Objectives. RadioButton. Drag radio buttons to form. Chapter 3 Controls for Windows Forms 2004 Art Gittleman

Chapter 3

Controls for Windows

Forms

© 2004 Art Gittleman

Objectives

• Choose a date or number • Time events

• Make menu choices • Respond to dialogs

RadioButton

• May display text, an image, or both • Radio buttons from a group

user must select exactly one Example3-1 has three radio buttons Each represents a color

User selection changes Label text to the selected color

Drag radio buttons to form

Example3-1

Configure Properties

BackColor Red Font Bold True Text Red Anchor Top (Name) redButton

Configuring the Label

BorderStyle Fixed3D Font

Size 14

Text The text color is black TextAlign MiddleCenter

Anchor Left, Right Name display

The BorderStyle property

Used for the Label

None The default

FixedSingle Frames the label with black rectangle

Fixed3D Recesses the label

Handling a radio button click

private void redRadio_CheckedChanged (object sender, System.EventArgs e) {

display.ForeColor = Color.Red; display.Text = "The color is red"; }

Changes the foreground color and text of the label

The LinkLabel control

Lets us add links to web sites

This links to a site with information about George Washington

Handle a Link Click

Internet Explorer browser with the desired web site Event handling code:

private void presidentLink_LinkClicked(object sender, System.Windows.Forms.LinkLabelLinkClickedEventArgs e) {

System.Diagnostics.Process.Start(“IExplore”,

“http://www.whitehouse.gov/history/presidents/gw1.html”); }

Handle a Link Click

Use the Start method of the Process class to start the Internet Explorer browser with the desired web site

Event handling code:

private void presidentLink_LinkClicked(object sender, System.Windows.Forms.LinkLabelLinkClickedEventArgs e) {

System.Diagnostics.Process.Start(e.Link.LinkData.ToString( )); }

Add Radio Buttons to select

Handling a radio button selection

When the user selects a radio button we want to do three things

• Show the president’s name in the link • Underline the link

• Associate the link with the site containing the president’s biography.

The event handling code

(object sender, System.EventArgs e) {

presidentLink.Text = "George Washington"; presidentLink.LinkBehavior = LinkBehavior.AlwaysUnderline; presidentLink.Links[0].LinkData = "http://www.whitehouse.gov/history/presidents/gw1.html"; }

A Collection Of Links

A LinkLabel may have a collection of links. The Links property holds that collection Links[0] refers to the first link in the

collection.

The LinkLabel in Example3-2 has only one link

The LinkData specifies the web site for the link

Grouping Radio Buttons

Drag a GroupBox to the Form

Add each RadioButton to the GroupBox GroupBox has a border with a title Change its Text property to

Choose a President

To change the title in the group box border A Form may have more than one group

Selecting a Style

The Border Style group box

Choose a border style for the link label The user chooses exactly one radio button

from each group – one to choose the president and one to choose the border style

Border Style event handling

(object sender, System.EventArgs e) {

presidentLink.BorderStyle = BorderStyle.FixedSingle; }

private void threeDBorder_CheckedChanged (object sender, System.EventArgs e) {

presidentLink.BorderStyle = BorderStyle.Fixed3D; }

The PictureBox control

The SizeMode property

Normal Places the image in the upper-left corner, clipped if too large StretchImage Stretches or shrinks the image to fit AutoSize Resizes the PictureBox to the size of

the image

CenterImage Displays the image in the center if the PictureBox is larger than the image. Centers and clips the image if it is larger.

Size modes in Example3-3

Left AutoSize Right (top to bottom)

Normal CenterImage StretchImage Can set border styles too

None, FixedSingle, or Fixed3D

The CheckBox control

Make multiple selections Or select nothing

May have a label, an image, a background image

May appear with a box to check or like a button

Example3-4

Steps to add an image

• Click on the View, Properties menu item to show the list of properties.

• Click on the Image property to display a small button at the right.

• Click on the small button to pop up a window to open a file.

• Browse to locate the desired image and click the Openbutton.

Alignment

ImageAlign property -- place the image at different positions within a CheckBox. CheckAlign property functions in the same

way for the position of the box that the user checks.

TextAlign property determines the placement of the text

Steps to set alignment

• Click on the View, Properties menu item to show the list of properties.

