From 283ede86ad14d19e075c9329241471299f717e1b Mon Sep 17 00:00:00 2001
From: nerix <nerixdev@outlook.de>
Date: Sun, 10 Sep 2023 17:08:13 +0200
Subject: [PATCH] Only layout visible `ChannelView`s (#4811)

---
 CHANGELOG.md                       |  1 +
 src/widgets/helper/ChannelView.cpp | 58 ++++++++++++++++++------------
 src/widgets/helper/ChannelView.hpp | 11 +++---
 3 files changed, 42 insertions(+), 28 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c8a25d80a..8af8f78a2 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -13,6 +13,7 @@
 - Dev: Do a pretty major refactor of the Settings classes. List settings (e.g. highlights) are most heavily modified, and should have an extra eye kept on them. (#4775)
 - Dev: Remove `boost::noncopyable` use & `boost_random` dependency. (#4776)
 - Dev: Fix clang-tidy `cppcoreguidelines-pro-type-member-init` warnings. (#4426)
+- Dev: Immediate layout for invisible `ChannelView`s is skipped. (#4811)
 
 ## 2.4.5
 
diff --git a/src/widgets/helper/ChannelView.cpp b/src/widgets/helper/ChannelView.cpp
index 0dcd55260..c8abae676 100644
--- a/src/widgets/helper/ChannelView.cpp
+++ b/src/widgets/helper/ChannelView.cpp
@@ -228,8 +228,15 @@ void ChannelView::initializeLayout()
 void ChannelView::initializeScrollbar()
 {
     this->scrollBar_->getCurrentValueChanged().connect([this] {
-        this->performLayout(true);
-        this->queueUpdate();
+        if (this->isVisible())
+        {
+            this->performLayout(true);
+            this->queueUpdate();
+        }
+        else
+        {
+            this->layoutQueued_ = true;
+        }
     });
 }
 
@@ -413,33 +420,35 @@ void ChannelView::scaleChangedEvent(float scale)
 
 void ChannelView::queueUpdate()
 {
-    //    if (this->updateTimer.isActive()) {
-    //        this->updateQueued = true;
-    //        return;
-    //    }
-
-    //    this->repaint();
-
     this->update();
-
-    //    this->updateTimer.start();
 }
 
 void ChannelView::queueLayout()
 {
-    //    if (!this->layoutCooldown->isActive()) {
-    this->performLayout();
-
-    //        this->layoutCooldown->start();
-    //    } else {
-    //        this->layoutQueued = true;
-    //    }
+    if (this->isVisible())
+    {
+        this->performLayout();
+    }
+    else
+    {
+        this->layoutQueued_ = true;
+    }
 }
 
-void ChannelView::performLayout(bool causedByScrollbar)
+void ChannelView::showEvent(QShowEvent * /*event*/)
+{
+    if (this->layoutQueued_)
+    {
+        this->performLayout(false, true);
+    }
+}
+
+void ChannelView::performLayout(bool causedByScrollbar, bool causedByShow)
 {
     // BenchmarkGuard benchmark("layout");
 
+    this->layoutQueued_ = false;
+
     /// Get messages and check if there are at least 1
     const auto &messages = this->getMessagesSnapshot();
 
@@ -451,7 +460,7 @@ void ChannelView::performLayout(bool causedByScrollbar)
     this->layoutVisibleMessages(messages);
 
     /// Update scrollbar
-    this->updateScrollbar(messages, causedByScrollbar);
+    this->updateScrollbar(messages, causedByScrollbar, causedByShow);
 
     this->goToBottom_->setVisible(this->enableScrollingToBottom_ &&
                                   this->scrollBar_->isVisible() &&
@@ -490,7 +499,7 @@ void ChannelView::layoutVisibleMessages(
 
 void ChannelView::updateScrollbar(
     const LimitedQueueSnapshot<MessageLayoutPtr> &messages,
-    bool causedByScrollbar)
+    bool causedByScrollbar, bool causedByShow)
 {
     if (messages.size() == 0)
     {
@@ -539,6 +548,7 @@ void ChannelView::updateScrollbar(
         showScrollbar && !causedByScrollbar)
     {
         this->scrollBar_->scrollToBottom(
+            !causedByShow &&
             getSettings()->enableSmoothScrollingNewMessages.getValue());
     }
 }
@@ -799,7 +809,7 @@ void ChannelView::setChannel(ChannelPtr underlyingChannel)
 
     this->underlyingChannel_ = underlyingChannel;
 
-    this->queueLayout();
+    this->performLayout();
     this->queueUpdate();
 
     // Notifications
@@ -903,6 +913,10 @@ void ChannelView::messageAppended(MessagePtr &message,
         else
         {
             this->scrollBar_->offsetMinimum(1);
+            if (this->showingLatestMessages_ && !this->isVisible())
+            {
+                this->scrollBar_->scrollToBottom(false);
+            }
             this->selection_.shiftMessageIndex(1);
         }
     }
diff --git a/src/widgets/helper/ChannelView.hpp b/src/widgets/helper/ChannelView.hpp
index f28abf408..1fb4c3941 100644
--- a/src/widgets/helper/ChannelView.hpp
+++ b/src/widgets/helper/ChannelView.hpp
@@ -181,6 +181,7 @@ protected:
     void mouseDoubleClickEvent(QMouseEvent *event) override;
 
     void hideEvent(QHideEvent *) override;
+    void showEvent(QShowEvent *event) override;
 
     void handleLinkClick(QMouseEvent *event, const Link &link,
                          MessageLayout *layout);
@@ -200,11 +201,12 @@ private:
     void messageReplaced(size_t index, MessagePtr &replacement);
     void messagesUpdated();
 
-    void performLayout(bool causedByScrollbar = false);
+    void performLayout(bool causedByScrollbar = false,
+                       bool causedByShow = false);
     void layoutVisibleMessages(
         const LimitedQueueSnapshot<MessageLayoutPtr> &messages);
     void updateScrollbar(const LimitedQueueSnapshot<MessageLayoutPtr> &messages,
-                         bool causedByScrollbar);
+                         bool causedByScrollbar, bool causedByShow);
 
     void drawMessages(QPainter &painter);
     void setSelection(const SelectionItem &start, const SelectionItem &end);
@@ -256,11 +258,8 @@ private:
     void showReplyThreadPopup(const MessagePtr &message);
     bool canReplyToMessages() const;
 
-    QTimer *layoutCooldown_{};
-    bool layoutQueued_{};
+    bool layoutQueued_ = false;
 
-    QTimer updateTimer_;
-    bool updateQueued_ = false;
     bool lastMessageHasAlternateBackground_ = false;
     bool lastMessageHasAlternateBackgroundReverse_ = true;