Add the ability to filter files in the File Dialog

cmd/fyne_demo/screens/window.go

@@ -145,6 +145,18 @@ func loadDialogGroup(win fyne.Window) *widget.Group {
 				fileOpened(reader)
 			}, win)
 		}),
+		widget.NewButton("File Open With Filter (only show txt or png)", func() {
+			fd := dialog.NewFileOpen(func(reader fyne.FileReadCloser, err error) {
+				if err != nil {
+					dialog.ShowError(err, win)
+					return
+				}
+
+				fileOpened(reader)
+			}, win)
+			fd.SetFilter(dialog.NewExtensionFileFilter([]string{".png", ".txt"}))
+			fd.Show()
+		}),
 		widget.NewButton("File Save", func() {
 			dialog.ShowFileSave(func(writer fyne.FileWriteCloser, err error) {
 				if err != nil {
@@ -155,6 +167,18 @@ func loadDialogGroup(win fyne.Window) *widget.Group {
 				fileSaved(writer)
 			}, win)
 		}),
+		widget.NewButton("File Save With Filter (only show images)", func() {
+			fd := dialog.NewFileSave(func(writer fyne.FileWriteCloser, err error) {
+				if err != nil {
+					dialog.ShowError(err, win)
+					return
+				}
+
+				fileSaved(writer)
+			}, win)
+			fd.SetFilter(dialog.NewMimeTypeFileFilter([]string{"image/*"}))
+			fd.Show()
+		}),
 		widget.NewButton("Custom Dialog (Login Form)", func() {
 			username := widget.NewEntry()
 			password := widget.NewPasswordEntry()

dialog/file.go

@@ -20,22 +20,79 @@ type textWidget interface {
 }
 
 type fileDialog struct {
+	file       *FileDialog
 	fileName   textWidget
+	dismiss    *widget.Button
 	open       *widget.Button
 	breadcrumb *widget.Box
 	files      *fyne.Container
 	fileScroll *widget.ScrollContainer
-	parent     fyne.Window
 
 	win      *widget.PopUp
 	selected *fileDialogItem
-	callback interface{}
 	dir      string
-	save     bool
+}
+
+// FileDialog is a dialog containing a file picker for use in opening or saving files.
+type FileDialog struct {
+	save             bool
+	nativePicker     bool
+	callback         interface{}
+	onClosedCallback func(bool)
+	filter           FileFilter
+	parent           fyne.Window
+	dialog           *fileDialog
+	dismissText      string
+}
+
+// Declare conformity to Dialog interface
+var _ Dialog = (*FileDialog)(nil)
+
+// FileFilter is an interface that can be implemented to provide a filter to a file dialog.
+type FileFilter interface {
+	Matches(fyne.URI) bool
+}
+
+type extensionFileFilter struct {
+	extensions []string
+}
+
+type mimeTypeFileFilter struct {
+	mimeTypes []string
+}
+
+// Matches returns true if a file URI has one of the filtered extensions.
+func (e *extensionFileFilter) Matches(uri fyne.URI) bool {
+	extension := uri.Extension()
+	for _, ext := range e.extensions {
+		if extension == ext {
+			return true
+		}
+	}
+	return false
+}
+
+// Matches returns true if a file URI has one of the filtered mimetypes.
+func (mt *mimeTypeFileFilter) Matches(uri fyne.URI) bool {
+	mimeType, mimeSubType := mimeTypeSplit(uri)
+	for _, mimeTypeFull := range mt.mimeTypes {
+		mimeTypeSplit := strings.Split(mimeTypeFull, "/")
+		if len(mimeTypeSplit) <= 1 {
+			continue
+		}
+		mType := mimeTypeSplit[0]
+		mSubType := strings.Split(mimeTypeSplit[1], ";")[0]
+		if mType == mimeType {
+			if mSubType == mimeSubType || mSubType == "*" {
+				return true
+			}
+		}
+	}
+	return false
 }
 
 func (f *fileDialog) makeUI() fyne.CanvasObject {
-	if f.save {
+	if f.file.save {
 		saveName := widget.NewEntry()
 		saveName.OnChanged = func(s string) {
 			if s == "" {
@@ -50,28 +107,34 @@ func (f *fileDialog) makeUI() fyne.CanvasObject {
 	}
 
 	label := "Open"
-	if f.save {
+	if f.file.save {
 		label = "Save"
 	}
 	f.open = widget.NewButton(label, func() {
-		if f.callback == nil {
+		if f.file.callback == nil {
 			f.win.Hide()
+			if f.file.onClosedCallback != nil {
+				f.file.onClosedCallback(false)
+			}
 			return
 		}
 
