Avoid breaking kerning with continuous spell checking

There is a mismatch between the way text is tokenized in Row objects
and the way it is shown on screen. When metrics are computed,
continuous spell checking has not been done yet. Yet, the row painter
explicitly breaks words at spell status boundaries. This creates
problem with a text like "PMP," (see bug #9649), where there is a
negative kerning before the comma.

This is solved by not taking in account spell status when drawing
text, and drawing spell underlines separately.

* replace Paragraph::isSameSpellRange with new method getSpellRange.

* merge RowPainter::paintChars into RowPainter::paintFromPos

* move the actual text painting code into the new paintTextAndSel.

* merge some code from paintFromPos to paintMisspelledMark

* in paintMisspelledMark, scan the string which needs to be annotated
  and add dashed line below text marked as misspelled.

Fixes bug #9649.

src/Paragraph.cpp

@@ -3131,10 +3131,9 @@ bool Paragraph::isHardHyphenOrApostrophe(pos_type pos) const
 }
 
 
-bool Paragraph::isSameSpellRange(pos_type pos1, pos_type pos2) const
+FontSpan const & Paragraph::getSpellRange(pos_type pos) const
 {
-	return pos1 == pos2
-		|| d->speller_state_.getRange(pos1) == d->speller_state_.getRange(pos2);
+	return d->speller_state_.getRange(pos);
 }
 
 

src/Paragraph.h

@@ -483,10 +483,9 @@ public:
 	/// \return true if one of the tested positions is misspelled.
 	bool isMisspelled(pos_type pos, bool check_boundary = false) const;
 
-	/// \return true if both positions are inside the same
-	/// spell range - i.e. the same word.
-	/// use it for positions inside misspelled range only.
-	bool isSameSpellRange(pos_type pos1, pos_type pos2) const;
+	/// \return the spell range (misspelled area) around position.
+	/// Range is empty if word at position is correctly spelled.
+	FontSpan const & getSpellRange(pos_type pos) const;
 
 	/// spell check of whole paragraph
 	/// remember results until call of requestSpellCheck()

src/RowPainter.cpp

@@ -163,9 +163,117 @@ void RowPainter::paintInset(Inset const * inset, pos_type const pos)
 }
 
