Return correct hit-test values for title bar buttons on Windows (#4994)

Co-authored-by: Rasmus Karlsson <rasmus.karlsson@pajlada.com>

src/widgets/helper/TitlebarButton.cpp

@@ -124,4 +124,39 @@ void TitleBarButton::paintEvent(QPaintEvent *event)
     this->paintButton(painter);
 }
 
+void TitleBarButton::ncEnter()
+{
+    this->enterEvent(nullptr);
+    this->update();
+}
+
+void TitleBarButton::ncLeave()
+{
+    this->leaveEvent(nullptr);
+    this->update();
+}
+
+void TitleBarButton::ncMove(QPoint at)
+{
+    QMouseEvent evt(QMouseEvent::MouseMove, at, Qt::NoButton, Qt::NoButton,
+                    Qt::NoModifier);
+    this->mouseMoveEvent(&evt);
+}
+
+void TitleBarButton::ncMousePress(QPoint at)
+{
+    QMouseEvent evt(QMouseEvent::MouseButtonPress, at, Qt::LeftButton,
+                    Qt::NoButton, Qt::NoModifier);
+    this->mousePressEvent(&evt);
+    this->update();
+}
+
+void TitleBarButton::ncMouseRelease(QPoint at)
+{
+    QMouseEvent evt(QMouseEvent::MouseButtonRelease, at, Qt::LeftButton,
+                    Qt::NoButton, Qt::NoModifier);
+    this->mouseReleaseEvent(&evt);
+    this->update();
+}
+
 }  // namespace chatterino

src/widgets/helper/TitlebarButton.hpp

@@ -23,6 +23,24 @@ public:
     TitleBarButtonStyle getButtonStyle() const;
     void setButtonStyle(TitleBarButtonStyle style_);
 
+    /// Simulate a `mouseEnter` event.
+    void ncEnter();
+
+    /// Simulate a `mouseLeave` event.
+    void ncLeave();
+
+    /// Simulate a `mouseMove` event.
+    /// @param at a local position relative to this widget
+    void ncMove(QPoint at);
+
+    /// Simulate a `mousePress` event with the left mouse button.
+    /// @param at a local position relative to this widget
+    void ncMousePress(QPoint at);
+
+    /// Simulate a `mouseRelease` event with the left mouse button.
+    /// @param at a local position relative to this widget
+    void ncMouseRelease(QPoint at);
+
 protected:
     void paintEvent(QPaintEvent *) override;
 

