Drag & Drop

[Peter Redei]

I can not figure it out how to implement a simple drag & drop in PBDLL 6.0.
What I want is to drag one image control to another place in the same window with the normal Windows left mouse button down. I would appreciate any sample code.

Sincerely,


Peter Redei

------------------

[Jules Marchildon]

hi peter,



regards, jules

[Chris Boss]

Peter;

First, subclass your controls.

Then process the %WM_NCHITTEST message and call the DefWindowProc to
get the proper return value.

Now if the DefWindowProc returns the value :

%HTCLIENT

Then replace the value with :

%HTCAPTION

This will make Windows think you clicked on a Caption bar (which
a control does not have) rather than the client area of the control.
This will impliment the standard windows drag function and you can
move the control around just like any Dialog can be moved around
by dragging on the Caption bar.


------------------

[Jules Marchildon]

Peter,

Sorry, I misunderstood.

Try this instead...

This will snap to a 8x8 grid, you can remove that feature.
Unlike Chris suggestion, this will move the window dynamically. A nicer
effect rather than the windows standard Focus Rectangle.

'----------------------------------------------------
'Snap-to-grid demo. Another C to PB conversion
'Final code fixes by Jim Huguley.
'October 19th, 1999
'----------------------------------------------------
 

$COMPILE EXE
$INCLUDE "WIN32API.INC"
  
'---
GLOBAL ghInst       AS LONG
GLOBAL ghWnd        AS LONG
GLOBAL ghWndChild   AS LONG
GLOBAL szNullString AS ASCIIZ*20
GLOBAL szAppName    AS ASCIIZ*20
GLOBAL szChildName  AS ASCIIZ*20
GLOBAL szMoveMe     AS ASCIIZ*20
 

'----------------------------------------------------------
FUNCTION WINMAIN(BYVAL hInstance AS LONG, _
                 BYVAL hPrevInstance AS LONG, _
                 lpszCmdLine AS ASCIIZ PTR, _
                 BYVAL nCmdShow AS LONG) AS LONG
 

LOCAL Msg        AS tagMsg
LOCAL wc         AS WNDCLASSEX
LOCAL hFormBrush AS LONG
LOCAL hFormBM    AS LONG

  
'---
IF ISFALSE(hPrevInstance) THEN
 
'**Register Parent Window Class
szAppName        = "BASE1"
wc.cbSize        = SIZEOF(wc)
wc.style         = %CS_BYTEALIGNCLIENT
wc.lpfnWndProc   = CODEPTR(WndProc)
wc.cbClsExtra    = 0
wc.cbWndExtra    = 0
wc.hInstance     = hInstance
wc.hIcon         = %NULL
wc.hCursor       = LoadCursor(%NULL, BYVAL %IDC_ARROW)
wc.hbrBackground = GetStockObject(%WHITE_BRUSH)
wc.lpszMenuName  = %NULL
wc.lpszClassName = VARPTR(szAppName)
RegisterClassEx wc
'---
 
'**Register the Child Window Class
szChildName         = "Ben"
wc.cbSize           = SIZEOF(wc)
wc.style            = %CS_HREDRAW OR %CS_VREDRAW OR %CS_BYTEALIGNCLIENT
wc.lpfnWndProc      = CODEPTR(FormWndProc)
wc.cbClsExtra       = 0
wc.cbWndExtra       = 0
wc.hInstance        = hInstance
wc.hIcon            = %NULL
wc.hCursor          = LoadCursor(hInstance, "HAND")
wc.hbrBackground    = GetStockObject(%LTGRAY_BRUSH)
wc.lpszMenuName     = %NULL
wc.lpszClassName    = VARPTR(szChildName)
RegisterClassEx wc

ELSE
    EXIT FUNCTION
END IF
'---

 
  ghInst = hInstance
 
  ghWnd  = CreateWindow (szAppName, "PASSMSG Sample", _
                         %WS_OVERLAPPEDWINDOW OR %WS_BORDER, _
                         GetSystemMetrics ( %SM_CXSCREEN ) \4, _
                         GetSystemMetrics ( %SM_CYSCREEN ) \4, _
                         GetSystemMetrics ( %SM_CXSCREEN ) \2, _
                         GetSystemMetrics ( %SM_CYSCREEN ) \2, _
                         %NULL, %NULL, hInstance, %NULL)
 
  szNullString = ""
  ghWndChild =   CreateWindow (szChildName, szNullString, _
                               %WS_CHILD OR %WS_VISIBLE, _
                               10, 10, _
                               100, 100, _
                               ghWnd, BYVAL %NULL, hInstance, %NULL)

 
  ShowWindow  ghWnd, %SW_SHOW
  UpdateWindow ghWnd
 
'---
WHILE GetMessage(Msg, %NULL, 0, 0)
    TranslateMessage Msg
    DispatchMessage Msg
WEND
 
  DeleteObject  hFormBrush
 
  FUNCTION = Msg.wParam
END FUNCTION

 
'-------------------------------------------------------
FUNCTION WndProc(BYVAL hWnd AS LONG, _
                 BYVAL Msg AS LONG,BYVAL wParam AS LONG, _
                 BYVAL lParam AS LONG) AS LONG
 
