From 72f0fafe46737239c28cc5e5d03911008a34f3bb Mon Sep 17 00:00:00 2001
From: Nuno Cruces <ncruces@users.noreply.github.com>
Date: Fri, 13 Dec 2019 13:45:23 +0000
Subject: [PATCH] File dialogs for windows.

---
 dialog/dialog_windows.go | 155 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 155 insertions(+)
 create mode 100644 dialog/dialog_windows.go

diff --git a/dialog/dialog_windows.go b/dialog/dialog_windows.go
new file mode 100644
index 0000000..bb9984b
--- /dev/null
+++ b/dialog/dialog_windows.go
@@ -0,0 +1,155 @@
+package dialog
+
+import (
+	"path/filepath"
+	"syscall"
+	"unicode/utf16"
+	"unsafe"
+)
+
+func OpenFile(title, defaultPath string, filters []FileFilter) (string, error) {
+	comdlg32 := syscall.NewLazyDLL("comdlg32.dll")
+	getOpenFileName := comdlg32.NewProc("GetOpenFileNameW")
+
+	var args _OPENFILENAME
+	args.StructSize = uint32(unsafe.Sizeof(args))
+
+	if title != "" {
+		args.Title = syscall.StringToUTF16Ptr(title)
+	}
+	if defaultPath != "" {
+		args.InitialDir = syscall.StringToUTF16Ptr(defaultPath)
+	}
+	args.Filter = &windowsFilters(filters)[0]
+
+	res := [1024]uint16{}
+	args.File = &res[0]
+	args.MaxFile = uint32(len(res))
+
+	_, _, _ = getOpenFileName.Call(uintptr(unsafe.Pointer(&args)))
+	return syscall.UTF16ToString(res[:]), nil
+}
+
+func OpenFiles(title, defaultPath string, filters []FileFilter) ([]string, error) {
+	comdlg32 := syscall.NewLazyDLL("comdlg32.dll")
+	getOpenFileName := comdlg32.NewProc("GetOpenFileNameW")
+
+	var args _OPENFILENAME
+	args.StructSize = uint32(unsafe.Sizeof(args))
+	args.Flags = 0x00080200 // OFN_ALLOWMULTISELECT|OFN_EXPLORER
+
+	if title != "" {
+		args.Title = syscall.StringToUTF16Ptr(title)
+	}
+	if defaultPath != "" {
+		args.InitialDir = syscall.StringToUTF16Ptr(defaultPath)
+	}
+	args.Filter = &windowsFilters(filters)[0]
+
+	res := [65536]uint16{}
+	args.File = &res[0]
+	args.MaxFile = uint32(len(res))
+
+	_, _, _ = getOpenFileName.Call(uintptr(unsafe.Pointer(&args)))
+
+	var i int
+	var nul bool
+	var split []string
+	for j, p := range res {
+		if p == 0 {
+			if nul {
+				break
+			}
+			if i < j {
+				split = append(split, string(utf16.Decode(res[i:j])))
+			}
+			i = j + 1
+			nul = true
+		} else {
+			nul = false
+		}
+	}
+	if len := len(split) - 1; len > 0 {
+		base := split[0]
+		for i := 0; i < len; i++ {
+			split[i] = filepath.Join(base, string(split[i+1]))
+		}
+		split = split[:len]
+	}
+	return split, nil
+}
+
+func SaveFile(title, defaultPath string, confirmOverwrite bool, filters []FileFilter) (string, error) {
+	comdlg32 := syscall.NewLazyDLL("comdlg32.dll")
+	getSaveFileName := comdlg32.NewProc("GetSaveFileNameW")
+
+	var args _OPENFILENAME
+	args.StructSize = uint32(unsafe.Sizeof(args))
+
+	if title != "" {
+		args.Title = syscall.StringToUTF16Ptr(title)
+	}
+	if defaultPath != "" {
+		args.InitialDir = syscall.StringToUTF16Ptr(defaultPath)
+	}
+	if confirmOverwrite {
+		args.Flags |= 0x00000002 // OFN_OVERWRITEPROMPT
+	}
+	args.Filter = &windowsFilters(filters)[0]
+
+	res := [1024]uint16{}
+	args.File = &res[0]
+	args.MaxFile = uint32(len(res))
+
+	_, _, _ = getSaveFileName.Call(uintptr(unsafe.Pointer(&args)))
+	return syscall.UTF16ToString(res[:]), nil
+}
+
+func PickFolder(title, defaultPath string) (string, error) {
+	// TODO
+	return "", nil
+}
+
+func windowsFilters(filters []FileFilter) []uint16 {
+	var res []uint16
+	for _, f := range filters {
+		res = append(res, utf16.Encode([]rune(f.Name))...)
+		res = append(res, 0)
+		for _, e := range f.Exts {
+			res = append(res, uint16('*'))
+			res = append(res, utf16.Encode([]rune(e))...)
+			res = append(res, uint16(';'))
+		}
+		res = append(res, 0)
+	}
+	if res != nil {
+		res = append(res, 0)
+	}
+	return res
+}
+
+type _OPENFILENAME struct {
+	StructSize      uint32
+	Owner           uintptr
+	Instance        uintptr
+	Filter          *uint16
+	CustomFilter    *uint16
+	MaxCustomFilter uint32
+	FilterIndex     uint32
+	File            *uint16
+	MaxFile         uint32
+	FileTitle       *uint16
+	MaxFileTitle    uint32
+	InitialDir      *uint16
+	Title           *uint16
+	Flags           uint32
+	FileOffset      uint16
+	FileExtension   uint16
+	DefExt          *uint16
+	CustData        uintptr
+	FnHook          uintptr
+	TemplateName    *uint16
+	PvReserved      unsafe.Pointer
+	DwReserved      uint32
+	FlagsEx         uint32
+}