From 226bc52ece48f6057e22c726442decc09af3539b Mon Sep 17 00:00:00 2001
From: Yuhang Zhao <2546789017@qq.com>
Date: Sat, 17 Oct 2020 17:29:58 +0800
Subject: [PATCH] Fix the acrylic effect.

Signed-off-by: Yuhang Zhao <2546789017@qq.com>
---
 examples/Win32Demo/widget.cpp |  7 +------
 winnativeeventfilter.cpp      | 16 +++++++++++++++-
 winnativeeventfilter.h        |  5 ++++-
 3 files changed, 20 insertions(+), 8 deletions(-)

diff --git a/examples/Win32Demo/widget.cpp b/examples/Win32Demo/widget.cpp
index 8ab5768..4ae45a1 100644
--- a/examples/Win32Demo/widget.cpp
+++ b/examples/Win32Demo/widget.cpp
@@ -96,12 +96,7 @@ Widget::Widget(QWidget *parent) : QWidget(parent), ui(new Ui::Widget)
         updateWindow(this);
     });
     connect(ui->blurEffectCB, &QCheckBox::stateChanged, this, [this](int state) {
-        const bool enable = state == Qt::Checked;
-        QPalette palette = {};
-        // Choose the gradient color you like.
-        palette.setColor(QPalette::Window, QColor(255, 255, 255, 220));
-        setPalette(enable ? palette : QPalette());
-        WinNativeEventFilter::setBlurEffectEnabled(getRawHandle(this), enable);
+        WinNativeEventFilter::setBlurEffectEnabled(getRawHandle(this), state == Qt::Checked);
         updateWindow(this);
     });
     connect(ui->resizableCB, &QCheckBox::stateChanged, this, [this](int state) {
diff --git a/winnativeeventfilter.cpp b/winnativeeventfilter.cpp
index 7ebcb03..e785bae 100644
--- a/winnativeeventfilter.cpp
+++ b/winnativeeventfilter.cpp
@@ -2357,14 +2357,28 @@ bool WinNativeEventFilter::displaySystemMenu(void *handle,
     return false;
 }
 
-bool WinNativeEventFilter::setBlurEffectEnabled(void *handle, const bool enabled)
+bool WinNativeEventFilter::setBlurEffectEnabled(void *handle,
+                                                const bool enabled,
+                                                const QColor &gradientColor)
 {
     Q_ASSERT(handle);
     const auto hwnd = reinterpret_cast<HWND>(handle);
     if (WNEF_EXECUTE_WINAPI_RETURN(IsWindow, FALSE, hwnd)) {
+#ifdef QT_WIDGETS_LIB
+        // Is it possible to set a palette to a QWindow?
+        QWidget *widget = QWidget::find(reinterpret_cast<WId>(hwnd));
+        if (widget && widget->isTopLevel()) {
+            // Qt will paint a solid white background to the window,
+            // it will cover the blurred effect, so we need to
+            // make the background become totally transparent. Achieve
+            // this by setting a palette to the window.
+            widget->setPalette(enabled ? QPalette(QColor(0, 0, 0, 0)) : QPalette());
+        }
+#endif
         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;
diff --git a/winnativeeventfilter.h b/winnativeeventfilter.h
index 98680b8..96c4e84 100644
--- a/winnativeeventfilter.h
+++ b/winnativeeventfilter.h
@@ -26,6 +26,7 @@
 
 #include "framelesshelper_global.h"
 #include <QAbstractNativeEventFilter>
+#include <QColor>
 #include <QList>
 #include <QRect>
 
@@ -141,7 +142,9 @@ public:
 
     // Enable or disable the blur effect for a specific window.
     // On Win10 it's the Acrylic effect.
-    static bool setBlurEffectEnabled(void *handle /* HWND */, const bool enabled = true);
+    static bool setBlurEffectEnabled(void *handle /* HWND */,
+                                     const bool enabled = true,
+                                     const QColor &gradientColor = QColor(255, 255, 255, 0));
 
     // Thin wrapper of DwmExtendFrameIntoClientArea().
     static void updateFrameMargins(void *handle /* HWND */);