[LyX/master] Rework display of numbers in margins of hull insets

[Jean-Marc Lasgouttes]

commit da57154f94077604d9bddcff7360307897cbad3f
Author: Jean-Marc Lasgouttes <lasgouttes at lyx.org>
Date:   Thu Jul 1 18:35:16 2021 +0200

    Rework display of numbers in margins of hull insets
    
    This requires the introduction of the booleans selected_left and
    selected_right in PainterInfo. These tell whether the selection
    continues at the left/right of the inset.
    
    This information allows to
    
    1/ paint equation number in the right color: either current text color
       or selection text color.
    
    2/ before that, paint a small background rectangle of the correct color.
    
    This allows to avoid painting a large rectangle of an arbitrary color
    that was the cause of the bug.
    
    Fixes bug #12319.
---
 src/MetricsInfo.cpp          |    3 ++-
 src/MetricsInfo.h            |    3 +++
 src/RowPainter.cpp           |    6 +++++-
 src/mathed/InsetMathHull.cpp |   32 +++++++++++++++++++++-----------
 4 files changed, 31 insertions(+), 13 deletions(-)

diff --git a/src/MetricsInfo.cpp b/src/MetricsInfo.cpp
index 24656ed..4688d12 100644
--- a/src/MetricsInfo.cpp
+++ b/src/MetricsInfo.cpp
@@ -132,7 +132,8 @@ MetricsInfo::MetricsInfo(BufferView * bv, FontInfo font, int textwidth,
 /////////////////////////////////////////////////////////////////////////
 
 PainterInfo::PainterInfo(BufferView * bv, lyx::frontend::Painter & painter)
-	: pain(painter), ltr_pos(false), change(), selected(false),
+	: pain(painter), ltr_pos(false), change(),
+	  selected(false), selected_left(false), selected_right(false),
 	  do_spellcheck(true), full_repaint(true), background_color(Color_background),
 	  leftx(0), rightx(0)
 {
diff --git a/src/MetricsInfo.h b/src/MetricsInfo.h
index bfd9d07..94f8670 100644
--- a/src/MetricsInfo.h
+++ b/src/MetricsInfo.h
@@ -141,12 +141,15 @@ public:
 	Change change;
 	/// Whether the parent is selected as a whole
 	bool selected;
+	/// Whether the left/right margins are selected
+	bool selected_left, selected_right;
 	/// Whether the spell checker is enabled for the parent
 	bool do_spellcheck;
 	/// True when it can be assumed that the screen has been cleared
 	bool full_repaint;
 	/// Current background color
 	ColorCode background_color;
+	/// The left and right position of current line (inside margins).
 	/// Useful for drawing display math numbering
 	int leftx, rightx;
 };
diff --git a/src/RowPainter.cpp b/src/RowPainter.cpp
index 44e4f72..400b7b6 100644
--- a/src/RowPainter.cpp
+++ b/src/RowPainter.cpp
@@ -82,7 +82,11 @@ FontInfo RowPainter::labelFont(bool end) const
 
 void RowPainter::paintInset(Row::Element const & e) const
 {
-	// Handle selection
+	// Handle selection (first left/right, then middle).
+	pi_.selected_left = pi_.selected
+	                    || (row_.isRTL() ? row_.end_margin_sel : row_.begin_margin_sel);
+	pi_.selected_right = pi_.selected
+	                     || (row_.isRTL() ? row_.begin_margin_sel : row_.end_margin_sel);
 	bool const pi_selected = pi_.selected;
 	Cursor const & cur = pi_.base.bv->cursor();
 	if (cur.selection() && cur.text() == &text_
diff --git a/src/mathed/InsetMathHull.cpp b/src/mathed/InsetMathHull.cpp
index fb52049..97d95da 100644
--- a/src/mathed/InsetMathHull.cpp
+++ b/src/mathed/InsetMathHull.cpp
@@ -589,13 +589,9 @@ void InsetMathHull::drawBackground(PainterInfo & pi, int x, int y) const
 		    dim.wid, dim.asc + dim.des, backgroundColor(pi));
 		return;
 	}
-	// If there are numbers, the margins around the (displayed)
-	// equation have to be cleared.
-	if (numberedType())
-		pi.pain.fillRectangle(pi.leftx, y - dim.asc,
-				pi.rightx - pi.leftx, dim.height(), pi.background_color);
+
 	pi.pain.fillRectangle(x + 1, y - dim.asc + 1, dim.wid - 2,
-			dim.asc + dim.des - 1, pi.backgroundColor(this));
+	                      dim.height() - 1, pi.backgroundColor(this));
 }
 
 
@@ -626,11 +622,6 @@ void InsetMathHull::draw(PainterInfo & pi, int x, int y) const
 	}
 
 	// First draw the numbers
-	ColorCode color = pi.selected && lyxrc.use_system_colors
-				? Color_selectiontext : standardColor();
-	bool const really_change_color = pi.base.font.color() == Color_none;
-	Changer dummy0 = really_change_color ? pi.base.font.changeColor(color)
-		: noChange();
 	if (numberedType()) {
 		BufferParams::MathNumber const math_number = buffer().params().getMathNumber();
 		for (row_type row = 0; row < nrows(); ++row) {
@@ -639,18 +630,37 @@ void InsetMathHull::draw(PainterInfo & pi, int x, int y) const
 			Dimension dimnl;
 			mathed_string_dim(pi.base.font, nl, dimnl);
 			if (math_number == BufferParams::LEFT) {
+				ColorCode const col = pi.selected_left
+					? Color_selectiontext
+					: pi.base.font.color();
+				Changer dummy0 = pi.base.font.changeColor(col);
 				if (dimnl.wid > x - pi.leftx)
 					yy += rowinfo(row).descent + dimnl.asc;
+				pi.pain.fillRectangle(pi.leftx, yy - dimnl.asc,
+					dimnl.width(), dimnl.height(),
+					pi.selected_left ? Color_selection : pi.background_color);
 				pi.draw(pi.leftx, yy, nl);
 			} else {
+				ColorCode const col = pi.selected_right
+					? Color_selectiontext
+					: pi.base.font.color();
+				Changer dummy0 = pi.base.font.changeColor(col);
 				if (dimnl.wid > pi.rightx - x - dim.wid)
 					yy += rowinfo(row).descent + dimnl.asc;
+				pi.pain.fillRectangle(pi.rightx - dimnl.wid, yy - dimnl.asc,
+					dimnl.width(), dimnl.height(),
+					pi.selected_right ? Color_selection : pi.background_color);
 				pi.draw(pi.rightx - dimnl.wid, yy, nl);
 			}
 		}
 	}
 
 	// Then the equations
+	ColorCode color = pi.selected && lyxrc.use_system_colors
+		? Color_selectiontext : standardColor();
+	bool const really_change_color = pi.base.font.color() == Color_none;
+	Changer dummy0 = really_change_color ? pi.base.font.changeColor(color)
+		: noChange();
 	Changer dummy1 = pi.base.changeFontSet(standardFont());
 	Changer dummy2 = pi.base.font.changeStyle(display() ? DISPLAY_STYLE
 	                                                    : TEXT_STYLE);