refactor(capslockindicator): encapsulate event handling

Use an event filter on QCoreApplication instead of requiring the caller
to manually call updateIndicator() when the caps lock state changed.

src/widget/capslockindicator.cpp

@@ -2,6 +2,7 @@
 #ifdef QTOX_PLATFORM_EXT
 #include "src/platform/capslock.h"
 #endif
+#include <QCoreApplication>
 
 CapsLockIndicator::CapsLockIndicator(QLineEdit *parent) :
     QAction(parent),
@@ -9,6 +10,8 @@ CapsLockIndicator::CapsLockIndicator(QLineEdit *parent) :
 {
     setIcon(QIcon(":img/caps_lock.svg"));
     setToolTip(tr("CAPS-LOCK ENABLED"));
+
+    QCoreApplication::instance()->installEventFilter(this);
 }
 
 void CapsLockIndicator::updateIndicator()
@@ -24,3 +27,21 @@ void CapsLockIndicator::updateIndicator()
     else
         parent->removeAction(this);
 }
+
+bool CapsLockIndicator::eventFilter(QObject *obj, QEvent *event)
+{
+    switch (event->type())
+    {
+    case QEvent::Show:
+        if (obj == this)
+            updateIndicator();
+        break;
+    case QEvent::KeyRelease:
+        updateIndicator();
+        break;
+    default:
+        break;
+    }
+
+    return QAction::eventFilter(obj, event);
+}

src/widget/capslockindicator.h

@@ -8,6 +8,11 @@ class CapsLockIndicator : QAction
 {
 public:
     CapsLockIndicator(QLineEdit *widget);
+
+protected:
+    bool eventFilter(QObject *obj, QEvent *event);
+
+private:
     void updateIndicator();
 
 private:

src/widget/loginscreen.cpp

@@ -120,11 +120,6 @@ bool LoginScreen::event(QEvent* event)
         emit windowStateChanged(windowState());
         break;
 #endif
-    case QEvent::Show:
-    case QEvent::KeyRelease:
-        capsIndicator->updateIndicator();
-        confimCapsIndicator->updateIndicator();
-        break;
     default:
         break;
     }