Superclassed Ownerdrawn Button

[BOB MECHLER]

What event in the SuperClass CallBack procedure can be used to draw it?

I know how to use WM_DRAWITEM in a dialog callback. Do owernerdrawn buttons, even if superclassed, have to rely on the parent control's WM_DRAWITEM event?

Bob Mechler

[Michael Mattias]

Don't use OwnerDraw style and just do it on WM_PAINT in superclass procedure.

This is kind of the whole idea behind superclassing... "It's just like <something> except for (in this case, the WM_PAINT processing).

No, I have no clue if using 'DDT' is going to interfere with this, but it will work just fine with SDK-style windows.

[BOB MECHLER]

Thanks. And probably switch to a Superclassed Label instead of a button, right?

Bob Mechler

[Michael Mattias]

Depends on what you are trying to accomplish with that label.

Not that you can do a hell of a lot with a label anyway, but hey, it's your label.

[Dominic Mitchell]

Don't use OwnerDraw style and just do it on WM_PAINT in superclass procedure.

This is kind of the whole idea behind superclassing... "It's just like <something> except for (in this case, the WM_PAINT processing).

These statements, I am afraid, are not correct by any stretch of the imagination.

Go ahead and try it for a normal(e.g. BS_PUSHBUTTON) button. I guarantee you are in for a shock.

[Chris Boss]

When superclassing a control (a new class based on an existing class, which is different than subclassing) you have to be careful in how you process the window procedure messages. You have to make sure you don't work against the original class and how it works.

If you want to build a custom class using ownerdraw, it may be better to build your own custom class (not a superclass) which acts as a container. Then have the container control create the ownerdraw control as a child of itself. Then the container class can handle the ownerdraw messages from its ownerdrawn child control.

So the child control can get messages sent to its container, you can have the container class forward messages to the child control. This way the container could support all the messages of the child.

[BOB MECHLER]

The container class? Is there an example? I've never used one.

I didn't have any luck using WM_PAINT in the SuperClass of the button or label. It either GPF'd or drew it partially.

There are some really nice examples I've found of gradient buttons (which is what I really want). None of them are superclassed though.

I want to superclass a gradient button in order to give it additional default functionality. One would be to call a function I'll call ValidateForm(param,param,....) which will have the same name in all programs just code that returns the id's of fields not yet matching that program's needs or that it's ready to save the record or do the processing. That way the SuperClassed button will look exactly the same and be reusable by just supplying the location and size.

I'll look for some container class examples next.

Bob Mechler

[Michael Mattias]

ahead and try it for a normal(e.g. BS_PUSHBUTTON) button. I guarantee you are in for a shock.

I did start playing with it.

Shock? No.

Chagrin at forgetting that when you try to "make your own button" control a lot of the info you need to make it act like a button is not readily available? Yes.

While the focus rectangle handling is the same for BS_OWNERDRAW 'standard' buttons and "superclass-created" buttons, with the latter you have to keep track of the "pushed state" yourself, which necessitates processing the WM_LBUTTONUP notification, as well as WM_Keyup/keydown looking for <spacebar> and storing that current pushed state.. as well as send notifications to the parent for some of those actions.

On the plus side, I think its only the pushed state is what you have to monitor, as you can always ask for the size and location (GetWindowRect) and the focused state (compare GetFocus() with this hwnd).

Darned, I should have (but didn't) try BM_GETSTATE message. I wonder if that might not make life easier. I'll try that later today or maybe tomorrow and see if I can post a little baby demo.

Ok, so the button is a bad example. Let's go back to the label, that's a lot cleaner.


MCM

[Chris Boss]

Bob,

An even simpler method would be to simply write a subroutine which does the drawing for ownerdraw buttons which can be called in the Dialogs WM_DRAWITEM message. That message will only be sent for ownerdraw controls and not other controls.

ie.

CASE %WM_DRAWITEM
    FUNCTION=MyButtonDrawRoutine(CBWPARAM, CBLPARAM)
    EXIT FUNCTION

Do all your drawing in the routine you write.

To make it more powerful, have the routine read back the text from the button control (send WM_GETTEXT to the control).

You can parse out the text and embed macros to define the drawing process.

For example embed macros like this:

"My Buttons Text {{RED}}"

By embeding macros in double brackets, you can parse out any macros and leave only the text. This way you can then define the macros for each button, such as colors, font, etc. in the buttons text . This makes it easy to use PBForms to design the dialog. You simply write the buttons text plus macros in the designers text field for the controls.

[BOB MECHLER]

I like it Chris.

I'll also need to add a test for buttons since WM_DRAWITEM handles ownerdrawing of several other controls.

IF @lDisPtr.CtlType = %ODT_BUTTON for the drawing routine since I also want to owerdraw the tab labels on my tab control.

Bob Mechler

[Chris Boss]

Bob,

A very useful API function is:

GetClassName

You can test any window handle to see what window class it is. It is a great way to test in WM_DRAWITEM what class generated the message.

[Michael Mattias]

LOCAL pDI AS DRAWITEMSTRUCT PTR 

.....
    CASE %WM_DRAWITEM
       pDI =  CBLPARAM
      SELECT CASE @pDI.CtlId
           CASE %BUTTON_1 
               CALL ButtonOneProc

            CASE %BUTTON_2 
               CALL ButtonTwoProc
  
        .....

