Add the ability to filter files in the File Dialog

cmd/fyne_demo/screens/window.go

@@ -145,6 +145,16 @@ func loadDialogGroup(win fyne.Window) *widget.Group {
 				fileOpened(reader)
 			}, win)
 		}),
+		widget.NewButton("File Open With Filter (only show txt or png)", func() {
+			dialog.ShowFileOpenWithFilter(func(reader fyne.FileReadCloser, err error) {
+				if err != nil {
+					dialog.ShowError(err, win)
+					return
+				}
+
+				fileOpened(reader)
+			}, win, dialog.NewExtensionFileFilter([]string{".png", ".txt"}))
+		}),
 		widget.NewButton("File Save", func() {
 			dialog.ShowFileSave(func(writer fyne.FileWriteCloser, err error) {
 				if err != nil {
@@ -155,6 +165,16 @@ func loadDialogGroup(win fyne.Window) *widget.Group {
 				fileSaved(writer)
 			}, win)
 		}),
+		widget.NewButton("File Save With Filter (only show images)", func() {
+			dialog.ShowFileSaveWithFilter(func(writer fyne.FileWriteCloser, err error) {
+				if err != nil {
+					dialog.ShowError(err, win)
+					return
+				}
+
+				fileSaved(writer)
+			}, win, dialog.NewMimeTypeFileFilter([]string{"image/*"}))
+		}),
 		widget.NewButton("Custom Dialog (Login Form)", func() {
 			username := widget.NewEntry()
 			password := widget.NewPasswordEntry()

dialog/file.go

@@ -30,10 +30,54 @@ type fileDialog struct {
 	win      *widget.PopUp
 	selected *fileDialogItem
 	callback interface{}
+	filter   FileFilter
 	dir      string
 	save     bool
 }
 
+// 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 := mimeTypeGet(uri)
+	for _, mimeTypeFull := range mt.mimeTypes {
+		mimeTypeSplit := strings.Split(mimeTypeFull, "/")
+		if len(mimeTypeSplit) <= 1 {
+			continue
+		}
+		mType := mimeTypeSplit[0]
+		mSubType := mimeTypeSplit[1]
+		if mType == mimeType {
+			if mSubType == mimeSubType || mSubType == "*" {
+				return true
+			}
+		}
+	}
+	return false
+}
+
 func (f *fileDialog) makeUI() fyne.CanvasObject {
 	if f.save {
 		saveName := widget.NewEntry()
@@ -165,11 +209,13 @@ 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 {
+			if f.filter != nil && !f.filter.Matches(storage.NewURI(itemPath)) {
+				continue
+			}
 			icons = append(icons, f.newFileItem(itemPath, false))
 		}
 	}
@@ -232,8 +278,8 @@ func (f *fileDialog) setSelected(file *fileDialogItem) {
 	}
 }
 
-func showFileDialog(save bool, callback interface{}, parent fyne.Window) {
-	d := &fileDialog{callback: callback, save: save, parent: parent}
+func showFileDialog(save bool, callback interface{}, parent fyne.Window, filter FileFilter) {
+	d := &fileDialog{callback: callback, save: save, parent: parent, filter: filter}
 	ui := d.makeUI()
 	dir, err := os.UserHomeDir()
 	if err != nil {
@@ -251,13 +297,34 @@ func showFileDialog(save bool, callback interface{}, parent fyne.Window) {
 	d.win.Show()
 }
 
+// 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}
+}
+
 // ShowFileOpen 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) {
 	if fileOpenOSOverride(callback, parent) {
 		return
 	}
-	showFileDialog(false, callback, parent)
+	showFileDialog(false, callback, parent, nil)
+}
+
+// ShowFileOpenWithFilter shows a file dialog with a filter limiting displayed files to choose a file to open.
+// The dialog will appear over the window specified.
+func ShowFileOpenWithFilter(callback func(fyne.FileReadCloser, error), parent fyne.Window, filter FileFilter) {
+	if fileOpenOSOverride(callback, parent) {
+		return
+	}
+	showFileDialog(false, callback, parent, filter)
 }
 
 // ShowFileSave shows a file dialog allowing the user to choose a file to save to (new or overwrite).
@@ -267,5 +334,15 @@ func ShowFileSave(callback func(fyne.FileWriteCloser, error), parent fyne.Window
 	if fileSaveOSOverride(callback, parent) {
 		return
 	}
-	showFileDialog(true, callback, parent)
+	showFileDialog(true, callback, parent, nil)
+}
+
+// ShowFileSaveWithFilter shows a file dialog with a filter limiting displayed files 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 ShowFileSaveWithFilter(callback func(fyne.FileWriteCloser, error), parent fyne.Window, filter FileFilter) {
+	if fileSaveOSOverride(callback, parent) {
+		return
+	}
+	showFileDialog(true, callback, parent, filter)
 }

dialog/fileicon.go

@@ -6,7 +6,6 @@ import (
 
 	"fyne.io/fyne"
 	"fyne.io/fyne/canvas"
-	"fyne.io/fyne/storage"
 	"fyne.io/fyne/theme"
 	"fyne.io/fyne/widget"
 )
@@ -29,9 +28,9 @@ type fileIconRenderer struct {
 const ratioDown float64 = 0.45
 
