Add mechanism to change icons in RTL mode

When the cursor in RTL text, icons for "depth-increment" or
"layout-toggle Enumerate" look wrong.

To fix this, the lfun "bidi" is introduced. "bidi ltr func" behaves
like "func" in LTR text, but is unknown in RTL text. "bidi rtl" does
the opposite. This allows to add two icons, but only have one icon
available. When no document is available, only LTR is assumed.

To make this work, the handling of unknown functions in toolbar has
been changed so this these functions can change dynamically their
existence.

The icon themes `default', `oxygen' and `classic' have been updated
accordingly.

Fixes bug #4451.

lib/Makefile.am

@@ -516,6 +516,20 @@ dist_images_DATA1X = \
 	images/all-changes-accept.svgz \
 	images/all-changes-reject.svgz \
 	images/banner.svgz \
+	images/bidi_ltr_depth-decrement.svgz \
+	images/bidi_ltr_depth-increment.svgz \
+	images/bidi_ltr_layout-toggle_Description.svgz \
+	images/bidi_ltr_layout-toggle_Enumerate.svgz \
+	images/bidi_ltr_layout-toggle_Itemize.svgz \
+	images/bidi_ltr_layout-toggle_List.svgz \
+	images/bidi_ltr_layout-toggle_Section.svgz \
+	images/bidi_rtl_depth-decrement.svgz \
+	images/bidi_rtl_depth-increment.svgz \
+	images/bidi_rtl_layout-toggle_Description.svgz \
+	images/bidi_rtl_layout-toggle_Enumerate.svgz \
+	images/bidi_rtl_layout-toggle_Itemize.svgz \
+	images/bidi_rtl_layout-toggle_List.svgz \
+	images/bidi_rtl_layout-toggle_Section.svgz \
 	images/bookmark-goto.svgz \
 	images/bookmark-goto_0.svgz \
 	images/bookmark-save.svgz \
@@ -1802,6 +1816,20 @@ imagesoxygendir = $(imagesdir)/oxygen
 dist_imagesoxygen_DATA1X = \
 	images/oxygen/all-changes-accept.svgz \
 	images/oxygen/all-changes-reject.svgz \
+	images/oxygen/bidi_ltr_depth-decrement.svgz \
+	images/oxygen/bidi_ltr_depth-increment.svgz \
+	images/oxygen/bidi_ltr_layout-toggle_Description.svgz \
+	images/oxygen/bidi_ltr_layout-toggle_Enumerate.svgz \
+	images/oxygen/bidi_ltr_layout-toggle_Itemize.svgz \
+	images/oxygen/bidi_ltr_layout-toggle_List.svgz \
+	images/oxygen/bidi_ltr_layout-toggle_Section.svgz \
+	images/oxygen/bidi_rtl_depth-decrement.svgz \
+	images/oxygen/bidi_rtl_depth-increment.svgz \
+	images/oxygen/bidi_rtl_layout-toggle_Description.svgz \
+	images/oxygen/bidi_rtl_layout-toggle_Enumerate.svgz \
+	images/oxygen/bidi_rtl_layout-toggle_Itemize.svgz \
+	images/oxygen/bidi_rtl_layout-toggle_List.svgz \
+	images/oxygen/bidi_rtl_layout-toggle_Section.svgz \
 	images/oxygen/bookmark-goto.svgz \
 	images/oxygen/bookmark-goto_0.svgz \
 	images/oxygen/bookmark-save.svgz \
@@ -2005,6 +2033,20 @@ imagesclassicdir = $(imagesdir)/classic
 dist_imagesclassic_DATA = \
 	images/classic/all-changes-accept.png  \
 	images/classic/all-changes-reject.png  \
+	images/classic/bidi_ltr_depth-decrement.png \
+	images/classic/bidi_ltr_depth-increment.png \
+	images/classic/bidi_ltr_layout-toggle_Description.png \
+	images/classic/bidi_ltr_layout-toggle_Enumerate.png \
+	images/classic/bidi_ltr_layout-toggle_Itemize.png \
+	images/classic/bidi_ltr_layout-toggle_List.png \
+	images/classic/bidi_ltr_layout-toggle_Section.png \
+	images/classic/bidi_rtl_depth-decrement.png \
+	images/classic/bidi_rtl_depth-increment.png \
+	images/classic/bidi_rtl_layout-toggle_Description.png \
+	images/classic/bidi_rtl_layout-toggle_Enumerate.png \
+	images/classic/bidi_rtl_layout-toggle_Itemize.png \
+	images/classic/bidi_rtl_layout-toggle_List.png \
+	images/classic/bidi_rtl_layout-toggle_Section.png \
 	images/classic/bookmark-goto.png  \
 	images/classic/bookmark-goto_0.png  \
 	images/classic/bookmark-save.png  \

lib/ui/stdtoolbars.inc

@@ -113,12 +113,20 @@ ToolbarSet
 
 	Toolbar "extra" "Extra"
 		Item "Default" "layout"
-		Item "Numbered list" "layout-toggle Enumerate"
-		Item "Itemized list" "layout-toggle Itemize"
-		Item "List" "layout-toggle List"
-		Item "Description" "layout-toggle Description"
-		Item "Increase depth" "depth-increment"
-		Item "Decrease depth" "depth-decrement"
+		# The bidi function is used here to select a different
+		# icon depending on the direction of the current text.
+		Item "Numbered list" "bidi ltr layout-toggle Enumerate"
+		Item "Numbered list" "bidi rtl layout-toggle Enumerate"
+		Item "Itemized list" "bidi ltr layout-toggle Itemize"
+		Item "Itemized list" "bidi rtl layout-toggle Itemize"
+		Item "List" "bidi ltr layout-toggle List"
+		Item "List" "bidi rtl layout-toggle List"
+		Item "Description" "bidi ltr layout-toggle Description"
+		Item "Description" "bidi rtl layout-toggle Description"
+		Item "Increase depth" "bidi ltr depth-increment"
+		Item "Increase depth" "bidi rtl depth-increment"
+		Item "Decrease depth" "bidi ltr depth-decrement"
+		Item "Decrease depth" "bidi rtl depth-decrement"
 		Separator
 		Item "Insert figure float" "float-insert figure"
 		Item "Insert table float" "float-insert table"

