[Windows] Add Suspend/Resume callback support (#1474)

* Add Suspend/Resume callback support

* Fix comment

v2/internal/frontend/desktop/windows/win32/window.go

@@ -38,6 +38,27 @@ const (
 	GCLP_HBRBACKGROUND int32 = -10
 )
 
+// Power
+const (
+	// WM_POWERBROADCAST - Notifies applications that a power-management event has occurred.
+	WM_POWERBROADCAST = 536
+
+	// PBT_APMPOWERSTATUSCHANGE - Power status has changed.
+	PBT_APMPOWERSTATUSCHANGE = 10
+
+	// PBT_APMRESUMEAUTOMATIC -Operation is resuming automatically from a low-power state. This message is sent every time the system resumes.
+	PBT_APMRESUMEAUTOMATIC = 18
+
+	// PBT_APMRESUMESUSPEND - Operation is resuming from a low-power state. This message is sent after PBT_APMRESUMEAUTOMATIC if the resume is triggered by user input, such as pressing a key.
+	PBT_APMRESUMESUSPEND = 7
+
+	// PBT_APMSUSPEND - System is suspending operation.
+	PBT_APMSUSPEND = 4
+
+	// PBT_POWERSETTINGCHANGE - A power setting change event has been received.
+	PBT_POWERSETTINGCHANGE = 32787
+)
+
 // http://msdn.microsoft.com/en-us/library/windows/desktop/bb773244.aspx
 type MARGINS struct {
 	CxLeftWidth, CxRightWidth, CyTopHeight, CyBottomHeight int32

v2/internal/frontend/desktop/windows/window.go

@@ -24,6 +24,8 @@ type Window struct {
 	isDarkMode                               bool
 	isActive                                 bool
 	hasBeenShown                             bool
+	OnSuspend                                func()
+	OnResume                                 func()
 }
 
 func NewWindow(parent winc.Controller, appoptions *options.App, versionInfo *operatingsystem.WindowsVersionInfo) *Window {
@@ -83,6 +85,8 @@ func NewWindow(parent winc.Controller, appoptions *options.App, versionInfo *ope
 	result.updateTheme()
 
 	if appoptions.Windows != nil {
+		result.OnSuspend = appoptions.Windows.OnSuspend
+		result.OnResume = appoptions.Windows.OnResume
 		if appoptions.Windows.WindowIsTranslucent {
 			// TODO: Migrate to win32 package
 			if !win32.IsWindowsVersionAtLeast(10, 0, 22579) {
@@ -144,6 +148,18 @@ func (w *Window) SetMaxSize(maxWidth int, maxHeight int) {
 func (w *Window) WndProc(msg uint32, wparam, lparam uintptr) uintptr {
 
 	switch msg {
+	case win32.WM_POWERBROADCAST:
+		switch wparam {
+		case win32.PBT_APMSUSPEND:
+			if w.OnSuspend != nil {
+				w.OnSuspend()
+			}
+		case win32.PBT_APMRESUMEAUTOMATIC:
+			if w.OnResume != nil {
+				w.OnResume()
+			}
+		}
+
 	case w32.WM_SETTINGCHANGE:
 		settingChanged := w32.UTF16PtrToString((*uint16)(unsafe.Pointer(lparam)))
 		if settingChanged == "ImmersiveColorSet" {
@@ -154,7 +170,7 @@ func (w *Window) WndProc(msg uint32, wparam, lparam uintptr) uintptr {
 		w32.SetFocus(w.Handle())
 	case w32.WM_MOVE, w32.WM_MOVING:
 		if w.notifyParentWindowPositionChanged != nil {
-			w.notifyParentWindowPositionChanged()
+			_ = w.notifyParentWindowPositionChanged()
 		}
 	case w32.WM_ACTIVATE:
 		//if !w.frontendOptions.Frameless {

v2/pkg/options/windows/windows.go

@@ -86,6 +86,11 @@ type Options struct {
 	// ResizeDebounceMS is the amount of time to debounce redraws of webview2
 	// when resizing the window
 	ResizeDebounceMS uint16
+
+	// OnSuspend is called when Windows enters low power mode
+	OnSuspend func()
+	// OnResume is called when Windows resumes from low power mode
+	OnResume func()
 }
 
 func DefaultMessages() *Messages {

website/docs/reference/options.mdx

@@ -520,6 +520,24 @@ Type: uint16
 ResizeDebounceMS is the amount of time to debounce redraws of webview2 when resizing the window.
 The default value (0) will perform redraws as fast as it can.
 
+### OnSuspend
+
+Name: OnSuspend
+
+Type: func()
+
+If set, this function will be called when windows initiates a switch to low power mode (suspend/hibernate)
+
+### OnResume
+
+Name: OnResume
+
+Type: func()
+
+If set, this function will be called when windows resumes from low power mode (suspend/hibernate)
+
+
+
 ## Mac Specific Options
 
 ### TitleBar