1 files changed, 203 insertions, 0 deletions
diff --git a/src/plugins/platforms/wasm/qwasmwindowstack.cpp b/src/plugins/platforms/wasm/qwasmwindowstack.cpp
new file mode 100644
index 0000000000..d3769c7a1b
--- /dev/null
+++ b/src/plugins/platforms/wasm/qwasmwindowstack.cpp
@@ -0,0 +1,203 @@
+// Copyright (C) 2022 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR GPL-3.0-only
+
+#include "qwasmwindowstack.h"
+
+QT_BEGIN_NAMESPACE
+
+QWasmWindowStack::QWasmWindowStack(WindowOrderChangedCallbackType windowOrderChangedCallback)
+    : m_windowOrderChangedCallback(std::move(windowOrderChangedCallback)),
+      m_regularWindowsBegin(m_windowStack.begin()),
+      m_alwaysOnTopWindowsBegin(m_windowStack.begin())
+{
+}
+
+QWasmWindowStack::~QWasmWindowStack() = default;
+
+void QWasmWindowStack::pushWindow(QWasmWindow *window, PositionPreference position)
+{
+    Q_ASSERT(m_windowStack.count(window) == 0);
+
+    if (position == PositionPreference::StayOnTop) {
+        const auto stayOnTopDistance =
+                std::distance(m_windowStack.begin(), m_alwaysOnTopWindowsBegin);
+        const auto regularDistance = std::distance(m_windowStack.begin(), m_regularWindowsBegin);
+        m_windowStack.push_back(window);
+        m_alwaysOnTopWindowsBegin = m_windowStack.begin() + stayOnTopDistance;
+        m_regularWindowsBegin = m_windowStack.begin() + regularDistance;
+    } else if (position == PositionPreference::Regular) {
+        const auto regularDistance = std::distance(m_windowStack.begin(), m_regularWindowsBegin);
+        m_alwaysOnTopWindowsBegin = m_windowStack.insert(m_alwaysOnTopWindowsBegin, window) + 1;
+        m_regularWindowsBegin = m_windowStack.begin() + regularDistance;
+    } else {
+        const auto stayOnTopDistance =
+                std::distance(m_windowStack.begin(), m_alwaysOnTopWindowsBegin);
+        m_regularWindowsBegin = m_windowStack.insert(m_regularWindowsBegin, window) + 1;
+        m_alwaysOnTopWindowsBegin = m_windowStack.begin() + stayOnTopDistance + 1;
+    }
+
+    m_windowOrderChangedCallback();
+}
+
+void QWasmWindowStack::removeWindow(QWasmWindow *window)
+{
+    Q_ASSERT(m_windowStack.count(window) == 1);
+
+    auto it = std::find(m_windowStack.begin(), m_windowStack.end(), window);
+    const auto position = getWindowPositionPreference(it);
+    const auto stayOnTopDistance = std::distance(m_windowStack.begin(), m_alwaysOnTopWindowsBegin);
+    const auto regularDistance = std::distance(m_windowStack.begin(), m_regularWindowsBegin);
+
+    m_windowStack.erase(it);
+
+    m_alwaysOnTopWindowsBegin = m_windowStack.begin() + stayOnTopDistance
+            - (position != PositionPreference::StayOnTop ? 1 : 0);
+    m_regularWindowsBegin = m_windowStack.begin() + regularDistance
+            - (position == PositionPreference::StayOnBottom ? 1 : 0);
+
+    m_windowOrderChangedCallback();
+}
+
+void QWasmWindowStack::raise(QWasmWindow *window)
+{
+    Q_ASSERT(m_windowStack.count(window) == 1);
+
+    if (window == topWindow())
+        return;
+
+    auto it = std::find(m_windowStack.begin(), m_windowStack.end(), window);
+    auto itEnd = ([this, position = getWindowPositionPreference(it)]() {
+        switch (position) {
+        case PositionPreference::StayOnTop:
+            return m_windowStack.end();
+        case PositionPreference::Regular:
+            return m_alwaysOnTopWindowsBegin;
+        case PositionPreference::StayOnBottom:
+            return m_regularWindowsBegin;
+        }
+    })();
+    std::rotate(it, it + 1, itEnd);
+    m_windowOrderChangedCallback();
+}
+
+void QWasmWindowStack::lower(QWasmWindow *window)
+{
+    Q_ASSERT(m_windowStack.count(window) == 1);
+
+    if (window == *m_windowStack.begin())
