Two phase drawing.

6 files changed, 160 insertions, 38 deletions

diff --git a/gtk/PlatGTK.cxx b/gtk/PlatGTK.cxx
index 7088a5f7e..9724c38bb 100644
--- a/gtk/PlatGTK.cxx
+++ b/gtk/PlatGTK.cxx
@@ -601,8 +601,10 @@ public:
 	void Ellipse(PRectangle rc, ColourAllocated fore, ColourAllocated back);
 	void Copy(PRectangle rc, Point from, Surface &surfaceSource);
 
+	void DrawTextBase(PRectangle rc, Font &font_, int ybase, const char *s, int len, ColourAllocated fore);
 	void DrawTextNoClip(PRectangle rc, Font &font_, int ybase, const char *s, int len, ColourAllocated fore, ColourAllocated back);
 	void DrawTextClipped(PRectangle rc, Font &font_, int ybase, const char *s, int len, ColourAllocated fore, ColourAllocated back);
+	void DrawTextTransparent(PRectangle rc, Font &font_, int ybase, const char *s, int len, ColourAllocated fore);
 	void MeasureWidths(Font &font_, const char *s, int len, int *positions);
 	int WidthText(Font &font_, const char *s, int len);
 	int WidthChar(Font &font_, char ch);
@@ -821,9 +823,8 @@ void SurfaceImpl::Copy(PRectangle rc, Point from, Surface &surfaceSource) {
 
 #define MAX_US_LEN 5000
 
-void SurfaceImpl::DrawTextNoClip(PRectangle rc, Font &font_, int ybase, const char *s, int len,
-                                 ColourAllocated fore, ColourAllocated back) {
-	FillRectangle(rc, back);
+void SurfaceImpl::DrawTextBase(PRectangle rc, Font &font_, int ybase, const char *s, int len,
+                                 ColourAllocated fore) {
 	PenColour(fore);
 	if (gc && drawable) {
 		// Draw text as a series of segments to avoid limitations in X servers
@@ -896,10 +897,23 @@ void SurfaceImpl::DrawTextNoClip(PRectangle rc, Font &font_, int ybase, const ch
 	}
 }
 
+void SurfaceImpl::DrawTextNoClip(PRectangle rc, Font &font_, int ybase, const char *s, int len,
+                                 ColourAllocated fore, ColourAllocated back) {
+	FillRectangle(rc, back);
+	DrawTextBase(rc, font_, ybase, s, len, fore);
+}
+
 // On GTK+, exactly same as DrawTextNoClip
 void SurfaceImpl::DrawTextClipped(PRectangle rc, Font &font_, int ybase, const char *s, int len,
                                   ColourAllocated fore, ColourAllocated back) {
-	DrawTextNoClip(rc, font_, ybase, s, len, fore, back);
+	FillRectangle(rc, back);
+	DrawTextBase(rc, font_, ybase, s, len, fore);
+}
+
+// On GTK+, exactly same as DrawTextNoClip
+void SurfaceImpl::DrawTextTransparent(PRectangle rc, Font &font_, int ybase, const char *s, int len,
+                                  ColourAllocated fore) {
+	DrawTextBase(rc, font_, ybase, s, len, fore);
 }
 
 void SurfaceImpl::MeasureWidths(Font &font_, const char *s, int len, int *positions) {
diff --git a/include/Platform.h b/include/Platform.h
index b19cdce8d..bb429729e 100644
--- a/include/Platform.h
+++ b/include/Platform.h
@@ -314,6 +314,7 @@ public:
 
 	virtual void DrawTextNoClip(PRectangle rc, Font &font_, int ybase, const char *s, int len, ColourAllocated fore, ColourAllocated back)=0;
 	virtual void DrawTextClipped(PRectangle rc, Font &font_, int ybase, const char *s, int len, ColourAllocated fore, ColourAllocated back)=0;
+	virtual void DrawTextTransparent(PRectangle rc, Font &font_, int ybase, const char *s, int len, ColourAllocated fore)=0;
 	virtual void MeasureWidths(Font &font_, const char *s, int len, int *positions)=0;
 	virtual int WidthText(Font &font_, const char *s, int len)=0;
 	virtual int WidthChar(Font &font_, char ch)=0;
diff --git a/include/Scintilla.h b/include/Scintilla.h
index 8df32be4c..386271bbe 100644
--- a/include/Scintilla.h
+++ b/include/Scintilla.h
@@ -395,6 +395,8 @@ typedef sptr_t (*SciFnDirect)(sptr_t ptr, unsigned int iMessage, uptr_t wParam,
 #define SCI_SETVSCROLLBAR 2280
 #define SCI_GETVSCROLLBAR 2281
 #define SCI_APPENDTEXT 2282
+#define SCI_GETTWOPHASEDRAW 2283
+#define SCI_SETTWOPHASEDRAW 2284
 #define SCI_LINEDOWN 2300
 #define SCI_LINEDOWNEXTEND 2301
 #define SCI_LINEUP 2302
diff --git a/include/Scintilla.iface b/include/Scintilla.iface
index bade44fd2..dd4d2d37e 100644
--- a/include/Scintilla.iface
+++ b/include/Scintilla.iface
@@ -1022,6 +1022,13 @@ get bool GetVScrollBar=2281(,)
 # Append a string to the end of the document without changing the selection.
 fun void AppendText=2282(int length, string text)
 
