Merge pull request #10619 from jfbu/latex_coloredshadows

LaTeX: refactor sphinxShadowBox to allow colors for frame and shadow

3 files changed, 89 insertions, 20 deletions

diff --git a/doc/latex.rst b/doc/latex.rst
index 294de5599..0140d0b2c 100644
--- a/doc/latex.rst
+++ b/doc/latex.rst
@@ -846,7 +846,7 @@ Do not use quotes to enclose values, whether numerical or strings.
     Default: ``5pt``
 
 ``shadowsize``
-    The width of the lateral "shadow" to the right.
+    The width of the lateral "shadow" to the right and bottom.
 
     Default: ``4pt``
 
@@ -855,6 +855,20 @@ Do not use quotes to enclose values, whether numerical or strings.
 
     Default: ``\fboxrule``
 
+``shadowBorderColor``
+    The color of the frame around :dudir:`topic` boxes.
+
+    Default: ``{rgb}{0,0,0}`` (black)
+
+    .. versionadded:: 5.1.0
+
+``shadowShadowColor``
+    The color of the lateral "shadow" to the right and bottom.
+
+    Default: ``{rgb}{0,0,0}`` (black)
+
+    .. versionadded:: 5.1.0
+
 |notebdcolors|
     The colour for the two horizontal rules used by Sphinx in LaTeX for styling
     a :dudir:`note` type admonition.
diff --git a/sphinx/texinputs/sphinx.sty b/sphinx/texinputs/sphinx.sty
index 930d1b64f..b67722c1b 100644
--- a/sphinx/texinputs/sphinx.sty
+++ b/sphinx/texinputs/sphinx.sty
@@ -6,7 +6,7 @@
 %
 
 \NeedsTeXFormat{LaTeX2e}[1995/12/01]
-\ProvidesPackage{sphinx}[2021/01/27 v4.0.0 LaTeX package (Sphinx markup)]
+\ProvidesPackage{sphinx}[2022/06/30 v5.1.0 LaTeX package (Sphinx markup)]
 
 % provides \ltx@ifundefined
 % (many packages load ltxcmds: graphicx does for pdftex and lualatex but
@@ -154,6 +154,9 @@
 }%
 % Default color chosen to be as in minted.sty LaTeX package!
 \sphinxDeclareSphinxColorOption{VerbatimHighlightColor}{{rgb}{0.878,1,1}}
+% topic and contents boxes
+\sphinxDeclareSphinxColorOption{shadowBorderColor}{{rgb}{0,0,0}}
+\sphinxDeclareSphinxColorOption{shadowShadowColor}{{rgb}{0,0,0}}
 % admonition boxes, "light" style
 \sphinxDeclareSphinxColorOption{noteBorderColor}{{rgb}{0,0,0}}
 \sphinxDeclareSphinxColorOption{hintBorderColor}{{rgb}{0,0,0}}
diff --git a/sphinx/texinputs/sphinxlatexshadowbox.sty b/sphinx/texinputs/sphinxlatexshadowbox.sty
index 8d6c78666..12d3cec09 100644
--- a/sphinx/texinputs/sphinxlatexshadowbox.sty
+++ b/sphinx/texinputs/sphinxlatexshadowbox.sty
@@ -1,7 +1,7 @@
 %% TOPIC AND CONTENTS BOXES
 %
 % change this info string if making any custom modification
-\ProvidesFile{sphinxlatexshadowbox.sty}[2021/01/27 sphinxShadowBox]
+\ProvidesFile{sphinxlatexshadowbox.sty}[2022/06/30 sphinxShadowBox]
 
 % Provides support for this output mark-up from Sphinx latex writer:
 %
@@ -17,41 +17,93 @@
 % Requires:
 \RequirePackage{framed}
 
