From a3b83b7f81192bdbeabb1ba8a7eed57beb4d4233 Mon Sep 17 00:00:00 2001
From: Le Tan <tamlokveer@gmail.com>
Date: Wed, 7 Dec 2016 22:53:02 +0800
Subject: [PATCH] dynamically show or hide left corner tab list widget

Signed-off-by: Le Tan <tamlokveer@gmail.com>
---
 src/veditwindow.cpp | 32 ++++++++++++++++++++++++++++++++
 src/veditwindow.h   |  4 ++++
 2 files changed, 36 insertions(+)

diff --git a/src/veditwindow.cpp b/src/veditwindow.cpp
index 88f286d2..841318bf 100644
--- a/src/veditwindow.cpp
+++ b/src/veditwindow.cpp
@@ -18,6 +18,8 @@ VEditWindow::VEditWindow(VNote *vnote, QWidget *parent)
     setMovable(true);
     setContextMenuPolicy(Qt::CustomContextMenu);
 
+    tabBar()->installEventFilter(this);
+
     connect(this, &VEditWindow::tabCloseRequested,
             this, &VEditWindow::handleTabCloseRequest);
     connect(this, &VEditWindow::tabBarClicked,
@@ -520,3 +522,33 @@ void VEditWindow::updateNotebookInfo(const VNotebook *p_notebook)
         }
     }
 }
+
+bool VEditWindow::eventFilter(QObject *watched, QEvent *event)
+{
+    if (event->type() == QEvent::Resize) {
+        setLeftCornerWidgetVisible(scrollerVisible());
+    }
+    return QTabWidget::eventFilter(watched, event);
+}
+
+bool VEditWindow::scrollerVisible() const
+{
+    QTabBar *bar = tabBar();
+    int barWidth = bar->width();
+    int nrTab = count();
+    int tabsWidth = 0;
+    for (int i = 0; i < nrTab; ++i) {
+        tabsWidth += bar->tabRect(i).width();
+    }
+    return tabsWidth > barWidth;
+}
+
+void VEditWindow::setLeftCornerWidgetVisible(bool p_visible)
+{
+    if (p_visible) {
+        setCornerWidget(leftBtn, Qt::TopLeftCorner);
+        leftBtn->setVisible(true);
+    } else {
+        setCornerWidget(NULL, Qt::TopLeftCorner);
+    }
+}
diff --git a/src/veditwindow.h b/src/veditwindow.h
index 4479caa4..ccedfa32 100644
--- a/src/veditwindow.h
+++ b/src/veditwindow.h
@@ -42,6 +42,7 @@ public:
 
 protected:
     void mousePressEvent(QMouseEvent *event) Q_DECL_OVERRIDE;
+    bool eventFilter(QObject *watched, QEvent *event) Q_DECL_OVERRIDE;
 
 signals:
     void tabStatusChanged(const VFile *p_file, bool p_editMode);
@@ -77,6 +78,9 @@ private:
     inline QString generateTooltip(const VFile *p_file) const;
     inline QString generateTabText(const QString &p_name, bool p_modified) const;
     bool canRemoveSplit();
+    // If the scroller of the tabBar() is visible.
+    bool scrollerVisible() const;
+    void setLeftCornerWidgetVisible(bool p_visible);
 
     VNote *vnote;
     // Button in the right corner