systemicon.go

package main

import (
	"path/filepath"
	"strings"
	"sync"
	"syscall"
	"unsafe"
)

// ---------------- 系统文件图标（SHGetFileInfo → HICON → PNG data URI） ----------------
// 按扩展名缓存（exe/lnk/ico/dll 按路径缓存），设置 useSystemIcons 关闭时返回空。

var (
	procSHGetFileInfoW = syscall.NewLazyDLL("shell32.dll").NewProc("SHGetFileInfoW")
	procGetIconInfo    = syscall.NewLazyDLL("user32.dll").NewProc("GetIconInfo")
	procDestroyIcon    = syscall.NewLazyDLL("user32.dll").NewProc("DestroyIcon")
)

type SHFILEINFOW struct {
	HIcon         uintptr
	IIcon         int32
	DwAttributes  uint32
	SzDisplayName [260]uint16
	SzTypeName    [80]uint16
}

type ICONINFO struct {
	FIcon    uint32
	XHotspot uint32
	YHotspot uint32
	HbmMask  uintptr
	HbmColor uintptr
}

const (
	shgfiIcon         = 0x00000100
	shgfiSmallIcon    = 0x00000001
	shgfiUseFileAttrs = 0x00000010
	fileAttrDirectory = 0x00000010
	fileAttrNormal    = 0x00000080
)

var (
	iconCacheMu sync.Mutex
	iconCache   = map[string]string{}
)

// sysIconsEnabled 由 startup/UpdateSettings 维护（避免频繁读文件）
var sysIconsEnabled = true

// getSystemIcon 返回路径的系统图标（PNG data URI），空串表示无图标
func getSystemIcon(path string, isDir bool) string {
	if !sysIconsEnabled {
		return ""
	}
	key := "dir"
	if !isDir {
		ext := strings.ToLower(filepath.Ext(path))
		switch ext {
		case ".exe", ".lnk", ".ico", ".cur", ".dll":
			key = path // 图标因文件而异，按路径缓存
		default:
			key = ext
		}
	}
	iconCacheMu.Lock()
	if v, ok := iconCache[key]; ok {
		iconCacheMu.Unlock()
		return v
	}
	iconCacheMu.Unlock()

	uri := extractSystemIcon(path, isDir)
	iconCacheMu.Lock()
	iconCache[key] = uri
	iconCacheMu.Unlock()
	return uri
}

// extractSystemIcon 用 SHGetFileInfoW 提取 16x16 图标并转 PNG data URI
func extractSystemIcon(path string, isDir bool) string {
	p, _ := syscall.UTF16PtrFromString(path)
	var sfi SHFILEINFOW
	attrs := uintptr(fileAttrNormal)
	if isDir {
		attrs = fileAttrDirectory
	}
	r, _, _ := procSHGetFileInfoW.Call(
		uintptr(unsafe.Pointer(p)), attrs, uintptr(unsafe.Pointer(&sfi)),
		uintptr(unsafe.Sizeof(sfi)), shgfiIcon|shgfiSmallIcon|shgfiUseFileAttrs)
	if r == 0 || sfi.HIcon == 0 {
		return ""
	}
	defer procDestroyIcon.Call(sfi.HIcon)

	var ii ICONINFO
	rr, _, _ := procGetIconInfo.Call(sfi.HIcon, uintptr(unsafe.Pointer(&ii)))
	if rr == 0 {
		return ""
	}
	if ii.HbmMask != 0 {
		shellDeleteObject.Call(ii.HbmMask)
	}
	if ii.HbmColor == 0 {
		return ""
	}
	defer shellDeleteObject.Call(ii.HbmColor)
	return shellMenuIcon(ii.HbmColor) // 复用 HBITMAP → PNG data URI
}