feat: Add setting to hide scrollbar thumb (#5731)

Hiding the scrollbar thumb will disable all mouse click/drag interaction
in the scrollbar

src/widgets/OverlayWindow.cpp

@@ -126,7 +126,7 @@ OverlayWindow::OverlayWindow(IndirectChannel channel,
     this->holder_.managedConnect(this->channel_.getChannelChanged(), [this]() {
         this->channelView_.setChannel(this->channel_.get());
     });
-    this->channelView_.scrollbar()->setShowThumb(false);
+    this->channelView_.scrollbar()->setHideThumb(true);
 
     this->setAutoFillBackground(false);
     this->resize(300, 500);

src/widgets/Scrollbar.cpp

@@ -41,6 +41,13 @@ Scrollbar::Scrollbar(size_t messagesLimit, ChannelView *parent)
             &Scrollbar::resetBounds);
 
     this->setMouseTracking(true);
+
+    getSettings()->hideScrollbarThumb.connect(
+        [this](bool newValue) {
+            this->settingHideThumb = newValue;
+            this->update();
+        },
+        this->signalHolder);
 }
 
 boost::circular_buffer<ScrollbarHighlight> Scrollbar::getHighlights() const
@@ -285,7 +292,7 @@ void Scrollbar::paintEvent(QPaintEvent * /*event*/)
     bool enableElevatedMessageHighlights =
         getSettings()->enableElevatedMessageHighlight;
 
-    if (this->showThumb_)
+    if (this->shouldShowThumb())
     {
         this->thumbRect_.setX(xOffset);
 
@@ -369,6 +376,11 @@ void Scrollbar::resizeEvent(QResizeEvent * /*event*/)
 
 void Scrollbar::mouseMoveEvent(QMouseEvent *event)
 {
+    if (!this->shouldHandleMouseEvents())
+    {
+        return;
+    }
+
     if (this->mouseDownLocation_ == MouseLocation::Outside)
     {
         auto moveLocation = this->locationOfMouseEvent(event);
@@ -394,12 +406,22 @@ void Scrollbar::mouseMoveEvent(QMouseEvent *event)
 
 void Scrollbar::mousePressEvent(QMouseEvent *event)
 {
+    if (!this->shouldHandleMouseEvents())
+    {
+        return;
+    }
+
     this->mouseDownLocation_ = this->locationOfMouseEvent(event);
     this->update();
 }
 
 void Scrollbar::mouseReleaseEvent(QMouseEvent *event)
 {
+    if (!this->shouldHandleMouseEvents())
+    {
+        return;
+    }
+
     auto releaseLocation = this->locationOfMouseEvent(event);
     if (this->mouseDownLocation_ != releaseLocation)
     {
@@ -452,17 +474,27 @@ void Scrollbar::updateScroll()
     this->update();
 }
 
-void Scrollbar::setShowThumb(bool showThumb)
+void Scrollbar::setHideThumb(bool hideThumb)
 {
-    if (this->showThumb_ == showThumb)
+    if (this->hideThumb == hideThumb)
     {
         return;
     }
 
-    this->showThumb_ = showThumb;
+    this->hideThumb = hideThumb;
     this->update();
 }
 
+bool Scrollbar::shouldShowThumb() const
+{
+    return !(this->hideThumb || this->settingHideThumb);
+}
+
+bool Scrollbar::shouldHandleMouseEvents() const
+{
+    return this->shouldShowThumb();
+}
+
 Scrollbar::MouseLocation Scrollbar::locationOfMouseEvent(
     QMouseEvent *event) const
 {

src/widgets/Scrollbar.hpp

@@ -5,6 +5,7 @@
 
 #include <boost/circular_buffer.hpp>
 #include <pajlada/signals/signal.hpp>
+#include <pajlada/signals/signalholder.hpp>
 #include <QPropertyAnimation>
 #include <QWidget>
 
@@ -127,7 +128,12 @@ public:
     /// unaffected by simultaneous shifts of minimum and maximum.
     qreal getRelativeCurrentValue() const;
 
-    void setShowThumb(bool showthumb);
+    void setHideThumb(bool hideThumb);
+
+    /// Returns true if we should show the thumb (the handle you can drag)
+    bool shouldShowThumb() const;
+
+    bool shouldHandleMouseEvents() const;
 
     // offset the desired value without breaking smooth scolling
     void offset(qreal value);
@@ -171,7 +177,9 @@ private:
     boost::circular_buffer<ScrollbarHighlight> highlights_;
 
     bool atBottom_{false};
-    bool showThumb_ = true;
+    bool hideThumb{false};
+    /// Controlled by the "Hide scrollbar thumb" setting
+    bool settingHideThumb{false};
 
     MouseLocation mouseOverLocation_ = MouseLocation::Outside;
     MouseLocation mouseDownLocation_ = MouseLocation::Outside;
@@ -189,6 +197,8 @@ private:
 
     pajlada::Signals::NoArgSignal currentValueChanged_;
     pajlada::Signals::NoArgSignal desiredValueChanged_;
+
+    pajlada::Signals::SignalHolder signalHolder;
 };
 
 }  // namespace chatterino

src/widgets/settingspages/GeneralPage.cpp

@@ -458,6 +458,11 @@ void GeneralPage::initLayout(GeneralPageView &layout)
         },
         false);
 
+    layout.addCheckbox(
+        "Hide scrollbar thumb", s.hideScrollbarThumb, false,
+        "Hiding the scrollbar thumb (the handle you can drag) will disable "
+        "all mouse interaction in the scrollbar.");
+
     layout.addTitle("Messages");
     layout.addCheckbox(
         "Separate with lines", s.separateMessages, false,