+# Is drawing done in two phases with backgrounds drawn before faoregrounds?
+get bool GetTwoPhaseDraw=2283(,)
+
+# In twoPhaseDraw mode, drawing is performed in two phases, first the background
+# and then the foreground. This avoids chopping off characters that overlap the next run.
+set void SetTwoPhaseDraw=2284(bool twoPhase,)
+
 ## New messages go here
 
 ## Start of key messages
diff --git a/src/Editor.cxx b/src/Editor.cxx
index 8ac091e8d..0c540d513 100644
--- a/src/Editor.cxx
+++ b/src/Editor.cxx
@@ -297,6 +297,7 @@ Editor::Editor() {
 	mouseDownCaptures = true;
 
 	bufferedDraw = true;
+	twoPhaseDraw = true;
 
 	lastClickTime = 0;
 	dwellDelay = SC_TIME_FOREVER;
@@ -1764,6 +1765,34 @@ void Editor::LayoutLine(int line, Surface *surface, ViewStyle &vstyle, LineLayou
 	}
 }
 
+ColourAllocated Editor::TextBackground(ViewStyle &vsDraw, bool overrideBackground,
+	ColourAllocated background, bool inSelection, int styleMain, int i, LineLayout *ll) {
+	if (inSelection) {
+		if (vsDraw.selbackset) {
+			if (primarySelection)
+				return vsDraw.selbackground.allocated;
+			else
+				return vsDraw.selbackground2.allocated;
+		}
+	} else {
+		if ((vsDraw.edgeState == EDGE_BACKGROUND) &&
+			(i >= ll->edgeColumn) &&
+			(ll->chars[i] != '\n') &&
+			(ll->chars[i] != '\r'))
+			return vsDraw.edgecolour.allocated;
+		if (overrideBackground)
+			return background;
+	}
+	return vsDraw.styles[styleMain].back.allocated;
+}
+
+void Editor::DrawIndentGuide(Surface *surface, int lineVisible, int lineHeight, int start, PRectangle rcSegment, bool highlight) {
+	Point from(0, ((lineVisible & 1) && (lineHeight & 1)) ? 1 : 0);
+	PRectangle rcCopyArea(start + 1, rcSegment.top, start + 2, rcSegment.bottom);
+	surface->Copy(rcCopyArea, from,
+		highlight ? *pixmapIndentGuideHighlight : *pixmapIndentGuide);
+}
+
 void Editor::DrawLine(Surface *surface, ViewStyle &vsDraw, int line, int lineVisible, int xStart,
                       PRectangle rcLine, LineLayout *ll, int subLine) {
 
@@ -1810,6 +1839,9 @@ void Editor::DrawLine(Surface *surface, ViewStyle &vsDraw, int line, int lineVis
 		}
 	}
 
+	bool drawWhitespaceBackground = (vsDraw.viewWhitespace != wsInvisible) &&
+		(!overrideBackground) && (vsDraw.whitespaceBackgroundSet);
+
 	bool inIndentation = subLine == 0;	// Do not handle indentation except on first subline.
 	int indentWidth = pdoc->indentInChars * vsDraw.spaceWidth;
 	if (indentWidth == 0)
@@ -1818,7 +1850,6 @@ void Editor::DrawLine(Surface *surface, ViewStyle &vsDraw, int line, int lineVis
 	int posLineStart = pdoc->LineStart(line);
 	int posLineEnd = pdoc->LineStart(line + 1);
 
