Initial GoWallpaper implementation

wallpaper_windows.go

@@ -0,0 +1,89 @@
+//go:build windows
+
+package main
+
+import (
+	"errors"
+	"fmt"
+	"path/filepath"
+	"unsafe"
+
+	"golang.org/x/sys/windows"
+	"golang.org/x/sys/windows/registry"
+)
+
+const (
+	spiSetDesktopWallpaper = 0x0014
+	spifUpdateINIFile      = 0x0001
+	spifSendChange         = 0x0002
+)
+
+var (
+	user32                    = windows.NewLazySystemDLL("user32.dll")
+	procSystemParametersInfoW = user32.NewProc("SystemParametersInfoW")
+)
+
+func validWallpaperStyle(style string) bool {
+	switch style {
+	case "keep", "fill", "fit", "stretch", "tile", "center", "span":
+		return true
+	default:
+		return false
+	}
+}
+
+func setWallpaper(path, style string) error {
+	absPath, err := filepath.Abs(path)
+	if err != nil {
+		return err
+	}
+	if style != "keep" {
+		if err := setWallpaperStyle(style); err != nil {
+			return err
+		}
+	}
+	pathPtr, err := windows.UTF16PtrFromString(absPath)
+	if err != nil {
+		return err
+	}
+	r1, _, callErr := procSystemParametersInfoW.Call(
+		spiSetDesktopWallpaper,
+		0,
+		uintptr(unsafe.Pointer(pathPtr)),
+		spifUpdateINIFile|spifSendChange,
+	)
+	if r1 == 0 {
+		if callErr != nil && !errors.Is(callErr, windows.ERROR_SUCCESS) {
+			return fmt.Errorf("调用 Windows 壁纸接口: %w", callErr)
+		}
+		return errors.New("Windows 拒绝设置壁纸")
+	}
+	return nil
+}
+
+func setWallpaperStyle(style string) error {
+	values := map[string][2]string{
+		"fill":    {"10", "0"},
+		"fit":     {"6", "0"},
+		"stretch": {"2", "0"},
+		"tile":    {"0", "1"},
+		"center":  {"0", "0"},
+		"span":    {"22", "0"},
+	}
+	value, ok := values[style]
+	if !ok {
+		return fmt.Errorf("不支持的壁纸显示方式: %s", style)
+	}
+	key, err := registry.OpenKey(registry.CURRENT_USER, `Control Panel\Desktop`, registry.SET_VALUE)
+	if err != nil {
+		return fmt.Errorf("打开壁纸设置: %w", err)
+	}
+	defer key.Close()
+	if err := key.SetStringValue("WallpaperStyle", value[0]); err != nil {
+		return fmt.Errorf("设置壁纸样式: %w", err)
+	}
+	if err := key.SetStringValue("TileWallpaper", value[1]); err != nil {
+		return fmt.Errorf("设置壁纸平铺方式: %w", err)
+	}
+	return nil
+}