windows forms ii

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Windows Forms II

Chapter 20

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RadioButton / GroupBox Controls

Used to solicit a multiple choice input. Radio buttons work as a group.

Selecting one unselects any previous choice. The GroupBox defines the group.

Expand “All Windows Forms” in Toolbox. Drag GroupBox to the form. Drag four radio buttons from the Toolbox

and drop inside the GroupBox. You can also copy and paste controls.

Ctrl-C, Ctrl-V

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GroupBox Properties

Text Property

Location and size are normally set interactively via the designer.

The usual appearance properties are available.

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RadioButton Properties

Checked is true for a button that is selected. (Max of 1 per group.)

Text

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Add an OK Button

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Code for Button Click Event

enum Classification {Unknown, Freshman, Sophomore, Junior, Senior};

Classification year = Classification.Unknown;

private void btnOK_Click(object sender, System.EventArgs e){ if (rbFreshman.Checked) year = Classification.Freshman; else if (rbSophomore.Checked) year = Classification.Sophomore; else if (rbJunior.Checked) year = Classification.Junior; else if (rbSenior.Checked) year = Classification.Senior;

if (year == Classification.Unknown) MessageBox.Show("Please select year"); else MessageBox.Show("You will be recorded as a " + year.ToString());}

End of Section

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The PictureBox Control

Allows you to include images on your form.

Typically a jpeg or gif file Other possibilities.

Important Properties: Image (Browse to file) Location Size SizeMode

Normal, StretchImage, AutoSize, CenterImage, Zoom BorderStyle

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The PictureBox Control

Need an image file? Try google > images

From search on University of South Florida

Image file is in Downloads area of class web site: http://www.cse.usf.edu/~turnerr/Software_Systems_Develo

pment/Downloads/USF_Bull.gif

Download to desktop

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The PictureBox Control

Setting the Image Property

Select the Image property.

Click on the elipses (...) button. 10

Setting the Image Property

Click on Import.

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Setting the Image

Navigate to the image file.

Select the file and click Open.

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Setting the Image

Click OK.

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Setting the Image

The image file has been copied into the project.

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SizeMode Values

From the Help page for SizeMode:

Valid values for this property are taken from the PictureBoxSizeMode enumeration.

By default, in PictureBoxSizeMode.Normal mode, the Image is placed in the upper left corner of the PictureBox, and any part of the image too big for the PictureBox is clipped.

PictureBoxSizeMode.Zoom causes the image to be stretched or shrunk to fit the PictureBox, while maintaining the aspect ratio.

Using the PictureBoxSizeMode.StretchImage value causes the image to stretch to fit the PictureBox.

Using the PictureBoxSizeMode.AutoSize value causes the control to resize to always fit the image.

Using the PictureBoxSizeMode.CenterImage value causes the image to be centered in the client area.

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The PictureBox Control

Set size mode to Zoom.

Build and run. 16

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SizeMode Zoom

SizeMode = Zoom

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SizeMode Normal

SizeMode = Normal

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CenterImage

SizeMode = CenterImage

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AutoSize

SizeMode = Autosize

Most of the PictureBox falls outside the form.

AutoSize

Window resized to hold entire PictureBox control. 21

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The PictureBox Control

Conclusions: Try to match size of actual image to size

that you need on the form.

If not, Zoom is usually the best bet.

But, at least, be sure the ratio of height to width is about the same.

End of Section

Where is the image?

It's embedded in the program

You don't need to retain or deploy the original image file. 23

Form1.resx

In the project folder, you can drill down and find the file.

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Form1.resx

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Form1.resx

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Form1.resx

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Form1.resx

End of Section28

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The ComboBox Control

“Combination” of text entry box and dropdown list. Select from list or enter text.

Important Properties: Items (Collection of strings to display.)

Can be set using the designer or by program. DropDownStyle

Simple Text Entry Only DropDown Text Entry or Select DropDownList Select Only

Text Whatever was selected or entered

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The ComboBox Control

Set name to cbYear.

Setting the Choices

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Setting the Choices

Click OK.

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Getting the User’s Choice

Build and run.

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Program Running

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The ComboBox Control

After clicking on the arrow:

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The ComboBox Control

After user selects Sophomore

Getting the User’s Choice

End of Section

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Handling the FormClosing Event

In Design View, select the form (by clicking anywhere on the background.)

In the Properties window, select Events. (Lightening bolt icon at top of window.)

Beside “FormClosing” type the name that you want to give to the event handler (e.g., FormIsClosing) Don't use the event name, FormClosing.

Press Enter.

Setting the Event Handler

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Handling the FormClosing Event

This creates the following stub in the code file:

private void FormIsClosing(

object sender, System.ComponentModel.CancelEventArgs e)

{

}

This function will be called when the user clicks the Close button on the form.

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Using a MessageBox to Get User Input

Add this code inside the FormIsClosing function.

DialogResult result =

MessageBox.Show("Are you sure you want to quit?",

"Confirm",

MessageBoxButtons.YesNo,

MessageBoxIcon.Question);

e.Cancel = (result == DialogResult.No);

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MessageBox Example

MessageBox.Show("Are you sure you want to quit?", "Confirm", MessageBoxButtons.YesNo, MessageBoxIcon.Question);

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Add a Close Button

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Close Button Click Event Handler

private void btnClose_Click(object sender, EventArgs e)

{

this.Close();

}

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We still get the FormClosing Event

End of Section

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Summany

Visual Studio makes it easy to create simple Windows forms applications.

There is an enormous amount of information about Windows forms. Only a small amount of it is necessary in

order to create simple applications. Need to be aware of what exists. Need to be able to find what you need

when you need it.

End of Presentation