Drawing and measuring should not change ViewStyle which is set by the container

so mark ViewStyle parameters as const.
Provide a FontAlias copy constructor and use it to work around non-const Font
arguments to Surface when sourced from const ViewStyle.

8 files changed, 52 insertions, 42 deletions

diff --git a/src/Editor.cxx b/src/Editor.cxx
index 18eafa271..49fa40910 100644
--- a/src/Editor.cxx
+++ b/src/Editor.cxx
@@ -1739,7 +1739,7 @@ int Editor::SubstituteMarkerIfEmpty(int markerCheck, int markerDefault) const {
 	return markerCheck;
 }
 
-bool ValidStyledText(ViewStyle &vs, size_t styleOffset, const StyledText &st) {
+bool ValidStyledText(const ViewStyle &vs, size_t styleOffset, const StyledText &st) {
 	if (st.multipleStyles) {
 		for (size_t iStyle=0; iStyle<st.length; iStyle++) {
 			if (!vs.ValidStyle(styleOffset + st.styles[iStyle]))
@@ -1752,7 +1752,7 @@ bool ValidStyledText(ViewStyle &vs, size_t styleOffset, const StyledText &st) {
 	return true;
 }
 
-static int WidthStyledText(Surface *surface, ViewStyle &vs, int styleOffset,
+static int WidthStyledText(Surface *surface, const ViewStyle &vs, int styleOffset,
 	const char *text, const unsigned char *styles, size_t len) {
 	int width = 0;
 	size_t start = 0;
@@ -1761,14 +1761,15 @@ static int WidthStyledText(Surface *surface, ViewStyle &vs, int styleOffset,
 		size_t endSegment = start;
 		while ((endSegment+1 < len) && (static_cast<size_t>(styles[endSegment+1]) == style))
 			endSegment++;
-		width += static_cast<int>(surface->WidthText(vs.styles[style + styleOffset].font, text + start,
+		FontAlias fontText = vs.styles[style + styleOffset].font;
+		width += static_cast<int>(surface->WidthText(fontText, text + start,
 			static_cast<int>(endSegment - start + 1)));
 		start = endSegment + 1;
 	}
 	return width;
 }
 
-static int WidestLineWidth(Surface *surface, ViewStyle &vs, int styleOffset, const StyledText &st) {
+static int WidestLineWidth(Surface *surface, const ViewStyle &vs, int styleOffset, const StyledText &st) {
 	int widthMax = 0;
 	size_t start = 0;
 	while (start < st.length) {
@@ -1777,7 +1778,8 @@ static int WidestLineWidth(Surface *surface, ViewStyle &vs, int styleOffset, con
 		if (st.multipleStyles) {
 			widthSubLine = WidthStyledText(surface, vs, styleOffset, st.text + start, st.styles + start, lenLine);
 		} else {
-			widthSubLine = static_cast<int>(surface->WidthText(vs.styles[styleOffset + st.style].font,
+			FontAlias fontText = vs.styles[styleOffset + st.style].font;
+			widthSubLine = static_cast<int>(surface->WidthText(fontText,
 				st.text + start, static_cast<int>(lenLine)));
 		}
 		if (widthSubLine > widthMax)
@@ -1787,7 +1789,7 @@ static int WidestLineWidth(Surface *surface, ViewStyle &vs, int styleOffset, con
 	return widthMax;
 }
 
-void DrawStyledText(Surface *surface, ViewStyle &vs, int styleOffset, PRectangle rcText, int ascent,
+void DrawStyledText(Surface *surface, const ViewStyle &vs, int styleOffset, PRectangle rcText, int ascent,
 	const StyledText &st, size_t start, size_t length) {
 