+        return;
+
+    auto it = std::find(m_windowStack.begin(), m_windowStack.end(), window);
+    auto itBegin = ([this, position = getWindowPositionPreference(it)]() {
+        switch (position) {
+        case PositionPreference::StayOnTop:
+            return m_alwaysOnTopWindowsBegin;
+        case PositionPreference::Regular:
+            return m_regularWindowsBegin;
+        case PositionPreference::StayOnBottom:
+            return m_windowStack.begin();
+        }
+    })();
+
+    std::rotate(itBegin, it, it + 1);
+    m_windowOrderChangedCallback();
+}
+
+void QWasmWindowStack::windowPositionPreferenceChanged(QWasmWindow *window,
+                                                       PositionPreference position)
+{
+    auto it = std::find(m_windowStack.begin(), m_windowStack.end(), window);
+    const auto currentPosition = getWindowPositionPreference(it);
+
+    const auto zones = static_cast<int>(position) - static_cast<int>(currentPosition);
+    Q_ASSERT(zones != 0);
+
+    if (zones < 0) {
+        // Perform right rotation so that the window lands on top of regular windows
+        const auto begin = std::make_reverse_iterator(it + 1);
+        const auto end = position == PositionPreference::Regular
+                ? std::make_reverse_iterator(m_alwaysOnTopWindowsBegin)
+                : std::make_reverse_iterator(m_regularWindowsBegin);
+        std::rotate(begin, begin + 1, end);
+        if (zones == -2) {
+            ++m_alwaysOnTopWindowsBegin;
+            ++m_regularWindowsBegin;
+        } else if (position == PositionPreference::Regular) {
+            ++m_alwaysOnTopWindowsBegin;
+        } else {
+            ++m_regularWindowsBegin;
+        }
+    } else {
+        // Perform left rotation so that the window lands at the bottom of always on top windows
+        const auto begin = it;
+        const auto end = position == PositionPreference::Regular ? m_regularWindowsBegin
+                                                                 : m_alwaysOnTopWindowsBegin;
+        std::rotate(begin, begin + 1, end);
+        if (zones == 2) {
+            --m_alwaysOnTopWindowsBegin;
+            --m_regularWindowsBegin;
+        } else if (position == PositionPreference::Regular) {
+            --m_regularWindowsBegin;
+        } else {
+            --m_alwaysOnTopWindowsBegin;
+        }
+    }
+    m_windowOrderChangedCallback();
+}
+
+QWasmWindowStack::iterator QWasmWindowStack::begin()
+{
+    return m_windowStack.rbegin();
+}
+
+QWasmWindowStack::iterator QWasmWindowStack::end()
+{
+    return m_windowStack.rend();
+}
+
+QWasmWindowStack::const_iterator QWasmWindowStack::begin() const
+{
+    return m_windowStack.rbegin();
+}
+
+QWasmWindowStack::const_iterator QWasmWindowStack::end() const
+{
+    return m_windowStack.rend();
+}
+
+QWasmWindowStack::const_reverse_iterator QWasmWindowStack::rbegin() const
+{
+    return m_windowStack.begin();
+}
+
+QWasmWindowStack::const_reverse_iterator QWasmWindowStack::rend() const
+{
+    return m_windowStack.end();
+}
+
+bool QWasmWindowStack::empty() const
+{
+    return m_windowStack.empty();
+}
+
+size_t QWasmWindowStack::size() const
+{
+    return m_windowStack.size();
+}
+
+QWasmWindow *QWasmWindowStack::topWindow() const
+{
+    return m_windowStack.empty() ? nullptr : m_windowStack.last();
+}
+
+QWasmWindowStack::PositionPreference
+QWasmWindowStack::getWindowPositionPreference(StorageType::iterator windowIt) const
+{
+    if (windowIt >= m_alwaysOnTopWindowsBegin)
+        return PositionPreference::StayOnTop;
+    if (windowIt >= m_regularWindowsBegin)
+        return PositionPreference::Regular;
+    return PositionPreference::StayOnBottom;
+}
+
+QT_END_NAMESPACE