Remove deprecated functions

According to Microsoft's documentation, DwmIsCompositionEnabled()
will always return true since Windows 8 [1].
And the DWM composition can't be disabled programmatically since
Windows 8 as well [2].

Since Qt 6 will only support Windows 10, it's apparently these two
functions and their usages are totally useless.

[1] https://docs.microsoft.com/en-us/windows/win32/api/dwmapi/nf-dwmapi-dwmiscompositionenabled
[2] https://docs.microsoft.com/en-us/windows/win32/api/dwmapi/nf-dwmapi-dwmenablecomposition

Change-Id: Ia4040118b719fa8edd8504f9112fbe7e3844e0fa
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>
Reviewed-by: Oliver Wolff <oliver.wolff@qt.io>

8 files changed, 7 insertions, 66 deletions

diff --git a/src/imports/winextras/plugins.qmltypes b/src/imports/winextras/plugins.qmltypes
index fff1181..a23a7b1 100644
--- a/src/imports/winextras/plugins.qmltypes
+++ b/src/imports/winextras/plugins.qmltypes
@@ -14,7 +14,6 @@ Module {
         prototype: "QQuickItem"
         exports: ["QtWinExtras/DwmFeatures 1.0"]
         exportMetaObjectRevisions: [0]
-        Property { name: "compositionEnabled"; type: "bool" }
         Property { name: "colorizationColor"; type: "QColor"; isReadonly: true }
         Property { name: "realColorizationColor"; type: "QColor"; isReadonly: true }
         Property { name: "colorizationOpaqueBlend"; type: "bool"; isReadonly: true }
diff --git a/src/imports/winextras/qquickdwmfeatures.cpp b/src/imports/winextras/qquickdwmfeatures.cpp
index 124d957..7baf536 100644
--- a/src/imports/winextras/qquickdwmfeatures.cpp
+++ b/src/imports/winextras/qquickdwmfeatures.cpp
@@ -73,16 +73,6 @@ QQuickDwmFeatures::QQuickDwmFeatures(QQuickItem *parent) :
 
 QQuickDwmFeatures::~QQuickDwmFeatures() = default;
 
-void QQuickDwmFeatures::setCompositionEnabled(bool enabled)
-{
-    QtWin::setCompositionEnabled(enabled);
-}
-
-bool QQuickDwmFeatures::isCompositionEnabled() const
-{
-    return QtWin::isCompositionEnabled();
-}
-
 QColor QQuickDwmFeatures::colorizationColor() const
 {
     return QtWin::colorizationColor();
@@ -325,9 +315,7 @@ bool QQuickDwmFeatures::eventFilter(QObject *object, QEvent *event)
     if (object == window()) {
         if (event->type() == QWinEvent::CompositionChange) {
             d->updateSurfaceFormat();
-            if (static_cast<QWinCompositionChangeEvent *>(event)->isCompositionEnabled())
-                d->updateAll();
-            emit compositionEnabledChanged();
+            d->updateAll();
         } else if (event->type() == QWinEvent::ColorizationChange) {
             emit colorizationColorChanged();
             emit realColorizationColorChanged();
@@ -388,11 +376,10 @@ void QQuickDwmFeaturesPrivate::updateSurfaceFormat()
 {
     Q_Q(QQuickDwmFeatures);
     if (q->window()) {
-        const bool compositionEnabled = q->isCompositionEnabled();
         QSurfaceFormat format = q->window()->format();
-        format.setAlphaBufferSize(compositionEnabled ? 8 : 0);
+        format.setAlphaBufferSize(8);
         q->window()->setFormat(format);
-        q->window()->setColor(compositionEnabled ? QColor(Qt::transparent) : originalSurfaceColor);
+        q->window()->setColor(Qt::transparent);
     }
 }
 
diff --git a/src/imports/winextras/qquickdwmfeatures_p.h b/src/imports/winextras/qquickdwmfeatures_p.h
index 3887d24..c420659 100644
--- a/src/imports/winextras/qquickdwmfeatures_p.h
+++ b/src/imports/winextras/qquickdwmfeatures_p.h
@@ -65,7 +65,6 @@ class QQuickDwmFeaturesPrivate;
 class QQuickDwmFeatures : public QQuickItem
 {
     Q_OBJECT
-    Q_PROPERTY(bool compositionEnabled READ isCompositionEnabled WRITE setCompositionEnabled NOTIFY compositionEnabledChanged)
     Q_PROPERTY(QColor colorizationColor READ colorizationColor NOTIFY colorizationColorChanged)
     Q_PROPERTY(QColor realColorizationColor READ realColorizationColor NOTIFY realColorizationColorChanged)
     Q_PROPERTY(bool colorizationOpaqueBlend READ colorizationOpaqueBlend NOTIFY colorizationOpaqueBlendChanged)
@@ -83,8 +82,6 @@ public:
     explicit QQuickDwmFeatures(QQuickItem *parent = nullptr);
     ~QQuickDwmFeatures();
 