-		if f.save {
-			callback := f.callback.(func(fyne.FileWriteCloser, error))
+		if f.file.save {
+			callback := f.file.callback.(func(fyne.FileWriteCloser, error))
 			name := f.fileName.(*widget.Entry).Text
 			path := filepath.Join(f.dir, name)
 
 			info, err := os.Stat(path)
 			if os.IsNotExist(err) {
 				f.win.Hide()
+				if f.file.onClosedCallback != nil {
+					f.file.onClosedCallback(true)
+				}
 				callback(storage.SaveFileToURI(storage.NewURI("file://" + path)))
 				return
 			} else if info.IsDir() {
 				ShowInformation("Cannot overwrite",
-					"Files cannot replace a directory,\ncheck the file name and try again", f.parent)
+					"Files cannot replace a directory,\ncheck the file name and try again", f.file.parent)
 				return
 			}
 
@@ -84,27 +147,39 @@ func (f *fileDialog) makeUI() fyne.CanvasObject {
 
 					callback(storage.SaveFileToURI(storage.NewURI("file://" + path)))
 					f.win.Hide()
-				}, f.parent)
+					if f.file.onClosedCallback != nil {
+						f.file.onClosedCallback(true)
+					}
+				}, f.file.parent)
 		} else if f.selected != nil {
-			callback := f.callback.(func(fyne.FileReadCloser, error))
+			callback := f.file.callback.(func(fyne.FileReadCloser, error))
 			f.win.Hide()
+			if f.file.onClosedCallback != nil {
+				f.file.onClosedCallback(true)
+			}
 			callback(storage.OpenFileFromURI(storage.NewURI("file://" + f.selected.path)))
 		}
 	})
 	f.open.Style = widget.PrimaryButton
 	f.open.Disable()
-	buttons := widget.NewHBox(
-		widget.NewButton("Cancel", func() {
-			f.win.Hide()
-			if f.callback != nil {
-				if f.save {
-					f.callback.(func(fyne.FileWriteCloser, error))(nil, nil)
-				} else {
-					f.callback.(func(fyne.FileReadCloser, error))(nil, nil)
-				}
+	dismissLabel := "Cancel"
+	if f.file.dismissText != "" {
+		dismissLabel = f.file.dismissText
+	}
+	f.dismiss = widget.NewButton(dismissLabel, func() {
+		f.win.Hide()
+		if f.file.onClosedCallback != nil {
+			f.file.onClosedCallback(false)
+		}
+		if f.file.callback != nil {
+			if f.file.save {
+				f.file.callback.(func(fyne.FileWriteCloser, error))(nil, nil)
+			} else {
+				f.file.callback.(func(fyne.FileReadCloser, error))(nil, nil)
 			}
-		}),
-		f.open)
+		}
+	})
+	buttons := widget.NewHBox(f.dismiss, f.open)
 	footer := fyne.NewContainerWithLayout(layout.NewBorderLayout(nil, nil, nil, buttons),
 		buttons, widget.NewHScrollContainer(f.fileName))
 
@@ -165,11 +240,10 @@ func (f *fileDialog) refreshDir(dir string) {
 		if isHidden(file.Name(), dir) {
 			continue
 		}
-
 		itemPath := filepath.Join(dir, file.Name())
 		if file.IsDir() {
 			icons = append(icons, f.newFileItem(itemPath, true))
-		} else {
+		} else if f.file.filter == nil || f.file.filter.Matches(storage.NewURI("file://"+itemPath)) {
 			icons = append(icons, f.newFileItem(itemPath, false))
 		}
 	}
@@ -232,8 +306,8 @@ func (f *fileDialog) setSelected(file *fileDialogItem) {
 	}
 }
 
-func showFileDialog(save bool, callback interface{}, parent fyne.Window) {
-	d := &fileDialog{callback: callback, save: save, parent: parent}
+func showFile(file *FileDialog) *fileDialog {
+	d := &fileDialog{file: file}
 	ui := d.makeUI()
 	dir, err := os.UserHomeDir()
 	if err != nil {
@@ -245,27 +319,122 @@ func showFileDialog(save bool, callback interface{}, parent fyne.Window) {
 	size := ui.MinSize().Add(fyne.NewSize(fileIconCellWidth*2+theme.Padding()*4,
 		(fileIconSize+fileTextSize)+theme.Padding()*4))
 
