qt: Add -custom-css-dir commmand line parameter (#3557)

* qt: Change themes path from ":themes" to ":css"

Required for the introduction of a custom css directory which will
happen with the follow-up commits.

* qt: Renamed trad.css to traditional.css

* qt: Add -custom-css-dir startup parameter

This allows to load a custom directory as css directory.

The custom directory currently needs to have the files:

- general.css
- dark.css
- light.css
- traditional.css
- scrollbars.css

src/Makefile.qt.include

@@ -353,7 +353,7 @@ RES_CSS = \
   qt/res/css/general.css \
   qt/res/css/light.css \
   qt/res/css/scrollbars.css \
-  qt/res/css/trad.css
+  qt/res/css/traditional.css
 
 RES_FONTS = \
   qt/res/fonts/Montserrat/Montserrat-Black.otf \

src/qt/dash.cpp

@@ -740,6 +740,41 @@ int main(int argc, char *argv[])
         }
         GUIUtil::setFontScale(nScale);
     }
+    // Validate/set custom css directory
+    if (gArgs.IsArgSet("-custom-css-dir")) {
+        fs::path customDir = fs::path(gArgs.GetArg("-custom-css-dir", ""));
+        QString strCustomDir = QString::fromStdString(customDir.string());
+        std::vector<QString> vecRequiredFiles = GUIUtil::listStyleSheets();
+        QString strFile;
+
+        if (!fs::is_directory(customDir)) {
+            QMessageBox::critical(0, QObject::tr(PACKAGE_NAME),
+                                  QObject::tr("Error: Invalid -custom-css-dir path.") + "\n\n" + strCustomDir);
+            return EXIT_FAILURE;
+        }
+
+        for (auto itCustomDir = fs::directory_iterator(customDir); itCustomDir != fs::directory_iterator(); ++itCustomDir) {
+            if (fs::is_regular_file(*itCustomDir) && itCustomDir->path().extension() == ".css") {
+                strFile = QString::fromStdString(itCustomDir->path().filename().string());
+                auto itFile = std::find(vecRequiredFiles.begin(), vecRequiredFiles.end(), strFile);
+                if (itFile != vecRequiredFiles.end()) {
+                    vecRequiredFiles.erase(itFile);
+                }
+            }
+        }
+
+        if (vecRequiredFiles.size()) {
+            QString strMissingFiles;
+            for (const auto& strMissingFile : vecRequiredFiles) {
+                strMissingFiles += strMissingFile + "\n";
+            }
+            QMessageBox::critical(0, QObject::tr(PACKAGE_NAME),
+                                  QObject::tr("Error: %1 CSS file(s) missing in -custom-css-dir path.").arg(vecRequiredFiles.size()) + "\n\n" + strMissingFiles);
+            return EXIT_FAILURE;
+        }
+
+        GUIUtil::setStyleSheetDirectory(strCustomDir);
+    }
 
     // Subscribe to global signals from core
     uiInterface.InitMessage.connect(InitMessage);

src/qt/dash.qrc

@@ -57,6 +57,9 @@
     <qresource prefix="/css">
         <file alias="general">res/css/general.css</file>
         <file alias="scrollbars">res/css/scrollbars.css</file>
+        <file alias="Dark">res/css/dark.css</file>
+        <file alias="Light">res/css/light.css</file>
+        <file alias="Traditional">res/css/traditional.css</file>
     </qresource>
     <qresource prefix="/fonts">
         <file alias="Montserrat-Black">res/fonts/Montserrat/Montserrat-Black.otf</file>
@@ -78,11 +81,6 @@
         <file alias="Montserrat-Thin">res/fonts/Montserrat/Montserrat-Thin.otf</file>
         <file alias="Montserrat-ThinItalic">res/fonts/Montserrat/Montserrat-ThinItalic.otf</file>
     </qresource>
-    <qresource prefix="/themes">
-        <file alias="Dark">res/css/dark.css</file>
-        <file alias="Light">res/css/light.css</file>
-        <file alias="Traditional">res/css/trad.css</file>
-    </qresource>
     <qresource prefix="/images">
         <file alias="arrow_down_normal">res/images/arrow_down_normal.png</file>
         <file alias="arrow_down_hover">res/images/arrow_down_hover.png</file>