-    void setCompositionEnabled(bool enabled);
-    bool isCompositionEnabled() const;
     QColor colorizationColor() const;
     QColor realColorizationColor() const;
     bool colorizationOpaqueBlend() const;
@@ -116,7 +113,6 @@ public:
 Q_SIGNALS:
     void colorizationColorChanged();
     void realColorizationColorChanged();
-    void compositionEnabledChanged();
     void colorizationOpaqueBlendChanged();
     void topGlassMarginChanged();
     void rightGlassMarginChanged();
diff --git a/src/winextras/qwinevent.cpp b/src/winextras/qwinevent.cpp
index a1e77b4..6d5dbcb 100644
--- a/src/winextras/qwinevent.cpp
+++ b/src/winextras/qwinevent.cpp
@@ -58,8 +58,8 @@ QWinColorizationChangeEvent::QWinColorizationChangeEvent(QRgb color, bool opaque
 
 QWinColorizationChangeEvent::~QWinColorizationChangeEvent() = default;
 
-QWinCompositionChangeEvent::QWinCompositionChangeEvent(bool enabled)
-    : QWinEvent(CompositionChange), enabled(enabled)
+QWinCompositionChangeEvent::QWinCompositionChangeEvent()
+    : QWinEvent(CompositionChange)
 {
 }
 
diff --git a/src/winextras/qwinevent.h b/src/winextras/qwinevent.h
index ad77eb3..f4212fd 100644
--- a/src/winextras/qwinevent.h
+++ b/src/winextras/qwinevent.h
@@ -76,13 +76,8 @@ private:
 class Q_WINEXTRAS_EXPORT QWinCompositionChangeEvent : public QWinEvent
 {
 public:
-    explicit QWinCompositionChangeEvent(bool enabled);
+    explicit QWinCompositionChangeEvent();
     ~QWinCompositionChangeEvent();
-
-    inline bool isCompositionEnabled() const { return enabled; }
-
-private:
-    bool enabled;
 };
 
 QT_END_NAMESPACE
diff --git a/src/winextras/qwineventfilter.cpp b/src/winextras/qwineventfilter.cpp
index 4b88f54..db264b6 100644
--- a/src/winextras/qwineventfilter.cpp
+++ b/src/winextras/qwineventfilter.cpp
@@ -79,7 +79,7 @@ bool QWinEventFilter::nativeEventFilter(const QByteArray &, void *message, long
         event = new QWinColorizationChangeEvent(QRgb(msg->wParam), msg->lParam);
         break;
     case WM_DWMCOMPOSITIONCHANGED :
-        event = new QWinCompositionChangeEvent(QtWin::isCompositionEnabled());
+        event = new QWinCompositionChangeEvent();
         break;
     case WM_THEMECHANGED :
         event = new QWinEvent(QWinEvent::ThemeChange);
diff --git a/src/winextras/qwinfunctions.cpp b/src/winextras/qwinfunctions.cpp
index b0e0ff4..77e5733 100644
--- a/src/winextras/qwinfunctions.cpp
+++ b/src/winextras/qwinfunctions.cpp
@@ -1835,40 +1835,6 @@ void QtWin::disableBlurBehindWindow(QWindow *window)
 /*!
     \since 5.2
 
-    Returns the DWM composition state.
- */
-bool QtWin::isCompositionEnabled()
-{
-    QWinEventFilter::setup();
-
-    BOOL enabled = FALSE;
-    DwmIsCompositionEnabled(&enabled);
-    return enabled;
-}
-
-/*!
-    \since 5.2
-
-    Sets whether the Windows Desktop composition is \a enabled.
-
-    \note The underlying function was declared deprecated as of Windows 8 and
-    takes no effect.
- */
-
-QT_WARNING_PUSH
-QT_WARNING_DISABLE_MSVC(4995)
-void QtWin::setCompositionEnabled(bool enabled)
-{
-    QWinEventFilter::setup();
-
-    UINT compositionEnabled = enabled;
-    DwmEnableComposition(compositionEnabled);
-}
-QT_WARNING_POP
-
-/*!
-    \since 5.2
-
     Returns whether the colorization color is an opaque blend.
  */
 bool QtWin::isCompositionOpaque()
diff --git a/src/winextras/qwinfunctions.h b/src/winextras/qwinfunctions.h
index 8f27a6f..dd17cef 100644
--- a/src/winextras/qwinfunctions.h
+++ b/src/winextras/qwinfunctions.h
@@ -118,8 +118,6 @@ namespace QtWin
     Q_WINEXTRAS_EXPORT void enableBlurBehindWindow(QWindow *window);
     Q_WINEXTRAS_EXPORT void disableBlurBehindWindow(QWindow *window);
 
-    Q_WINEXTRAS_EXPORT bool isCompositionEnabled();
-    Q_WINEXTRAS_EXPORT void setCompositionEnabled(bool enabled);
     Q_WINEXTRAS_EXPORT bool isCompositionOpaque();
 
     Q_WINEXTRAS_EXPORT void setCurrentProcessExplicitAppUserModelID(const QString &id);