 	if (st.multipleStyles) {
@@ -1799,12 +1801,13 @@ void DrawStyledText(Surface *surface, ViewStyle &vs, int styleOffset, PRectangle
 			while (end < length-1 && st.styles[start+end+1] == style)
 				end++;
 			style += styleOffset;
-			int width = static_cast<int>(surface->WidthText(vs.styles[style].font,
+			FontAlias fontText = vs.styles[style].font;
+			int width = static_cast<int>(surface->WidthText(fontText,
 				st.text + start + i, static_cast<int>(end - i + 1)));
 			PRectangle rcSegment = rcText;
 			rcSegment.left = static_cast<XYPOSITION>(x);
 			rcSegment.right = static_cast<XYPOSITION>(x + width + 1);
-			surface->DrawTextNoClip(rcSegment, vs.styles[style].font,
+			surface->DrawTextNoClip(rcSegment, fontText,
 					static_cast<XYPOSITION>(ascent), st.text + start + i,
 					static_cast<int>(end - i + 1),
 					vs.styles[style].fore,
@@ -1814,7 +1817,8 @@ void DrawStyledText(Surface *surface, ViewStyle &vs, int styleOffset, PRectangle
 		}
 	} else {
 		size_t style = st.style + styleOffset;
-		surface->DrawTextNoClip(rcText, vs.styles[style].font,
+		FontAlias fontText = vs.styles[style].font;
+		surface->DrawTextNoClip(rcText, fontText,
 				rcText.top + vs.maxAscent, st.text + start,
 				static_cast<int>(length),
 				vs.styles[style].fore,
@@ -2162,8 +2166,7 @@ LineLayout *Editor::RetrieveLineLayout(int lineNumber) {
  * Copy the given @a line and its styles from the document into local arrays.
  * Also determine the x position at which each character starts.
  */
-void Editor::LayoutLine(int line, Surface *surface, ViewStyle &vstyle, LineLayout *ll, int width) {
-//void LayoutLine(int line, Surface *surface, ViewStyle &vstyle, LineLayout *ll, int width, Document *pdoc, PositionCache &posCache, SpecialRepresentations &reprs) {
+void Editor::LayoutLine(int line, Surface *surface, const ViewStyle &vstyle, LineLayout *ll, int width) {
 	if (!ll)
 		return;
 
@@ -2387,13 +2390,13 @@ void Editor::LayoutLine(int line, Surface *surface, ViewStyle &vstyle, LineLayou
 	}
 }
 
-ColourDesired Editor::SelectionBackground(ViewStyle &vsDraw, bool main) const {
+ColourDesired Editor::SelectionBackground(const ViewStyle &vsDraw, bool main) const {
 	return main ?
 		(primarySelection ? vsDraw.selColours.back : vsDraw.selBackground2) :
 		vsDraw.selAdditionalBackground;
 }
 
-ColourDesired Editor::TextBackground(ViewStyle &vsDraw, bool overrideBackground,
+ColourDesired Editor::TextBackground(const ViewStyle &vsDraw, bool overrideBackground,
         ColourDesired background, int inSelection, bool inHotspot, int styleMain, int i, LineLayout *ll) const {
 	if (inSelection == 1) {
 		if (vsDraw.selColours.back.isSet && (vsDraw.selAlpha == SC_ALPHA_NOALPHA)) {
@@ -2475,12 +2478,12 @@ static void SimpleAlphaRectangle(Surface *surface, PRectangle rc, ColourDesired
 	}
 }
 
-void DrawTextBlob(Surface *surface, ViewStyle &vsDraw, PRectangle rcSegment,
+void DrawTextBlob(Surface *surface, const ViewStyle &vsDraw, PRectangle rcSegment,
 				  const char *s, ColourDesired textBack, ColourDesired textFore, bool twoPhaseDraw) {
 	if (!twoPhaseDraw) {
 		surface->FillRectangle(rcSegment, textBack);
 	}
-	Font &ctrlCharsFont = vsDraw.styles[STYLE_CONTROLCHAR].font;
+	FontAlias ctrlCharsFont = vsDraw.styles[STYLE_CONTROLCHAR].font;
 	int normalCharHeight = static_cast<int>(surface->Ascent(ctrlCharsFont) -
 	        surface->InternalLeading(ctrlCharsFont));
 	PRectangle rcCChar = rcSegment;
@@ -2499,7 +2502,7 @@ void DrawTextBlob(Surface *surface, ViewStyle &vsDraw, PRectangle rcSegment,
 	        textBack, textFore);
 }
 
