HOWTO: Starting OLE Drag and Drop In Manual Mode

• Microsoft Visual FoxPro for Windows, version 6.0

SUMMARY

This article describes how to implement OLE Drag and Drop in manual mode allowing you to drag the caption of a Command button to a text box. The article also features the Data Object methods ClearData and SetData.

This article does not cover the background for OLE Drag and Drop. The purpose of the article is to provide an example that helps developers get started with manual mode OLE Drag and Drop. For more information on OLE Drag and Drop, see Chapter 31: Interoperability and the Internet in the Microsoft Visual FoxPro "Programmer's Guide," version 6.0.

MORE INFORMATION

The steps below illustrate how to implement OLE Drag and Drop in manual mode to drag the caption of a command button to a text box. In the steps where code is added to the various events and methods, the LPARAMETERS lines shown are already there by default. They should not be added a second time.

1. Create a new form and save the form. Be sure the default directory is set to the folder where the form is saved.



2. Add two command buttons and a text box.



3. Select the command button with the caption of "Command2" and change the caption to "Reset Controls".



4. Place the following code in the Click event of command2:

   
         Thisform.Text1.Value=SPACE(10) 




5. Copy the following file from the Visual Studio\Common\Graphics folder specified to the folder where the form is saved.

   
         \Icons\Misc\Eye.ico 




6. Set the following properties of command1:

   
         Caption="Text To Drag"
         OLEDragPicture="eye.ico" 




7. Add the following code to the Click event of command1:

   
         WAIT WINDOW "Hello" 




8. Add the following code to the MouseDown event of command1:

   
         LPARAMETERS nButton, nShift, nXCoord, nYCoord
         IF nButton=2
            *This.OLEDrag(.F.)
            This.OLEDrag(.T.)
         ENDIF 

   This code checks to see if the right mouse button is down. If it is, the OLEDrag method will be called. OLEDrag can be called with either true or false. The difference is shown later in this article.



9. Add the following code to the OLEDrag method of command1:

   
         LPARAMETERS lDetectDrag
         IF lDetectDrag
            This.ForeColor=RGB(0,255,64)
         ELSE
            This.ForeColor=RGB(255,0,255)
         ENDIF 

   The code above changes the color of the caption text of the command button. It is included here for a visual confirmation that the method is firing.



10. Add the following code to the OLEStartDrag event of command1:

    
          LPARAMETERS oDataObject, nEffect
          oDataObject.ClearData
          oDataObject.SetData("Hello",1) 

    In this event code, the data in the Data Object is being cleared, which in this case means that the caption of the command button is cleared from the Data Object. It is then being set to the word "Hello." This is done for illustration purposes only to show what can be done. If the actual command button caption is to be dropped into the text box, this code would not be used. When using OLE Drag and Drop in automatic mode, the OLEStartDrag event is the first event to fire. In manual mode, the MouseDown and OLEDrag methods have to run first to start OLEStartDrag.



11. Add the following code to the OLECompleteDrag event of command1:

    
          LPARAMETERS nEffect
          This.ResetToDefault("ForeColor") 

    This code sets the ForeColor, which is the color of the caption text, of command1 back to the default.



12. Set the OLEDropMode property of the text box to 1 - Enabled.



13. Save and run the form. Right-click the "Text To Drag" command button and drag and drop into the text box. Use the Reset Controls command button to reset. Try holding down the CTRL key while right dragging.

1. With the OLEDrag method being started with True, which is how it should be set after step 13 above, carefully right-click the "Text To Drag" command button. Be very careful not to move the mouse while doing this. There should be a slight delay before the eye icon and the "no drop" mouse pointer appear. Try this a few times. It should be necessary to reset the controls.



2. Modify the form. Open the MouseDown event of the "Text To Drag" command button. Remark out the This.OLEDrag (.T.) and unremark the This.OLEDrag (.F.) lines of code. Save and run the form.



3. Without moving the mouse, right-click the "Text To Drag" command button. Notice that the eye icon appears immediately. If the mouse is not moved, the "no drop" mouse pointer never appears.

1. Try setting the OLEDragMode property for the "Text To Drag" command button to 1 - Automatic. Save and run the form. Note that if the mouse pointer is moved around in the command button when the left mouse button is down, the OLEDragPicture, Eye.ico, never appears unless the mouse pointer goes out of the command button's border. Try the right mouse button also.



2. Try not clearing and setting the data in the OLEStartDrag event of the "Text To Drag" command button. See step 10 above.

REFERENCES

Visual FoxPro Books Online: Programmer's Guide; Chapter 31 - Interoperability and the Internet; OLE Drag and Drop topic.

Additional query words: FxprgGeneral vfoxwin kbvfp600

Keywords : kbVFp FxprgGeneral
Version : WINDOWS:6.0
Platform : WINDOWS
Issue type : kbhowto