-	int styleMask = pdoc->stylingBitsMask;
 	int startseg = ll->LineStart(subLine);
 	int subLineStart = ll->positions[startseg];
 	int lineStart = 0;
@@ -1827,7 +1858,63 @@ void Editor::DrawLine(Surface *surface, ViewStyle &vsDraw, int line, int lineVis
 		lineStart = ll->LineStart(subLine);
 		lineEnd = ll->LineStart(subLine+1);
 	}
-	for (int i = lineStart; i < lineEnd; i++) {
+	int i;
+
+	// Background drawing loop
+	for (i = lineStart; twoPhaseDraw && (i < lineEnd); i++) {
+
+		int iDoc = i + posLineStart;
+		// If there is the end of a style run for any reason
+		if ((ll->styles[i] != ll->styles[i + 1]) ||
+				i == (lineEnd-1) ||
+		        IsControlCharacter(ll->chars[i]) || IsControlCharacter(ll->chars[i + 1]) ||
+		        ((ll->selStart != ll->selEnd) && ((iDoc + 1 == ll->selStart) || (iDoc + 1 == ll->selEnd))) ||
+		        (i == (ll->edgeColumn - 1))) {
+			rcSegment.left = ll->positions[startseg] + xStart - subLineStart;
+			rcSegment.right = ll->positions[i + 1] + xStart - subLineStart;
+			// Only try to draw if really visible - enhances performance by not calling environment to
+			// draw strings that are completely past the right side of the window.
+			if ((rcSegment.left <= rcLine.right) && (rcSegment.right >= rcLine.left)) {
+				int styleMain = ll->styles[i];
+				bool inSelection = (iDoc >= ll->selStart) && (iDoc < ll->selEnd) && (ll->selStart != ll->selEnd);
+				ColourAllocated textBack = TextBackground(vsDraw, overrideBackground, background, inSelection, styleMain, i, ll);
+				if (ll->chars[i] == '\t') {
+					// Tab display
+					if (drawWhitespaceBackground &&
+						(!inIndentation || vsDraw.viewWhitespace == wsVisibleAlways))
+						textBack = vsDraw.whitespaceBackground.allocated;
+					surface->FillRectangle(rcSegment, textBack);
+				} else if (IsControlCharacter(ll->chars[i])) {
+					// Control character display
+					inIndentation = false;
+					surface->FillRectangle(rcSegment, textBack);
+				} else {
+					// Normal text display
+					surface->FillRectangle(rcSegment, textBack);
+					if (vsDraw.viewWhitespace != wsInvisible ||
+					        (inIndentation && vsDraw.viewIndentationGuides)) {
+						for (int cpos = 0; cpos <= i - startseg; cpos++) {
+							if (ll->chars[cpos + startseg] == ' ') {
+								if (drawWhitespaceBackground &&
+									(!inIndentation || vsDraw.viewWhitespace == wsVisibleAlways)) {
+									PRectangle rcSpace(ll->positions[cpos + startseg] + xStart, rcSegment.top,
+										ll->positions[cpos + startseg + 1] + xStart, rcSegment.bottom);
+									surface->FillRectangle(rcSpace, vsDraw.whitespaceBackground.allocated);
+								}
+							} else {
+								inIndentation = false;
+							}
+						}
+					}
+				}
+			}
+			startseg = i + 1;
+		}
+	}
+	inIndentation = subLine == 0;	// Do not handle indentation except on first subline.
+	startseg = ll->LineStart(subLine);
+	// Foreground drawing loop
+	for (i = lineStart; i < lineEnd; i++) {
 
