implement default styles for dark mode, and allow enabling them (both GUI and HTML) in one step through menu entry

src/qtgui/guiutils.cpp

@@ -220,6 +220,7 @@ void rwSettings(bool writing)
 
     SETTING_RW(prefs.reslistheadertext, "/Recoll/prefs/reslist/headertext", 
                String, "");
+    SETTING_RW(prefs.darkMode, "/Recoll/prefs/darkMode", Bool, 0);
     SETTING_RW(prefs.qssFile, "/Recoll/prefs/stylesheet", String, "");
     SETTING_RW(prefs.snipCssFile, "/Recoll/prefs/snippets/cssfile", String, "");
     SETTING_RW(prefs.queryStemLang, "/Recoll/prefs/query/stemLang", String,

src/qtgui/guiutils.h

@@ -131,6 +131,8 @@ class PrefsPack {
     QString synFile;
     bool    synFileEnable;
 
+    bool darkMode;
+    
     QStringList restableFields;
     vector<int> restableColWidths;
 

src/qtgui/rclmain.ui

@@ -117,6 +117,8 @@
     <addaction name="queryPrefsAction"/>
     <addaction name="extIdxAction"/>
     <addaction name="separator"/>
+    <addaction name="enbDarkModeAction"/>
+    <addaction name="separator"/>
     <addaction name="enbSynAction"/>
     <addaction name="separator"/>
    </widget>
@@ -415,6 +417,20 @@
     <cstring>enbSynAction</cstring>
    </property>
   </action>
+  <action name="enbDarkModeAction">
+   <property name="checkable">
+    <bool>true</bool>
+   </property>
+   <property name="text">
+    <string>Use default dark mode</string>
+   </property>
+   <property name="iconText">
+    <string>Dark mode</string>
+   </property>
+   <property name="name" stdset="0">
+    <cstring>enbDarkModeAction</cstring>
+   </property>
+  </action>
   <action name="toggleFullScreenAction">
    <property name="text">
     <string>&amp;Full Screen</string>

src/qtgui/rclmain_w.cpp

@@ -68,6 +68,7 @@
 #include "systray.h"
 #include "rclmain_w.h"
 #include "rclhelp.h"
+#include "readfile.h"
 #include "moc_rclmain_w.cpp"
 
 using std::pair;
@@ -162,6 +163,7 @@ void RclMain::init()
 
     enbSynAction->setDisabled(prefs.synFile.isEmpty());
     enbSynAction->setChecked(prefs.synFileEnable);
+    enbDarkModeAction->setChecked(prefs.darkMode);
     
     // Stemming language menu
     g_stringNoStem = tr("(no stemming)");
@@ -360,6 +362,8 @@ void RclMain::init()
             this, SLOT(showExtIdxDialog()));
     connect(enbSynAction, SIGNAL(toggled(bool)),
             this, SLOT(setSynEnabled(bool)));
+    connect(enbDarkModeAction, SIGNAL(toggled(bool)),
+            this, SLOT(setDarkModeEnabled(bool)));
 
     connect(toggleFullScreenAction, SIGNAL(triggered()), 
             this, SLOT(toggleFullScreen()));
@@ -478,6 +482,61 @@ void RclMain::setSynEnabled(bool on)
         uiprefs->synFileCB->setChecked(prefs.synFileEnable);
 }
 
+void RclMain::setDarkModeEnabled(bool on)
+{
+    string fn;
+    
+    if (on) {
+        if (!prefs.reslistheadertext.isEmpty() || !prefs.qssFile.isEmpty()) {
+            QString message =
+                tr("This will replace the current contents of the result list"
+                   " header string and GUI qss file name. Continue ?");
+            switch(QMessageBox::warning(0, "Recoll", message, 
+                                        "Yes", "No", 0, 0, 1)) {
+            case 0: 
+                break;
+            case 1:
+                goto resetcheckednosigs;
+            }
+        }
+        string datadir = theconfig->getDatadir();
+        fn = path_cat(path_cat(datadir, "examples"), "recoll-dark.qss");
+        if (!path_readable(fn)) {
+            goto unreadable;
+        }
+        prefs.qssFile = u8s2qs(fn);
+        fn = path_cat(path_cat(datadir, "examples"), "recoll-dark.css");
+        string data;
+        string reason;
+        if (!file_to_string(fn, data, &reason)) {
+            goto unreadable;
+        }
+        prefs.reslistheadertext = u8s2qs(data);
+    } else {
+        prefs.reslistheadertext.clear();
+        prefs.qssFile.clear();
+    }
+
+    applyStyleSheet();
+    prefs.darkMode = on;
+    if (uiprefs) {
+        uiprefs->resetStylesheet(prefs.qssFile);
+    }
+    QMessageBox::warning(0, "Recoll", tr("You will need to run a query to "
+                                         "complete the display change."));
+    return;
+
+unreadable:
+    QMessageBox::warning(0, "Recoll", tr("Could not read: ") + u8s2qs(fn));
+    prefs.reslistheadertext.clear();
+    prefs.qssFile.clear();
+    // And reset checkbox state:
+resetcheckednosigs:
+    bool oldState = enbDarkModeAction->blockSignals(true);
+    enbDarkModeAction->setChecked(!on);
+    enbDarkModeAction->blockSignals(oldState);
+}
+
 void RclMain::resultCount(int n)
 {
     actionSortByDateAsc->setEnabled(n>0);

src/qtgui/rclmain_w.h

@@ -113,6 +113,7 @@ public slots:
     virtual void showDocHistory();
     virtual void showExtIdxDialog();
     virtual void setSynEnabled(bool);
+    virtual void setDarkModeEnabled(bool);
     virtual void showUIPrefs();
     virtual void showIndexConfig();
     virtual void execIndexConfig();

src/qtgui/uiprefs_w.cpp

@@ -469,10 +469,14 @@ void UIPrefsDialog::showStylesheetDialog()
     }
 }
 
-void UIPrefsDialog::resetStylesheet()
+void UIPrefsDialog::resetStylesheet(QString fn)
 {
-    qssFile = "";
-    stylesheetPB->setText(tr("Choose"));
+    qssFile = fn;
+    if (fn.isEmpty()) {
+        stylesheetPB->setText(tr("Choose"));
+    } else {
+        stylesheetPB->setText(fn);
+    }
 }
 void UIPrefsDialog::showSnipCssDialog()
 {

src/qtgui/uiprefs_w.h

@@ -53,7 +53,7 @@ public slots:
     virtual void showStylesheetDialog();
     virtual void showSynFileDialog();
     virtual void showSnipCssDialog();
-    virtual void resetStylesheet();
+    virtual void resetStylesheet(QString fn = QString());
     virtual void resetSnipCss();
     virtual void showViewAction();
     virtual void showViewAction(const QString& mt);

src/sampleconf/recoll-dark.css

@@ -1,5 +1,5 @@
 
-/* Result list HTML Header insert */
+<!-- Result list HTML Header insert -->
 
 <style>