[LyX/master] Remove space between button and text with inlines collapsible insets

[Jean-Marc Lasgouttes]

commit 04ece4f0d6af818b3bc572b558181b947a109580
Author: Jean-Marc Lasgouttes <lasgouttes at lyx.org>
Date:   Sun Dec 11 20:59:43 2022 +0100

    Remove space between button and text with inlines collapsible insets
    
    Typically there are two sources of spacing:
    * the button has two pixels added to the left and to the right
    * the frame around the text also has 2 pixels to the left and to the right
    
    Note that this value of two pixels is given here for simplicity, but
    these are parameterized by methods like textOffset or leftOffset.
    
    What we want to remove is the space after the button and the space
    before the frame. This is done in 3 places
    
    In dimensionCollapsed(), the extra space is removed from the dimension
    after its computation
    
    In metrics(), the space avoided before the frame is removed from width.
    
    In draw, the whome text inset is drawn with a negative offset.
    
    Fixes #12335.
---
 src/insets/InsetCollapsible.cpp |   15 +++++++++++----
 1 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/src/insets/InsetCollapsible.cpp b/src/insets/InsetCollapsible.cpp
index c19d3a4..d629aaa 100644
--- a/src/insets/InsetCollapsible.cpp
+++ b/src/insets/InsetCollapsible.cpp
@@ -188,8 +188,13 @@ Dimension InsetCollapsible::dimensionCollapsed(BufferView const & bv) const
 	Dimension dim;
 	FontInfo labelfont(getLabelfont());
 	labelfont.realize(sane_font);
+	int const offset = Inset::textOffset(&bv);
 	theFontMetrics(labelfont).buttonText(
-		buttonLabel(bv), Inset::textOffset(&bv), dim.wid, dim.asc, dim.des);
+		buttonLabel(bv), offset, dim.wid, dim.asc, dim.des);
+	// remove spacing on the right for left buttons
+	if (geometry(bv) == LeftButton)
+		// this form makes a difference if offset is even
+		dim.wid -= offset - offset / 2;
 	return dim;
 }
 
@@ -236,8 +241,8 @@ void InsetCollapsible::metrics(MetricsInfo & mi, Dimension & dim) const
 			InsetText::metrics(mi, textdim);
 			view_[&bv].openinlined_ = (textdim.wid + dim.wid) < mi.base.textwidth;
 			if (view_[&bv].openinlined_) {
-				// Correct for button width.
-				dim.wid += textdim.wid;
+				// Correct for button width but remove spacing before frame
+				dim.wid += textdim.wid - leftOffset(mi.base.bv) / 2;
 				dim.des = max(dim.des - textdim.asc + dim.asc, textdim.des);
 				dim.asc = textdim.asc;
 			} else {
@@ -314,7 +319,9 @@ void InsetCollapsible::draw(PainterInfo & pi, int x, int y) const
 	case LeftButton:
 	case TopButton: {
 		if (g == LeftButton) {
-			textx = x + dimc.width();
+			// correct for spacing added before the frame in
+			// InsetText::draw. We want the button to touch the frame.
+			textx = x + dimc.width() - leftOffset(pi.base.bv) / 2;
 			texty = baseline;
 		} else {
 			textx = x;