src/widgets/helper/TitlebarButtons.cpp

@@ -0,0 +1,116 @@
+#include "widgets/helper/TitlebarButtons.hpp"
+
+#ifdef USEWINSDK
+
+#    include "widgets/helper/TitlebarButton.hpp"
+
+#    include <Windows.h>
+
+#    include <cassert>
+
+namespace chatterino {
+
+TitleBarButtons::TitleBarButtons(QWidget *window, TitleBarButton *minButton,
+                                 TitleBarButton *maxButton,
+                                 TitleBarButton *closeButton)
+    : QObject(window)
+    , window_(window)
+    , minButton_(minButton)
+    , maxButton_(maxButton)
+    , closeButton_(closeButton)
+{
+}
+
+void TitleBarButtons::hover(size_t ht, QPoint at)
+{
+    TitleBarButton *hovered{};
+    TitleBarButton *other1{};
+    TitleBarButton *other2{};
+    switch (ht)
+    {
+        case HTMAXBUTTON:
+            hovered = this->maxButton_;
+            other1 = this->minButton_;
+            other2 = this->closeButton_;
+            break;
+        case HTMINBUTTON:
+            hovered = this->minButton_;
+            other1 = this->maxButton_;
+            other2 = this->closeButton_;
+            break;
+        case HTCLOSE:
+            hovered = this->closeButton_;
+            other1 = this->minButton_;
+            other2 = this->maxButton_;
+            break;
+        default:
+            assert(false && "TitleBarButtons::hover precondition violated");
+            return;
+    }
+    hovered->ncEnter();
+    hovered->ncMove(hovered->mapFromGlobal(at));
+    other1->ncLeave();
+    other2->ncLeave();
+}
+
+void TitleBarButtons::leave()
+{
+    this->minButton_->ncLeave();
+    this->maxButton_->ncLeave();
+    this->closeButton_->ncLeave();
+}
+
+void TitleBarButtons::mousePress(size_t ht, QPoint at)
+{
+    auto *button = this->buttonForHt(ht);
+    button->ncMousePress(button->mapFromGlobal(at));
+}
+
+void TitleBarButtons::mouseRelease(size_t ht, QPoint at)
+{
+    auto *button = this->buttonForHt(ht);
+    button->ncMouseRelease(button->mapFromGlobal(at));
+}
+
+void TitleBarButtons::updateMaxButton()
+{
+    this->maxButton_->setButtonStyle(
+        this->window_->windowState().testFlag(Qt::WindowMaximized)
+            ? TitleBarButtonStyle::Unmaximize
+            : TitleBarButtonStyle::Maximize);
+}
+
+void TitleBarButtons::setSmallSize()
+{
+    this->minButton_->setScaleIndependantSize(30, 30);
+    this->maxButton_->setScaleIndependantSize(30, 30);
+    this->closeButton_->setScaleIndependantSize(30, 30);
+}
+
+void TitleBarButtons::setRegularSize()
+{
+    this->minButton_->setScaleIndependantSize(46, 30);
+    this->maxButton_->setScaleIndependantSize(46, 30);
+    this->closeButton_->setScaleIndependantSize(46, 30);
+}
+
+TitleBarButton *TitleBarButtons::buttonForHt(size_t ht) const
+{
+    switch (ht)
+    {
+        case HTMAXBUTTON:
+            return this->maxButton_;
+        case HTMINBUTTON:
+            return this->minButton_;
+        case HTCLOSE:
+            return this->closeButton_;
+        default:
+            assert(false &&
+                   "TitleBarButtons::buttonForHt precondition violated");
+            return nullptr;
+    }
+}
+
+}  // namespace chatterino
+
+#endif

src/widgets/helper/TitlebarButtons.hpp

@@ -0,0 +1,69 @@
+#pragma once
+
+class QPoint;
+class QWidget;
+
+#include <QtGlobal>
+
+namespace chatterino {
+
+#ifdef USEWINSDK
+
+class TitleBarButton;
+class TitleBarButtons : QObject
+{
+public:
+    /// The parent of this object is set to `window`.
+    ///
+    /// All parameters must have a parent;
+    /// they're not deleted in the destructor.
+    TitleBarButtons(QWidget *window, TitleBarButton *minButton,
+                    TitleBarButton *maxButton, TitleBarButton *closeButton);
+
+    /// Hover over the button `ht` at the global position `at`.
+    ///
+    /// @pre `ht` must be one of { HTMAXBUTTON, HTMINBUTTON, HTCLOSE }.
+    /// @param ht The hovered button
+    /// @param at The global position of the event
+    void hover(size_t ht, QPoint at);
+
+    /// Leave all buttons - simulate `leaveEvent` for all buttons.
+    void leave();
+
+    /// Press the left mouse over the button `ht` at the global position `at`.
+    ///
+    /// @pre `ht` must be one of { HTMAXBUTTON, HTMINBUTTON, HTCLOSE }.
+    /// @param ht The clicked button
+    /// @param at The global position of the event
+    void mousePress(size_t ht, QPoint at);
+
+    /// Release the left mouse button over the button `ht` at the
+    /// global position `at`.
+    ///
+    /// @pre `ht` must be one of { HTMAXBUTTON, HTMINBUTTON, HTCLOSE }.
+    /// @param ht The clicked button
+    /// @param at The global position of the event
+    void mouseRelease(size_t ht, QPoint at);
+
+    /// Update the maximize/restore button to show the correct image
+    /// according to the current window state.
+    void updateMaxButton();
+
+    /// Set buttons to be narrow.
+    void setSmallSize();
+    /// Set buttons to be regular size.
+    void setRegularSize();
+
+private:
+    /// @pre ht must be one of { HTMAXBUTTON, HTMINBUTTON, HTCLOSE }.
+    TitleBarButton *buttonForHt(size_t ht) const;
+
+    QWidget *window_ = nullptr;
+    TitleBarButton *minButton_ = nullptr;
+    TitleBarButton *maxButton_ = nullptr;
+    TitleBarButton *closeButton_ = nullptr;
+};
+
+#endif
+
+}  // namespace chatterino