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8/10/2019 Synapseindia Dot Net Development Windows Programming

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Windows Programming

Using C#

Forms Programming I


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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-aloneWindows GUI applications

The API has been modernized for .NET

It now supports a modern delegate-basedprogramming 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 datastructures which are used throughout the GUI

programming model

It also provides support for low-level drawingoperations

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

Xget/set of X coordinate

Yget/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

Widthget/set width

Heightget/set height


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System.Drawing.Rectangle

Structure representing a rectangle as the point of the top-left-corner, width andheight

Constructor Rectangle(Point tlc, Size sz)

Rectangle(int tlx, int tly, int wd, int ht) Properties

Xget/set top left X coordinate

Yget/set top left Y coordinate

Heightget/set height

Widthget/set width

Bottomget Y coordinate of rectangle bottom

Topget Y coordinate of rectangle top

Leftget X coordinate of right of rectangle

Rightget 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 Aget alpha value

Rget red value

Gget green value Bget 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 FontFamilyget the FontFamily value

Styleget the FontStyle Value

Sizeget the font size

Boldget true if bold

Italicget 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 thatmore than one style should apply at once


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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 anddelegates


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Form Properties

Property Description

Location Point of to left corner

Size Size of form in pixels

Text Text displayed or caption

AutoScaleDimensions DPI resolution of display it was built for. Will be scaled tolook correct on other displays.

BackColor Background color

ForeColor Foreground or drawing color

ClientSize Size of drawing area without borders or scrollbars

Controls A collection of controls owned by the form

WindowState Whether maximized, minimized or normal

DefaultSize Size when initially created

MinimumSize Minimum size window can be resized to

MaximumSize Maximum size window can be resized to


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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

handlervoid EventHandler(object sender,

EventArgs e)


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Form Events

Event Description

Load Just before form is loaded the first time

Closing Just before the form is closed

Closed When the form is actually closed

Shown Occurs when a form is first displayed

ResizeBegin Resize operation has begun

ResizeEnd Resize operation has ended


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Form Methods

Method Description

Activate Activates the window and gives it focus

Close Closes the form

Show Makes the form visible

BringToFront Moves to top of stacking order

Hide Makes the form invisible

Focus Gives the form focus


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Creating Windows Applications

We will demonstrate how to build a simple GUIinterface using a text editor

Most of the time, the designer in Visual Studio willbe used

Doing it by hand

Shows how it works under the hood

Lets you make modifications by hand Provides an understanding so you can create your own

controls


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In creating a GUI application we will use

Applicationa class with static methods to control

operation of an application Labela widget that can display static text or an image

Buttona push button with a textual or image

displayed. Able to respond to mouse clicks.


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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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Next, create the label and set its properties

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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Create the cancel button and set its properties

cancelButton = new Button();

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

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

cancelButton.Text = "&Cancel";

cancelButton.Click += newEventHandler(cancelButton_Click);


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Set the properties of the main form

this.AutoScaleDimensions = newSizeF(95.0f, 95.0f);

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

this.Text = "Hello, World";


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Add the controls to the formthis.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 andwrite the code for them

It speeds writing code

You cannot make major modifications to the code itgenerates


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CheckBoxes

Labeled boxes which can be checked or unchecked

Checkedget/set Boolean to determine if box ischecked

CheckedChangeddelegate 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 textlabel

It contains a group of controls just like group box BorderStyleget/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 containerusually a group box or panel


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Radio Buttons

Checkedget/set Boolean indicating if the button is

checked

CheckedChangeddelegate invoked when the

button is checked or unchecked

* see TextBoxDemo


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TextBox

This is a single line or multi-line text editor

Multilineget/set Boolean to make multiline

AcceptsReturnin a multiline box, if true thenpressing Return will create a new line. If false then the

button referenced by the AcceptButtonproperty of the

form, will be clicked.

PasswordCharif this is set to a char, then the box

becomes a password box


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TextBox

ReadOnlyif true, the control is grayed out and willnot accept user input

ScrollBarsdetermines which scrollbars will be

used: ScrollBars.None, Vertical, Horizontal, Both TextAlignget/set HorizontalAlignment.Left,

Center, or Right

TextChangedevent raised when the text is changed


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File Dialog

The file dialog allows you to navigate throughdirectories 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 hadnavigated to


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File Dialog

InitialDirectorystring representing the

directory to start in

Filtera string indicating the different types offiles to be displayed

A set of pairs of display name and pattern separated by

vertical bars

Windows Bitmap|*.bmp|JPEG|*.jpg|GIF|*.gif

FilterIndexthe filter to use as an origin 1 index


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File Dialog

FileNamethe name of the file selected

ShowDialoga method to show the dialog and block untilcancel or OK is clicked

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 typessuch as BMP, GIF, or JPG

FromFile(string fname)loads any supportedimage format from a file

FromStream(stream)loads an image from a stream

Heightimage height

Widthimage width *see ImageViewer


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PictureBox Class

This displays an image

Imageassigned an Image object to display

SizeModedetermines 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 explainthe 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 eachcomponent

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 Minimumsmallest selectable value

Maximumlargest selectable value

Incrementsize of increment per click

Valuethe selected value

ValueChangedevent 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 MinDatethe first selectable date

MaxDatethe last selectable date

SelectionStartDateTime of start of selection

SelectionEndDateTime of end of selection

DateChangedevent 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

FormatLong, Short, Time, Custom

ValueDateTime value selected

ValueChangedevent which fires when date or timechanges

* 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

Nowreturns a DateTime object set to the current localtime


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DateTime

Dayday from 1-31

Monthmonth from 1-12

Yeartear from 1-9999 Hourfrom 0-23

Minuteminute from 0 -59

Secondsecond from 0 -59 Millisecondmillisecond from 0-999


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DateTime

DayOfWeekget enumeration of Sunday, Monday,

DayOfYearday of year from 1366

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

MultiColumndisplays list as multiple columns

SelectedIndexindex of selected item

SelectedIndicescollection of selected indices

SelectedItemthe selected item


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ListBox

SelectedItemscollection of selected items

SelectionModehow items can be selected

Noneno selection

Onesingle selection

MultiSimpleeach click selects additional item

MultiExtendeduses shift and control keys

Sortedif true the items will be sorted alphabetically


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ListBox

Itemsa collection of items in the list box

ClearSelectedmethod to clear selection

GetSelectedreturns true if the parameter passedis selected

SelectedIndexChangedevent 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()

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

Simpletext is editable & list always visible

DropDowndefault indicating text is editable & usermust click to see list

DropDownListvalue is not editable & user must

click to see list

Itemsthe collection of items in the list


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ComboBox

MaxDropDownItemsmax number of items inpulldown before scrollbar used

SelectedIndexindex of selection

SelectedItemselected item

Sortedwhether entries are sorted

SelectedIndexChangedevent raised when

selection changes

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