-void Editor::DrawEOL(Surface *surface, ViewStyle &vsDraw, PRectangle rcLine, LineLayout *ll,
+void Editor::DrawEOL(Surface *surface, const ViewStyle &vsDraw, PRectangle rcLine, LineLayout *ll,
         int line, int lineEnd, int xStart, int subLine, XYACCUMULATOR subLineStart,
         bool overrideBackground, ColourDesired background,
         bool drawWrapMarkEnd, ColourDesired wrapColour) {
@@ -2650,7 +2653,7 @@ void Editor::DrawEOL(Surface *surface, ViewStyle &vsDraw, PRectangle rcLine, Lin
 	}
 }
 
-void Editor::DrawIndicator(int indicNum, int startPos, int endPos, Surface *surface, ViewStyle &vsDraw,
+void Editor::DrawIndicator(int indicNum, int startPos, int endPos, Surface *surface, const ViewStyle &vsDraw,
 		int xStart, PRectangle rcLine, LineLayout *ll, int subLine) {
 	const XYPOSITION subLineStart = ll->positions[ll->LineStart(subLine)];
 	PRectangle rcIndic(
@@ -2661,7 +2664,7 @@ void Editor::DrawIndicator(int indicNum, int startPos, int endPos, Surface *surf
 	vsDraw.indicators[indicNum].Draw(surface, rcIndic, rcLine);
 }
 
-void Editor::DrawIndicators(Surface *surface, ViewStyle &vsDraw, int line, int xStart,
+void Editor::DrawIndicators(Surface *surface, const ViewStyle &vsDraw, int line, int xStart,
         PRectangle rcLine, LineLayout *ll, int subLine, int lineEnd, bool under) {
 	// Draw decorators
 	const int posLineStart = pdoc->LineStart(line);
@@ -2710,7 +2713,7 @@ void Editor::DrawIndicators(Surface *surface, ViewStyle &vsDraw, int line, int x
 	}
 }
 
-void Editor::DrawAnnotation(Surface *surface, ViewStyle &vsDraw, int line, int xStart,
+void Editor::DrawAnnotation(Surface *surface, const ViewStyle &vsDraw, int line, int xStart,
     PRectangle rcLine, LineLayout *ll, int subLine) {
 	int indent = static_cast<int>(pdoc->GetLineIndentation(line) * vsDraw.spaceWidth);
 	PRectangle rcSegment = rcLine;
@@ -2767,7 +2770,7 @@ void Editor::DrawAnnotation(Surface *surface, ViewStyle &vsDraw, int line, int x
 	}
 }
 
-void Editor::DrawLine(Surface *surface, ViewStyle &vsDraw, int line, int lineVisible, int xStart,
+void Editor::DrawLine(Surface *surface, const ViewStyle &vsDraw, int line, int lineVisible, int xStart,
         PRectangle rcLine, LineLayout *ll, int subLine) {
 
 	if (subLine >= ll->lines) {
@@ -2780,7 +2783,7 @@ void Editor::DrawLine(Surface *surface, ViewStyle &vsDraw, int line, int lineVis
 	// Using one font for all control characters so it can be controlled independently to ensure
 	// the box goes around the characters tightly. Seems to be no way to work out what height
 	// is taken by an individual character - internal leading gives varying results.
-	Font &ctrlCharsFont = vsDraw.styles[STYLE_CONTROLCHAR].font;
+	FontAlias ctrlCharsFont = vsDraw.styles[STYLE_CONTROLCHAR].font;
 