 
-void RowPainter::paintChars(pos_type & vpos, Font const & font)
+void RowPainter::paintSeparator(double orig_x, double width,
+	FontInfo const & font)
+{
+	pi_.pain.textDecoration(font, int(orig_x), yo_, int(width));
+	x_ += width;
+}
+
+
+void RowPainter::paintForeignMark(double orig_x, Language const * lang, int desc) const
+{
+	if (!lyxrc.mark_foreign_language)
+		return;
+	if (lang == latex_language)
+		return;
+	if (lang == pi_.base.bv->buffer().params().language)
+		return;
+
+	int const y = yo_ + solid_line_offset_ + desc + solid_line_thickness_ / 2;
+	pi_.pain.line(int(orig_x), y, int(x_), y, Color_language,
+		Painter::line_solid, solid_line_thickness_);
+}
+
+
+void RowPainter::paintMisspelledMark(double const orig_x,
+                                     docstring const & str, Font const & font,
+                                     pos_type const start_pos,
+                                     bool const changed) const
+{
+	// if changed the misspelled marker gets placed slightly lower than normal
+	// to avoid drawing at the same vertical offset
+	int const y = yo_ + solid_line_offset_ + solid_line_thickness_
+		+ (changed ? solid_line_thickness_ + 1 : 0)
+		+ dotted_line_offset_;
+
+	//FIXME: this could be computed only once, it is probably not costly.
+	// check for cursor position
+	// don't draw misspelled marker for words at cursor position
+	// we don't want to disturb the process of text editing
+	DocIterator const nw = pi_.base.bv->cursor().newWord();
+	pos_type cpos = -1;
+	if (!nw.empty() && par_.id() == nw.paragraph().id()) {
+		cpos = nw.pos();
+		if (cpos > 0 && cpos == par_.size() && !par_.isWordSeparator(cpos-1))
+			--cpos;
+		else if (cpos > 0 && par_.isWordSeparator(cpos))
+			--cpos;
+	}
+
+	pos_type pos = start_pos;
+	while (pos < start_pos + pos_type(str.length())) {
+		if (!par_.isMisspelled(pos)) {
+			++pos;
+			continue;
+		}
+
+		FontSpan const & range = par_.getSpellRange(pos);
+
+		// Skip element which are being edited
+		if (range.contains(cpos)) {
+			// the range includes the last element
+			pos = range.last + 1;
+			continue;
+		}
+
+		FontMetrics const & fm = theFontMetrics(font);
+		int x1 = fm.pos2x(str, range.first - start_pos,
+		                  font.isVisibleRightToLeft());
+		int x2 = fm.pos2x(str, range.last - start_pos + 1,
+		                  font.isVisibleRightToLeft());
+		if (x1 > x2)
+			swap(x1, x2);
+
+		pi_.pain.line(int(orig_x) + x1, y, int(orig_x) + x2, y,
+		              Color_error,
+		              Painter::line_onoffdash, dotted_line_thickness_);
+		pos = range.last + 1;
+	}
+}
+
+
+void RowPainter::paintTextAndSel(docstring const & str, Font const & font,
+                                 Change const & change,
+                                 pos_type start_pos, pos_type end_pos)
+{
+	// at least part of text selected?
+	bool const some_sel = (end_pos >= row_.sel_beg && start_pos < row_.sel_end)
+		|| pi_.selected;
+	// all the text selected?
+	bool const all_sel = (start_pos >= row_.sel_beg && end_pos < row_.sel_end)
+		|| pi_.selected;
+
+	if (all_sel) {
+		Font copy = font;
+		copy.fontInfo().setPaintColor(Color_selectiontext);
+		x_ += pi_.pain.text(int(x_), yo_, str, copy);
+	} else if (change.changed()) {
+		Font copy = font;
+		copy.fontInfo().setPaintColor(change.color());
+		x_ += pi_.pain.text(int(x_), yo_, str, copy);
+	} else if (!some_sel) {
+		x_ += pi_.pain.text(int(x_), yo_, str, font);
+	} else {
+		x_ += pi_.pain.text(int(x_), yo_, str, font, Color_selectiontext,
+				    max(row_.sel_beg, start_pos) - start_pos,
+				    min(row_.sel_end, end_pos) - start_pos);
+	}
+}
+
+
+void RowPainter::paintFromPos(pos_type & vpos, bool changed)
 {
-	// This method takes up 70% of time when typing
 	pos_type pos = bidi_.vis2log(vpos);
 	pos_type start_pos = pos;
 	// first character
@@ -174,12 +282,12 @@ void RowPainter::paintChars(pos_type & vpos, Font const & font)
 	char_type const c = par_.getChar(pos);
 	str.push_back(c);
 
+	double const orig_x = x_;
+
+	Font const font = text_metrics_.displayFont(pit_, pos);
 	FontSpan const font_span = par_.fontSpan(pos);
 	// Track-change status.
 	Change const & change_running = par_.lookupChange(pos);
-	// spelling correct?
-	bool const spell_state =
-		lyxrc.spellcheck_continuously && par_.isMisspelled(pos);
 
 	// collect as much similar chars as we can
 	pos_type const end = row_.endpos();
@@ -189,12 +297,6 @@ void RowPainter::paintChars(pos_type & vpos, Font const & font)
 		if (!font_span.contains(pos))
 			break;
 
-		bool const new_spell_state =
-			lyxrc.spellcheck_continuously && par_.isMisspelled(pos);
-		if (new_spell_state != spell_state)
-			// Spell checker state changed here.
-			break;
-
 		Change const & change = par_.lookupChange(pos);
 		if (!change_running.isSimilarTo(change))
 			// Track change type or author has changed.
@@ -244,93 +346,16 @@ void RowPainter::paintChars(pos_type & vpos, Font const & font)
 		swap(start_pos, pos);
 	}
 
-	// at least part of text selected?
-	bool const some_sel = (pos >= row_.sel_beg && start_pos < row_.sel_end)
-		|| pi_.selected;
-	// all the text selected?
-	bool const all_sel = (start_pos >= row_.sel_beg && pos < row_.sel_end)
-		|| pi_.selected;
+	// Actually paint the text, taking care about the selection
+	paintTextAndSel(str, font, change_running, start_pos, pos);
 