-	d.win = widget.NewModalPopUp(ui, parent.Canvas())
+	d.win = widget.NewModalPopUp(ui, file.parent.Canvas())
 	d.win.Resize(size)
 
 	d.win.Show()
+	return d
+}
+
+// Show shows the file dialog.
+func (f *FileDialog) Show() {
+	if f.save {
+		if fileSaveOSOverride(f.callback.(func(fyne.FileWriteCloser, error)), f.parent) {
+			f.nativePicker = true
+			return
+		}
+	} else {
+		if fileOpenOSOverride(f.callback.(func(fyne.FileReadCloser, error)), f.parent) {
+			f.nativePicker = true
+			return
+		}
+	}
+	if f.dialog != nil {
+		f.dialog.win.Show()
+		return
+	}
+	f.dialog = showFile(f)
+}
+
+// Hide hides the file dialog.
+func (f *FileDialog) Hide() {
+	if f.nativePicker {
+		return
+	}
+	f.dialog.win.Hide()
+	if f.onClosedCallback != nil {
+		f.onClosedCallback(false)
+	}
+}
+
+// SetDismissText allows custom text to be set in the confirmation button
+func (f *FileDialog) SetDismissText(label string) {
+	if f.nativePicker {
+		return
+	}
+	f.dialog.dismiss.SetText(label)
+	widget.Refresh(f.dialog.win)
+}
+
+// SetOnClosed sets a callback function that is called when
+// the dialog is closed.
+func (f *FileDialog) SetOnClosed(closed func()) {
+	// If there is already a callback set, remember it and call both.
+	if f.nativePicker {
+		return
+	}
+	originalCallback := f.onClosedCallback
+
+	f.onClosedCallback = func(response bool) {
+		closed()
+		if originalCallback != nil {
+			originalCallback(response)
+		}
+	}
+}
+
+// SetFilter sets a filter for limiting files that can be chosen in the file dialog.
+func (f *FileDialog) SetFilter(filter FileFilter) {
+	f.filter = filter
+	if f.dialog != nil {
+		f.dialog.refreshDir(f.dialog.dir)
+	}
+}
+
+// NewExtensionFileFilter takes a string slice of extensions with a leading . and creates a filter for the file dialog.
+// Example: .jpg, .mp3, .txt, .sh
+func NewExtensionFileFilter(extensions []string) FileFilter {
+	return &extensionFileFilter{extensions: extensions}
+}
+
+// NewMimeTypeFileFilter takes a string slice of mimetypes, including globs, and creates a filter for the file dialog.
+// Example: image/*, audio/mp3, text/plain, application/*
+func NewMimeTypeFileFilter(mimeTypes []string) FileFilter {
+	return &mimeTypeFileFilter{mimeTypes: mimeTypes}
+}
+
+// NewFileOpen creates a file dialog allowing the user to choose a file to open.
+// The dialog will appear over the window specified when Show() is called.
+func NewFileOpen(callback func(fyne.FileReadCloser, error), parent fyne.Window) *FileDialog {
+	dialog := &FileDialog{callback: callback, parent: parent}
+	return dialog
+}
+
+// NewFileSave creates a file dialog allowing the user to choose a file to save to (new or overwrite).
+// If the user chooses an existing file they will be asked if they are sure.
+// The dialog will appear over the window specified when Show() is called.
+func NewFileSave(callback func(fyne.FileWriteCloser, error), parent fyne.Window) *FileDialog {
+	dialog := &FileDialog{callback: callback, parent: parent, save: true}
+	return dialog
 }
 
-// ShowFileOpen shows a file dialog allowing the user to choose a file to open.
+// ShowFileOpen creates and shows a file dialog allowing the user to choose a file to open.
 // The dialog will appear over the window specified.
 func ShowFileOpen(callback func(fyne.FileReadCloser, error), parent fyne.Window) {
+	dialog := NewFileOpen(callback, parent)
 	if fileOpenOSOverride(callback, parent) {
 		return
 	}
-	showFileDialog(false, callback, parent)
+	dialog.Show()
 }
 
-// ShowFileSave shows a file dialog allowing the user to choose a file to save to (new or overwrite).
+// ShowFileSave creates and shows a file dialog allowing the user to choose a file to save to (new or overwrite).
 // If the user chooses an existing file they will be asked if they are sure.
 // The dialog will appear over the window specified.
 func ShowFileSave(callback func(fyne.FileWriteCloser, error), parent fyne.Window) {
+	dialog := NewFileSave(callback, parent)
 	if fileSaveOSOverride(callback, parent) {
 		return
 	}
-	showFileDialog(true, callback, parent)
+	dialog.Show()
 }