src/qt/guiutil.cpp

@@ -80,12 +80,24 @@ void ForceActivation();
 
 namespace GUIUtil {
 
+// The default stylesheet directory
+static const QString defaultStylesheetDirectory = ":css";
+// The actual stylesheet directory
+static QString stylesheetDirectory = defaultStylesheetDirectory;
 // The name of the traditional theme
 static const QString traditionalTheme = "Traditional";
 // The theme to set by default if settings are missing or incorrect
 static const QString defaultTheme = "Light";
 // The prefix a theme name should have if we want to apply dark colors and styles to it
 static const QString darkThemePrefix = "Dark";
+// Mapping css file => theme.
+static const std::map<QString, QString> mapStyleToTheme{
+    {"general.css", ""},
+    {"dark.css", "Dark"},
+    {"light.css", "Light"},
+    {"traditional.css", "Traditional"},
+    {"scrollbars.css", ""}
+};
 
 /** Font related default values. */
 static const FontFamily defaultFontFamily = FontFamily::SystemDefault;
@@ -971,48 +983,73 @@ void migrateQtSettings()
     }
 }
 
+void setStyleSheetDirectory(const QString& path)
+{
+    stylesheetDirectory = path;
+}
+
+bool isStyleSheetDirectoryCustom()
+{
+    return stylesheetDirectory != defaultStylesheetDirectory;
+}
+
+const std::vector<QString> listStyleSheets()
+{
+    std::vector<QString> vecStylesheets;
+    for (const auto& it : mapStyleToTheme) {
+        vecStylesheets.push_back(it.first);
+    }
+    return vecStylesheets;
+}
+
+const std::vector<QString> listThemes()
+{
+    std::vector<QString> vecThemes;
+    for (const auto& it : mapStyleToTheme) {
+        if (!it.second.isEmpty()) {
+            vecThemes.push_back(it.second);
+        }
+    }
+    return vecThemes;
+}
+
 // Open CSS when configured
 QString loadStyleSheet()
 {
     static std::unique_ptr<QString> stylesheet;
 
-    if (stylesheet.get() == nullptr) {
-
+    if (stylesheet == nullptr) {
         stylesheet = std::make_unique<QString>();
 
         QSettings settings;
-        QDir themes(":themes");
+        QDir themes(":css");
         QString theme = settings.value("theme", "").toString();
 
         // Make sure settings are pointing to an existent theme
-        if (theme.isEmpty() || !themes.exists(theme)) {
+        if (!isStyleSheetDirectoryCustom() && (theme.isEmpty() || !themes.exists(theme))) {
             theme = defaultTheme;
             settings.setValue("theme", theme);
         }
 
+        auto loadFile = [&](const QString& name) {
+            QFile qFile(stylesheetDirectory + "/" + name + (isStyleSheetDirectoryCustom() ? ".css" : ""));
+            if (qFile.open(QFile::ReadOnly)) {
+                stylesheet->append(QLatin1String(qFile.readAll()));
+            }
+        };
+
         // If light/dark theme is used load general styles first
         if (dashThemeActive()) {
-            QFile qFileGeneral(":css/general");
-            if (qFileGeneral.open(QFile::ReadOnly)) {
-                stylesheet.get()->append(QLatin1String(qFileGeneral.readAll()));
-            }
-
+            loadFile("general");
 #ifndef Q_OS_MAC
-            // Apply some styling to scrollbars
-            QFile qFileScrollbars(QString(":/css/scrollbars"));
-            if (qFileScrollbars.open(QFile::ReadOnly)) {
-                stylesheet.get()->append(QLatin1String(qFileScrollbars.readAll()));
-            }
+            loadFile("scrollbars");
 #endif
         }
 
-        QFile qFileTheme(":themes/" + theme);
-        if (qFileTheme.open(QFile::ReadOnly)) {
-            stylesheet.get()->append(QLatin1String(qFileTheme.readAll()));
-        }
+        loadFile(theme);
     }
 
