Dragdetect

[Chris Holbrook]

Well here I was studying this for the fun of it...

Sorry for my impatience!

I'm wondering why there are no significant references to DragDetect in the forums. Maybe there is an even simpler way of doing it which I have missed.

[Rodney Hicks]

Well here I was studying this for the fun of it. Don't mind though, I learned a little more, thank ye.

[Chris Holbrook]

Doh! Idiot child!

It is so simple to drag with this technique. Rather than attempting (as I did at first) to control a loop containing the "dragdraw" actions, just call DragDetect like a "black box", as below. Also I had forgotten to convert the point to screen coordinates.

' to investigate DragDetect API
' Chris Holbrook 10 Dec 2008

#compile exe
#dim all
#include once "win32api.inc"

%pic_margin = 3

global GrDialogProc as long               ' used in subclassing the grapic control to get mouse msgs
global GrOldProc as long                  ' used in subclassing the grapic control to get mouse msgs
global gMousePt as pointapi                     ' Mouse x and y
global gLbDOWN as long,gRBDOWN as long    ' Left and right mouse button

'--------------------------------------------------------------------------------
function GrProc(byval hWnd as dword, byval wMsg as dword, byval wParam as dword, byval lParam as long) as long
    static startpt, dragpt as pointAPI
    

  select case wMsg
     '
     case %wm_mousemove
         gMousePt.X = lo(word,lParam)
         gMousePt.Y = hi(word,lParam)  ' Current Mouse X and Y Position in the graphic window
         if glbdown then
            ?"StartDrag"
            startpt = gmousept
            clienttoscreen hwnd, startpt
'            while dragdetect (hWnd, startpt)
'                sleep 2
'                getcursorpos ( dragpt)       ' screen coordinates
'                screentoclient(hWnd, dragpt) ' mouse coordinates
'                ? "DrawDrag", dragpt.x, dragpt.y
'            wend
            dragdetect (hWnd, startpt)
            ?"EndDrag"
             gmousept = dragpt
         end if
         exit function
    '
    case %wm_lbuttondown
        gMousePt.X = lo(word,lParam)
        gMousePt.Y = hi(word,lParam)          ' Current Mouse X and Y Position in the graphic window
        gLBDOWN = 1
        exit function                      ' Left button pressed

    case %wm_lbuttonup
        glbdown = 0
        exit function
    '
  end select
 function = CallWindowProc(GrOldProc, hWnd, wMsg, wParam, lParam)

end function
    '----------------------------------------------------------------------
'-----------------------------------------------------------------------------------
function pbmain () as long
    local skey as string
    local currentrect as rect
    local hGW as dword
    local clicked, X, Y as long
    local lastpt as pointapi
    local hWin as dword

    ' Create and show a Graphic window on screen


    graphic window "", 450, 130, 500, 500 to hWin

    graphic attach hWin, 0, redraw
    hGW = GetWindow(hWin, %GW_CHILD) ' Retrieve hWnd of graphic window

    ' Subclass the Graphic control
    GrOldProc = SetWindowLong(hGW, %GWL_WNDPROC, codeptr(GrProc))
    graphic set pos (0,0)

    setrect currentrect, 0, 70, 250, 250
    lastpt = gMousePt
    graphic box (currentrect.nleft, currentrect.ntop)- (currentrect.nright, currentrect.nbottom),0,0,-2,0
    graphic redraw
    do
        graphic clear -1, 0
        graphic print "resize and drag a box on a GRAPHIC WINDOW"
        graphic print "start with cursor in the graphic window(this one)"
        graphic print "Use the mouse to size the box. Left button down to drag it"
        graphic print "system drag rect is" + str$(getsystemmetrics(%SM_CXDRAG)) + " x" + _
                      str$(getsystemmetrics(%SM_CXDRAG))
        graphic print "<Esc> to exit"

        graphic box (currentrect.nleft, currentrect.ntop)- (currentrect.nright, currentrect.nbottom),0,0,-2,0
        graphic redraw
        if gLBdown then
            offsetrect currentrect, gMousePt.X - lastpt.X , gMousePt.Y - lastpt.Y
        else
            currentrect.nright  = gMousePt.X
            currentrect.nbottom = gMousePt.Y
        end if
        skey = ""
        graphic inkey$ to skey
        if skey$ = $esc then exit loop
        lastpt = gMousePt
        sleep 50
    loop

    SetWindowLong(hGW, %GWL_WNDPROC, GrOldProc) ' remove subclassing
    graphic window end

end function

[Chris Holbrook]

I chanced upon the DragDetect API the other day but so far I cannot make it work.