src/FuncCode.h

@@ -485,6 +485,7 @@ enum FuncCode
 	LFUN_BUFFER_WRITE_AS_TEMPLATE,	// spitz, 20190323
 	LFUN_TABULAR_STYLE_INSERT,	// spitz, 20190325
 	LFUN_PARAGRAPH_SELECT,          // Kornel, 20190416
+	LFUN_BIDI,
 	LFUN_LASTACTION                 // end of the table
 };
 

src/LyXAction.cpp

@@ -332,6 +332,20 @@ void LyXAction::init()
 		{ LFUN_BIBTEX_DATABASE_DEL, "bibtex-database-del", Noop, Edit },
 
 
+/*!
+ * \var lyx::FuncCode lyx::LFUN_BIDI
+ * \li Action: Helper function for bidirectional toolbar icons
+ * \li Notion: In a text, the function is marked as `unknown' when the
+               current direction does not correspond to DIRECTION (ltr
+               or rtl). Otherwise the function behaves exactly as
+               ACTION. The result is that ACTION will be associated to
+               a different icon depending on text direction.
+ * \li Syntax: bidi <DIRECTION> <ACTION>
+ * \li Origin: JMarc, 21 July 2019
+ * \endvar
+ */
+		{ LFUN_BIDI, "bidi", Noop, System },
+
 /*!
  * \var lyx::FuncCode lyx::LFUN_BOOKMARK_CLEAR
  * \li Action: Clears the list of saved bookmarks.

src/frontends/qt/Action.cpp

@@ -76,6 +76,7 @@ void Action::update()
 		setCheckable(false);
 	}
 
+	setVisible(!status.unknown());
 	setEnabled(status.enabled());
 }
 

src/frontends/qt/GuiApplication.cpp

@@ -70,11 +70,11 @@
 #include "support/lassert.h"
 #include "support/lstrings.h"
 #include "support/lyxalgo.h" // sorted
-#include "support/textutils.h"
 #include "support/Messages.h"
 #include "support/os.h"
 #include "support/Package.h"
 #include "support/TempFile.h"
+#include "support/textutils.h"
 
 #ifdef Q_OS_MAC
 #include "support/AppleScript.h"
@@ -928,7 +928,7 @@ public:
 struct GuiApplication::Private
 {
 	Private(): language_model_(0), meta_fake_bit(NoModifier),
-		global_menubar_(0)
+	           global_menubar_(0)
 	{
 	#if (QT_VERSION < 0x050000) || (QT_VERSION >= 0x050400)
 	#if defined(Q_OS_WIN) || defined(Q_CYGWIN_WIN)
@@ -1292,6 +1292,24 @@ bool GuiApplication::getStatus(FuncRequest const & cmd, FuncStatus & flag) const
 		break;
 	}
 
+	case LFUN_BIDI: {
+		string const dir = cmd.getArg(0);
+		string const lfun = cmd.getLongArg(1);
+		BufferView const * bv =
+			current_view_ ? current_view_->currentBufferView() : nullptr;
+		bool rtl = bv ? bv->cursor().innerParagraph().isRTL(bv->buffer().params())
+		              : layoutDirection() == Qt::RightToLeft;
+		if (((rtl && dir != "rtl") || (!rtl && dir != "ltr"))) {
+			flag.setUnknown(true);
+			flag.setEnabled(false);
+		} else {
+			FuncRequest func(lyxaction.lookupFunc(lfun));
+			func.setOrigin(cmd.origin());
+			flag = getStatus(func);
+		}
+		break;
+	}
+
 	case LFUN_CURSOR_FOLLOWS_SCROLLBAR_TOGGLE:
 	case LFUN_REPEAT:
 	case LFUN_PREFERENCES_SAVE:
@@ -1869,6 +1887,7 @@ void GuiApplication::dispatch(FuncRequest const & cmd, DispatchResult & dr)
 		lyxrc.cursor_follows_scrollbar = !lyxrc.cursor_follows_scrollbar;
 		break;
 
+	// --- syntax commands ----------------------------
 	case LFUN_REPEAT: {
 		// repeat command
 		string countstr;
@@ -2020,6 +2039,18 @@ void GuiApplication::dispatch(FuncRequest const & cmd, DispatchResult & dr)
 		break;
 	}
 
+	case LFUN_BIDI: {
+		string const lfun = cmd.getLongArg(1);
+		FuncRequest func(lyxaction.lookupFunc(cmd.getLongArg(1)));
+		func.setOrigin(cmd.origin());
+		FuncStatus const stat = getStatus(func);
+		if (stat.enabled()) {
+			dispatch(func);
+			break;
+		}
+		break;
+	}
+
 	case LFUN_PREFERENCES_SAVE:
 		lyxrc.write(support::makeAbsPath("preferences",
 			package().user_support().absFileName()), false);

src/frontends/qt/GuiToolbar.cpp

@@ -519,8 +519,7 @@ void GuiToolbar::add(ToolbarItem const & item)
 		break;
 	}
 	case ToolbarItem::COMMAND: {
-		if (!getStatus(*item.func_).unknown())
-			addAction(addItem(item));
+		addAction(addItem(item));
 		break;
 		}
 	default: