add windows support

Author: chunhunghan

image_picker/file_unsupported.go

@@ -1,4 +1,4 @@
-// +build !darwin,!linux
+// +build !darwin,!linux,!windows
 
 package image_picker
 

image_picker/file_windows.go

@@ -0,0 +1,101 @@
+package image_picker
+
+import (
+	"strings"
+	"syscall"
+	"unicode/utf16"
+	"unsafe"
+
+	"github.com/pkg/errors"
+)
+
+var (
+	comdlg32         = syscall.NewLazyDLL("comdlg32.dll")
+	getOpenFileNameW = comdlg32.NewProc("GetOpenFileNameW")
+)
+
+const (
+	maxPath          = 260
+	ofnExplorer      = 0x00080000
+	ofnFileMustExist = 0x00001000
+	ofnHideReadOnly  = 0x00000004
+)
+
+type openfilenameW struct {
+	lStructSize       uint32
+	hwndOwner         syscall.Handle
+	hInstance         syscall.Handle
+	lpstrFilter       *uint16
+	lpstrCustomFilter *uint16
+	nMaxCustFilter    uint32
+	nFilterIndex      uint32
+	lpstrFile         *uint16
+	nMaxFile          uint32
+	lpstrFileTitle    *uint16
+	nMaxFileTitle     uint32
+	lpstrInitialDir   *uint16
+	lpstrTitle        *uint16
+	flags             uint32
+	nFileOffset       uint16
+	nFileExtension    uint16
+	lpstrDefExt       *uint16
+	lCustData         uintptr
+	lpfnHook          syscall.Handle
+	lpTemplateName    *uint16
+	pvReserved        unsafe.Pointer
+	dwReserved        uint32
+	flagsEx           uint32
+}
+
+func utf16PtrFromString(s string) *uint16 {
+	b := utf16.Encode([]rune(s))
+	return &b[0]
+}
+
+func stringFromUtf16Ptr(p *uint16) string {
+	b := *(*[maxPath]uint16)(unsafe.Pointer(p))
+	r := utf16.Decode(b[:])
+	return strings.Trim(string(r), "\x00")
+}
+
+func getOpenFileName(lpofn *openfilenameW) bool {
+	ret, _, _ := getOpenFileNameW.Call(uintptr(unsafe.Pointer(lpofn)), 0, 0)
+	return ret != 0
+}
+
+func fileDialog(title string, fileType string) (string, error) {
+	var ofn openfilenameW
+	buf := make([]uint16, maxPath)
+
+	t, _ := syscall.UTF16PtrFromString(title)
+
+	ofn.lStructSize = uint32(unsafe.Sizeof(ofn))
+	ofn.lpstrTitle = t
+	ofn.lpstrFile = &buf[0]
+	ofn.nMaxFile = uint32(len(buf))
+
+	var filters string
+	switch fileType {
+	case "image":
+		filters = "Images (*.jpeg,*.png,*.gif)\x00*.jpg;*.jpeg;*.png;*.gif\x00All Files (*.*)\x00*.*\x00\x00"
+	case "video":
+		filters = "Videos (*.webm,*.wmv,*.mpeg,*.mkv,*.mp4,*.avi,*.mov,*.flv)\x00*.webm;*.wmv;*.mpeg;*.mkv;*mp4;*.avi;*.mov;*.flv\x00All Files (*.*)\x00*.*\x00\x00"
+	default:
+		return "", errors.New("unsupported fileType")
+	}
+
+	if filters != "" {
+		ofn.lpstrFilter = utf16PtrFromString(filters)
+	}
+
+	flags := ofnExplorer | ofnFileMustExist | ofnHideReadOnly
+
+	ofn.flags = uint32(flags)
+
+	if getOpenFileName(&ofn) {
+		return stringFromUtf16Ptr(ofn.lpstrFile), nil
+	}
+
+	return "", nil
+
+}