Windows Programming Using C#

Forms Programming I

Contents

• System.Drawing Namespace
• System.Windows.Forms Namespace
• Creating forms applications by hand
• Creating forms applications using Visual Studio designer

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Forms Programming

• Forms programming allows you to create stand-alone Windows GUI applications
• The API has been modernized for .NET
• It now supports a modern delegate-based programming model
• Forms programming uses
• System.Drawing
• Basic GDI+ functionality
• System.Windows.Forms
• Higher-level controls

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System.Drawing

• This namespace provides many graphic data structures which are used throughout the GUI programming model
• It also provides support for low-level drawing operations
• These can be used to draw anything, not just what is offered by the pre-built controls

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System.Drawing.Point

• Structure which represents a 2-D point
• Constructor
• Point(int x, int y)
• Properties
• X – get/set of X coordinate
• Y – get/set of Y coordinate

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System.Drawing.Size

• Structure which stores the width and height of something
• Constructor
• Size(int width, int height)
• Properties
• Width – get/set width
• Height – get/set height

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System.Drawing.Rectangle

• Structure representing a rectangle as the point of the top-left-corner, width and height
• Constructor
• Rectangle(Point tlc, Size sz)
• Rectangle(int tlx, int tly, int wd, int ht)
• Properties
• X – get/set top left X coordinate
• Y – get/set top left Y coordinate
• Height – get/set height
• Width – get/set width
• Bottom – get Y coordinate of rectangle bottom
• Top – get Y coordinate of rectangle top
• Left – get X coordinate of right of rectangle
• Right – get X coordinate of left of rectangle

​

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System.Drawing.Color

• Structure representing an alpha-RGB color
• Methods
• Color FromARGB(int r, int g, int b)
• Color FromARGB(int alpha, int r, int g, int b)
• Properties
• A – get alpha value
• R – get red value
• G – get green value
• B – get blue value
• Black, White, Red, Green, Yellow, Cyan, Coral, Blue, etc. – get values of pre-defined colors

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System.Drawing.Font

• Class representing a font, size and style
• Constructor
• Font(string family, int points, FontStyle style)
• Properties
• FontFamily – get the FontFamily value
• Style – get the FontStyle Value
• Size – get the font size
• Bold – get true if bold
• Italic – get true if italic

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System.Drawing.FontStyle

• An enumeration with members
• Bold, Italic, Regular, Strikeout, Underline
• The values can be ORed together to indicate that more than one style should apply at once

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System.Windows.Forms

• This namespace contains all of the controls used on the average Windows interface
• A control is a higher-level object composed of
• A window in which the control is drawn
• Visual parts of the control which are drawn in the window
• A set of delegates which are triggered when various events occur

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Form Class

• This is the top-level window class
• This class contains all other controls
• Normally, your top-level form inherits from the Form class
• Although the class has numerous methods, most of the time you interact with it via properties and delegates

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Form Properties

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Form Events

• Forms provide support for a large number of events
• You add one or more delegates to these events
• When the event happens, the delegates are invoked
• The delegates must have the signature of an event handler

void EventHandler(object sender, EventArgs e)

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Form Events

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Form Methods

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Creating Windows Applications

• We will demonstrate how to build a simple GUI interface using a text editor
• Most of the time, the designer in Visual Studio will be used
• Doing it by hand
• Shows how it works under the hood
• Let’s you make modifications by hand
• Provides an understanding so you can create your own controls

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Creating Windows Applications

• In creating a GUI application we will use
• Application – a class with static methods to control operation of an application
• Label – a widget that can display static text or an image
• Button – a push button with a textual or image displayed. Able to respond to mouse clicks.

