) return buff;
 		buff += Utf8Encode(buff, SCC_RED);
 		buff = strecpy(buff, "-", last);
@@ -485,8 +487,8 @@ static char *FormatGenericCurrency(char *buff, const CurrencySpec *spec, Money n
 	if (spec->symbol_pos != 0) buff = strecpy(buff, spec->suffix, last);
 
 	if (negative) {
-		if (buff + Utf8CharLen(SCC_PREVIOUS_COLOUR) > last) return buff;
-		buff += Utf8Encode(buff, SCC_PREVIOUS_COLOUR);
+		if (buff + Utf8CharLen(SCC_POP_COLOUR) > last) return buff;
+		buff += Utf8Encode(buff, SCC_POP_COLOUR);
 		*buff = '\0';
 	}
 

src/table/control_codes.h

@@ -115,7 +115,8 @@ enum StringControlCode {
 	SCC_GRAY,
 	SCC_DKBLUE,
 	SCC_BLACK,
-	SCC_PREVIOUS_COLOUR,
+	SCC_PUSH_COLOUR,
+	SCC_POP_COLOUR,
 
 	/**
 	 * The next variables are part of a NewGRF subsystem for creating text strings.

src/table/strgen_tables.h

@@ -60,6 +60,8 @@ static const CmdStruct _cmd_structs[] = {
 	{"GRAY",              EmitSingleChar, SCC_GRAY,               0, -1, C_DONTCOUNT},
 	{"DKBLUE",            EmitSingleChar, SCC_DKBLUE,             0, -1, C_DONTCOUNT},
 	{"BLACK",             EmitSingleChar, SCC_BLACK,              0, -1, C_DONTCOUNT},
+	{"PUSH_COLOUR",       EmitSingleChar, SCC_PUSH_COLOUR,        0, -1, C_DONTCOUNT},
+	{"POP_COLOUR",        EmitSingleChar, SCC_POP_COLOUR,         0, -1, C_DONTCOUNT},
 
 	{"REV",               EmitSingleChar, SCC_REVISION,           0, -1, C_NONE}, // openttd revision string