Avoid breaking text into substrings on selection boundaries for drawing

when the selection is empty (thus only needing a caret drawn) or when the
selection settings do not need the text drawn as pieces such as when the
selection is drawn translucently.

3 files changed, 20 insertions, 11 deletions

diff --git a/src/Editor.cxx b/src/Editor.cxx
index 9f50e331d..2d438e8db 100644
--- a/src/Editor.cxx
+++ b/src/Editor.cxx
@@ -2600,11 +2600,15 @@ void Editor::DrawLine(Surface *surface, ViewStyle &vsDraw, int line, int lineVis
 		}
 	}
 
+	bool selBackDrawn = vsDraw.selbackset && 
+		((vsDraw.selAlpha == SC_ALPHA_NOALPHA) || (vsDraw.selAdditionalAlpha == SC_ALPHA_NOALPHA));
+
 	// Does not take margin into account but not significant
 	int xStartVisible = subLineStart - xStart;
 
 	ll->psel = &sel;
-	BreakFinder bfBack(ll, lineStart, lineEnd, posLineStart, IsUnicodeMode(), xStartVisible);
+
+	BreakFinder bfBack(ll, lineStart, lineEnd, posLineStart, IsUnicodeMode(), xStartVisible, selBackDrawn);
 	int next = bfBack.First();
 
 	// Background drawing loop
@@ -2694,7 +2698,8 @@ void Editor::DrawLine(Surface *surface, ViewStyle &vsDraw, int line, int lineVis
 
 	inIndentation = subLine == 0;	// Do not handle indentation except on first subline.
 	// Foreground drawing loop
-	BreakFinder bfFore(ll, lineStart, lineEnd, posLineStart, IsUnicodeMode(), xStartVisible);
+	BreakFinder bfFore(ll, lineStart, lineEnd, posLineStart, IsUnicodeMode(), xStartVisible,
+		((!twoPhaseDraw && selBackDrawn) || vsDraw.selforeset));
 	next = bfFore.First();
 
 	while (next < lineEnd) {
diff --git a/src/PositionCache.cxx b/src/PositionCache.cxx
index 580a1797c..fa2d581e1 100644
--- a/src/PositionCache.cxx
+++ b/src/PositionCache.cxx
@@ -386,7 +386,7 @@ static int NextBadU(const char *s, int p, int len, int &trailBytes) {
 	return -1;
 }
 
-BreakFinder::BreakFinder(LineLayout *ll_, int lineStart_, int lineEnd_, int posLineStart_, bool utf8_, int xStart) :
+BreakFinder::BreakFinder(LineLayout *ll_, int lineStart_, int lineEnd_, int posLineStart_, bool utf8_, int xStart, bool breakForSelection) :
 	ll(ll_),
 	lineStart(lineStart_),
 	lineEnd(lineEnd_),
@@ -412,13 +412,17 @@ BreakFinder::BreakFinder(LineLayout *ll_, int lineStart_, int lineEnd_, int posL
 		nextBreak--;
 	}
 
-	SelectionSegment segmentLine(SelectionPosition(posLineStart), SelectionPosition(posLineStart + lineEnd));
-	for (size_t r=0; r<ll->psel->Count(); r++) {
-		SelectionSegment portion = ll->psel->Range(r).Intersect(segmentLine);
-		if (portion.start.IsValid())
-			Insert(portion.start.Position() - posLineStart - 1);
-		if (portion.end.IsValid())
-			Insert(portion.end.Position() - posLineStart - 1);
+	if (breakForSelection) {
+		SelectionSegment segmentLine(SelectionPosition(posLineStart), SelectionPosition(posLineStart + lineEnd));
+		for (size_t r=0; r<ll->psel->Count(); r++) {
+			SelectionSegment portion = ll->psel->Range(r).Intersect(segmentLine);
+			if (!(portion.start == portion.end)) {
+				if (portion.start.IsValid())
+					Insert(portion.start.Position() - posLineStart - 1);
+				if (portion.end.IsValid())
+					Insert(portion.end.Position() - posLineStart - 1);
+			}
+		}
 	}
 
 	Insert(ll->edgeColumn - 1);
diff --git a/src/PositionCache.h b/src/PositionCache.h
index a86881070..e99ae5870 100644
--- a/src/PositionCache.h
+++ b/src/PositionCache.h
@@ -136,7 +136,7 @@ class BreakFinder {
 	int subBreak;
 	void Insert(int val);
 public:
-	BreakFinder(LineLayout *ll_, int lineStart_, int lineEnd_, int posLineStart_, bool utf8_, int xStart);
+	BreakFinder(LineLayout *ll_, int lineStart_, int lineEnd_, int posLineStart_, bool utf8_, int xStart, bool breakForSelection);
 	~BreakFinder();
 	int First();
 	int Next();