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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

Initiation

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

Dragging

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

Dropping

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.

Copying

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

Preview

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

What is scarcity.
Npoanlarb Reply
when there is adequate resources
Fiona
why our wants are limited
Npoanlarb Reply
nooo want is unlimited but resources are limited
Ruchi
and do to that there occurs scarcity and we have to make choice in order to have what we need if need be I will explain more
Madara
our wants are not limited but rather the resources
Moses
as we know that there are two principle of microeconomics scarcity of resources and they have alternative uses...
Ruchi
yes .....
Mathias
because our resources are limited./we have a limited resources.
Ijeoma
what is demand
Thank Reply
demand is something wt we called in economic theory of demand it simply means if price of product is increase then demand of product will decrease
Ruchi
inverse relationship between demand and price
Ruchi
in microeconomic
Ruchi
demand is what and how much you want and what's your need...
Shikhar
how can one be so with economics even while you have less knowledge in mathematics.
OKORO Reply
why is it that some products increases everyday by day
Chiamaka Reply
because demand is increase
Ruchi
because demand is increase
Patience
but how demand increases?
Aziz
Because of the Marketing and purchasing power of people.
AmarbirSingh
but how could we know that people's demands have increased everyday by day and how could we know that this is time to produced the products in the market. Is any connection among them
yaqoob
for normal good people demand remain the same if price of product will increase or not
Ruchi
see that some product which increases day by day is comes under normal good which is used by consumer
Ruchi
Seems hot discussing going here
Shamamet
If there are less products demand starts to increase for those products
Shamamet
Economics is really interesting to learn ....
Shamamet
see there is Inferior goods ands normal goods inferior good demand is rarely increase whereas as we talk about normal good demand will absolutely Increase whether price is increase or not
Ruchi
and demand for normal goods increase cause people's income as a while increases time to time
Abhisek
and it might also be that the cost of raw materials are high.
ATTAH
may be
Ruchi
obviously because demand is increasing.....and price is getting low.....
Shikhar
hmmm there is inverse relationship between demand and price
Ruchi
This is because the supply of those products in relation to raw materials are decreasing and they are also necessities. This crate shortage in the market, so sellers will rise the prices of those products.
Abdul
Importance of economics
Odunayomi Reply
the nature and significance of economics studies
Deborah
What is demand
Shuaib Reply
deman is amount of goods and services a consumer is willing and able to buy or purchase at a given price.
Sainabou
the willingness and ability of a body to purchase goods nd servicesbis called demand ,so if she/has ability but doesn't have willingness it's not a demand same if she or he has willingness but doesn't has ability it's not a demand too
Gul
Demand refers to as quantities of a goods and services in which consumers are willing and able to purchase at a given period of time and demand can also be defined as the desire or willingness and backed by the ability to pay.
Fadiga
Yeah
Mathias
What is Choice
Kofi
Choice refers to the ability of a consumer or producer to decide which good, service or resource to purchase or provide from a range of possible options. Being free to chose is regarded as a fundamental indicator of economic well being and development.
Shonal
choice is a act of selecting or choosing from the numerous or plenty wants.
Fadiga
demand is want and it is also what you need and able to afford a particular period of time... because demand changes with time.
Ijeoma
Demand refers to the ability of the consumer to pay for a particular product at a given price
Abdul
how does consumer make profit
Clifford Reply
by buying goods in bulk.
Ijeoma
Compare and contract the function of commercial bank and the central bank of Nigeria
Akwi Reply
what do think is the difference between overhead costs and prime cost
Abdoulkarim
what is economics
Mohamed Reply
economics is a social science that study's how resources can be used to produce goods and services for society
Nathan
Economic is a science which studies human behavior as a relationship between ends and scares means which have alternatives uses or purposes.
Fadiga
what is economics
Mohamed Reply
what is the basic economic problem
John Reply
rules
Buayadarat_Gaming
unlimited wants vs limited resources
Nathan
what economics is all about?
Nomuhle Reply
what is a new paradigm shift
Austen Reply
Paradigm shift it is the reconcilliation of fedural goods in production
Shyline
fedural? what is that?
Aziz
factors that affecting economic system
Bemen Reply
crux
Shyline
what is meant by broadening the tax base?
Fiona Reply
Difference between extinct and extici spicies
Amanpreet Reply
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Source:  OpenStax, Object-oriented programming (oop) with actionscript. OpenStax CNX. Jun 04, 2010 Download for free at http://cnx.org/content/col11202/1.19
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