 // NewFileIcon takes a filepath and creates an icon with an overlayed label using the detected mimetype and extension
-func NewFileIcon(path string) fyne.CanvasObject {
+func NewFileIcon(uri fyne.URI) fyne.CanvasObject {
 
-	ext, mimeType, mimeSubType := mimeTypeGet(path)
+	ext, mimeType, mimeSubType := mimeTypeGet(uri)
 
 	var res fyne.Resource
 	switch mimeType {
@@ -97,8 +96,7 @@ func (s fileIconRenderer) Refresh() {
 	canvas.Refresh(s.item)
 }
 
-func mimeTypeGet(path string) (ext, mimeType, mimeSubType string) {
-	uri := storage.NewURI(path)
+func mimeTypeGet(uri fyne.URI) (ext, mimeType, mimeSubType string) {
 	ext = uri.Extension()
 	if len(ext) > 5 {
 		ext = ext[:5]

dialog/fileicon_test.go

@@ -10,42 +10,43 @@ import (
 	"github.com/stretchr/testify/assert"
 
 	"fyne.io/fyne"
+	"fyne.io/fyne/storage"
 	"fyne.io/fyne/theme"
 )
 
 func TestNewFileIcon(t *testing.T) {
 	f := &fileDialog{}
 	_ = f.makeUI()
 
-	item := NewFileIcon("/path/to/filename.zip")
+	item := NewFileIcon(storage.NewURI("/path/to/filename.zip"))
 
 	assert.Equal(t, item.(*fileIcon).extension, ".zip")
 	assert.Equal(t, item.(*fileIcon).mimeType, "application")
 	assert.Equal(t, item.(*fileIcon).mimeSubType, "zip")
 	assert.Equal(t, item.(*fileIcon).resource, theme.FileApplicationIcon())
 
-	item = NewFileIcon("/path/to/filename.mp3")
+	item = NewFileIcon(storage.NewURI("/path/to/filename.mp3"))
 
 	assert.Equal(t, item.(*fileIcon).extension, ".mp3")
 	assert.Equal(t, item.(*fileIcon).mimeType, "audio")
 	assert.Equal(t, item.(*fileIcon).mimeSubType, "mpeg")
 	assert.Equal(t, item.(*fileIcon).resource, theme.FileAudioIcon())
 
-	item = NewFileIcon("/path/to/filename.png")
+	item = NewFileIcon(storage.NewURI("/path/to/filename.png"))
 
 	assert.Equal(t, item.(*fileIcon).extension, ".png")
 	assert.Equal(t, item.(*fileIcon).mimeType, "image")
 	assert.Equal(t, item.(*fileIcon).mimeSubType, "png")
 	assert.Equal(t, item.(*fileIcon).resource, theme.FileImageIcon())
 
-	item = NewFileIcon("/path/to/filename.txt")
+	item = NewFileIcon(storage.NewURI("/path/to/filename.txt"))
 
 	assert.Equal(t, item.(*fileIcon).extension, ".txt")
 	assert.Equal(t, item.(*fileIcon).mimeType, "text")
 	assert.Equal(t, item.(*fileIcon).mimeSubType, "plain")
 	assert.Equal(t, item.(*fileIcon).resource, theme.FileTextIcon())
 
-	item = NewFileIcon("/path/to/filename.mp4")
+	item = NewFileIcon(storage.NewURI("/path/to/filename.mp4"))
 
 	assert.Equal(t, item.(*fileIcon).extension, ".mp4")
 	assert.Equal(t, item.(*fileIcon).mimeType, "video")
@@ -62,14 +63,14 @@ func TestNewFileIconNoExtension(t *testing.T) {
 	binFileWithNoExt := filepath.Join(workingDir, "testdata/bin")
 	textFileWithNoExt := filepath.Join(workingDir, "testdata/text")
 
-	item := NewFileIcon(binFileWithNoExt)
+	item := NewFileIcon(storage.NewURI(binFileWithNoExt))
 
 	assert.Equal(t, item.(*fileIcon).extension, "")
 	assert.Equal(t, item.(*fileIcon).mimeType, "application")
 	assert.Equal(t, item.(*fileIcon).mimeSubType, "octet-stream")
 	assert.Equal(t, item.(*fileIcon).resource, theme.FileApplicationIcon())
 
-	item = NewFileIcon(textFileWithNoExt)
+	item = NewFileIcon(storage.NewURI(textFileWithNoExt))
 
 	assert.Equal(t, item.(*fileIcon).extension, "")
 	assert.Equal(t, item.(*fileIcon).mimeType, "text")

dialog/fileitem.go

@@ -6,6 +6,7 @@ import (
 
 	"fyne.io/fyne"
 	"fyne.io/fyne/canvas"
+	"fyne.io/fyne/storage"
 	"fyne.io/fyne/theme"
 	"fyne.io/fyne/widget"
 )
@@ -60,7 +61,7 @@ func (f *fileDialog) newFileItem(path string, dir bool) *fileDialogItem {
 	if dir {
 		icon = canvas.NewImageFromResource(theme.FolderIcon())
 	} else {
-		icon = NewFileIcon(path)
+		icon = NewFileIcon(storage.NewURI(path))
 	}
 	name := fileName(path)