Installation

Browsing Properties

Place DXFReader ActiveX Control on the Windows Form and explore its properties (View»Properties Window). You might notice that several properties have been added or changed, including the default name of the control. Visual Studio .NET prefixes all ActiveX controls with Ax (in Visual Basic .NET) or ax (in Visual C# .NET). For example, when you drop the first instance of a DXFReader on a Visual Basic 6.0 form, Visual Basic 6.0 names that control DXFReader1. When you drop the first instance of a DXFReader ActiveX Control in Visual Studio .NET, Visual Basic .NET names the control AxDXFReader1.

Browsing Generated Code

Open the code editor, and examine the code that Visual Studio .NET automatically generated. In both Visual Basic .NET and Visual C# .NET, the code generated contains a call to InitializeComponent() to initialize properties on the Windows Form and controls, a call to Dispose() for resource cleanup, and declaration of and reference to the instance of the graph you placed on the form.

Changes to the Visual Basic Language

Microsoft made many changes to its Visual Basic language to add object-oriented features and make it more like other .NET languages. This section describes programming changes you will encounter, specifically with respect to default properties and the Item method, as you develop applications with DXFReader ActiveX Control in Visual Basic .NET or Visual C# .NET.

Default Properties

Unlike Visual Basic 6.0, Visual Basic .NET does not support default properties, which are the most commonly used properties of the control. For example, you might use the following Visual Basic 6.0 syntax to set the value of DXFReader file name:

DXFReader1 = "MyFile.dxf"


In Visual Studio .NET, you must modify the code to explicitly name the property. In this example, explicitly name the Value property:

'Visual Basic .NET
AxDXFReader1.FileName = "MyFile.dxf"


'Visual C# .NET
axDXFReader1.FileName = "MyFile.dxf";


Item Method

You can retrieve an item from a collection in Visual Basic 6.0 without explicitly stating the Item method, as demonstrated in the following example:

'Visual Basic 6.0: Retrieving an Item in a Collection
DXFReader1.Entities(1).EntityType = "LINE"

In Visual Studio .NET, you must explicitly use the Item method when you retrieve items from a collection, as shown in the following examples:

'Visual Basic .NET: Retrieving an Item in a Collection
AxDXFReader1.Entities.Item(1).EntityType = "LINE"

'Visual C# .NET: Retrieving an Item in a Collection

object ind;
ind = 1;
DXFReaderLayer Layer;
Layer = (DXFReaderLayer)axDXFReader1.Layers.Item(ref ind);
MessageBox.Show("Layer # 1 name: " + Layer.LayerName, "", MessageBoxButtons.OK, MessageBoxIcon.Information);

Collection objects implement the IEnumerable interface, so you can iterate through items in a collection using For Each just as you can in Visual Basic 6.0. The following examples show how to iterate through a collection of Entities objects on DXFReader:

'Visual Basic .NET: Iterating through a Collection

Dim Entity As DXFReaderEntity

For Each Entity In .Entities
   MsgBox(Entity.EntityType)
Next Entity

'Visual C# .NET: Iterating through a Collection

foreach (DXFReaderEntity Entity in axDXFReader1.Entities)
   MessageBox.Show(Entity.EntityType, "Test", MessageBoxButtons.OK, MessageBoxIcon.Information);

Event Handling

Microsoft implemented a new event model in Visual Studio .NET. In this event model, an object generates an event in response to some action or change in state, such as a mouse click or x number of points being acquired. The object that generates the event is called the event sender. Another object, called the event receiver, handles the event and responds by executing an event handler, which processes the event. However, the event sender needs a pointer to the event receiver. The .NET Framework refers to this pointer as a delegate. A delegate is a class that holds a reference to a method.

Installing DXFReader in Visual Basic

To install and use DXFReader in Visual Basic there are slight differences between these processes in Visual Basic 5 and Visual Basic 6, but they are largely superficial.

The figures that follow show dialogs and screens used to install DXFReader in Visual Basic 5/6.

In Visual Basic 5/6, select the Components command from the Project menu. It will present the dialog shown in figure below.
Check the box next to the control you want to use and click the OK button. In the figure below the control "Kadmos DXF Reader" has been selected.

If the control does not appear in the list, click the Browse button and locate the DXFReader control's .OCX file. Select the file and click OK.

At this point Visual Basic will add entries to your system registry so the control will be listed in the future.

After you have selected the control, it will appear in the toolbox along with Visual Basic's controls as showed in the figure below.