 	// See if something overrides the line background color:  Either if caret is on the line
 	// and background color is set for that, or if a marker is defined that forces its background
@@ -3007,7 +3010,7 @@ void Editor::DrawLine(Surface *surface, ViewStyle &vsDraw, int line, int lineVis
 		if (rcSegment.Intersects(rcLine)) {
 			int styleMain = ll->styles[i];
 			ColourDesired textFore = vsDraw.styles[styleMain].fore;
-			Font &textFont = vsDraw.styles[styleMain].font;
+			FontAlias textFont = vsDraw.styles[styleMain].font;
 			//hotspot foreground
 			if (ll->hsStart != -1 && iDoc >= ll->hsStart && iDoc < hsEnd) {
 				if (vsDraw.hotspotColours.fore.isSet)
@@ -3253,7 +3256,7 @@ void Editor::DrawLine(Surface *surface, ViewStyle &vsDraw, int line, int lineVis
 	}
 }
 
-void Editor::DrawBlockCaret(Surface *surface, ViewStyle &vsDraw, LineLayout *ll, int subLine,
+void Editor::DrawBlockCaret(Surface *surface, const ViewStyle &vsDraw, LineLayout *ll, int subLine,
 							int xStart, int offset, int posCaret, PRectangle rcCaret, ColourDesired caretColour) {
 
 	int lineStart = ll->LineStart(subLine);
@@ -3312,7 +3315,8 @@ void Editor::DrawBlockCaret(Surface *surface, ViewStyle &vsDraw, LineLayout *ll,
 	// This character is where the caret block is, we override the colours
 	// (inversed) for drawing the caret here.
 	int styleMain = ll->styles[offsetFirstChar];
-	surface->DrawTextClipped(rcCaret, vsDraw.styles[styleMain].font,
+	FontAlias fontText = vsDraw.styles[styleMain].font;
+	surface->DrawTextClipped(rcCaret, fontText,
 	        rcCaret.top + vsDraw.maxAscent, ll->chars + offsetFirstChar,
 	        numCharsToDraw, vsDraw.styles[styleMain].back,
 	        caretColour);
@@ -3386,7 +3390,7 @@ void Editor::RefreshPixMaps(Surface *surfaceWindow) {
 	}
 }
 
