added a search bar to the file dialog

the search bar takes advantage of the existing filtering system in order
to only show files or filders that match a specific prompt. for now,
there is no way to recursively search through files, or use something
like regex, though that could be added as options later.

the main internal change needed is, in order to be backwards compatible,
having a list of filters instead of just a single filter at a time. that
way, library users can still have many filters while including the
search bar.

dialog/file.go

@@ -89,7 +89,7 @@ type FileDialog struct {
 
 	confirmText, dismissText string
 	desiredSize              fyne.Size
-	filter                   storage.FileFilter
+	filter                   []storage.FileFilter
 	save                     bool
 	// this will be applied to dialog.dir when it's loaded
 	startingLocation fyne.ListableURI
@@ -203,6 +203,23 @@ func (f *fileDialog) makeUI() fyne.CanvasObject {
 		f.optionsMenu(fyne.CurrentApp().Driver().AbsolutePositionForObject(optionsButton), optionsButton.Size())
 	})
 
+	searchBar := widget.NewEntry()
+	searchBar.OnChanged = func(filterText string) {
+		for _, filter := range f.file.filter {
+			if filter, ok := filter.(*storage.SearchFilter); ok {
+				filter.FilterText = filterText
+			}
+		}
+		f.refreshDir(f.dir)
+	}
+	searchBar.Hidden = true
+	// we should only draw the search bar if we've added a search filter
+	for _, filter := range f.file.filter {
+		if _, ok := filter.(*storage.SearchFilter); ok {
+			searchBar.Hidden = false
+		}
+	}
+
 	newFolderButton := widget.NewButtonWithIcon("", theme.FolderNewIcon(), func() {
 		newFolderEntry := widget.NewEntry()
 		ShowForm(lang.L("New Folder"), lang.L("Create Folder"), lang.L("Cancel"), []*widget.FormItem{
@@ -234,8 +251,8 @@ func (f *fileDialog) makeUI() fyne.CanvasObject {
 		optionsButton,
 	)
 
-	header := container.NewBorder(nil, nil, nil, optionsbuttons,
-		optionsbuttons, widget.NewLabelWithStyle(title, fyne.TextAlignLeading, fyne.TextStyle{Bold: true}),
+	header := container.NewBorder(nil, nil, container.NewHBox(widget.NewLabelWithStyle(title, fyne.TextAlignLeading, fyne.TextStyle{Bold: true}), searchBar), optionsbuttons,
+		optionsbuttons,
 	)
 
 	footer := container.NewBorder(nil, nil, nil, buttons,
@@ -415,8 +432,18 @@ func (f *fileDialog) refreshDir(dir fyne.ListableURI) {
 			continue
 		} else if err == nil { // URI points to a directory
 			icons = append(icons, listable)
-		} else if f.file.filter == nil || f.file.filter.Matches(file) {
-			icons = append(icons, file)
+		} else {
+			filterMatches := true
+			for _, filter := range f.file.filter {
+				if !filter.Matches(file) {
+					filterMatches = false
+					break
+				}
+			}
+
+			if filterMatches {
+				icons = append(icons, file)
+			}
 		}
 	}
 
@@ -801,12 +828,34 @@ func (f *FileDialog) SetFilter(filter storage.FileFilter) {
 		fyne.LogError("Cannot set a filter for a folder dialog", nil)
 		return
 	}
-	f.filter = filter
+	f.filter = []storage.FileFilter{filter}
 	if f.dialog != nil {
 		f.dialog.refreshDir(f.dialog.dir)
 	}
 }
 
+// AddFilter adds to the list of existing filters for limiting files that can be chosen in the file dialog
+func (f *FileDialog) AddFilter(filter storage.FileFilter) {
+	if f.isDirectory() {
+		fyne.LogError("Cannot set a filter for a folder dialog", nil)
+		return
+	}
+	if f.filter == nil {
+		f.filter = []storage.FileFilter{}
+	}
+	f.filter = append(f.filter, filter)
+	if f.dialog != nil {
+		f.dialog.refreshDir(f.dialog.dir)
+	}
+}
+
+type ShowSearchBarArgs struct{}
+
+// ShowSearchBar adds a search bar to the file dialog, and allows filtering for specific text in the local directory
+func (f *FileDialog) ShowSearchBar(ShowSearchBarArgs) {
+	f.AddFilter(&storage.SearchFilter{})
+}
+
 // SetFileName sets the filename in a FileDialog in save mode.
 // This is normally called before the dialog is shown.
 func (f *FileDialog) SetFileName(fileName string) {

dialog/folder.go

@@ -18,7 +18,10 @@ func NewFolderOpen(callback func(fyne.ListableURI, error), parent fyne.Window) *
 	dialog := &FileDialog{}
 	dialog.callback = callback
 	dialog.parent = parent
-	dialog.filter = folderFilter
+	if dialog.filter == nil {
+		dialog.filter = []storage.FileFilter{}
+	}
+	dialog.filter = append(dialog.filter, folderFilter)
 	return dialog
 }
 
@@ -38,5 +41,11 @@ func ShowFolderOpen(callback func(fyne.ListableURI, error), parent fyne.Window)
 }
 
 func (f *FileDialog) isDirectory() bool {
-	return f.filter == folderFilter
+	for _, filter := range f.filter {
+		if filter == folderFilter {
+			return true
+		}
+	}
+
+	return false
 }

storage/filter.go

@@ -24,6 +24,11 @@ type MimeTypeFileFilter struct {
 	MimeTypes []string
 }
 
+// SearchFilter represents a file or directory filter based on user inputted text
+type SearchFilter struct {
+	FilterText 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()
@@ -63,3 +68,7 @@ func (mt *MimeTypeFileFilter) Matches(uri fyne.URI) bool {
 func NewMimeTypeFileFilter(mimeTypes []string) FileFilter {
 	return &MimeTypeFileFilter{MimeTypes: mimeTypes}
 }
+
+func (s *SearchFilter) Matches(uri fyne.URI) bool {
+	return strings.Contains(uri.Name(), s.FilterText)
+}