Improve Filelight installation UX

Before this commit pressing the free space button when Filelight
is not installed would show a singular action called "Install
Filelight to View Disk Usage Statistics…". Pressing this button
would open the store page for Filelight. This is an okay user
experience, but we can do better.

This commit makes it so pressing the free space button when
Filelight is not installed shows an attractive UI that makes clear
that freeing up disk space can be accomplished nicely by installing
Filelight. The "Install Filelight…" button on this UI is connected
to PackageKit directly, so we do not need to show a separate store
like Discover and instead trigger an installation right then and
there. For this, the recently introduced DolphinPackageInstaller
KJob is used.

Installation progress is reported through the status bar similar to
the progress reporting of slowly loading directories or searches.
Installation failure or success is ultimately shown within Dolphin
as a passive notification above the view.

On Microsoft Windows or when PackageKit is not available, the
install button will only open a store page for Filelight.

CCBUG: 477739

1 files changed, 32 insertions, 0 deletions

diff --git a/src/statusbar/statusbarspaceinfo.h b/src/statusbar/statusbarspaceinfo.h
index 23a77d045..237192c9c 100644
--- a/src/statusbar/statusbarspaceinfo.h
+++ b/src/statusbar/statusbarspaceinfo.h
@@ -6,6 +6,8 @@
 #ifndef STATUSBARSPACEINFO_H
 #define STATUSBARSPACEINFO_H
 
+#include <KMessageWidget>
+
 #include <QUrl>
 #include <QWidget>
 
@@ -14,6 +16,7 @@ class QShowEvent;
 class QMenu;
 class QMouseEvent;
 class QToolButton;
+class QWidgetAction;
 
 class KCapacityBar;
 
@@ -40,6 +43,19 @@ public:
 
     void update();
 
+Q_SIGNALS:
+    /**
+     * Requests for @p message with the given @p messageType to be shown to the user in a non-modal way.
+     */
+    void showMessage(const QString &message, KMessageWidget::MessageType messageType);
+
+    /**
+     * Requests for a progress update to be shown to the user in a non-modal way.
+     * @param currentlyRunningTaskTitle     The task that is currently progressing.
+     * @param installationProgressPercent   The current percentage of completion.
+     */
+    void showInstallationProgress(const QString &currentlyRunningTaskTitle, int installationProgressPercent);
+
 protected:
     void showEvent(QShowEvent *event) override;
     void hideEvent(QHideEvent *event) override;
@@ -48,13 +64,29 @@ protected:
     void updateMenu();
 
 private Q_SLOTS:
+    /**
+     * Asynchronously starts a Filelight installation using DolphinPackageInstaller. @see DolphinPackageInstaller.
+     * Installation success or failure is reported through showMessage(). @see StatusBarSpaceInfo::showMessage().
+     * Installation progress is reported through showInstallationProgress(). @see StatusBarSpaceInfo::showInstallationProgress().
+     */
+    void slotInstallFilelightButtonClicked();
+
     void slotValuesChanged();
 
 private:
+    /**
+     * Creates a new QWidgetAction that contains a UI to install Filelight.
+     * m_installFilelightWidgetAction is initialised after calling this method once.
+     */
+    void initialiseInstallFilelightWidgetAction();
+
+private:
     QScopedPointer<SpaceInfoObserver> m_observer;
     KCapacityBar *m_capacityBar;
     QToolButton *m_textInfoButton;
     QMenu *m_buttonMenu;
+    /** An action containing a UI to install Filelight. */
+    QWidgetAction *m_installFilelightWidgetAction;
     QUrl m_url;
     bool m_ready;
     bool m_shown;