Multiselect

Gets or sets whether the user can select

multiple files in the dialog. The FileNames

property inherited from the FileDialog class

should be used to retrieve the selected files.

Public Properties

ShowReadOnly

Gets or sets whether the dialog should contain

a read-only check box. Defaults to false.

ReadOnlyChecked

Gets or sets whether the read only checkbox is

checked. Defaults to false.

Public Methods

OpenFile

Returns a Stream with read-only access for the

file specified by the FileName property.

IMPLEMENT ADD HANDLER

Action

Result

1

Open the Windows Forms

As we have seen before, a graphic of the current layout for

Designer window for the

this form is displayed.

MainForm.cs file.

2

Add a Click event handler for

A new menuAdd_Click method is added to and displayed in

the Add item under the Edit

the MainForm.cs source file.

menu.

The line to add the handler is created by Visual Studio in the

How-to

InitializeComponent method automatically:

Double-click on the menu

menuAdd.Click += new

item.

EventHandler (this.menuAdd_Click);

3

Remove the

Note: This code opens a single file and arranges to dis-

menuLoad_Click handler and

play it in the window. Here, we just want to add the file

copy its code into the

to the album, so some changes are required. The code

menuAdd_Click handler.

in the subsequent steps is based on the Load handler,

although there are some differences. In particular, we

do not handle any exceptions that might occur. This is

done intentionally so that we can discuss the handling

of such exceptions in chapter 7.

MULTIPLE FILE SELECTION

167

Action

Result

4

Initialize an OpenFileDialog

protected void menuAdd_Click

instance to allow multiple

(object sender, System.EventArgs e)

selections of various image

{

OpenFileDialog dlg = new OpenFileDialog();

file types.

How-to

dlg.Title = "Add Photos";

dlg.Multiselect = true;

Use the Multiselect

dlg.Filter

property to allow multiple files

= "Image Files (JPEG, GIF, BMP, etc.)|"

to be selected.

+ "*.jpg;*.jpeg;*.gif;*.bmp;"

Note: The Filter setting

+ "*.tif;*.tiff;*.png|"

+ "JPEG files (*.jpg;*.jpeg)|*.jpg;*.jpeg|"

here includes most of the

+ "GIF files (*.gif)|*.gif|"

common formats users are

+ "BMP files (*.bmp)|*.bmp|"

+ "TIFF files (*.tif;*.tiff)|*.tif;*.tiff|"

likely to see. All of these for-

+ "PNG files (*.png)|*.png|"

mats are supported by the

+ "All files (*.*)|*.*";

Bitmap class.

dlg.InitialDirectory

= Environment.CurrentDirectory;

5

Invoke the dialog and process

if (dlg.ShowDialog() == DialogResult.OK)

an OK response.

{

6

Extract the array of files

string[] files = dlg.FileNames;

selected by the user.

7

Turn off the status bar panels

statusBar1.ShowPanels = false;

while the images are loading.

statusBar1.Text

= String.Format("Loading {0} Files",

files.Length);

8

Iterate through the array of

int index = 0;

selected files.

foreach (string s in files)

{

9

Add each image to the album

Photograph photo = new Photograph(s);

if it is not already present.

// Add the file (if not already present)

How-to

index = _album.IndexOf(photo);

Use the IndexOf method to

if (index < 0)

see if the photo is already in

{

index = _album.Add(photo);

the album.

_bAlbumChanged = true;

}

}

Note: The IndexOf method relies on the Equals override

we implemented in chapter 5.

10

Dispose of the nonmemory

dlg.Dispose();

resources used by the dialog.

11

Invalidate the main window to

this.Invalidate();

display the new settings.

}

}

168

CHAPTER 6 COMMON FILE DIALOGS