UP, DOWN arrow keys pressed in xBrowse

[fraxzi]

Hello All,

I use bKeyDown and bKeyChar but I cant trap the UP and DOWN arrow keys..

No problem If using mouse to navigate but if UP,DOWN keys are pressed?



Regards,
Fraxzi

[frose]

Fraxzi,

modifying the METHOD KeyDown() in xbrowse.prg works for me. For example I wanted to trap the key VK_TAB:

Code: Select all

CASE nKey == VK_TAB
      My_Tab()
 

[fraxzi]

Fraxzi,

modifying the METHOD KeyDown() in xbrowse.prg works for me. For example I wanted to trap the key VK_TAB:

Code: Select all

CASE nKey == VK_TAB
      My_Tab()
 

Thanks Frose!

as-much-as possible not to modify the original class so I wont forget the modification after an upgrade...
That would be the last resort.


Regards,
Fraxzi

[James Bott]

Fraxzi,

You will have to subclass xbrowse and create a new keyDown() method.

James

[fraxzi]

Thanks James,

Do you have a sample I can start with?


Fraxzi

[James Bott]

Code: Select all

#include "fivewin.ch"
#include "vkey.ch"

CLASS MyBrowse from TXBrowse
   method KeyDown()
endclass

Method KeyDown( nKey, nFlags ) CLASS MyBrowse

  do case
     case nKey == VK_UP
        // do whatever
     case nKey == VK_DOWN
        // do whatever
  enddo

return super:keyDown( nKey, nFlags )

[fraxzi]

Code: Select all

#include "fivewin.ch"
#include "vkey.ch"

CLASS MyBrowse from TXBrowse
   method KeyDown()
endclass

Method KeyDown( nKey, nFlags ) CLASS MyBrowse

  do case
     case nKey == VK_UP
        // do whatever
     case nKey == VK_DOWN
        // do whatever
  enddo

return super:keyDown( nKey, nFlags )

Hello James,

Thank you for the reply.

with the above, can I alter the Method Keydown() on an already created object TXBrowse?


Regards,
Fraxzi

[James Bott]

Fraxzi,

with the above, can I alter the Method Keydown() on an already created object TXBrowse?

Well, you have to use MyBrowse instead of TXBrowse, but other than the way you call it:

Instead of:

oBrw:= TXBrowse():new( oWnd )

You use:

oBrw:= MyBrowse():new( oWnd )

The syntax is exactly the same as TXBrowse (because everything else is TXBrowse code). So the only code you need to change is the above line.

You may want to read the Introduction to Object Oriented Programming articles on my website for a better understanding of OOP and subclassing.

http://www.gointellitech.com/program.htm

Regards,
James

[frose]

James,

thank you very much for this tip, how to use inheritance and subtyping, polymorphism or overriding. How easy OOP can be

[fraxzi]

Fraxzi,

with the above, can I alter the Method Keydown() on an already created object TXBrowse?

Well, you have to use MyBrowse instead of TXBrowse, but other than the way you call it:

Instead of:

oBrw:= TXBrowse():new( oWnd )

You use:

oBrw:= MyBrowse():new( oWnd )

The syntax is exactly the same as TXBrowse (because everything else is TXBrowse code). So the only code you need to change is the above line.

You may want to read the Introduction to Object Oriented Programming articles on my website for a better understanding of OOP and subclassing.

http://www.gointellitech.com/program.htm

Regards,
James

Thank you so much for the great idea!

I did this to preserved my predefined xBrowse:

Code: Select all

...
   REDEFINE XBROWSE oBrw ID 1023 OF oDlg;
                  AUTOSORT UPDATE AUTOCOLS FASTEDIT LINES CELL;
                  ARRAY { {'Test'} };
                  CLASS MyxBrowse()
...

CLASS MyxBrowse from TXBrowse
   METHOD KeyDown( nKey, nFlags )
ENDCLASS

METHOD KeyDown( nKey, nFlags ) CLASS MyxBrowse

  DO CASE
     CASE nKey == VK_UP
        // do whatever
          msginfo( 'Up Key' test )
     CASE nKey == VK_DOWN
        // do whatever
  ENDCASE

RETURN Super:KeyDown( nKey, nFlags )
...
 

It works like magic! I wouldn't discover this without your input.

Thanks so much!

[Enrico Maria Giordano]

Unfortunately the name of the original class is used inside various FWH sources and this prevents the full working inheritance.

EMG

[nageswaragunupudi]

Unfortunately the name of the original class is used inside various FWH sources and this prevents the full working inheritance.

EMG

I think this is not correct. XBrowse is intentionally coded to enable use of Inherited classes.

If we use the the statement

Code: Select all

SET XBROWSE TO MyBrowse()

or

Code: Select all

SetXBrowse( { || MyBrowse() }

the entire FWH library will use MyBrowse() instead of TXBrowse()
What is hardcoded is TXBrows() not TXBrowse(). TXBrows() by default returns TXBrowse() and when SetXBrowse( ... ) is executed, TXBrows() returns the new class not the parent TXBrowse() class.

After executing the above statement, all commands work with the MyBrowse() instead of TXBrowse()

But I noticed some bugs if we change different child classes within the same program. From my experience I advise using SET XBROWSE TO command at the beginning of the program.

Using the clause CLASS for each browse is supposed to use the child class only for that browse, but I faced some problems in its working.

[Enrico Maria Giordano]

Please search for the string "txbrowse" inside FWH source code.

EMG

[anserkk]

Please search for the string "txbrowse" inside FWH source code.

Out of 105 references, 102 reference are in xBrowse.Prg itself and 1 reference in btnbmp.prg, 1 in database.prg and 1 in Dialog.prg

Regards
Anser

[Enrico Maria Giordano]

Exactly. The problem are the ones in btnbmp.prg, database.prg and dialog.prg.

EMG