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Creating Windows Applications

• The first step is to create a class which
• Inherits from Form
• Declares the widgets within it

​

public class GreetingForm : Form {

Label greetingLabel;

Button cancelButton;

…

}

​

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Creating Windows Applications

• Next, create the label and set its properties

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greetingLabel = new Label();

greetingLabel.Location = new Point(16, 24);

greetingLabel.Text = "Hello, World";

greetingLabel.Size = new Size(216, 24);

greetingLabel.ForeColor = Color.Black;

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Creating Windows Applications

• Create the cancel button and set its properties

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cancelButton = new Button();

cancelButton.Location = new Point(150, 200);

cancelButton.Size = new Size(112, 32);

cancelButton.Text = "&Cancel";

cancelButton.Click += new EventHandler(cancelButton_Click);

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Creating Windows Applications

• Set the properties of the main form

​

this.AutoScaleDimensions = new SizeF(95.0f, 95.0f);

this.ClientSize = new Size(300, 300);

this.Text = "Hello, World";

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Creating Windows Applications

• Add the controls to the form

this.Controls.Add(cancelButton);

this.Controls.Add(greetingLabel);

• And provide the event handler

​

protected void cancelButton_Click(

object sender, EventArgs e) {

Application.Exit();

}

• * see HelloForm

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Visual Studio Designer

• This is a drag and drop interface for drawing a GUI
• The code is automatically generated
• You can hook event handlers onto the events and write the code for them
• It speeds writing code
• You cannot make major modifications to the code it generates

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CheckBoxes

• Labeled boxes which can be checked or unchecked
• Checked – get/set Boolean to determine if box is checked
• CheckedChanged – delegate called when the box is checked or unchecked
• * see ListBoxDemo

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GroupBox

• Displays a border around a group of controls
• Can have optional label controlled by Text property
• Controls can be added by
• Placing them within the group box in the designer
• Adding to the Controls list programmatically
• * see TextBoxDemo

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Panels

• A panel is like a group box but does not have a text label
• It contains a group of controls just like group box
• BorderStyle – get/set border style as
• BorderStyle.Fixed3D
• BorderStyle.FixedSingle
• BorderStyle.None

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Radio Buttons

• Radio buttons are similar to checkboxes, but
• Appear slightly different
• Allow buttons to be grouped so that only one can be checked at a time
• A group is formed when the radio buttons are in the same container – usually a group box or panel

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Radio Buttons

• Checked – get/set Boolean indicating if the button is checked
• CheckedChanged – delegate invoked when the button is checked or unchecked

​

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• * see TextBoxDemo

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TextBox

• This is a single line or multi-line text editor
• Multiline – get/set Boolean to make multiline
• AcceptsReturn – in a multiline box, if true then pressing Return will create a new line. If false then the button referenced by the AcceptButton property of the form, will be clicked.
• PasswordChar – if this is set to a char, then the box becomes a password box

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TextBox

• ReadOnly – if true, the control is grayed out and will not accept user input
• ScrollBars – determines which scrollbars will be used: ScrollBars.None, Vertical, Horizontal, Both
• TextAlign – get/set HorizontalAlignment.Left, Center, or Right
• TextChanged – event raised when the text is changed

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File Dialog

• The file dialog allows you to navigate through directories and load or save files
• This is an abstract class and you use
• OpenFileDialog
• SaveFileDialog
• You should create the dialog once and reuse it so that it will remember the last directory the user had navigated to

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File Dialog

• InitialDirectory – string representing the directory to start in
• Filter – a string indicating the different types of files to be displayed
• A set of pairs of display name and pattern separated by vertical bars
• Windows Bitmap|*.bmp|JPEG|*.jpg|GIF|*.gif
• FilterIndex – the filter to use as an origin 1 index

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File Dialog

• FileName – the name of the file selected
• ShowDialog – a method to show the dialog and block until cancel or OK is clicked

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if (openDialog.ShowDialog() == DialogResult.OK) {

Image img = Image.FromFile(openDialog.FileName);

pictureBox1.Image = img;

}

• * see ImageViewer

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Image Class

• An abstract class that can store an image
• Several concrete classes are used for image types such as BMP, GIF, or JPG
• FromFile(string fname) – loads any supported image format from a file
• FromStream(stream) – loads an image from a stream
• Height – image height
• Width – image width
• *see ImageViewer

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PictureBox Class

• This displays an image
• Image – assigned an Image object to display
• SizeMode – determines what to do if the image does not fit into the window
• Normal
• StretchImage
• AutoSize
• CenterImage
• Zoom
• * see ImageViewer

