新增: 壁纸切换（主题/本地图片/Bing/纯色渐变）

bing.go

@@ -0,0 +1,82 @@
+package main
+
+import (
+	"encoding/json"
+	"io"
+	"log"
+	"os"
+	"path/filepath"
+	"strings"
+	"time"
+)
+
+const bingAPI = "https://www.bing.com/HPImageArchive.aspx?format=js&idx=0&n=1&mkt=zh-CN"
+
+type bingResponse struct {
+	Images []struct {
+		URL       string `json:"url"`
+		URLBase   string `json:"urlbase"`
+		Copyright string `json:"copyright"`
+	} `json:"images"`
+}
+
+func fetchBingWallpaper() {
+	resp, err := httpClient.Get(bingAPI)
+	if err != nil {
+		log.Println("Bing API 请求失败:", err)
+		return
+	}
+	defer resp.Body.Close()
+	data, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return
+	}
+	var br bingResponse
+	if json.Unmarshal(data, &br) != nil || len(br.Images) == 0 {
+		log.Println("Bing API 解析失败")
+		return
+	}
+
+	imgURL := br.Images[0].URL
+	if !strings.HasPrefix(imgURL, "http") {
+		imgURL = "https://www.bing.com" + imgURL
+	}
+
+	imgResp, err := httpClient.Get(imgURL)
+	if err != nil {
+		log.Println("Bing 图片下载失败:", err)
+		return
+	}
+	defer imgResp.Body.Close()
+	imgData, err := io.ReadAll(imgResp.Body)
+	if err != nil {
+		return
+	}
+
+	bingPath := filepath.Join(configDir(), "bing_wallpaper.jpg")
+	if err := os.WriteFile(bingPath, imgData, 0644); err != nil {
+		log.Println("Bing 壁纸缓存失败:", err)
+		return
+	}
+	log.Printf("Bing 壁纸已缓存: %s (%d bytes)", bingPath, len(imgData))
+
+	reloadWallpaper()
+}
+
+func bingWallpaperLoop() {
+	cfg := loadConfig()
+	if cfg.WallpaperType == WPBing {
+		bingPath := filepath.Join(configDir(), "bing_wallpaper.jpg")
+		if _, err := os.Stat(bingPath); err != nil {
+			fetchBingWallpaper()
+		}
+	}
+
+	ticker := time.NewTicker(4 * time.Hour)
+	for range ticker.C {
+		cfg := loadConfig()
+		if cfg.WallpaperType == WPBing {
+			fetchBingWallpaper()
+		}
+	}
+}