fix: prevent unnecessary redraws during window minimize/restore (#3955)

* fix: prevent unnecessary redraws during window minimize/restore

This fixes the window flickering issue when minimizing/restoring by:
1. Adding isMinimizing flag to track window state
2. Adding SetPadding filter to prevent redundant redraws
3. Properly handling minimize/restore window states

Fixes #3951

* docs: improve comments and changelog for frameless window flickering fix

- Add detailed comments about frameless window fix
- Update changelog to clarify this is a frameless window issue
- Add bilingual comments for better understanding

Fixes #3951

---------

Co-authored-by: Lea Anthony <lea.anthony@gmail.com>

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

@@ -170,10 +170,21 @@ func (f *Frontend) Run(ctx context.Context) error {
 			// depends on the content in the WebView, see https://github.com/wailsapp/wails/issues/1319
 			event, _ := arg.Data.(*winc.SizeEventData)
 			if event != nil && event.Type == w32.SIZE_MINIMIZED {
+				// Set minimizing flag to prevent unnecessary redraws during minimize/restore for frameless windows
+				// 设置最小化标志以防止无边框窗口在最小化/恢复过程中的不必要重绘
+				// This fixes window flickering when minimizing/restoring frameless windows
+				// 这修复了无边框窗口在最小化/恢复时的闪烁问题
+				// Reference: https://github.com/wailsapp/wails/issues/3951
+				f.mainWindow.isMinimizing = true
 				return
 			}
 		}
 
+		// Clear minimizing flag for all non-minimize size events
+		// 对于所有非最小化的尺寸变化事件,清除最小化标志
+		// Reference: https://github.com/wailsapp/wails/issues/3951
+		f.mainWindow.isMinimizing = false
+
 		if f.resizeDebouncer != nil {
 			f.resizeDebouncer(func() {
 				f.mainWindow.Invoke(func() {

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

@@ -3,10 +3,11 @@
 package windows
 
 import (
-	"github.com/wailsapp/go-webview2/pkg/edge"
 	"sync"
 	"unsafe"
 
+	"github.com/wailsapp/go-webview2/pkg/edge"
+
 	"github.com/wailsapp/wails/v2/internal/frontend/desktop/windows/win32"
 	"github.com/wailsapp/wails/v2/internal/system/operatingsystem"
 
@@ -37,6 +38,13 @@ type Window struct {
 	OnResume  func()
 
 	chromium *edge.Chromium
+
+	// isMinimizing indicates whether the window is currently being minimized
+	// 标识窗口是否处于最小化状态,用于解决最小化/恢复时的闪屏问题
+	// This flag is used to prevent unnecessary redraws during minimize/restore transitions for frameless windows
+	// 此标志用于防止无边框窗口在最小化/恢复过程中的不必要重绘
+	// Reference: https://github.com/wailsapp/wails/issues/3951
+	isMinimizing bool
 }
 
 func NewWindow(parent winc.Controller, appoptions *options.App, versionInfo *operatingsystem.WindowsVersionInfo, chromium *edge.Chromium) *Window {
@@ -256,7 +264,7 @@ func (w *Window) WndProc(msg uint32, wparam, lparam uintptr) uintptr {
 				rgrc := (*w32.RECT)(unsafe.Pointer(lparam))
 				if w.Form.IsFullScreen() {
 					// In Full-Screen mode we don't need to adjust anything
-					w.chromium.SetPadding(edge.Rect{})
+					w.SetPadding(edge.Rect{})
 				} else if w.IsMaximised() {
 					// If the window is maximized we must adjust the client area to the work area of the monitor. Otherwise
 					// some content goes beyond the visible part of the monitor.
@@ -287,7 +295,7 @@ func (w *Window) WndProc(msg uint32, wparam, lparam uintptr) uintptr {
 							}
 						}
 					}
-					w.chromium.SetPadding(edge.Rect{})
+					w.SetPadding(edge.Rect{})
 				} else {
 					// This is needed to workaround the resize flickering in frameless mode with WindowDecorations
 					// See: https://stackoverflow.com/a/6558508
@@ -296,7 +304,7 @@ func (w *Window) WndProc(msg uint32, wparam, lparam uintptr) uintptr {
 					// Increasing the bottom also worksaround the flickering but we would loose 1px of the WebView content
 					// therefore let's pad the content with 1px at the bottom.
 					rgrc.Bottom += 1
-					w.chromium.SetPadding(edge.Rect{Bottom: 1})
+					w.SetPadding(edge.Rect{Bottom: 1})
 				}
 				return 0
 			}
@@ -339,3 +347,17 @@ func invokeSync[T any](cba *Window, fn func() (T, error)) (res T, err error) {
 	wg.Wait()
 	return res, err
 }
+
+// SetPadding is a filter that wraps chromium.SetPadding to prevent unnecessary redraws during minimize/restore
+// 包装了chromium.SetPadding的过滤器,用于防止窗口最小化/恢复过程中的不必要重绘
+// This fixes window flickering when minimizing/restoring frameless windows
+// 这修复了无边框窗口在最小化/恢复时的闪烁问题
+// Reference: https://github.com/wailsapp/wails/issues/3951
+func (w *Window) SetPadding(padding edge.Rect) {
+	// Skip SetPadding if window is being minimized to prevent flickering
+	// 如果窗口正在最小化,跳过设置padding以防止闪烁
+	if w.isMinimizing {
+		return
+	}
+	w.chromium.SetPadding(padding)
+}

website/src/pages/changelog.mdx

@@ -27,6 +27,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Fixed typo by @takuyahara in [PR](https://github.com/wailsapp/wails/pull/3846)
 - Fixed incorrect TS definition of `WindowSetSize` by @leaanthony
 - chore: fix some comments in [PR](https://github.com/wailsapp/wails/pull/3932) by @lvyaoting
+- [windows] Fixed frameless window flickering when minimizing/restoring by preventing unnecessary redraws [#3951](https://github.com/wailsapp/wails/issues/3951)
 
 
 ### Changed