Gui: support application icon override

Add logic for dynamic changing icons in BitmapFactory, Command,
TreeWidget, and OverlayManager.

Add option 'Preference -> General -> Icon set' for user to select
different icon set. 'Icon set' conf files are normal text files stored
in <UserAppDataDir>/Gui/IconSets/.

Add 'Tools -> Icon browser' to help creating user defined icon set.

Icon set changes is handled by MainWindow by handling
QEvent::StyleChange. Preference 'Icon set' configuration is set through
MainWindow::setOverrideExtraIcons(). Stylesheet can also override icon
by setting MainWindow property 'overrideIcons' as shown below (iconset:
is in <UserAppDataDir>/Gui/IconSets/). It takes precedenece over 'Icon
set'.

Gui--MainWindow {
  qproperty-overrideIcons : url(
TreeItemVisible, iconset:MyIcons/TreeItemVisible.svg
TreeItemInvisible, iconset:MyIcons/TreeItemInvisible.svg
);}

@StudioPetrikas

Author: realthunder

src/Gui/Action.cpp

@@ -945,14 +945,14 @@ void WorkbenchTabBar::updateWorkbenches()
         else if (tab->tabData(i).toString() == action->objectName())
             changed = false;
 
-        if (changed) {
-            tab->setTabIcon(i, action->icon());
-            tab->setTabData(i, action->objectName());
-            tab->setTabToolTip(i, 
-                    Action::createToolTip(action->toolTip(),
+        tab->setTabIcon(i, action->icon());
+        tab->setTabToolTip(i, 
+                Action::createToolTip(action->toolTip(),
                                         action->text(),
                                         action->font(),
                                         action->shortcut().toString(QKeySequence::NativeText)));
+        if (changed) {
+            tab->setTabData(i, action->objectName());
         }
         if (showText) {
             if (tab->tabText(i) != action->text())

src/Gui/Application.cpp

@@ -1628,7 +1628,7 @@ QPixmap Application::workbenchIcon(const QString& wb) const
     if (pcWorkbench) {
         // make a unique icon name
         std::stringstream str;
-        str << static_cast<const void *>(pcWorkbench) << std::ends;
+        str << "Icon_" << wb.toLatin1().constData();
         std::string iconName = str.str();
         QPixmap icon;
         if (BitmapFactory().findPixmapInCache(iconName.c_str(), icon))
@@ -2146,6 +2146,11 @@ void postAppSetup()
                         + "Gui/Stylesheets/menu").c_str());
     QDir::setSearchPaths(QString::fromLatin1("qssm"), qssMenuPaths);
 
+    QStringList iconSetPaths;
+    iconSetPaths << QString::fromUtf8((App::Application::getUserAppDataDir()
+                        + "Gui/IconSets").c_str());
+    QDir::setSearchPaths(QString::fromLatin1("iconset"), iconSetPaths);
+
     // set search paths for images
     QStringList imagePaths;
     imagePaths << QString::fromUtf8((App::Application::getUserAppDataDir() + "Gui/images").c_str())
@@ -2197,7 +2202,12 @@ void postAppSetup()
 #else
     // Option to opt-out from using a Linux desktop icon theme.
     // https://forum.freecadweb.org/viewtopic.php?f=4&t=35624
-    bool themePaths = hTheme->GetBool("ThemeSearchPaths",true);
+    //
+    // bool themePaths = hTheme->GetBool("ThemeSearchPaths",true);
+    //
+    // Disable system theme by default, as it rarely works with FreeCAD, because
+    // there are so many icons can't be find in common themes.
+    bool themePaths = hTheme->GetBool("_ThemeSearchPaths",false);
     if (!themePaths) {
         QStringList searchPaths;
         searchPaths.prepend(QString::fromUtf8(":/icons"));
@@ -2618,11 +2628,32 @@ void Application::setStyleSheet(const QString& qssFile, bool tiledBackground)
         qApp->setPalette(newPal);
     }
 
-
     QString current = mw->property("fc_currentStyleSheet").toString();
     mw->setProperty("fc_currentStyleSheet", qssFile);
 
-    if (!qssFile.isEmpty() && current != qssFile) {
+    auto hGrp = App::GetApplication().GetParameterGroupByPath("User parameter:BaseApp/Preferences/MainWindow");
+    QString iconSet = QString::fromUtf8(hGrp->GetASCII("IconSet").c_str());
+    if (!iconSet.isEmpty()) {
+        QString prefix(QLatin1String("iconset:"));
+        QFile f;
+        if (QFile::exists(iconSet)) {
+            f.setFileName(iconSet);
+        }
+        else if (QFile::exists(prefix + iconSet)) {
+            f.setFileName(prefix + iconSet);
+        }
+
+        if (!f.fileName().isEmpty() && f.open(QFile::ReadOnly | QFile::Text)) {
+            QTextStream str(&f);
+            getMainWindow()->setOverrideExtraIcons(str.readAll());
+        }
+    }
+
+    // Icon set change is also triggered by style change, so we'll set
+    // stylesheet regardless of changes
+    //
+    // if (!qssFile.isEmpty() && current != qssFile) {
+    if (!qssFile.isEmpty()) {
         // Search for stylesheet in user-defined search paths.
         // For qss they are set-up in runApplication() with the prefix "qss"
         QString prefix(QLatin1String("qss:"));