• Click on the ImageAlign, CheckAlign, or TextAlign property to display a small button at the right.

• Click on the small button to pop up a grid of three rows and three columns that allows us to choose the alignment position.

• Click to choose one of the nine positions. The three vertical positions Top, Middle, and Bottom combine with the three horizontal positions, Left, Center, and Right to give the nine choices.

FlatStyle property for CheckBox

Flat The box appears flat

Popup Appears flat until the mouse passing over makes it appear three-dimensional

Standard Appears three-dimensional System Appearance determined by

the user’s operating system

Event-handling code

private void berryBox_CheckedChanged (object sender, System.EventArgs e) {

display.Text = "Strawberry " + berryBox.Checked;

}

Label shows the last box checked or unchecked

ListBox and ComboBox

ListBox shows all the elements ComboBox pops them up

Click on Items property to display a String Collection Editor to enter the items

SelectedItem property refers to the selected item

Example3-5

String Collection Editor

ListBox SelectionMode

None No items can be selected One One item can be selected MultiSimple Multiple items can be

selected MultiExtended Multiple items can be

selected and the user can use the shift, control, and arrow keys to make the selection

Selecting a list item

When the user selects an item, say hamburger

Program displays message in a label

hamburger has 9 letters

build this expression in four parts hamburger the selected item has

9 the length of the selected word letters

ListBox event handler

private void foodList_SelectedIndexChanged (object sender, System.EventArgs e) { display.Text = foodList.SelectedItem.ToString() + " has “ + foodList.SelectedItem.ToString().Length.ToString() + " letters"; }

ComboBox event handler

private void drinksCombo_SelectedIndexChanged (object sender, System.EventArgs e)

{

display.Text = "It's "

+ foodList.SelectedItem.ToString() + " and " + drinksCombo.Text; }

Display a message showing the food and drink selected

Keeping Track

Various controls help us keep track of dates, time, and numbers

DateTimePicker NumericUpDown StatusBar Timer

Example3-6

Example3-6 operation

DateTimePickerat top of form User chooses a date

NumericUpDownin the middle User selects a number

Buttonat bottom

User presses to display date in a label and number selected in another label

StatusBarat bottom shows current time

Timerupdates it every second, and changes label colors

DateTimePicker Format

Long Tuesday , January 28, 2003 Short 1/28/03

Time 10:32:56 AM

Button Click handling

private void showButton_Click

(object sender, System.EventArgs e) {

dateDisplay.Text = "Date selected: " + date.Value.ToLongDateString(); numberDisplay.Text = "Number selected "

+ number.Value.ToString(); }

A Timer control

Timer Tick event every second

(object sender, System.EventArgs e) { currentDateTime.Text = DateTime.Now.ToString(); number.BackColor = dateDisplay.BackColor; dateDisplay.BackColor = numberDisplay.BackColor; numberDisplay.BackColor = number.BackColor; }

Copies time to status bar

Permutes background colors to give flashing effect

Menus

Drag a MainMenu control

Add a File menu

Add menu items

File menu

Open, Save, Print Format menu

Font, Color menu Foreground Background

Click on menu item – Event handler pops up a dialog

Open menu click event handler

private void openMenu_Click

(object sender, System.EventArgs e) {

openDialog.ShowDialog();

displayBox.LoadFile(openDialog.FileName, RichTextBoxStreamType.PlainText); }

Pops up a dialog to select the file Loads the selected file in a RichTextBox

Save Click event handler

private void saveMenu_Click

(object sender, System.EventArgs e) {

saveDialog.ShowDialog();

displayBox.SaveFile(saveDialog.FileName, RichTextBoxStreamType.PlainText); }

Pops up a dialog to enter a file name Saves file in RichTextBox using that name

Foreground Menu Click

private void foregroundMenu_Click (object sender, System.EventArgs e) {

colorDialog.ShowDialog();

displayBox.ForeColor =colorDialog.Color; }

Pops up a dialog to choose a color Changes the RichTextBox text color

Font Menu Click

private void fontMenu_Click

(object sender, System.EventArgs e) {

fontDialog.ShowDialog();

displayBox.Font = fontDialog.Font; }

Pops up a font dialog to choose a font Changes the font of the RichTextBox text