Add Selection Mode

The selection mode action is a checkable toggle action named
"Select Files and Folders" which has "Space" as the default
shortcut.

In selection mode a bottom bar with contextual actions is shown.
These should mostly mirror the actions which are available through
the right-click context menu aka DolphinContextMenu.

Resizing of the window might make a overflow button appear in the
bottom selection mode bar.

This commit makes press and hold in the view activate selection
mode. This behaviour is not triggered if the press and hold is
used to either start a rubberband selection or a drag operation
within a short time. The length of the short timeframe is defined
by a QStyleHint. This is currently not implemented in touch
because I can't test it.

Mix the selection mode bars' background colors using a nice
combination of colors from the current color scheme

BUG: 427202

4 files changed, 84 insertions, 15 deletions

diff --git a/src/views/dolphinview.cpp b/src/views/dolphinview.cpp
index 0e97b8561..56867dd13 100644
--- a/src/views/dolphinview.cpp
+++ b/src/views/dolphinview.cpp
@@ -20,6 +20,7 @@
 #include "kitemviews/kitemlistselectionmanager.h"
 #include "kitemviews/private/kitemlistroleeditor.h"
 #include "settings/viewmodes/viewmodesettings.h"
+#include "selectionmode/singleclickselectionproxystyle.h"
 #include "versioncontrol/versioncontrolobserver.h"
 #include "viewproperties.h"
 #include "views/tooltips/tooltipmanager.h"
@@ -172,6 +173,7 @@ DolphinView::DolphinView(const QUrl& url, QWidget* parent) :
     connect(controller, &KItemListController::increaseZoom, this, &DolphinView::slotIncreaseZoom);
     connect(controller, &KItemListController::decreaseZoom, this, &DolphinView::slotDecreaseZoom);
     connect(controller, &KItemListController::swipeUp, this, &DolphinView::slotSwipeUp);
+    connect(controller, &KItemListController::selectionModeRequested, this, &DolphinView::selectionModeRequested);
 
     connect(m_model, &KFileItemModel::directoryLoadingStarted,       this, &DolphinView::slotDirectoryLoadingStarted);
     connect(m_model, &KFileItemModel::directoryLoadingCompleted,     this, &DolphinView::slotDirectoryLoadingCompleted);
@@ -262,7 +264,7 @@ bool DolphinView::isActive() const
     return m_active;
 }
 
-void DolphinView::setMode(Mode mode)
+void DolphinView::setViewMode(Mode mode)
 {
     if (mode != m_mode) {
         ViewProperties props(viewPropertiesUrl());
@@ -276,11 +278,30 @@ void DolphinView::setMode(Mode mode)
     }
 }
 
-DolphinView::Mode DolphinView::mode() const
+DolphinView::Mode DolphinView::viewMode() const
 {
     return m_mode;
 }
 
+void DolphinView::setSelectionMode(const bool enabled)
+{
+    if (enabled) {
+        m_proxyStyle = std::make_unique<SingleClickSelectionProxyStyle>();
+        setStyle(m_proxyStyle.get());
+        m_view->setStyle(m_proxyStyle.get());
+    } else {
+        setStyle(QApplication::style());
+        m_view->setStyle(QApplication::style());
+    }
+    m_container->controller()->setSelectionMode(enabled);
+}
+
+bool DolphinView::selectionMode() const
+{
+    return m_container->controller()->selectionMode();
+}
+
+
 void DolphinView::setPreviewsShown(bool show)
 {
     if (previewsShown() == show) {
diff --git a/src/views/dolphinview.h b/src/views/dolphinview.h
index d1ecf74ba..37af97137 100644
--- a/src/views/dolphinview.h
+++ b/src/views/dolphinview.h
@@ -23,6 +23,8 @@
 #include <QUrl>
 #include <QWidget>
 
+#include <memory>
+
 typedef KIO::FileUndoManager::CommandType CommandType;
 class QVBoxLayout;
 class DolphinItemListView;
@@ -36,6 +38,7 @@ class ViewProperties;
 class QLabel;
 class QGraphicsSceneDragDropEvent;
 class QHelpEvent;
+class QProxyStyle;
 class QRegularExpression;
 
 /**
@@ -106,8 +109,11 @@ public:
      * (GeneralSettings::globalViewProps() returns false), then the
      * changed view mode will be stored automatically.
      */
-    void setMode(Mode mode);
-    Mode mode() const;
+    void setViewMode(Mode mode);
+    Mode viewMode() const;
+
+    void setSelectionMode(bool enabled);
+    bool selectionMode() const;
 
     /**
      * Turns on the file preview for the all files of the current directory,
@@ -600,6 +606,13 @@ Q_SIGNALS:
     void goForwardRequested();
 
     /**
+     * Is emitted when the selection mode is requested for the current view.
+     * This typically happens on press and hold.
+     * @see KItemListController::longPress()
+     */
+    void selectionModeRequested();
+
+    /**
      * Is emitted when the user wants to move the focus to another view.
      */
     void toggleActiveViewRequested();
@@ -916,6 +929,9 @@ private:
     QLabel* m_placeholderLabel;
     QTimer* m_showLoadingPlaceholderTimer;
 
+    /// Used for selection mode. @see setSelectionMode()
+    std::unique_ptr<QProxyStyle> m_proxyStyle;
+
     // For unit tests
     friend class TestBase;
     friend class DolphinDetailsViewTest;
diff --git a/src/views/dolphinviewactionhandler.cpp b/src/views/dolphinviewactionhandler.cpp
index f59daab42..a66d1f6dd 100644
--- a/src/views/dolphinviewactionhandler.cpp
+++ b/src/views/dolphinviewactionhandler.cpp
@@ -29,6 +29,8 @@
 #include <QMenu>
 #include <QPointer>
 
