Fix scrollbar

src/widgets/chatwidgetview.cpp

@@ -8,10 +8,11 @@
 #include "util/distancebetweenpoints.h"
 #include "widgets/chatwidget.h"
 
-#include <math.h>
 #include <QDebug>
 #include <QGraphicsBlurEffect>
 #include <QPainter>
+
+#include <math.h>
 #include <chrono>
 #include <functional>
 
@@ -19,7 +20,7 @@ namespace chatterino {
 namespace widgets {
 
 ChatWidgetView::ChatWidgetView(ChatWidget *parent)
-    : QWidget()
+    : QWidget(parent)
     , _chatWidget(parent)
     , _scrollbar(this)
     , _userPopupWidget(_chatWidget->getChannelRef())
@@ -34,7 +35,10 @@ ChatWidgetView::ChatWidgetView(ChatWidget *parent)
     QObject::connect(&SettingsManager::getInstance(), &SettingsManager::wordTypeMaskChanged, this,
                      &ChatWidgetView::wordTypeMaskChanged);
 
-    _scrollbar.getCurrentValueChanged().connect([this] { update(); });
+    _scrollbar.getCurrentValueChanged().connect([this] {
+        // Whenever the scrollbar value has been changed, re-render the ChatWidgetView
+        this->update();
+    });
 }
 
 ChatWidgetView::~ChatWidgetView()
@@ -55,6 +59,15 @@ bool ChatWidgetView::layoutMessages()
 
     bool showScrollbar = false, redraw = false;
 
+    // Bool indicating whether or not we were showing all messages
+    // True if one of the following statements are true:
+    // The scrollbar was not visible
+    // The scrollbar was visible and at the bottom
+    bool showingLatestMessages = false;
+    if (this->_scrollbar.isAtBottom() || !this->_scrollbar.isVisible()) {
+        showingLatestMessages = true;
+    }
+
     int start = _scrollbar.getCurrentValue();
     int layoutWidth = _scrollbar.isVisible() ? width() - _scrollbar.width() : width();
 
@@ -102,13 +115,22 @@ bool ChatWidgetView::layoutMessages()
 
     _scrollbar.setMaximum(messages.getSize());
 
+    if (showingLatestMessages && showScrollbar) {
+        // If we were showing the latest messages and the scrollbar now wants to be rendered, scroll
+        // to bottom
+        // TODO: Do we want to check if the user is currently moving the scrollbar?
+        // Perhaps also if the user scrolled with the scrollwheel in this ChatWidget in the last 0.2
+        // seconds or something
+        this->_scrollbar.scrollToBottom();
+    }
+
     return redraw;
 }
 
 void ChatWidgetView::updateGifEmotes()
 {
     _onlyUpdateEmotes = true;
-    update();
+    this->update();
 }
 
 ScrollBar *ChatWidgetView::getScrollbar()
@@ -123,7 +145,7 @@ void ChatWidgetView::resizeEvent(QResizeEvent *)
 
     layoutMessages();
 
-    update();
+    this->update();
 }
 
 void ChatWidgetView::paintEvent(QPaintEvent *event)
@@ -403,5 +425,6 @@ bool ChatWidgetView::tryGetMessageAt(QPoint p, std::shared_ptr<messages::Message
 
     return false;
 }
+
 }  // namespace widgets
 }  // namespace chatterino

src/widgets/chatwidgetview.h

@@ -1,5 +1,4 @@
-#ifndef CHATVIEW_H
+#pragma once
-#define CHATVIEW_H
 
 #include "channel.h"
 #include "messages/lazyloadedimage.h"
@@ -67,7 +66,6 @@ private slots:
         update();
     }
 };
+
 }  // namespace widgets
 }  // namespace chatterino
-
-#endif  // CHATVIEW_H

src/widgets/scrollbar.cpp

@@ -1,6 +1,7 @@
 #include "widgets/scrollbar.h"
 #include "colorscheme.h"
 
+#include <QDebug>
 #include <QMouseEvent>
 #include <QPainter>
 
@@ -88,6 +89,16 @@ void ScrollBar::addHighlight(ScrollBarHighlight *highlight)
     _mutex.unlock();
 }
 
+void ScrollBar::scrollToBottom()
+{
+    this->setDesiredValue(this->_maximum - this->getLargeChange());
+}
+
+bool ScrollBar::isAtBottom() const
+{
+    return this->getCurrentValue() == this->getMaximum() - this->getLargeChange();
+}
+
 void ScrollBar::setMaximum(qreal value)
 {
     _maximum = value;
@@ -188,6 +199,15 @@ void ScrollBar::setCurrentValue(qreal value)
     }
 }
 
+void ScrollBar::printCurrentState(const QString &prefix) const
+{
+    qDebug() << prefix                                         //
+             << "Current value: " << this->getCurrentValue()   //
+             << ". Maximum: " << this->getMaximum()            //
+             << ". Minimum: " << this->getMinimum()            //
+             << ". Large change: " << this->getLargeChange();  //
+}
+
 void ScrollBar::paintEvent(QPaintEvent *)
 {
     QPainter painter(this);
@@ -301,5 +321,6 @@ void ScrollBar::updateScroll()
 
     update();
 }
-}
+
-}
+}  // namespace widgets
+}  // namespace chatterino

src/widgets/scrollbar.h

@@ -1,5 +1,4 @@
-#ifndef SCROLLBAR_H
+#pragma once
-#define SCROLLBAR_H
 
 #include "widgets/scrollbarhighlight.h"
 
@@ -7,7 +6,6 @@
 #include <QPropertyAnimation>
 #include <QWidget>
 #include <boost/signals2.hpp>
-#include <functional>
 
 namespace chatterino {
 namespace widgets {
@@ -25,6 +23,10 @@ public:
 
     Q_PROPERTY(qreal _desiredValue READ getDesiredValue WRITE setDesiredValue)
 
+    void scrollToBottom();
+
+    bool isAtBottom() const;
+
     void setMaximum(qreal value);
     void setMinimum(qreal value);
     void setLargeChange(qreal value);
@@ -39,6 +41,8 @@ public:
     boost::signals2::signal<void()> &getCurrentValueChanged();
     void setCurrentValue(qreal value);
 
+    void printCurrentState(const QString &prefix = QString()) const;
+
 private:
     Q_PROPERTY(qreal _currentValue READ getCurrentValue WRITE setCurrentValue)
 
@@ -74,7 +78,6 @@ private:
 
     void updateScroll();
 };
-}
-}
 
-#endif  // SCROLLBAR_H
+}  // namespace widgets
+}  // namespace chatterino