-void Editor::DrawCarets(Surface *surface, ViewStyle &vsDraw, int lineDoc, int xStart,
+void Editor::DrawCarets(Surface *surface, const ViewStyle &vsDraw, int lineDoc, int xStart,
         PRectangle rcLine, LineLayout *ll, int subLine) {
 	// When drag is active it is the only caret drawn
 	bool drawDrag = posDrag.IsValid();
diff --git a/src/Editor.h b/src/Editor.h
index 15a0fcf04..4826a1852 100644
--- a/src/Editor.h
+++ b/src/Editor.h
@@ -435,27 +435,27 @@ protected:	// ScintillaBase subclass needs access to much of Editor
 	int SubstituteMarkerIfEmpty(int markerCheck, int markerDefault) const;
 	void PaintSelMargin(Surface *surface, PRectangle &rc);
 	LineLayout *RetrieveLineLayout(int lineNumber);
-	void LayoutLine(int line, Surface *surface, ViewStyle &vstyle, LineLayout *ll,
+	void LayoutLine(int line, Surface *surface, const ViewStyle &vstyle, LineLayout *ll,
 		int width=LineLayout::wrapWidthInfinite);
-	ColourDesired SelectionBackground(ViewStyle &vsDraw, bool main) const;
-	ColourDesired TextBackground(ViewStyle &vsDraw, bool overrideBackground, ColourDesired background, int inSelection, bool inHotspot, int styleMain, int i, LineLayout *ll) const;
+	ColourDesired SelectionBackground(const ViewStyle &vsDraw, bool main) const;
+	ColourDesired TextBackground(const ViewStyle &vsDraw, bool overrideBackground, ColourDesired background, int inSelection, bool inHotspot, int styleMain, int i, LineLayout *ll) const;
 	void DrawIndentGuide(Surface *surface, int lineVisible, int lineHeight, int start, PRectangle rcSegment, bool highlight);
 	static void DrawWrapMarker(Surface *surface, PRectangle rcPlace, bool isEndMarker, ColourDesired wrapColour);
-	void DrawEOL(Surface *surface, ViewStyle &vsDraw, PRectangle rcLine, LineLayout *ll,
+	void DrawEOL(Surface *surface, const ViewStyle &vsDraw, PRectangle rcLine, LineLayout *ll,
 		int line, int lineEnd, int xStart, int subLine, XYACCUMULATOR subLineStart,
 		bool overrideBackground, ColourDesired background,
 		bool drawWrapMark, ColourDesired wrapColour);
-	static void DrawIndicator(int indicNum, int startPos, int endPos, Surface *surface, ViewStyle &vsDraw,
+	static void DrawIndicator(int indicNum, int startPos, int endPos, Surface *surface, const ViewStyle &vsDraw,
 		int xStart, PRectangle rcLine, LineLayout *ll, int subLine);
-	void DrawIndicators(Surface *surface, ViewStyle &vsDraw, int line, int xStart,
+	void DrawIndicators(Surface *surface, const ViewStyle &vsDraw, int line, int xStart,
 		PRectangle rcLine, LineLayout *ll, int subLine, int lineEnd, bool under);
-	void DrawAnnotation(Surface *surface, ViewStyle &vsDraw, int line, int xStart,
+	void DrawAnnotation(Surface *surface, const ViewStyle &vsDraw, int line, int xStart,
         PRectangle rcLine, LineLayout *ll, int subLine);
-	void DrawLine(Surface *surface, ViewStyle &vsDraw, int line, int lineVisible, int xStart,
+	void DrawLine(Surface *surface, const ViewStyle &vsDraw, int line, int lineVisible, int xStart,
 		PRectangle rcLine, LineLayout *ll, int subLine);
-	void DrawBlockCaret(Surface *surface, ViewStyle &vsDraw, LineLayout *ll, int subLine,
+	void DrawBlockCaret(Surface *surface, const ViewStyle &vsDraw, LineLayout *ll, int subLine,
 		int xStart, int offset, int posCaret, PRectangle rcCaret, ColourDesired caretColour);
-	void DrawCarets(Surface *surface, ViewStyle &vsDraw, int line, int xStart,
+	void DrawCarets(Surface *surface, const ViewStyle &vsDraw, int line, int xStart,
 		PRectangle rcLine, LineLayout *ll, int subLine);
 	void RefreshPixMaps(Surface *surfaceWindow);
 	void Paint(Surface *surfaceWindow, PRectangle rcArea);
diff --git a/src/Indicator.cxx b/src/Indicator.cxx
index e51067a38..d8ad64ed6 100644
--- a/src/Indicator.cxx
+++ b/src/Indicator.cxx
@@ -23,7 +23,7 @@ static PRectangle PixelGridAlign(const PRectangle &rc) {
 	return PRectangle::FromInts(int(rc.left + 0.5), int(rc.top), int(rc.right + 0.5), int(rc.bottom));
 }
 
-void Indicator::Draw(Surface *surface, const PRectangle &rc, const PRectangle &rcLine) {
+void Indicator::Draw(Surface *surface, const PRectangle &rc, const PRectangle &rcLine) const {
 	surface->PenColour(fore);
 	int ymid = static_cast<int>(rc.bottom + rc.top) / 2;
 	if (style == INDIC_SQUIGGLE) {
diff --git a/src/Indicator.h b/src/Indicator.h
index 0284a855b..beda8214b 100644
--- a/src/Indicator.h
+++ b/src/Indicator.h
@@ -23,7 +23,7 @@ public:
 	int outlineAlpha;
 	Indicator() : style(INDIC_PLAIN), under(false), fore(ColourDesired(0,0,0)), fillAlpha(30), outlineAlpha(50) {
 	}
-	void Draw(Surface *surface, const PRectangle &rc, const PRectangle &rcLine);
+	void Draw(Surface *surface, const PRectangle &rc, const PRectangle &rcLine) const;
 };
 