src/Gui/Application.h

@@ -291,7 +291,10 @@ class GuiExport Application
     static PyObject* sAddIconPath              (PyObject *self,PyObject *args); // adds a path to an icon file
     static PyObject* sAddIcon                  (PyObject *self,PyObject *args); // adds an icon to the cache
     static PyObject* sGetIcon                  (PyObject *self,PyObject *args); // get an icon from the cache
+    static PyObject* sGetIconContext           (PyObject *self,PyObject *args);
+    static PyObject* sAddIconContext           (PyObject *self,PyObject *args);
     static PyObject* sIsIconCached             (PyObject *self,PyObject *args); // check if an icon is cached
+    static PyObject* sGetIconNames             (PyObject *self,PyObject *args); // get all cached icon names
 
     static PyObject* sSendActiveView           (PyObject *self,PyObject *args);
     static PyObject* sSendFocusView            (PyObject *self,PyObject *args);

src/Gui/ApplicationPy.cpp

@@ -33,6 +33,7 @@
 # include <Inventor/SoInput.h>
 # include <Inventor/actions/SoGetPrimitiveCountAction.h>
 # include <Inventor/nodes/SoSeparator.h>
+# include <QInputDialog>
 #endif
 
 #include <xercesc/util/XMLString.hpp>
@@ -110,11 +111,20 @@ PyMethodDef Application::Methods[] = {
    "addIcon(string, string or list) -> None\n\n"
    "Add an icon as file name or in XPM format to the system"},
   {"getIcon",                 (PyCFunction) Application::sGetIcon, METH_VARARGS,
-   "getIcon(string) -> QIcon\n\n"
+   "getIcon(key:string, original=False) -> QIcon\n\n"
    "Get an icon in the system"},
+  {"getIconContext",          (PyCFunction) Application::sGetIconContext, METH_VARARGS,
+   "getIconContext(string) -> list(string)\n\n"
+   "Get user defined icon usage context"},
+  {"addIconContext",          (PyCFunction) Application::sAddIconContext, METH_VARARGS,
+   "addIconContext(string) -> None\n\n"
+   "Set user defined icon usage context"},
   {"isIconCached",           (PyCFunction) Application::sIsIconCached, METH_VARARGS,
    "isIconCached(String) -> Bool\n\n"
    "Check if an icon with the given name is cached"},
+  {"getIconNames",                 (PyCFunction) Application::sGetIconNames, METH_VARARGS,
+   "getIconNames() -> list(string)\n\n"
+   "Get all cached icon names in the system"},
   {"getMainWindow",           (PyCFunction) Application::sGetMainWindow, METH_VARARGS,
    "getMainWindow() -> QMainWindow\n\n"
    "Return the main window instance"},
@@ -1289,15 +1299,40 @@ PyObject* Application::sAddIcon(PyObject * /*self*/, PyObject *args)
 PyObject* Application::sGetIcon(PyObject * /*self*/, PyObject *args)
 {
     char *iconName;
-    if (!PyArg_ParseTuple(args, "s", &iconName))
+    PyObject *original = Py_False;
+    if (!PyArg_ParseTuple(args, "s|O", &iconName, &original))
         return NULL;
 
     PythonWrapper wrap;
     wrap.loadGuiModule();
     wrap.loadWidgetsModule();
-    auto pixmap = BitmapFactory().pixmap(iconName);
+    QPixmap pxOriginal;
+    auto pixmap = BitmapFactory().pixmap(iconName, false, PyObject_IsTrue(original) ? &pxOriginal : nullptr);
     if(!pixmap.isNull())
-        return Py::new_reference_to(wrap.fromQIcon(new QIcon(pixmap)));
+        return Py::new_reference_to(wrap.fromQIcon(new QIcon(pxOriginal.isNull()?pixmap:pxOriginal)));
+    Py_Return;
+}
+
+PyObject* Application::sGetIconContext(PyObject * /*self*/, PyObject *args)
+{
+    char *iconName;
+    if (!PyArg_ParseTuple(args, "s", &iconName))
+        return NULL;
+
+    Py::List res;
+    for (auto &ctx : BitmapFactory().getContext(iconName))
+        res.append(Py::String(ctx));
+    return Py::new_reference_to(res);
+}
+
+PyObject* Application::sAddIconContext(PyObject * /*self*/, PyObject *args)
+{
+    char *iconName;
+    char *ctx;
+    if (!PyArg_ParseTuple(args, "ss", &iconName, &ctx))
+        return NULL;
+
+    BitmapFactory().addContext(iconName, ctx);
     Py_Return;
 }
 
@@ -1311,6 +1346,17 @@ PyObject* Application::sIsIconCached(PyObject * /*self*/, PyObject *args)
     return Py::new_reference_to(Py::Boolean(BitmapFactory().findPixmapInCache(iconName, icon)));
 }
 
+PyObject* Application::sGetIconNames(PyObject * /*self*/, PyObject *args)
+{
+    if (!PyArg_ParseTuple(args, ""))
+        return NULL;
+
+    Py::List res;
+    for (auto &name : BitmapFactory().pixmapNames())
+        res.append(Py::String(name.toUtf8().constData()));
+    return Py::new_reference_to(res);
+}
+
 PyObject* Application::sAddCommand(PyObject * /*self*/, PyObject *args)
 {
     char*       pName;