[Dominic Mitchell]

This stuff has been discussed at length before, see for example
http://www.powerbasic.com/support/pb...custom+control

If the control is subclassed/superclassed, and if you don't want to use a container, you can
also use message reflection. That is, the WM_DRAWITEM message is sent from the parent window
procedure to the subclassed/superclassed procedure for the control.

[Dominic Mitchell]

GetClassName

You can test any window handle to see what window class it is. It is a great way to test in WM_DRAWITEM what class generated the message.

But if he wants to know if it is a button, all he has to do is examine the value of the CtlType
member of the DRAWITEMSTRUCT struct. GetClassName fails if the control is superclassed, this
test does not.

[Dominic Mitchell]

Owerdrawn tab control.

ODT_TAB = 101

[Chris Holbrook]

This stuff has been discussed at length before, see for example
http://www.powerbasic.com/support/pb...custom+control

Great link, wish I had found it a year ago!

If the control is subclassed/superclassed, and if you don't want to use a container, you can
also use message reflection. That is, the WM_DRAWITEM message is sent from the parent window procedure to the subclassed/superclassed procedure for the control.

I use a global array of window handles and original classnames so that control can be passed back to the original classproc when appropriate.

[Chris Boss]

I like the idea mentioned about reflecting (forwarding) the WM_DRAWITEM message to the controls window procedure (if superclassed).

ie.

%BM_MyDraw = %WM_USER + 400

Then in response to the WM_DRAWITEM message do this:

CASE %WM_DRAWITEM
   LOCAL pDI AS DRAWITEMSTRUCT PTR 
   pDI =  CBLPARAM
   IF @pDI.CtlType = %ODT_BUTTON THEN
      FUNCTION=SendMessage(@pDI.hwnditem, %WM_DRAWITEM, CBWPARAM, CBLPARAM)
     EXIT FUNCTION
   END IF

This way you can handle all the drawing in the superclassed controls window procedure which is handy if you put it in a DLL.

[BOB MECHLER]

Before I saw your post I came up with this. It seems to work ok. Not sure I needed all the parameters but I did get gradient ownerdrawn buttons.

CASE %WM_DRAWITEM

        lDisPtr = CBLPARAM
        IF @lDisPtr.CtlType = %ODT_BUTTON THEN
          CALL PaintGRLabelBg(CBHNDL,CBCTL,CBWPARAM,CBLPARAM)    
          FUNCTION = %True                       
        END IF

    SUB PaintGRLabelBg(pCBHNDL&,pCBCTL&,pCBWPARAM&,pCBLPARAM&,pSelected&)
       LOCAL lZStr  AS ASCIIZ * 64 
       LOCAL Str AS STRING
       LOCAL V_hFont&
       LOCAL V_hCtl&
       LOCAL V_rc AS Rect
       LOCAL V_hdc&
       CONTROL GET TEXT pCBHNDL&,pCBCTL& TO Str
       CONTROL HANDLE  pCBHNDL&,pCBCTL& TO V_hCtl&     ' get the handle to the control
       V_hdc& = GetDc(V_hCtl&)
      ' this paints the actual label body
       LOCAL Xin AS LONG
       LOCAL Yin AS LONG
       DIM vert(1) AS TRIVERTEX
       DIM gRect AS GRADIENT_RECT
       GetClientRect V_hCtl&, V_rc
       Xin = V_rc.nRight - V_rc.nLeft            ' don't want to go all the way to the right, or we'll paint over the border
       Yin = V_rc.nBottom - V_rc.nTop            ' don't want to go all the way to the bottom, or we'll paint over the border
       Temp& = PB_BACK&
       cRed&   = Temp& MOD 256
       cGreen& = (Temp& \ 256) MOD 256
       cBlue&  = ((Temp& \ 256) \ 256) MOD 256 
       'cRed& = 192
       'cGreen& = 192
       'cBlue& = 60
       vert(0).x      = 0                      ' start at pixel 2 so we don't paint over the border
       vert(0).y      = 0                     ' start at pixel 22 so that we don't paint over the tabs
       vert(0).Red    = SetColor(cRed&)
       vert(0).Green  = SetColor(cGreen&)
       vert(0).Blue   = SetColor(cBlue&)
       vert(0).Alpha  = &h0000
       vert(1).x      = Xin
       vert(1).y      = Yin
       vert(1).Red    = SetColor(cRed& - 60)
       vert(1).Green  = SetColor(cGreen& - 60)
       vert(1).Blue   = SetColor(cBlue& - 60)
       vert(1).Alpha  = &h0000
       gRect.UpperLeft  = 0
       gRect.LowerRight = 1
       RoundRect V_hdc&,V_rc.nLeft - 1,V_rc.nTop - 1,V_rc.nRight + 1,V_rc.nBottom + 1,4,4
       GradientFill V_hdc&, vert(0), 2, gRect, 1, %GRADIENT_FILL_RECT_v
       SelectObject V_hdc&,V_hFontCap&
       lZstr = Str                            ' copy the text to the nul terminated string
       SetBkMode V_hdc&, %Transparent             ' set the bg for transparent
       SetTextColor V_hdc&, %BLACK 'GetSysColor(%COLOR_BTNTEXT)   ' set the foreground color to black
       TextOut V_hdc&, V_rc.nLeft + 4 , V_rc.nTop + 3 , lZStr, LEN (lZStr)  'draw the text
    END SUB

Bob Mechler

[BOB MECHLER]

Also thanks to Dominic for the excellent reference to the container control of the textbox and lookup button. The different approaches contributed for DDT and SDK warrant study.

Bob Mechler