Allow extensions to provide color palettes

Until now, .oxt extensions cannot provide additional color palettes (.soc files,
see e.g. Draw's "Format - Area... - Area - Color - Colors - Palette:" drop-down
list).  There are two ways how this feature could be added:

Either add a new file-entry media-type to extensions' META-INF/manifest.xml and
add support for that in the code.

Or leverage the existing code, which reads the configuration set
/org.openoffice.Office.Paths/Paths/Palette/InternalPaths, where each set element
denotes a directory, and scans those directories for .soc files.  So an
extension would include an .xcu file adding such a path (using %origin% to
denote a directory within the .oxt file itself) and a directory with one or more
.soc files.

For simplicity, this commit uses the second way.  The only problem with the
existing code is that extension configuration data using %origin% is rewritten
to vnd.sun.star.expand URIs which the palette-scanning code does not support.
So extend SvtPathOptions_Impl::GetPath's PATH_PALETTE case to expand such URIs.
(The choice of doing it in SvtPathOptions is somewhat arbitrary; there would be
other, more generic places where it might make sense to do such expansion, but
which would also carry a higher risk of regressions.)

<https://github.com/stbergmann/palette-extension> contains an example of such an
extension (with a LibreOffice-minimal-version of "LibreOffice 5.3", assuming
this commit will be backported to upcoming LO 5.3).

Some drawbacks of going this way are:

* No control over where extension palettes appear in the palette drop-down
  lists.  (But those lists appear to be sorted in some random order, anyway?)

* Commit on future support of the .soc file format (which, however, is XML) and
  the /org.openoffice.Office.Paths/Paths/Palette/InternalPaths configuration set
  in a backward-compatible way.  (But any other way of implementing this feature
  would also need a similar commitment.)

* Somewhat odd, indirect approach where an extension specifies a directory
  filled with .soc files, instead of specifying the .soc files diretly.

* With the current palette-management code, live extension addition/removal is
  not immediately reflected in all places that offer palette drop-down lists.
  (But this should be fixable, and would be an issue with other approaches,
  too.)

Change-Id: I68b30127d61764d1b5349f1f2af9c712828bee3e
(cherry picked from commit e2ea7bb3a6b681822a247e8c277694f921c92273)
Reviewed-on: https://gerrit.libreoffice.org/31501
Tested-by: Jenkins <ci@libreoffice.org>
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/unotools/source/config/pathoptions.cxx b/unotools/source/config/pathoptions.cxx
index 7b64c91a56d6..d9052456d3d2 100644
--- a/unotools/source/config/pathoptions.cxx
+++ b/unotools/source/config/pathoptions.cxx
@@ -32,6 +32,7 @@
 #include <unotools/bootstrap.hxx>
 
 #include <unotools/ucbhelper.hxx>
+#include <comphelper/getexpandeduri.hxx>
 #include <comphelper/processfactory.hxx>
 #include <com/sun/star/beans/XFastPropertySet.hpp>
 #include <com/sun/star/beans/XPropertySet.hpp>
@@ -237,6 +238,22 @@ const OUString& SvtPathOptions_Impl::GetPath( SvtPathOptions::Paths ePath )
             osl::FileBase::getSystemPathFromFileURL( aPathValue, aResult );
             aPathValue = aResult;
         }
+        else if (ePath == SvtPathOptions::PATH_PALETTE)
+        {
+            auto ctx = comphelper::getProcessComponentContext();
+            OUStringBuffer buf;
+            for (sal_Int32 i = 0;;)
+            {
+                buf.append(
+                    comphelper::getExpandedUri(
+                        ctx, aPathValue.getToken(0, ';', i)));
+                if (i == -1) {
+                    break;
+                }
+                buf.append(';');
+            }
+            aPathValue = buf.makeStringAndClear();
+        }
 
         m_aPathArray[ ePath ] = aPathValue;
         return m_aPathArray[ ePath ];