-    return *stylesheet.get();
+    return *stylesheet;
 }
 
 FontFamily fontFamilyFromString(const QString& strFamily)

src/qt/guiutil.h

@@ -230,6 +230,19 @@ namespace GUIUtil
     /** Modify Qt network specific settings on migration */
     void migrateQtSettings();
 
+    /** Change the stylesheet directory. This is used by
+        the parameter -custom-css-dir.*/
+    void setStyleSheetDirectory(const QString& path);
+
+    /** Check if a custom css directory has been set with -custom-css-dir */
+    bool isStyleSheetDirectoryCustom();
+
+    /** Return a list of all required css files */
+    const std::vector<QString> listStyleSheets();
+
+    /** Return a list of all theme css files */
+    const std::vector<QString> listThemes();
+
     /** Load global CSS theme */
     QString loadStyleSheet();
 

src/qt/optionsdialog.cpp

@@ -90,8 +90,7 @@ OptionsDialog::OptionsDialog(QWidget *parent, bool enableWallet) :
     }
 
     /* Theme selector */
-    QDir themes(":themes");
-    for (const QString &entry : themes.entryList()) {
+    for (const QString& entry : GUIUtil::listThemes()) {
         ui->theme->addItem(entry, QVariant(entry));
     }
 

src/qt/res/css/general.css

@@ -10,7 +10,7 @@ loaded and combined in `GUIUtil::loadStyleSheet()` in guitil.cpp.
 
 Hierarchy:
 
-*   general.css - base layout: Loaded first if selected theme is not "Traditional" (trad.css)
+*   general.css - base layout: Loaded first if selected theme is not "Traditional" (traditional.css)
 *   scrollbars.css - custom scrollbars: Loaded second only for windows/linux if general.css is loaded
 *   <theme.css> - theme css file:  Always loaded and loaded last.
 
@@ -18,7 +18,7 @@ To replace <theme.css> there are currently the following themes available:
 
 *   Dark (dark.css)
 *   Light (light.css)
-*   Traditional (trad.css)
+*   Traditional (traditional.css)
 
 NOTE: This file is only the base layout which is getting
 shared between all full themes (e.g. Dark or Light). It may contain

src/qt/res/css/traditional.css

@@ -17,7 +17,7 @@ Loaded in GUIUtil::loadStyleSheet() in guitil.cpp.
 /* do not modify! section updated by update-css-files.py
 <colors>
 
-# Used colors in trad.css for commit 3bebd1a5c
+# Used colors in traditional.css for commit 3bebd1a5c
 
 #fff
 #ccfafafa

src/qt/utilitydialog.cpp

@@ -88,6 +88,7 @@ HelpMessageDialog::HelpMessageDialog(QWidget *parent, HelpMode helpMode) :
             strUsage += HelpMessageOpt("-allowselfsignedrootcertificates", strprintf("Allow self signed root certificates (default: %u)", DEFAULT_SELFSIGNED_ROOTCERTS));
         }
         strUsage += HelpMessageOpt("-choosedatadir", strprintf(tr("Choose data directory on startup (default: %u)").toStdString(), DEFAULT_CHOOSE_DATADIR));
+        strUsage += HelpMessageOpt("-custom-css-dir", "Set a directory which contains custom css files. Those will be used as stylesheets for the UI.");
         strUsage += HelpMessageOpt("-font-family", tr("Set the font family. Possible values: %1. (default: %2)").arg("SystemDefault, Montserrat").arg(GUIUtil::fontFamilyToString(GUIUtil::getFontFamilyDefault())).toStdString());
         strUsage += HelpMessageOpt("-font-scale", tr("Set a scale factor which gets applied to the base font size. Possible range %1 (smallest fonts) to %2 (largest fonts). (default: %3)").arg(-100).arg(100).arg(GUIUtil::getFontScaleDefault()).toStdString());
         strUsage += HelpMessageOpt("-font-weight-bold", tr("Set the font weight for bold texts. Possible range %1 to %2 (default: %3)").arg(0).arg(8).arg(GUIUtil::weightToArg(GUIUtil::getFontWeightBoldDefault())).toStdString());