AxisCamControl Visual Basic Example - Axis Communications

AxisCamControl Visual Basic Example
These examples will give you a first look at how the AxisCamControl can be used in the Microsoft Visual Basic
environment. Please see the AxisCamControl API document included in the installation file for more details about
supported methods and properties.
In these examples, you will learn how to:
� Download and install the AxisCamControl.
� Add an ActiveX control to a VB project.
� Remove an ActiveX control from a VB project.
� Set the AxisCamControl’s URL property and get live images.
� Use the SaveImage and LoadImage methods.
� Use the OnNewEvent to be notified every time a new image has been captured.
� Read a Jpeg image from disk and display it in the control window using the SetImage method.
What is the AxisCamControl?
An ActiveX control is an extension to the Visual Basic Toolbox. You use ActiveX controls just as you would any of
the standard built-in controls, such as the CheckBox control. When you add an ActiveX control to a program, it
becomes part of the development and run-time environment and provides new functionality for your application.
The main objective of the AxisCamControl is to enable viewing directly in MS Internet Explorer, as well as to
enable easy software development using various development tools, such as Microsoft Visual Basic and Microsoft
Visual C++.
Possible Uses
� Create an application where live images can be shown to the user.
� Create an application where live images can be captured and saved to file.
Installation
To install the AxisCamControl on your PC, just follow these steps:
1. Download the installation file.
2. Unpack the AxisCamControl.zip file with e.g. WinZip.
3. Run the AXISCameraServerControl.exe program. This will unpack the control for you and also
register it so that it is readily available in Visual Basic, Visual C++ etc.
4. Read the included AxisCamControl document, which contains license information and documentation of
the control.
Adding Controls to a VB Project
The set of controls available in the toolbox can be customized for each project. Any given control must be in the
toolbox before you can add it to a form in the project.
Adding ActiveX Controls to a Project
You add ActiveX controls and insertable objects to your project by adding them to the toolbox.
Axis Communications AB does not provide support for application development of any kind. The information here
is provided "as is", and there is no guarantee that any of the examples shown will work in your particular
application.
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To add a control to a project's toolbox:
1. From the Project menu, choose Components.
The Components dialog box is displayed. The items listed in this dialog box include all registered ActiveX
controls, insertable objects, and ActiveX designers.
2. To add the AxisCamControl to the toolbox, select the checkbox to the left of the control name.
3. Choose OK to close the Components dialog box. All of the ActiveX controls that you selected will now
appear in the toolbox.
To add ActiveX controls to the Components dialog box, choose the Browse button, and search other directories for
files with an .ocx file name extension.
Removing Controls from a Project
To remove a control from a project:
1. From the Project menu, choose Components.
The Components dialog box is displayed.
2. Clear the check box next to each control you want to remove.
The control icons will be removed from the toolbox.
Note: You cannot remove a control from the toolbox if an instance of that control is used on any form in the project.
Basic Operation: Set the URL Property to Get Live Images
When using the control, the most basic and important property is the URL property. You start a download from an
AXIS camera/video server simply by assigning a correct URL to this property.
The following code uses two Command Button controls, cmdURL1 and cmdURL2. Set the caption of cmdURL1 to
URL1. The caption of the Command Button control cmdURL2 is set to URL2.
The IP address in the URL should be the correct IP address to an AXIS camera/video server. See the HTTP API for
the AXIS camera/video servers for more information. A trick to figure out the correct Motion JPEG URL for the
specific Axis Camera/Video product is to look in the html code of the internal web pages. To verify that you have
the correct URL, use Netscape Navigator and type the complete Motion JPEG URL into the location window. If the
URL is correct you will, for a period of time, see live updated images in your browser.
Private Sub cmdURL1_Click()
' Start the download and show the live images from an
' AXIS camera/video server with the IP address 10.13.10.81.
CamImage1.URL = "http:// 10.13.10.81/axis-cgi/mjpg/video.cgi"
End Sub
Add the code for URL2:
Private Sub cmdURL2_Click()
Axis Communications AB does not provide support for application development of any kind. The information here
is provided "as is", and there is no guarantee that any of the examples shown will work in your particular
application.
