Use blur instead of Acrylic on Win10.

Signed-off-by: Yuhang Zhao <2546789017@qq.com>

examples/Win32Demo/widget.cpp

@@ -25,12 +25,15 @@
 #include "widget.h"
 #include "../../winnativeeventfilter.h"
 #include "ui_widget.h"
+#include <QColorDialog>
+#include <QOperatingSystemVersion>
 #include <QStyleOption>
 
 namespace {
 
 const char useNativeTitleBar[] = "WNEF_USE_NATIVE_TITLE_BAR";
 const char preserveWindowFrame[] = "WNEF_FORCE_PRESERVE_WINDOW_FRAME";
+const char forceUseAcrylicEffect[] = "WNEF_FORCE_ACRYLIC_ON_WIN10";
 
 void *getRawHandle(QWidget *widget)
 {
@@ -48,12 +51,20 @@ void updateWindow(QWidget *widget)
     }
 }
 
+bool isGreaterThanWin10_1803()
+{
+    return QOperatingSystemVersion::current()
+           >= QOperatingSystemVersion(QOperatingSystemVersion::Windows, 10, 0, 17134);
+}
+
 } // namespace
 
 Widget::Widget(QWidget *parent) : QWidget(parent), ui(new Ui::Widget)
 {
     ui->setupUi(this);
 
+    ui->forceAcrylicCB->setEnabled(isGreaterThanWin10_1803());
+
     connect(ui->minimizeButton, &QPushButton::clicked, this, &Widget::showMinimized);
     connect(ui->maximizeButton, &QPushButton::clicked, this, [this]() {
         if (isMaximized()) {
@@ -96,9 +107,30 @@ Widget::Widget(QWidget *parent) : QWidget(parent), ui(new Ui::Widget)
         updateWindow(this);
     });
     connect(ui->blurEffectCB, &QCheckBox::stateChanged, this, [this](int state) {
-        WinNativeEventFilter::setBlurEffectEnabled(getRawHandle(this), state == Qt::Checked);
+        const bool enable = state == Qt::Checked;
+        QColor color = QColor(255, 255, 255, 0);
+        if (isGreaterThanWin10_1803() && ui->forceAcrylicCB->isChecked()) {
+            if (enable) {
+                color = QColorDialog::getColor(color,
+                                               this,
+                                               tr("Please select a gradient color"),
+                                               QColorDialog::ShowAlphaChannel);
+            }
+        }
+        WinNativeEventFilter::setBlurEffectEnabled(getRawHandle(this), enable, color);
         updateWindow(this);
     });
+    connect(ui->forceAcrylicCB, &QCheckBox::stateChanged, this, [this](int state) {
+        if (state == Qt::Checked) {
+            qputenv(forceUseAcrylicEffect, "1");
+        } else {
+            qunsetenv(forceUseAcrylicEffect);
+        }
+        if (ui->blurEffectCB->isChecked()) {
+            ui->blurEffectCB->click();
+            ui->blurEffectCB->click();
+        }
+    });
     connect(ui->resizableCB, &QCheckBox::stateChanged, this, [this](int state) {
         const bool enable = state == Qt::Checked;
         ui->maximizeButton->setEnabled(enable);

examples/Win32Demo/widget.ui

@@ -313,6 +313,13 @@
              </property>
             </widget>
            </item>
+           <item>
+            <widget class="QCheckBox" name="forceAcrylicCB">
+             <property name="text">
+              <string>Force enabling Acrylic effect</string>
+             </property>
+            </widget>
+           </item>
            <item>
             <widget class="QCheckBox" name="resizableCB">
              <property name="text">

winnativeeventfilter.cpp

@@ -2378,7 +2378,6 @@ bool WinNativeEventFilter::setBlurEffectEnabled(void *handle,
         if (isWin8OrGreater() && coreData()->m_lpSetWindowCompositionAttribute) {
             ACCENT_POLICY accentPolicy;
             SecureZeroMemory(&accentPolicy, sizeof(accentPolicy));
-            accentPolicy.GradientColor = gradientColor.rgba();
             WINDOWCOMPOSITIONATTRIBDATA wcaData;
             SecureZeroMemory(&wcaData, sizeof(wcaData));
             wcaData.Attrib = WCA_ACCENT_POLICY;
@@ -2386,10 +2385,20 @@ bool WinNativeEventFilter::setBlurEffectEnabled(void *handle,
             wcaData.cbData = sizeof(accentPolicy);
             if (enabled) {
                 if (isWin10OrGreater(17134)) {
-                    // Windows 10, version 1803 (10.0.17134)
+                    // Enabling the Acrylic effect for Win32 windows is
-                    // It's not allowed to enable the Acrylic effect for Win32
+                    // very buggy and it's a bug of Windows 10 itself so
-                    // applications until Win10 1803.
+                    // it's not fixable from my side.
-                    accentPolicy.AccentState = ACCENT_ENABLE_ACRYLICBLURBEHIND;
+                    if (qEnvironmentVariableIsSet("WNEF_FORCE_ACRYLIC_ON_WIN10")) {
+                        // Windows 10, version 1803 (10.0.17134)
+                        // It's not allowed to enable the Acrylic effect for Win32
+                        // applications until Win10 1803.
+                        accentPolicy.AccentState = ACCENT_ENABLE_ACRYLICBLURBEHIND;
+                        const QColor color = gradientColor.isValid() ? gradientColor
+                                                                     : QColor(255, 255, 255, 0);
+                        accentPolicy.GradientColor = color.rgba();
+                    } else {
+                        accentPolicy.AccentState = ACCENT_ENABLE_BLURBEHIND;
+                    }
                 } else if (isWin10OrGreater(10240)) {
                     // Windows 10, version 1507 (10.0.10240)
                     // The initial version of Win10.