 #ifdef SCI_NAMESPACE
diff --git a/src/PositionCache.cxx b/src/PositionCache.cxx
index 0d2033bb9..2badeffbc 100644
--- a/src/PositionCache.cxx
+++ b/src/PositionCache.cxx
@@ -637,7 +637,7 @@ void PositionCache::SetSize(size_t size_) {
 	pces.resize(size_);
 }
 
-void PositionCache::MeasureWidths(Surface *surface, ViewStyle &vstyle, unsigned int styleNumber,
+void PositionCache::MeasureWidths(Surface *surface, const ViewStyle &vstyle, unsigned int styleNumber,
 	const char *s, unsigned int len, XYPOSITION *positions, Document *pdoc) {
 
 	allClear = false;
@@ -667,7 +667,8 @@ void PositionCache::MeasureWidths(Surface *surface, ViewStyle &vstyle, unsigned
 		XYPOSITION xStartSegment = 0;
 		while (startSegment < len) {
 			unsigned int lenSegment = pdoc->SafeSegment(s + startSegment, len - startSegment, BreakFinder::lengthEachSubdivision);
-			surface->MeasureWidths(vstyle.styles[styleNumber].font, s + startSegment, lenSegment, positions + startSegment);
+			FontAlias fontStyle = vstyle.styles[styleNumber].font;
+			surface->MeasureWidths(fontStyle, s + startSegment, lenSegment, positions + startSegment);
 			for (unsigned int inSeg = 0; inSeg < lenSegment; inSeg++) {
 				positions[startSegment + inSeg] += xStartSegment;
 			}
@@ -675,7 +676,8 @@ void PositionCache::MeasureWidths(Surface *surface, ViewStyle &vstyle, unsigned
 			startSegment += lenSegment;
 		}
 	} else {
-		surface->MeasureWidths(vstyle.styles[styleNumber].font, s, len, positions);
+		FontAlias fontStyle = vstyle.styles[styleNumber].font;
+		surface->MeasureWidths(fontStyle, s, len, positions);
 	}
 	if (probe < pces.size()) {
 		// Store into cache
diff --git a/src/PositionCache.h b/src/PositionCache.h
index 614c81d38..53b407b71 100644
--- a/src/PositionCache.h
+++ b/src/PositionCache.h
@@ -189,7 +189,7 @@ public:
 	void Clear();
 	void SetSize(size_t size_);
 	size_t GetSize() const { return pces.size(); }
-	void MeasureWidths(Surface *surface, ViewStyle &vstyle, unsigned int styleNumber,
+	void MeasureWidths(Surface *surface, const ViewStyle &vstyle, unsigned int styleNumber,
 		const char *s, unsigned int len, XYPOSITION *positions, Document *pdoc);
 };
 
diff --git a/src/Style.cxx b/src/Style.cxx
index 8b5b42dbf..4297fa7cc 100644
--- a/src/Style.cxx
+++ b/src/Style.cxx
@@ -19,6 +19,10 @@ using namespace Scintilla;
 FontAlias::FontAlias() {
 }
 
+FontAlias::FontAlias(const FontAlias &other) {
+	SetID(other.fid);
+}
+
 FontAlias::~FontAlias() {
 	SetID(0);
 	// ~Font will not release the actual font resource since it is now 0
diff --git a/src/Style.h b/src/Style.h
index 4bd79de14..e8359e110 100644
--- a/src/Style.h
+++ b/src/Style.h
@@ -34,10 +34,10 @@ struct FontSpecification {
 // Just like Font but only has a copy of the FontID so should not delete it
 class FontAlias : public Font {
 	// Private so FontAlias objects can not be copied
-	FontAlias(const FontAlias &);
 	FontAlias &operator=(const FontAlias &);
 public:
 	FontAlias();
+	FontAlias(const FontAlias &);
 	virtual ~FontAlias();
 	void MakeAlias(Font &fontOrigin);
 	void ClearFont();