 		int iDoc = i + posLineStart;
 		// If there is the end of a style run for any reason
@@ -1842,30 +1929,21 @@ void Editor::DrawLine(Surface *surface, ViewStyle &vsDraw, int line, int lineVis
 			// draw strings that are completely past the right side of the window.
 			if ((rcSegment.left <= rcLine.right) && (rcSegment.right >= rcLine.left)) {
 				int styleMain = ll->styles[i];
-				ColourAllocated textBack = vsDraw.styles[styleMain].back.allocated;
 				ColourAllocated textFore = vsDraw.styles[styleMain].fore.allocated;
 				Font &textFont = vsDraw.styles[styleMain].font;
 				bool inSelection = (iDoc >= ll->selStart) && (iDoc < ll->selEnd) && (ll->selStart != ll->selEnd);
-				if (inSelection) {
-					if (vsDraw.selbackset) {
-						if (primarySelection)
-							textBack = vsDraw.selbackground.allocated;
-						else
-							textBack = vsDraw.selbackground2.allocated;
-					}
-					if (vsDraw.selforeset)
-						textFore = vsDraw.selforeground.allocated;
-				} else {
-					if (overrideBackground)
-						textBack = background;
-					if ((vsDraw.edgeState == EDGE_BACKGROUND) && (i >= ll->edgeColumn) && (ll->chars[i] != '\n') && (ll->chars[i] != '\r'))
-						textBack = vsDraw.edgecolour.allocated;
+				if (inSelection && (vsDraw.selforeset)) {
+					textFore = vsDraw.selforeground.allocated;
 				}
+				ColourAllocated textBack = TextBackground(vsDraw, overrideBackground, background, inSelection, styleMain, i, ll);
 				if (ll->chars[i] == '\t') {
-					// Manage tab display
-					if (!overrideBackground && vsDraw.whitespaceBackgroundSet && (vsDraw.viewWhitespace != wsInvisible) && (!inIndentation || vsDraw.viewWhitespace == wsVisibleAlways))
-						textBack = vsDraw.whitespaceBackground.allocated;
-					surface->FillRectangle(rcSegment, textBack);
+					// Tab display
+					if (!twoPhaseDraw) {
+						if (drawWhitespaceBackground &&
+							(!inIndentation || vsDraw.viewWhitespace == wsVisibleAlways))
+							textBack = vsDraw.whitespaceBackground.allocated;
+						surface->FillRectangle(rcSegment, textBack);
+					}
 					if ((vsDraw.viewWhitespace != wsInvisible) || ((inIndentation && vsDraw.viewIndentationGuides))) {
 						if (vsDraw.whitespaceForegroundSet)
 							textFore = vsDraw.whitespaceForeground.allocated;
@@ -1874,10 +1952,8 @@ void Editor::DrawLine(Surface *surface, ViewStyle &vsDraw, int line, int lineVis
 					if (inIndentation && vsDraw.viewIndentationGuides) {
 						for (int xIG = ll->positions[i] / indentWidth * indentWidth; xIG < ll->positions[i + 1]; xIG += indentWidth) {
 							if (xIG >= ll->positions[i] && xIG > 0) {
-								Point from(0, ((lineVisible & 1) && (vsDraw.lineHeight & 1)) ? 1 : 0);
-								PRectangle rcCopyArea(xIG + xStart + 1, rcSegment.top, xIG + xStart + 2, rcSegment.bottom);
-								surface->Copy(rcCopyArea, from, (ll->xHighlightGuide == xIG) ?
-									      *pixmapIndentGuideHighlight : *pixmapIndentGuide);
+								DrawIndentGuide(surface, lineVisible, vsDraw.lineHeight, xIG + xStart, rcSegment,
+									(ll->xHighlightGuide == xIG));
 							}
 						}
 					}
@@ -1889,12 +1965,14 @@ void Editor::DrawLine(Surface *surface, ViewStyle &vsDraw, int line, int lineVis
 						}
 					}
 				} else if (IsControlCharacter(ll->chars[i])) {
-					// Manage control character display
+					// Control character display
 					inIndentation = false;
 					if (controlCharSymbol < 32) {
 						// Draw the character
 						const char *ctrlChar = ControlCharacterString(ll->chars[i]);
-						surface->FillRectangle(rcSegment, textBack);
+						if (!twoPhaseDraw) {
+							surface->FillRectangle(rcSegment, textBack);
+						}
 						int normalCharHeight = surface->Ascent(ctrlCharsFont) -
 									   surface->InternalLeading(ctrlCharsFont);
 						PRectangle rcCChar = rcSegment;
@@ -1918,10 +1996,16 @@ void Editor::DrawLine(Surface *surface, ViewStyle &vsDraw, int line, int lineVis
 										  cc, 1, textBack, textFore);
 					}
 				} else {
-					// Manage normal display
-					surface->DrawTextNoClip(rcSegment, textFont,
+					// Normal text display
+					if (twoPhaseDraw) {
+						surface->DrawTextTransparent(rcSegment, textFont,
+					                  rcSegment.top + vsDraw.maxAscent, ll->chars + startseg,
+					                  i - startseg + 1, textFore);
+					} else {
+						surface->DrawTextNoClip(rcSegment, textFont,
 					                  rcSegment.top + vsDraw.maxAscent, ll->chars + startseg,
 					                  i - startseg + 1, textFore, textBack);
+					}
 					if (vsDraw.viewWhitespace != wsInvisible ||
 					        (inIndentation && vsDraw.viewIndentationGuides)) {
 						for (int cpos = 0; cpos <= i - startseg; cpos++) {
@@ -1931,7 +2015,8 @@ void Editor::DrawLine(Surface *surface, ViewStyle &vsDraw, int line, int lineVis
 										textFore = vsDraw.whitespaceForeground.allocated;
 									if (!inIndentation || vsDraw.viewWhitespace == wsVisibleAlways) {
 										int xmid = (ll->positions[cpos + startseg] + ll->positions[cpos + startseg + 1]) / 2;
-										if (!overrideBackground && vsDraw.whitespaceBackgroundSet) {
+										if (!twoPhaseDraw && drawWhitespaceBackground &&
+											(!inIndentation || vsDraw.viewWhitespace == wsVisibleAlways)) {
 											textBack = vsDraw.whitespaceBackground.allocated;
 											PRectangle rcSpace(ll->positions[cpos + startseg] + xStart, rcSegment.top, ll->positions[cpos + startseg + 1] + xStart, rcSegment.bottom);
 											surface->FillRectangle(rcSpace, textBack);
@@ -1945,10 +2030,8 @@ void Editor::DrawLine(Surface *surface, ViewStyle &vsDraw, int line, int lineVis
 								if (inIndentation && vsDraw.viewIndentationGuides) {
 									int startSpace = ll->positions[cpos + startseg];
 									if (startSpace > 0 && (startSpace % indentWidth == 0)) {
-										Point from(0, ((lineVisible & 1) && (vsDraw.lineHeight & 1)) ? 1 : 0);
-										PRectangle rcCopyArea(startSpace + xStart + 1, rcSegment.top, startSpace + xStart + 2, rcSegment.bottom);
-										surface->Copy(rcCopyArea, from, (ll->xHighlightGuide == ll->positions[cpos + startseg]) ?
-										              *pixmapIndentGuideHighlight : *pixmapIndentGuide);
+										DrawIndentGuide(surface, lineVisible, vsDraw.lineHeight, startSpace + xStart, rcSegment,
+											(ll->xHighlightGuide == ll->positions[cpos + startseg]));
 									}
 								}
 							} else {
@@ -1994,6 +2077,8 @@ void Editor::DrawLine(Surface *surface, ViewStyle &vsDraw, int line, int lineVis
 	}
 	// End of the drawing of the current line
 