-% Again based on use of "framed.sty", this allows breakable framed boxes.
+% Let's draw the contents first, then the frame and the shadow last,
+% to avoid problems with some pdf viewers.
 \long\def\spx@ShadowFBox#1{%
   \leavevmode\begingroup
-  % first we frame the box #1
+  % First we prepare a box with the contents and some reserved space for the
+  % frame and inner separation; with more parameters we could allow various
+  % border widths for top, bottom, left, right, but here all are equal.
   \setbox\@tempboxa
-   \hbox{\vrule\@width\sphinxshadowrule
-         \vbox{\hrule\@height\sphinxshadowrule
+   \hbox{\kern\sphinxshadowrule
+         \vbox{\kern\sphinxshadowrule
                \kern\sphinxshadowsep
                \hbox{\kern\sphinxshadowsep #1\kern\sphinxshadowsep}%
                \kern\sphinxshadowsep
-               \hrule\@height\sphinxshadowrule}%
-         \vrule\@width\sphinxshadowrule}%
-  % Now we add the shadow, like \shadowbox from fancybox.sty would do
-  \dimen@\dimexpr.5\sphinxshadowrule+\sphinxshadowsize\relax
+               \kern\sphinxshadowrule}%
+         \kern\sphinxshadowrule}%
+  % Now we rebox, adding the colored frame for which space was reserved.
+  \setbox\@tempboxa
+   \hbox{\unhcopy\@tempboxa % not \unhbox to be able to refer to \ht, \wd later
+         \kern-\wd\@tempboxa
+         {\color{sphinxshadowBorderColor}% color push here
+          \vrule\@width\sphinxshadowrule% TeX auto-computes the height
+          \vbox{\hrule\@height\sphinxshadowrule% TeX auto-computes the width
+                \kern\dimexpr\ht\@tempboxa-\sphinxshadowrule\relax
+                % This empty \hbox is here to give width used by \hrule
+                % As \dp\@tempboxa is zero, the \hbox location is at the
+                % bottom of frame.
+                \hbox{\kern\dimexpr\wd\@tempboxa-2\sphinxshadowrule\relax}%
+                \kern\dimexpr\dp\@tempboxa-\sphinxshadowrule\relax
+                \hrule\@height\sphinxshadowrule% TeX auto-computes the width
+                }%
+          \vrule\@width\sphinxshadowrule% TeX auto-computes the height
+         }% color pop will happen here
+        }%
+  % Now we add the shadow.
+  %
+  % Formerly, shadow was drawn partly on top of frame, but this was before
+  % both frame and shadow acquired colors.  The width of the part of the
+  % shadow on the right is hidden, so it will stick into the right page
+  % margin.
+  %
+  % The frame borders are included into this final \hbox, which is sent back
+  % to \MakeFramed/\endMakeFramed measurements and then finally to page
+  % shipout.  As \advance\hsize-\width appears in \MakeFramed, where \width is
+  % the computed extra width added by the framing plus inner separation (so
+  % actually 2\sphinxshadowrule+2\sphinxshadowsep), this all means that
+  % horizontally the frame will be perfectly adjusted to the *total* text
+  % width limits (i.e. independent of current list nesting; but anyhow
+  % Docutils does not allow nesting of topic within topics or body elements).
   \hbox{\vbox{\offinterlineskip
-              \hbox{\copy\@tempboxa\kern-.5\sphinxshadowrule
+              \hbox{\copy\@tempboxa % not \box as we need \wd and \ht next
                     % add shadow on right side
                     \lower\sphinxshadowsize
-                          \hbox{\vrule\@height\ht\@tempboxa \@width\dimen@}%
+                          \hbox{{\color{sphinxshadowShadowColor}%
+                                 \vrule\@height\ht\@tempboxa \@width\sphinxshadowsize}}%
                     }%
-              \kern-\dimen@ % shift back vertically to bottom of frame
+              \kern-\sphinxshadowsize % shift back vertically to bottom of frame
               % and add shadow at bottom
               \moveright\sphinxshadowsize
-                    \vbox{\hrule\@width\wd\@tempboxa \@height\dimen@}%
+                    \vbox{{\color{sphinxshadowShadowColor}%
+                           \hrule\@width\wd\@tempboxa \@height\sphinxshadowsize}}%
               }%
-        % move left by the size of right shadow so shadow adds no width
+        % move left by the size of right shadow so shadow adds no width, and
+        % will stick into right margin
+        % (we did not conceal of course from TeX the depth)
         \kern-\sphinxshadowsize
        }%
   \endgroup
 }
 
-% use framed.sty to allow page breaks in frame+shadow
-% works well inside Lists and Quote-like environments
-% produced by ``topic'' directive (or local contents)
-% could nest if LaTeX writer authorized it
+% Use framed.sty \MakeFramed/\endMakeFramed to allow page breaks for topic
+% boxes.  Originally Sphinx used \shadowbox from fancybox.sty but it did not
+% allow pagebreaks (which was problematic for "contents" directive if there
+% are many subsections).
+%
+% Docutils does not allow topic to be nested within topics or other body
+% elements.  But the LaTeX code here does allow it:
+%
+% - a topic inside another topic would be rendered in a minipage (thus not
+%   allowing pagebreaks).  Its external frame would adapt perfectly to
+%   the *current (smaller) width for text*.
+%
+% - a topic inside (nested) lists or quote environments would have its frame
+%   take the *full width* of the page, but its text contents on the other hand
+%   would obey exactly the current indentation plus inner separation.  This is
+%   in contrast with the framing used for literal blocks, also based, but in a
+%   more sophisticated way on usage of \MakeFramed/\endMakeFramed, and
+%   adjusting to current text indentation.
 \newenvironment{sphinxShadowBox}
   {\def\FrameCommand {\spx@ShadowFBox }%
    \advance\spx@image@maxheight