-	if (all_sel) {
-		Font copy = font;
-		copy.fontInfo().setPaintColor(Color_selectiontext);
-		x_ += pi_.pain.text(int(x_), yo_, str, copy);
-	} else if (change_running.changed()) {
-		Font copy = font;
-		copy.fontInfo().setPaintColor(change_running.color());
-		x_ += pi_.pain.text(int(x_), yo_, str, copy);
-	} else if (!some_sel) {
-		x_ += pi_.pain.text(int(x_), yo_, str, font);
-	} else {
-		x_ += pi_.pain.text(int(x_), yo_, str, font, Color_selectiontext,
-				    max(row_.sel_beg, start_pos) - start_pos,
-				    min(row_.sel_end, pos) - start_pos);
-	}
-}
-
-
-void RowPainter::paintSeparator(double orig_x, double width,
-	FontInfo const & font)
-{
-	pi_.pain.textDecoration(font, int(orig_x), yo_, int(width));
-	x_ += width;
-}
-
-
-void RowPainter::paintForeignMark(double orig_x, Language const * lang, int desc) const
-{
-	if (!lyxrc.mark_foreign_language)
-		return;
-	if (lang == latex_language)
-		return;
-	if (lang == pi_.base.bv->buffer().params().language)
-		return;
-
-	int const y = yo_ + solid_line_offset_ + desc + solid_line_thickness_ / 2;
-	pi_.pain.line(int(orig_x), y, int(x_), y, Color_language,
-		Painter::line_solid, solid_line_thickness_);
-}
-
-
-void RowPainter::paintMisspelledMark(double orig_x, bool changed) const
-{
-	// if changed the misspelled marker gets placed slightly lower than normal
-	// to avoid drawing at the same vertical offset
-	int const y = yo_ + solid_line_offset_ + solid_line_thickness_
-		+ (changed ? solid_line_thickness_ + 1 : 0)
-		+ dotted_line_offset_;
-	pi_.pain.line(int(orig_x), y, int(x_), y, Color_error,
-		Painter::line_onoffdash, dotted_line_thickness_);
-}
-
-
-void RowPainter::paintFromPos(pos_type & vpos, bool changed)
-{
-	pos_type const pos = bidi_.vis2log(vpos);
-	Font const font = text_metrics_.displayFont(pit_, pos);
-	double const orig_x = x_;
-
-	paintChars(vpos, font);
+	// The line that indicates word in a different language
 	paintForeignMark(orig_x, font.language());
 
 	// Paint the spelling mark if needed.
-	if (lyxrc.spellcheck_continuously && par_.isMisspelled(pos)) {
-		// check for cursor position
-		// don't draw misspelled marker for words at cursor position
-		// we don't want to disturb the process of text editing
-		BufferView const * bv = pi_.base.bv;
-		DocIterator const nw = bv->cursor().newWord();
-		bool new_word = false;
-		if (!nw.empty() && par_.id() == nw.paragraph().id()) {
-			pos_type cpos = nw.pos();
-			if (cpos > 0 && cpos == par_.size() && !par_.isWordSeparator(cpos-1))
-				--cpos;
-			else if (cpos > 0 && par_.isWordSeparator(cpos))
-				--cpos;
-			new_word = par_.isSameSpellRange(pos, cpos) ;
-		}
-		if (!new_word && pi_.do_spellcheck)
-			paintMisspelledMark(orig_x, changed);
+	if (lyxrc.spellcheck_continuously && pi_.do_spellcheck
+		&& par_.isMisspelled(start_pos)) {
+		paintMisspelledMark(orig_x, str, font, start_pos, changed);
 	}
 }
 

src/RowPainter.h

@@ -76,8 +76,12 @@ public:
 private:
 	void paintSeparator(double orig_x, double width, FontInfo const & font);
 	void paintForeignMark(double orig_x, Language const * lang, int desc = 0) const;
-	void paintMisspelledMark(double orig_x, bool changed) const;
-	void paintChars(pos_type & vpos, Font const & font);
+	void paintTextAndSel(docstring const & str, Font const & font,
+                         Change const & change,
+                         pos_type start_pos, pos_type end_pos);
+	void paintMisspelledMark(double orig_x,
+	                         docstring const & str, Font const & font,
+	                         pos_type pos, bool changed) const;
 	int paintAppendixStart(int y) const;
 	void paintFromPos(pos_type & vpos, bool changed);
 	void paintInset(Inset const * inset, pos_type const pos);