  STATIC bDragging AS LONG     'flag
  STATIC ptLastPos AS POINTAPI
 

SELECT CASE Msg

 
    CASE %WM_CREATE
 
    CASE %WM_LBUTTONDOWN
 
      ptLastPos.x = LOWRD ( lParam)
      ptLastPos.y = HIWRD ( lParam)
 
      ptLastPos.x = LOWRD ( lParam ) - LOWRD ( lParam ) MOD 8
      ptLastPos.y = HIWRD ( lParam ) - HIWRD ( lParam ) MOD 8

       
      IF ChildWindowFromPoint(hWnd, ptLastPos.x, ptLastPos.y ) <> hWnd THEN
 
        '**Must be the child!
        SetCapture hWnd
        bDragging = %TRUE
 
      END IF
 
    CASE %WM_LBUTTONUP
 
      IF bDragging = %TRUE THEN
 
        InvalidateRect  ghWndChild, BYVAL %NULL, %TRUE
        ReleaseCapture
        bDragging = %FALSE
 
      END IF
 
    CASE %WM_MOUSEMOVE
 
      IF bDragging = %TRUE THEN
 
        DIM ptNew AS POINTAPI
 
        ptNew.x = LOWRD ( lParam ) - LOWRD ( lParam ) MOD 8
        ptNew.y = HIWRD ( lParam ) - HIWRD ( lParam ) MOD 8

 
        IF (( ptNew.x <> ptLastPos.x ) OR ( ptNew.y <> ptLastPos.y )) THEN
 
            DIM ptTopLeft AS POINTAPI
 
            '**Figure out current position of Child window
 
            ptTopLeft.x = 0 'Modify these values if you add a thick border or other
            ptTopLeft.y = 0 'adornments to reflect the client area offset
 
            ClientToScreen  ghWndChild, ptTopLeft
            ScreenToClient  hWnd,       ptTopLeft
 
            '**Move child Window to new spot
 
            SetWindowPos ghWndChild, _
                         %NULL, _
                         ptTopLeft.x + (ptNew.x-ptLastPos.x), _
                         ptTopLeft.y + (ptNew.y-ptLastPos.y), _
                         0, _
                         0, _
                         %SWP_NOSIZE OR %SWP_NOZORDER
 
            InvalidateRect ghWndChild, BYVAL %NULL, %TRUE
            UpdateWindow ghWndChild
 
            ptLastPos = ptNew
 
        END IF
 
      END IF


 
    CASE %WM_DESTROY
 
      PostQuitMessage 0
 
    CASE ELSE
 
      FUNCTION = DefWindowProc ( hWnd, msg, wParam, lParam )
      EXIT FUNCTION
 
END SELECT
 
FUNCTION = 0
 
END FUNCTION

 

'-----------------------------------------------------
FUNCTION FormWndProc( BYVAL hWnd AS LONG, _
                      BYVAL Msg AS LONG, _
                      BYVAL wParam AS LONG, _
                      BYVAL lParam AS LONG) AS LONG

 
  LOCAL pt  AS POINTAPI
  LOCAL hDC AS LONG
  LOCAL ps  AS PAINTSTRUCT
  LOCAL rc  AS RECT
 
SELECT CASE Msg
 
    CASE %WM_ERASEBKGND  ' Eat this message to avoid flicker
 
    CASE %WM_CREATE
 
    'CASE %WM_LBUTTONDOWN
    'CASE %WM_LBUTTONUP
    'CASE %WM_MOUSEMOVE
 
     
    CASE %WM_LBUTTONDOWN , %WM_LBUTTONUP, %WM_MOUSEMOVE
 
      '**Pass all mouse messages on through to parent,
      '  in parent coordinates
 
      pt.x = LOWRD ( lParam )
      pt.y = HIWRD ( lParam )
 
      ClientToScreen hWnd,            pt
      ScreenToClient GetParent(hWnd), pt
 
      PostMessage  ghWnd, Msg, wParam, MAKLNG (pt.x, pt.y )
 
    CASE %WM_PAINT
 
      '**Just draw a simple little something nice centered
      '  in the window
 
      hDC = BeginPaint ( hWnd, ps )
      GetClientRect  hWnd, rc
 
      SetBkColor    hDC, RGB (   0,   0, 128 )
      SetTextColor  hDC, RGB ( 255, 255,   0 )
 
      DIM sz AS SIZEL
      szMoveMe = "Move Me!"
 
      GetTextExtentPoint32  hDC, szMoveMe, LEN(szMoveMe), sz
 
      pt.x = (rc.nright  - sz.cx)\2
      pt.y = (rc.nbottom - sz.cy)\2
 
      ExtTextOut  hDC, pt.x, pt.y, %ETO_OPAQUE, rc, szMoveMe, LEN(szMoveMe), BYVAL %NULL
 
      EndPaint  hWnd, ps

 
    CASE ELSE
 
      FUNCTION = DefWindowProc ( hWnd, msg, wParam, lParam )
      EXIT FUNCTION
 
END SELECT
 
FUNCTION = 0
 
END FUNCTION

Regards, Jules

[Jules Marchildon]

peter,

i think this is more what you are looking for...

http://www.powerbasic.com/support/pb...ad.php?t=22854

regards,
jules
mailto:[email protected][email protected]</a>

[Peter Redei]

Thank you Chris and Jules both very much. Now, I just need to get it work with all squares of a chess board.

Sincerely,


Peter Redei

------------------