Making A Video Shouldn't Be A Drag. It Should Be Drag And Drop!
Drag and Drop
33
1 Drag and Drop (Not in the Textbook)
description
Drag and Drop. (Not in the Textbook). Objectives. You will be able to use drag and drop in your Windows Forms applications. Drag and Drop Example. Simple example of drag and drop. User will be able to drag an image from one picture box to another. Getting Started. - PowerPoint PPT Presentation
Transcript of Drag and Drop
1
Drag and Drop
(Not in the Textbook)
2
Objectives
You will be able to use drag and drop in your Windows Forms applications.
3
Drag and Drop Example
Simple example of drag and drop.
User will be able to drag an image from one picture box to another.
4
Getting Started
Create a new Windows Forms application. Drag_Drop_Example
Put two picture boxes and a button on the form, as shown on the next slide. Set BorderStyle Set SizeMode to Zoom
Set the image for the left hand picture box but not for the right hand one.
http://www.cse.usf.edu/~turnerr/Software_Systems_Development/Downloads/USF_Bull_small.jpg
5
The Form
6
Set Properties
Picture Boxes: Set BorderStyle Set SizeMode to Zoom
Button Enabled = False
7
Add Event Handler
Display the events for pbSource.
Create an event handler for the MouseDown event
8
Add Event Handler
9
MouseDown Event Handler
private void pbSource_MouseDown(object sender, MouseEventArgs e)
{
pbSource.DoDragDrop(pbSource.Image,
DragDropEffects.Move);
}
10
Form Load Event Handler
Select the form and display its events.
Create an event handler for the Load event.
11
Form Load Event Handler
12
Form Load Event Handler
private void Form1_Load(object sender, EventArgs e)
{
pbTarget.AllowDrop = true;
}
13
More Event Handlers
Select pbTarget and display its events.
Create event handlers for DragEnter and DragDrop
14
More Event Handlers
private void pbTarget_DragEnter(object sender, DragEventArgs e)
{
e.Effect = DragDropEffects.Move;
}
private void pbTarget_DragDrop(object sender, DragEventArgs e)
{
DataObject dataObject = (DataObject) e.Data;
pbTarget.Image = (Image)dataObject.GetData(DataFormats.Bitmap);
pbSource.Image = null;
pbSource.Enabled = false;
btnResetImage.Enabled = true;
}
15
Button Click Handler
Double click on the Reset Image button to create a click event handler.
private void btnResetImage_Click(object sender, EventArgs e)
{
pbSource.Image = pbTarget.Image;
pbSource.Enabled = true;
pbTarget.Image = null;
btnResetImage.Enabled = false;
}
Build and run
16
Program in Action
Click on pbSource and drag to pbTarget
17
After Drag and Drop
Click on Reset Image
18
Back to Original Form
19
Multiple Sources
Add another picture box, pbSource2. Set its Image property. http://www.cse.usf.edu/~turnerr/Software_Systems_Develo
pment/Downloads/Water_Lilies.jpg
Create a MouseDown event handlerprivate void pbSource2_MouseDown(object sender, MouseEventArgs e)
{
pbSource.DoDragDrop(pbSource2.Image,
DragDropEffects.Move);
}
20
Remember the Source
public partial class Form1 : Form
{
PictureBox source;
....
private void pbSource_MouseDown(object sender, MouseEventArgs e)
{
source = pbSource;
pbSource.DoDragDrop(pbSource.Image,
DragDropEffects.Move);
}
private void pbSource2_MouseDown(object sender, MouseEventArgs e)
{
source = pbSource2;
pbSource2.DoDragDrop(pbSource2.Image,
DragDropEffects.Move);
}
21
Prevent Another Drag
private void pbTarget_DragDrop(object sender, DragEventArgs e)
{
DataObject dataObject = (DataObject) e.Data;
pbTarget.Image = (Image)dataObject.GetData(DataFormats.Bitmap);
btnResetImage.Enabled = true;
source.Image = null;
pbSource.Enabled = false;
pbSource2.Enabled = false;
}
22
Update Reset
private void btnResetImage_Click(object sender, EventArgs e)
{
if (pbSource.Image == null)
{
pbSource.Image = pbTarget.Image;
}
else
{
pbSource2.Image = pbTarget.Image;
}
pbTarget.Image = null;
pbSource.Enabled = true;
pbSource2.Enabled = true;
btnResetImage.Enabled = false;
}
23
Multiple Sources in Action
24
Multiple Sources in Action
25
Multiple Targets
Add a second target, pbTarget2
Add DragEnter and DragDrop event handlers.
26
27
Allow Drop in pbTarget2
private void Form1_Load(object sender, EventArgs e)
{
pbTarget.AllowDrop = true;
pbTarget2.AllowDrop = true;
}
28
pbTarget2 Event Handlers
private void pbTarget2_DragEnter(object sender, DragEventArgs e)
{
e.Effect = DragDropEffects.Move;
}
private void pbTarget2_DragDrop(object sender, DragEventArgs e)
{
DataObject dataObject = (DataObject)e.Data;
pbTarget2.Image = (Image)dataObject.GetData(DataFormats.Bitmap);
source.Image = null;
pbSource.Enabled = false;
pbSource2.Enabled = false;
btnResetImage.Enabled = true;
}
29
Update Resetprivate void btnResetImage_Click(object sender, EventArgs e)
{
PictureBox current_target;
if (pbTarget.Image != null)
{
current_target = pbTarget;
}
else
{
current_target = pbTarget2;
}
if (pbSource.Image == null)
{
pbSource.Image = current_target.Image;
}
else
{
pbSource2.Image = current_target.Image;
}
current_target.Image = null;
pbSource.Enabled = true;
pbSource2.Enabled = true;
btnResetImage.Enabled = false;
}
30
Initial Form
31
After Drag and Drop
32
After Reset Image
End of Presentation
33
Assignment
Do this example for yourself if you haven't done it in class.
Study and understand how to do drag and drop. What properties to update on each
event.