2

' Start the download and show the live images from an
' AXIS camera/video server with the IP address 10.13.10.82.
CamImage1.URL = "http:// 10.13.10.82/axis-cgi/mjpg/video.cgi "
End Sub
Run the application and make sure that you can go from one camera to the other, just by clicking the different
buttons.
Recorder Methods: SaveImage and LoadImage
The AxisCamControl can be used as a simple recorder where images can be captured and saved to file. The saved
images can also be displayed in the control window.
The SaveImage and LoadImage methods each have one argument, a file name, which is an absolute file path,
for example C:/Images/myImage.jpg.
Add two more Command Button controls to the form, cmdSave and cmdLoad. Set the caption of cmdSave to
Save and the caption of the Command Button control cmdLoad to Load.
Private Sub cmdSave_Click()
CamImage1.SaveImage "E:/Images/myImage.jpg”
End Sub
Private Sub cmdLoad_Click()
CamImage1.LoadImage "E:/Images/myImage.jpg”
End Sub
The following code saves an image and displays the saved images.
After the LoadImage method has been called, the control display status is turned off. To view live images again,
the display status must be set to True.
Add a fifth Command Button control, cmdDisplayOn and the code for this:
Private Sub cmdDisplayOn_Click()
CamImage1.Display = True
End Sub
Using Events: OnNewImage
AxisCamControl provides several events that enable your client application to track its state, for example, it sends
out the OnClick event every time there is a mouse click in the control window and the ClickEnabled property
is set to True.
Axis Communications AB does not provide support for application development of any kind. The information here
is provided "as is", and there is no guarantee that any of the examples shown will work in your particular
application.
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The OnNewImage event is generated every time a new image has been received from the Axis Network Camera or
Video Server. This event can be used in combination with the GetCurrentImage method to e.g. create a simple
application that saves all captured images to disk. In order to do this, add the following code to your project:
Private Sub CamImage1_OnNewImage()
Dim b As Variant
Dim Size As Variant
Dim a() As Byte
Call CamImage1.GetCurrentImage(b, Size)
a() = b
Open "C:/Test.jpg" For Binary Access Write As #1
Put #1, , a()
Close #1
End Sub
Each time an image is captured, the image data will be saved as a Jpeg image, Test.jpg, in the C: directory.
To let the application developer know when something goes wrong with the connection; the
OnConnectionBroken and OnConnectionFailed events are also supported.
Display Images using the SetImage Method
To display an image inside the control window both the LoadImage and the SetImage methods can be used. The
Load Image method opens a Jpeg file from disk and displays it. The SetImage method can be used to display Jpeg
image data. In this example a Jpeg image is read from file and displayed in the control window using the SetImage
method.
Dim MyFile As Long
Dim Buffer As String
Dim aVariant As Variant
Dim nLen As Long
Dim nPos As Long
Dim nGet As Long
Dim I As Long
MyFile = FreeFile
' Open the image file.
Open "C:/Test.jpg" For Binary Access Read As #MyFile
' Define a buffer to receive the image information
nLen = LOF(MyFile)
Axis Communications AB does not provide support for application development of any kind. The information here
is provided "as is", and there is no guarantee that any of the examples shown will work in your particular
application.
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' Allocate sufficient buffer to retrieve the image
Buffer = Space(nLen)
' Retrieve the buffer
Get #MyFile, , Buffer
Close #MyFile
' Convert the Buffer to a Byte Array
ReDim aBuffer(0 To nLen - 1) As Byte
For I = 1 To Len(Buffer)
Next
aBuffer(I - 1) = Asc(Mid(Buffer, I, 1))
' Pass the Byte array to a Variant
aVariant = aBuffer
Call CamImage1.SetImage(aVariant, Len(Buffer))
Axis Communications AB does not provide support for application development of any kind. The information here
is provided "as is", and there is no guarantee that any of the examples shown will work in your particular
application.
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