​

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ToolTips

• These are the small pop-up boxes which explain the purpose of a control
• To use
• Create a new tooltip in the designer
• Drop the tooltip onto the form
• The tooltip will appear on a tray below the form
• * see ImageViewer

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ToolTips

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ToolTips

• After the tooltip appears in the tray, a new tooltip property appears for every component
• This can be assigned different text for each component
• That text will be displayed when the mouse hovers over that component

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NumericUpDown

• This allows the selection of an integer from a limited range
• Also called a spinner
• Minimum – smallest selectable value
• Maximum – largest selectable value
• Increment – size of increment per click
• Value – the selected value
• ValueChanged – event raised when the value changes
• * see DateSelector

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MonthCalendar

• A control which displays a calendar for the selection of a range of dates
• MinDate – the first selectable date
• MaxDate – the last selectable date
• SelectionStart – DateTime of start of selection
• SelectionEnd – DateTime of end of selection
• DateChanged – event raised when date is changed
• * see DateSelector

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DateTimePicker

• Similar to a month calendar but
• Calendar pulls down and selection displayed
• More configurable
• Selects a single value, not a range
• Properties/methods
• Format – Long, Short, Time, Custom
• Value – DateTime value selected
• ValueChanged – event which fires when date or time changes
• * see DateSelector

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System.DateTime Structure

• A structure representing a date and time
• Constructors
• DateTime(int d, int m, int y)
• DateTime(int d, int m, int y, int h, int m, int s)
• Properties
• Now – returns a DateTime object set to the current local time

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DateTime

• Day – day from 1-31
• Month – month from 1-12
• Year – tear from 1-9999
• Hour – from 0-23
• Minute – minute from 0 -59
• Second – second from 0 -59
• Millisecond – millisecond from 0-999

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DateTime

• DayOfWeek – get enumeration of Sunday, Monday,…
• DayOfYear – day of year from 1 – 366
• Methods
• DateTime AddYears(double value)
• DateTime AddMonths(double value)
• DateTime AddDays(double value)
• DateTime AddHours(double value)
• DateTime AddSeconds(double value)
• DateTime AddMilliseconds(double value)

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DateTime

• TimeSpan Subtract(DateTime)
• int CompareTo(DateTime)
• static DateTime Parse(string)
• ToLongDateString()
• ToShortDateString()
• ToLongTimeString()
• ToShortTimeString()

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ListBox

• The ListBox presents a list of items which can be selected
• A scrollbar is displayed if needed
• MultiColumn – displays list as multiple columns
• SelectedIndex – index of selected item
• SelectedIndices – collection of selected indices
• SelectedItem – the selected item

​

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ListBox

• SelectedItems – collection of selected items
• SelectionMode – how items can be selected
• None – no selection
• One – single selection
• MultiSimple – each click selects additional item
• MultiExtended – uses shift and control keys
• Sorted – if true the items will be sorted alphabetically

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ListBox

• Items – a collection of items in the list box
• ClearSelected – method to clear selection
• GetSelected – returns true if the parameter passed is selected
• SelectedIndexChanged – event when selection changes
• * see ListBoxDemo

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Populating a ListBox

• Any object can be placed into a ListBox
• The display is generated by ToString()

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for(int i = 0; i < 50; i++) {

listBox1.Items.Add(

"Item " + i.ToString());

}

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ComboBox

• A combo box is like a list but lets you displays a selected value.
• The list pulls down when a selection is being made.
• Options allow the selected text to be editable or to require it to be selected from the drop-down list

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ComboBox

• DropDownStyle –
• Simple – text is editable & list always visible
• DropDown – default indicating text is editable & user must click to see list
• DropDownList – value is not editable & user must click to see list
• Items – the collection of items in the list

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ComboBox

• MaxDropDownItems – max number of items in pulldown before scrollbar used
• SelectedIndex – index of selection
• SelectedItem – selected item
• Sorted – whether entries are sorted
• SelectedIndexChanged – event raised when selection changes

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