From 953bc0934312a5b669d32441f7b64701de1f113c Mon Sep 17 00:00:00 2001
From: Lea Anthony <lea.anthony@gmail.com>
Date: Wed, 18 May 2022 18:52:45 +1000
Subject: [PATCH] Merge pull request #1400 from
 wailsapp/feature/native-translucency

Initial support for new native translucency in Windows Preview
---
 .../frontend/desktop/windows/win32/theme.go   | 32 +++++++++++++++----
 .../frontend/desktop/windows/window.go        |  7 +++-
 v2/pkg/options/windows/windows.go             | 13 ++++++++
 3 files changed, 44 insertions(+), 8 deletions(-)

diff --git a/v2/internal/frontend/desktop/windows/win32/theme.go b/v2/internal/frontend/desktop/windows/win32/theme.go
index aefa73813..89aa9fc74 100644
--- a/v2/internal/frontend/desktop/windows/win32/theme.go
+++ b/v2/internal/frontend/desktop/windows/win32/theme.go
@@ -1,11 +1,8 @@
-//go:build windows
-
 package win32
 
 import (
-	"unsafe"
-
 	"golang.org/x/sys/windows/registry"
+	"unsafe"
 )
 
 type DWMWINDOWATTRIBUTE int32
@@ -15,10 +12,19 @@ const DwmwaUseImmersiveDarkMode DWMWINDOWATTRIBUTE = 20
 const DwmwaBorderColor DWMWINDOWATTRIBUTE = 34
 const DwmwaCaptionColor DWMWINDOWATTRIBUTE = 35
 const DwmwaTextColor DWMWINDOWATTRIBUTE = 36
+const DwmwaSystemBackdropType DWMWINDOWATTRIBUTE = 38
 
 const SPI_GETHIGHCONTRAST = 0x0042
 const HCF_HIGHCONTRASTON = 0x00000001
 
+type BackdropType int32
+
+const DwmsbtAuto BackdropType = 0
+const DwmsbtDisable = 1         // None
+const DwmsbtMainWindow = 2      // Mica
+const DwmsbtTransientWindow = 3 // Acrylic
+const DwmsbtTabbedWindow = 4    // Tabbed
+
 func dwmSetWindowAttribute(hwnd uintptr, dwAttribute DWMWINDOWATTRIBUTE, pvAttribute unsafe.Pointer, cbAttribute uintptr) {
 	ret, _, err := procDwmSetWindowAttribute.Call(
 		hwnd,
@@ -46,7 +52,19 @@ func SetTheme(hwnd uintptr, useDarkMode bool) {
 		if IsWindowsVersionAtLeast(10, 0, 18985) {
 			attr = DwmwaUseImmersiveDarkMode
 		}
-		dwmSetWindowAttribute(hwnd, attr, unsafe.Pointer(&useDarkMode), unsafe.Sizeof(&useDarkMode))
+		var winDark int32
+		if useDarkMode {
+			winDark = 1
+		}
+		dwmSetWindowAttribute(hwnd, attr, unsafe.Pointer(&winDark), unsafe.Sizeof(winDark))
+	}
+}
+
+func EnableTranslucency(hwnd uintptr, backdrop BackdropType) {
+	if IsWindowsVersionAtLeast(10, 0, 22579) {
+		dwmSetWindowAttribute(hwnd, DwmwaSystemBackdropType, unsafe.Pointer(&backdrop), unsafe.Sizeof(backdrop))
+	} else {
+		println("Warning: Translucency unavailable on Windows < 22579")
 	}
 }
 
@@ -73,7 +91,6 @@ func IsCurrentlyDarkMode() bool {
 	if err != nil {
 		return false
 	}
-
 	return AppsUseLightTheme == 0
 }
 
@@ -91,5 +108,6 @@ func IsCurrentlyHighContrastMode() bool {
 		_ = err
 		return false
 	}
-	return result.DwFlags&HCF_HIGHCONTRASTON == HCF_HIGHCONTRASTON
+	r := result.DwFlags&HCF_HIGHCONTRASTON == HCF_HIGHCONTRASTON
+	return r
 }
diff --git a/v2/internal/frontend/desktop/windows/window.go b/v2/internal/frontend/desktop/windows/window.go
index 21170bfe7..36dc5bf25 100644
--- a/v2/internal/frontend/desktop/windows/window.go
+++ b/v2/internal/frontend/desktop/windows/window.go
@@ -78,7 +78,12 @@ func NewWindow(parent winc.Controller, appoptions *options.App, versionInfo *ope
 
 	if appoptions.Windows != nil {
 		if appoptions.Windows.WindowIsTranslucent {
-			result.SetTranslucentBackground()
+			// TODO: Migrate to win32 package
+			if !win32.IsWindowsVersionAtLeast(10, 0, 22579) {
+				result.SetTranslucentBackground()
+			} else {
+				win32.EnableTranslucency(result.Handle(), win32.BackdropType(appoptions.Windows.TranslucencyType))
+			}
 		}
 
 		if appoptions.Windows.DisableWindowIcon {
diff --git a/v2/pkg/options/windows/windows.go b/v2/pkg/options/windows/windows.go
index 4c553fc89..fb80cee16 100644
--- a/v2/pkg/options/windows/windows.go
+++ b/v2/pkg/options/windows/windows.go
@@ -23,6 +23,16 @@ const (
 	Light Theme = 2
 )
 
+type BackdropType int32
+
+const (
+	Auto            BackdropType = 0
+	Disable         BackdropType = 1 // None
+	MainWindow      BackdropType = 2 // Mica
+	TransientWindow BackdropType = 3 // Acrylic
+	TabbedWindow    BackdropType = 4 // Tabbed
+)
+
 func RGB(r, g, b uint8) int32 {
 	var col = int32(b)
 	col = col<<8 | int32(g)
@@ -67,6 +77,9 @@ type Options struct {
 	// Custom settings for dark/light mode
 	CustomTheme *ThemeSettings
 
+	// Windows 11 22579 minimum
+	TranslucencyType BackdropType
+
 	// User messages that can be customised
 	Messages *Messages
 }