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Events in WPF

Events

The events associated with any control or window in WPF are known as Rooted events

WPF supports 3 – types of rooted events

 

  1. Direct Events
  2. Bubbling Events
  3. Tunneling Events

 

Direct Events:- These are coursed directly when user clicks on the particular control

  1. Click event of a button
  2. Checked changed button of a radio button or checkbox
  • Selected index changed event of a list box etc

 

Bubbling Events:- Caving the events in the order of child controls to its parent controls is known as event bubbling

EG: Mouse down, Mouse up etc

 

Tunneling Events:- Calling the events in the order of parent control to its child controls is known as tunneling events

Eg:- Preview mouse down, Preview mouse up etc

 

Eg  with Bubbling Events:- Select the label

Screenshot_1

Go to properties window

       ↓

Click on events button

       ↓

Double click on Mouse down events

       ↓

Write the following code

Private void label – Mouse down (object sendes, mouse button event Args)
{
Message Box.show (‘Label”)
}

Switch to .xaml file design

       ↓

Select the window1

       ↓

Go to properties window

       ↓

Click on event button

       ↓

Double click on mouse down event

       ↓

Write the following code.

 

  • Private void window1_Mouse Design (object sender mouse button event args e)

{
Message Box show (“window”),
}
Run the application click on label and check

  • First we get message label then window
  • Here event firing is flowing from child control
    e label to parent control window
  • This is known as event bubbling and the events are called bubbling events

Example  With Tunneling Events

Steps to add a new window to the application

       ↓

Go to Solution explores

       ↓

Select the Solution

       ↓

click on sight mouse button

       ↓

Click on add

       ↓

Click on window

       ↓

window name

  ↓

Type

   ↓

click on add

 

Create a label and write the following code 5 preview mouse down event of label and window private void label_ Preview mouse down (object sender, mouse down event args e)
{
message box show (“label”)
}

Private void window2 _ Preview Mouse Down (object send Mouse down event Args e)

{
Message Box show (“window”);
}

 

Steps to change startup object

Go to solution explores

Double click on app. XML (This file is known as startup file in WPF)

Change start up rui like.

  • Startup uri= “window2.xam.”

Run the application & chact

  • When we click on label first we get a message window then label
  • Here event firing is following from parent control to child control

This is known as Event Tunneling and the events our known as Tunneling events.

Window Life Time in WPF:-

A window lifetime in WPF starts when it is instantiated, after which it is opened, activated can be deactivated  and then closed window lifetime will be ended when it is  closed nothing but when its object is destroyed.

 

Window lifetime events:-

Screenshot_1

 

Eg to open and close a window from other windows:-

Create a new WPF application

           ↓

create two windows with the names window1, window2

 

3

 

Window2   object= new                window2():

 

[Design the window1, create3 buttons and name as  btnopen, btnclose btntide, write the following code.]

Private void btn open_click(–)

{

Objt.show();
}
Private void btnhide_click()
{
obj_hide();
}

The private void btnclose_click(–)
{
Obj%close();
}

Run the apps and check

When user clicks on hide object will not be destroyed and next time user clicks on open window will  be displayed without any exception but when user clicks on close object will be destroyed and next time when user clicks on open it raises exception.

 

Properties of window object:-

11Back ground                                            11show in task bar.

11Border brush                                          11Size To content

11Border thickness                                   11Title

11Icon                                                            11Top Most

11IsEnabled                                                 11Window startup location

11Window state

  • Background:- Used to set or get background color to the window
  • Border brash:- Used to set or get the required color to the border of the window
  • Border thickness:- Used to set or get the thickness value to the border
  • Icon:– used to set or get the required Icon file that is to be displayed at the icon location of the window
  • Is Enabled when set to
    True:- The user can access the window at runtime
    False:-  Icon image will not appear within the taskbar
  • Show Task Bas

True: (Default) the icon image of the window will appear within the taskbar

False  : Icon image will not appear within the taskbar

 

Screenshot_2

 

 

 

Manual : When set to Manual window will have its own size. According to the contents of the window size will be increased or decreased

 

Height:- The Window will be scaled to content height

 

Width:The window width will be scaled to content width

 

Height & width:- Widow height & width will be scaled to contents height & width

  • Top Most:-

True:- When set to true the window will be within the topmost of all other windows

False:-  The window will not be the topmost one in all opened windows

  • Window start up location:- Used to set or get the required location within window when it is opened at runtime.
  • Window state:- When set to normal Window will be opened with its default size

 

Minimized:- Opened in minimized form

 

Maximized:- Window opened in maximized form

 

Summary
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Events in WPF
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