Despite its name, MS Visual C++ is not as visually oriented as Visual Basic. A Visual C++ program manages controls by building a class that represents the control. Class methods provide access to the control's properties, events and methods. The all process can be divided into five steps:

1 - Registering DXFReader in the system registry

Before Visual C++ can use a custom control, it must be registered in the system registry. If you installed DXFReader using the setup utility, the installation program provides to register it in the right way. DXFReader can also be registered with the RegSvr32.exe application provided with Visual C++. For example, the following code registers DXFReader located in the C:\WINDOWS\SYSTEM directory:

regsvr32 c:\windows\system\dxfreader.ocx

It is possible to use RegSvr32.exe to remove DXFReader's entries from the system registry with the /u flag, for example:

regsvr32 /u c:\windows\system\dxfreader.ocx

2 - Providing support for ActiveX

To create a MS Visual C++ project that support ActiveX controls, select the New command from the File menu. On the resulting dialog's Projects tab, select the MFC AppWizard (exe) option. Fill in the project name and location and click the OK Button.
Follow the AppWizard's instructions and select, for example, a dialog-based application. The AppWizard's second step will show a checkbox that determines whether the application will support ActiveX controls. Make sure the box is checked and continue through the AppWizard.

3 - Creating the Control

To insert an instance of DXFReader in the project, select the Resource View tab. Locate the resource that should contain the control and double-click on it to open it. Press the right mouse button over the resource to make the context menu shown in the following figure appear.

Select the Insert ActiveX Control command, and the dialog shown in the following figure will appear.

If DXFReader has been correctly registered by its installation program, or manually with the RegSvr32 application, it should appear in the dialog's list of controls with the name DXFREADERlib.DXFReader. Pick it and click on the OK button. At this point MS Visual C++ will add DXFReader to the project. If you want to add an instance of the DXFPlot control, simply pick DXFREADERlib.DXFPlot.

4 - Creating Event Handlers

Once DXFReader is added to the project you can provide support for control's events. Press the right mouse button over the control and select the Events... command from the context menu. The following figure will appear.

Select an event, for example MouseDown and click the Add Handler button. Enter the name you want to give the event handler function in the resulting input box. For example the control's MouseDown event will be handled by a member function named OnMouseDownDxfreader1.
After you have created the event handler function, you can use the Class View to locate and examine the function. Alternatively, you can select the event handler in the Events dialog and click the Edit Existing button.
The following code shows the function created to handle the DXFReader's MouseDown event. The call to ZoomSpotIn method was added manually.

void CDXFReaderTestDlg::OnMouseDownDxfreader1(short FAR* Button, short FAR* Shift, float FAR* x, float FAR* y)
{

   m_DXFReader.ZoomSpotIn (*x,*y);


}

5 - Supporting Control Properties

The simplest way to access DXFReader's properties in code is to package the control in a wrapper class. This class will provide member functions that manipulate the control itself.
Start by pressing the right mouse button over the control and selecting the ClassWizard command from the context menu. On the resulting dialog, pick the Member Variables tab. Select on the control's ID (IDC_DXFREADER1) and click the Add Variable button.
At this point MS Visual C++ will notify you that it has not yet build a wrapper class for the control as shown in the figure below.

Click the OK button to acknowledge the message, and ClassWizard will create the wrapper class.
ClassWizard will then present a dialog allowing you to select the classes you want created. DXFReader has the Font, Picture and Collection properties. Because they are objects, ClassWizard includes an option for creating a wrapper class for them as well for the main control.

For each of the classes you want created, select the class and enter a name, header file, and implementation file for that class. When you are finished, click the Ok button and ClassWizard will create the appropriate classes.

At this point ClassWizard is finally ready to create a variable representing the custom control. Enter the variable name in the dialog shown in the figure below and click the OK button.

ClassWizard will add a new variable to the project to hold the class instance representing DXFReader. The program can use this variable to manipulate the object and thus the control it represents.
The DXFReader's wrapper class will include public functions corresponding to the properties and methods exposed by the control. For each property, ClassWizard creates two functions: the name of the one starts with "Get" and the name of the other starts with "Set".

The following code will set the PlotRotation property of DXFReader to 1 (dr90) and then plot the drawing 90° rotated:

void CDXFReaderTestDlg::OnOk2()

{
   m_DXFReader.SetPlotRotation (1);
   m_DXFReader.Plot();
}