<< Chapter < Page Chapter >> Page >

Supplemental material

I recommend that you also study the other lessons in my extensive collection of online programmingtutorials. You will find a consolidated index at www.DickBaldwin.com .

General Background Information

For Adobe online documentation on this topic, see Using Drag and Drop .

A drag and drop operation is carried out in three stages:

  • Initiation
  • Dragging
  • Dropping


As you are probably already aware, initiation consists of the user pointing to an item with the mouse and pressing the mouse button.


During the drag operation, the user drags the item to another location on the screen without releasing the mouse button.


When the item has been dragged to the new location, the user releases the mouse button causing the item to remain in the new location.


It is also possible to copy an item using the drag and drop gestures, but that capability won't be illustrated in this lesson. Instead, this lesson willconcentrate on moving a Flex component from one location in its container to a different location in its container.

Classes and events

The sample program that I will explain in this lesson will use the following classes, methods, and events:

  • MouseEvent class
    • mouseDown event
  • DragEvent class
    • dragDrop event
    • dragEnter event
  • DragManager class
    • acceptDragDrop method
    • doDrag method
  • DragSource class
    • addData method
    • hasFormat method


I will explain a program named DragAndDrop01 . This program illustrates the fundamentals of drag and drop in ActionScript 3. The program places three imagesin the upper-left corner of a Canvas object as shown in Figure 1.

Program output at startup.

Program output at startup image.
Program output at startup.

The program file structure

The program file structure, taken from the Flex Builder 3 Navigator panel is as shown in Figure 2.

Program file structure.

Program file structure.
Program file structure.

Three image files

As you can see in Figure 2, the program uses the following image files :

  • 0 - space.jpg
  • 1 - snowscene.jpg
  • 2 - frog.jpg

The z-axes indices

The program sets the z-axis indices in the order shown in the above list on the Image objects produced using the image files. This causes the space image to be in the back (0), the frog image to be in the front (2), and the snowscene image to be in the middle (1).

The three images are initially placed in the upper-left corner of the canvas, which is shown as a cyan rectangle in Figure 1.

Any image can be dragged

If you run this program, you will see that any any of the images can be dragged and dropped anywhere within the canvas as long as the mouse pointer doesn't leave the canvas. However, if the edge of thedragged image goes outside the left edge or the top of the canvas, the drag and drop operation is aborted.

If the dragged image goes outside the right side or the bottom of the canvas, scroll bars automatically appear on the canvas as shown in Figure 3.

Program output after dragging the images

Figure 3 shows the program output after dragging the three images to different locations.

Program output after dragging the images.

Program output after dragging the images.
Program output after dragging the images.

Questions & Answers

Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
what school?
biomolecules are e building blocks of every organics and inorganic materials.
anyone know any internet site where one can find nanotechnology papers?
Damian Reply
sciencedirect big data base
Introduction about quantum dots in nanotechnology
Praveena Reply
what does nano mean?
Anassong Reply
nano basically means 10^(-9). nanometer is a unit to measure length.
do you think it's worthwhile in the long term to study the effects and possibilities of nanotechnology on viral treatment?
Damian Reply
absolutely yes
how to know photocatalytic properties of tio2 nanoparticles...what to do now
Akash Reply
it is a goid question and i want to know the answer as well
characteristics of micro business
for teaching engĺish at school how nano technology help us
Do somebody tell me a best nano engineering book for beginners?
s. Reply
there is no specific books for beginners but there is book called principle of nanotechnology
what is fullerene does it is used to make bukky balls
Devang Reply
are you nano engineer ?
fullerene is a bucky ball aka Carbon 60 molecule. It was name by the architect Fuller. He design the geodesic dome. it resembles a soccer ball.
what is the actual application of fullerenes nowadays?
That is a great question Damian. best way to answer that question is to Google it. there are hundreds of applications for buck minister fullerenes, from medical to aerospace. you can also find plenty of research papers that will give you great detail on the potential applications of fullerenes.
what is the Synthesis, properties,and applications of carbon nano chemistry
Abhijith Reply
Mostly, they use nano carbon for electronics and for materials to be strengthened.
is Bucky paper clear?
carbon nanotubes has various application in fuel cells membrane, current research on cancer drug,and in electronics MEMS and NEMS etc
so some one know about replacing silicon atom with phosphorous in semiconductors device?
s. Reply
Yeah, it is a pain to say the least. You basically have to heat the substarte up to around 1000 degrees celcius then pass phosphene gas over top of it, which is explosive and toxic by the way, under very low pressure.
Do you know which machine is used to that process?
how to fabricate graphene ink ?
for screen printed electrodes ?
What is lattice structure?
s. Reply
of graphene you mean?
or in general
in general
Graphene has a hexagonal structure
On having this app for quite a bit time, Haven't realised there's a chat room in it.
what is biological synthesis of nanoparticles
Sanket Reply
how did you get the value of 2000N.What calculations are needed to arrive at it
Smarajit Reply
Privacy Information Security Software Version 1.1a
Got questions? Join the online conversation and get instant answers!
Jobilize.com Reply

Get the best Algebra and trigonometry course in your pocket!

Source:  OpenStax, Object-oriented programming (oop) with actionscript. OpenStax CNX. Jun 04, 2010 Download for free at http://cnx.org/content/col11202/1.19
Google Play and the Google Play logo are trademarks of Google Inc.

Notification Switch

Would you like to follow the 'Object-oriented programming (oop) with actionscript' conversation and receive update notifications?