+	int styleMask = pdoc->stylingBitsMask;
+
 	// Fill in a PRectangle representing the end of line characters
 	int xEol = ll->positions[lineEnd] - subLineStart;
 	rcSegment.left = xEol + xStart;
@@ -5114,6 +5199,14 @@ sptr_t Editor::WndProc(unsigned int iMessage, uptr_t wParam, sptr_t lParam) {
 	case SCI_GETBUFFEREDDRAW:
 		return bufferedDraw;
 
+	case SCI_GETTWOPHASEDRAW:
+		return twoPhaseDraw;
+
+	case SCI_SETTWOPHASEDRAW:
+		twoPhaseDraw = wParam != 0;
+		InvalidateStyleRedraw();
+		break;
+
 	case SCI_SETTABWIDTH:
 		if (wParam > 0)
 			pdoc->tabInChars = wParam;
diff --git a/src/Editor.h b/src/Editor.h
index 5517065b6..ed5cc6612 100644
--- a/src/Editor.h
+++ b/src/Editor.h
@@ -199,6 +199,9 @@ protected:	// ScintillaBase subclass needs access to much of Editor
 	/** In bufferedDraw mode, graphics operations are drawn to a pixmap and then copied to
 	 * the screen. This avoids flashing but is about 30% slower. */
 	bool bufferedDraw;
+	/** In twoPhaseDraw mode, drawing is performed in two phases, first the background
+	* and then the foreground. This avoids chopping off characters that overlap the next run. */
+	bool twoPhaseDraw;
 
 	int xOffset;		///< Horizontal scrolled amount in pixels
 	int xCaretMargin;	///< Ensure this many pixels visible on both sides of caret
@@ -348,6 +351,8 @@ protected:	// ScintillaBase subclass needs access to much of Editor
 	LineLayout *RetrieveLineLayout(int lineNumber);
 	void LayoutLine(int line, Surface *surface, ViewStyle &vstyle, LineLayout *ll,
 		int width=LineLayout::wrapWidthInfinite);
+	ColourAllocated TextBackground(ViewStyle &vsDraw, bool overrideBackground, ColourAllocated background, bool inSelection, int styleMain, int i, LineLayout *ll);
+	void DrawIndentGuide(Surface *surface, int lineVisible, int lineHeight, int start, PRectangle rcSegment, bool highlight);
 	void DrawLine(Surface *surface, ViewStyle &vsDraw, int line, int lineVisible, int xStart,
 		PRectangle rcLine, LineLayout *ll, int subLine=0);
 	void Paint(Surface *surfaceWindow, PRectangle rcArea);