effects/overview: Make the window heap cover the maximize area

Currently, window thumbnails may be placed behind the panel, which
doesn't look good.

With this, the window heap will cover the same area as the maximize
area.

src/effects/CMakeLists.txt

@@ -86,6 +86,7 @@ set(kwin4_effect_builtins_sources
     magnifier/magnifier.cpp
     mouseclick/mouseclick.cpp
     mousemark/mousemark.cpp
+    overview/expoarea.cpp
     overview/expolayout.cpp
     overview/overvieweffect.cpp
     presentwindows/presentwindows.cpp

src/effects/overview/expoarea.cpp

@@ -0,0 +1,84 @@
+/*
+    SPDX-FileCopyrightText: 2021 Vlad Zahorodnii <vlad.zahorodnii@kde.org>
+
+    SPDX-License-Identifier: GPL-2.0-or-later
+*/
+
+#include "expoarea.h"
+
+namespace KWin
+{
+
+ExpoArea::ExpoArea(QObject *parent)
+    : QObject(parent)
+{
+}
+
+int ExpoArea::x() const
+{
+    return m_rect.x();
+}
+
+int ExpoArea::y() const
+{
+    return m_rect.y();
+}
+
+int ExpoArea::width() const
+{
+    return m_rect.width();
+}
+
+int ExpoArea::height() const
+{
+    return m_rect.height();
+}
+
+EffectScreen *ExpoArea::screen() const
+{
+    return m_screen;
+}
+
+void ExpoArea::setScreen(EffectScreen *screen)
+{
+    if (m_screen != screen) {
+        if (m_screen) {
+            disconnect(m_screen, &EffectScreen::geometryChanged, this, &ExpoArea::update);
+        }
+        m_screen = screen;
+        if (m_screen) {
+            connect(m_screen, &EffectScreen::geometryChanged, this, &ExpoArea::update);
+        }
+        update();
+        Q_EMIT screenChanged();
+    }
+}
+
+void ExpoArea::update()
+{
+    if (!m_screen) {
+        return;
+    }
+    const QRect oldRect = m_rect;
+
+    const int screen = effects->screens().indexOf(m_screen);
+    m_rect = effects->clientArea(MaximizeArea, screen, effects->currentDesktop());
+
+    // Map the area to the output local coordinates.
+    m_rect.translate(-m_screen->geometry().topLeft());
+
+    if (oldRect.x() != m_rect.x()) {
+        Q_EMIT xChanged();
+    }
+    if (oldRect.y() != m_rect.y()) {
+        Q_EMIT yChanged();
+    }
+    if (oldRect.width() != m_rect.width()) {
+        Q_EMIT widthChanged();
+    }
+    if (oldRect.height() != m_rect.height()) {
+        Q_EMIT heightChanged();
+    }
+}
+
+} // namespace KWin

src/effects/overview/expoarea.h

@@ -0,0 +1,48 @@
+/*
+    SPDX-FileCopyrightText: 2021 Vlad Zahorodnii <vlad.zahorodnii@kde.org>
+
+    SPDX-License-Identifier: GPL-2.0-or-later
+*/
+
+#pragma once
+
+#include <kwineffects.h>
+
+namespace KWin
+{
+
+class ExpoArea : public QObject
+{
+    Q_OBJECT
+    Q_PROPERTY(KWin::EffectScreen *screen READ screen WRITE setScreen NOTIFY screenChanged)
+    Q_PROPERTY(int x READ x NOTIFY xChanged)
+    Q_PROPERTY(int y READ y NOTIFY yChanged)
+    Q_PROPERTY(int width READ width NOTIFY widthChanged)
+    Q_PROPERTY(int height READ height NOTIFY heightChanged)
+
+public:
+    explicit ExpoArea(QObject *parent = nullptr);
+
+    EffectScreen *screen() const;
+    void setScreen(EffectScreen *screen);
+
+    int x() const;
+    int y() const;
+    int width() const;
+    int height() const;
+
+Q_SIGNALS:
+    void screenChanged();
+    void xChanged();
+    void yChanged();
+    void widthChanged();
+    void heightChanged();
+
+private:
+    void update();
+
+    QRect m_rect;
+    EffectScreen *m_screen = nullptr;
+};
+
+} // namespace KWin

src/effects/overview/overvieweffect.cpp

@@ -5,6 +5,7 @@
 */
 
 #include "overvieweffect.h"
+#include "expoarea.h"
 #include "expolayout.h"
 #include "overviewconfig.h"
 
@@ -64,6 +65,7 @@ void OverviewScreenView::stop()
 OverviewEffect::OverviewEffect()
     : m_shutdownTimer(new QTimer(this))
 {
+    qmlRegisterType<ExpoArea>("org.kde.kwin.private.overview", 1, 0, "ExpoArea");
     qmlRegisterType<ExpoLayout>("org.kde.kwin.private.overview", 1, 0, "ExpoLayout");
     qmlRegisterType<ExpoCell>("org.kde.kwin.private.overview", 1, 0, "ExpoCell");
 

src/effects/overview/qml/ScreenView.qml

@@ -6,6 +6,7 @@
 
 import QtQuick 2.12
 import org.kde.kwin 3.0 as KWinComponents
+import org.kde.kwin.private.overview 1.0
 import org.kde.plasma.core 2.0 as PlasmaCore
 
 FocusScope {
@@ -64,8 +65,16 @@ FocusScope {
         }
     }
 
+    ExpoArea {
+        id: heapArea
+        screen: targetScreen
+    }
+
     WindowHeap {
-        anchors.fill: parent
+        x: heapArea.x
+        y: heapArea.y
+        width: heapArea.width
+        height: heapArea.height
         focus: true
         organized: container.organized
         model: KWinComponents.ClientFilterModel {