+#include <iostream>
+
 DolphinViewActionHandler::DolphinViewActionHandler(KActionCollection* collection, QObject* parent) :
     QObject(parent),
     m_actionCollection(collection),
@@ -72,6 +74,8 @@ void DolphinViewActionHandler::setCurrentView(DolphinView* view)
             this, &DolphinViewActionHandler::slotZoomLevelChanged);
     connect(view, &DolphinView::writeStateChanged,
             this, &DolphinViewActionHandler::slotWriteStateChanged);
+    connect(view, &DolphinView::selectionModeRequested,
+            this, [this]() { Q_EMIT setSelectionMode(true); });
     connect(view, &DolphinView::selectionChanged,
             this, &DolphinViewActionHandler::slotSelectionChanged);
     slotSelectionChanged(m_currentView->selectedItems());
@@ -415,7 +419,7 @@ QActionGroup* DolphinViewActionHandler::createFileItemRolesActionGroup(const QSt
 void DolphinViewActionHandler::slotViewModeActionTriggered(QAction* action)
 {
     const DolphinView::Mode mode = action->data().value<DolphinView::Mode>();
-    m_currentView->setMode(mode);
+    m_currentView->setViewMode(mode);
 
     QAction* viewModeMenu = m_actionCollection->action(QStringLiteral("view_mode"));
     viewModeMenu->setIcon(action->icon());
@@ -423,20 +427,34 @@ void DolphinViewActionHandler::slotViewModeActionTriggered(QAction* action)
 
 void DolphinViewActionHandler::slotRename()
 {
-    Q_EMIT actionBeingHandled();
-    m_currentView->renameSelectedItems();
+    if (m_currentView->selectedItemsCount() == 0) {
+        Q_EMIT setSelectionMode(true, SelectionModeBottomBar::Contents::RenameContents);
+    } else {
+        Q_EMIT actionBeingHandled();
+        m_currentView->renameSelectedItems();
+    }
 }
 
 void DolphinViewActionHandler::slotTrashActivated()
 {
-    Q_EMIT actionBeingHandled();
-    m_currentView->trashSelectedItems();
+    if (m_currentView->selectedItemsCount() == 0) {
+        Q_EMIT setSelectionMode(true, SelectionModeBottomBar::Contents::MoveToTrashContents);
+    } else {
+        Q_EMIT actionBeingHandled();
+        m_currentView->trashSelectedItems();
+        Q_EMIT setSelectionMode(false);
+    }
 }
 
 void DolphinViewActionHandler::slotDeleteItems()
 {
-    Q_EMIT actionBeingHandled();
-    m_currentView->deleteSelectedItems();
+    if (m_currentView->selectedItemsCount() == 0) {
+        Q_EMIT setSelectionMode(true, SelectionModeBottomBar::Contents::DeleteContents);
+    } else {
+        Q_EMIT actionBeingHandled();
+        m_currentView->deleteSelectedItems();
+        Q_EMIT setSelectionMode(false);
+    }
 }
 
 void DolphinViewActionHandler::togglePreview(bool show)
@@ -455,7 +473,7 @@ void DolphinViewActionHandler::slotPreviewsShownChanged(bool shown)
 
 QString DolphinViewActionHandler::currentViewModeActionName() const
 {
-    switch (m_currentView->mode()) {
+    switch (m_currentView->viewMode()) {
     case DolphinView::IconsView:
         return QStringLiteral("icons");
     case DolphinView::DetailsView:
@@ -735,8 +753,13 @@ void DolphinViewActionHandler::slotAdjustViewProperties()
 
 void DolphinViewActionHandler::slotDuplicate()
 {
-    Q_EMIT actionBeingHandled();
-    m_currentView->duplicateSelectedItems();
+    if (m_currentView->selectedItemsCount() == 0) {
+        Q_EMIT setSelectionMode(true, SelectionModeBottomBar::Contents::DuplicateContents);
+    } else {
+        Q_EMIT actionBeingHandled();
+        m_currentView->duplicateSelectedItems();
+        Q_EMIT setSelectionMode(false);
+    }
 }
 
 void DolphinViewActionHandler::slotProperties()
@@ -758,7 +781,12 @@ void DolphinViewActionHandler::slotProperties()
 
 void DolphinViewActionHandler::slotCopyPath()
 {
-    m_currentView->copyPathToClipboard();
+    if (m_currentView->selectedItemsCount() == 0) {
+        Q_EMIT setSelectionMode(true, SelectionModeBottomBar::Contents::CopyLocationContents);
+    } else {
+        m_currentView->copyPathToClipboard();
+        Q_EMIT setSelectionMode(false);
+    }
 }
 
 void DolphinViewActionHandler::slotSelectionChanged(const KFileItemList& selection)
diff --git a/src/views/dolphinviewactionhandler.h b/src/views/dolphinviewactionhandler.h
index 6e9b4a432..f35512a5f 100644
--- a/src/views/dolphinviewactionhandler.h
+++ b/src/views/dolphinviewactionhandler.h
@@ -10,6 +10,7 @@
 #define DOLPHINVIEWACTIONHANDLER_H
 
 #include "dolphin_export.h"
+#include "selectionmode/selectionmodebottombar.h"
 #include "views/dolphinview.h"
 
 #include <QObject>
@@ -83,6 +84,9 @@ Q_SIGNALS:
      */
     void createDirectoryTriggered();
 
+    /** Used to request selection mode */
+    void setSelectionMode(bool enabled, SelectionModeBottomBar::Contents bottomBarContents = SelectionModeBottomBar::Contents::GeneralContents);
+
 private Q_SLOTS:
     /**
      * Emitted when the user requested a change of view mode