What it is supposed to do: msdn

What happens in my clumsy hands: the first few iterations of the while loop do just what I would expect. Then - GPF!

Here is my attempt in code. Any ideas on how to make this API work would be appreciated:

' to investigate DragDetect API
' Chris Holbrook 10 Dec 2008

#compile exe
#dim all
#include once "win32api.inc"

%pic_margin = 3

global GrDialogProc as long               ' used in subclassing the grapic control to get mouse msgs
global GrOldProc as long                  ' used in subclassing the grapic control to get mouse msgs
global gMousePt as pointapi                     ' Mouse x and y
global gLbDOWN as long,gRBDOWN as long    ' Left and right mouse button

'--------------------------------------------------------------------------------
function GrProc(byval hWnd as dword, byval wMsg as dword, byval wParam as dword, byval lParam as long) as long
    static startpt, dragpt as pointAPI
    

  select case wMsg
     '
     case %wm_mousemove
         gMousePt.X = lo(word,lParam)
         gMousePt.Y = hi(word,lParam)  ' Current Mouse X and Y Position in the graphic window
         if glbdown then
            ?"StartDrag"
            startpt = gmousept
            while dragdetect (hWnd, startpt)
                sleep 2
                getcursorpos ( dragpt)       ' screen coordinates
                screentoclient(hWnd, dragpt) ' window coordinates
                ? "DrawDrag", dragpt.x, dragpt.y
            wend
            ?"EndDrag"
             gmousept = dragpt
         end if
         exit function
    '
    case %wm_lbuttondown
        gMousePt.X = lo(word,lParam)
        gMousePt.Y = hi(word,lParam)          ' Current Mouse X and Y Position in the graphic window
        gLBDOWN = 1
        exit function                      ' Left button pressed

    case %wm_lbuttonup
        glbdown = 0
        exit function
    '
  end select
 function = CallWindowProc(GrOldProc, hWnd, wMsg, wParam, lParam)

end function
    '----------------------------------------------------------------------
'-----------------------------------------------------------------------------------
function pbmain () as long
    local skey as string
    local currentrect as rect
    local hGW as dword
    local clicked, X, Y as long
    local lastpt as point
    local hWin as dword

    ' Create and show a Graphic window on screen


    graphic window "", 450, 130, 500, 500 to hWin

    graphic attach hWin, 0, redraw
    hGW = GetWindow(hWin, %GW_CHILD) ' Retrieve hWnd of graphic window

    ' Subclass the Graphic control
    GrOldProc = SetWindowLong(hGW, %GWL_WNDPROC, codeptr(GrProc))
    graphic set pos (0,0)

    setrect currentrect, 0, 70, 250, 250
    lastpt = gMousePt
    graphic box (currentrect.nleft, currentrect.ntop)- (currentrect.nright, currentrect.nbottom),0,0,-2,0
    graphic redraw
    do
        graphic clear -1, 0
        graphic print "resize and drag a box on a GRAPHIC WINDOW"
        graphic print "start with cursor in the graphic window(this one)"
        graphic print "Use the mouse to size the box. Left button down to drag it"
        graphic print "system drag rect is" + str$(getsystemmetrics(%SM_CXDRAG)) + " x" + _
                      str$(getsystemmetrics(%SM_CXDRAG))
        graphic print "<Esc> to exit"

        graphic box (currentrect.nleft, currentrect.ntop)- (currentrect.nright, currentrect.nbottom),0,0,-2,0
        graphic redraw
        if gLBdown then
            offsetrect currentrect, gMousePt.X - lastpt.X , gMousePt.Y - lastpt.Y
        else
            currentrect.nright  = gMousePt.X
            currentrect.nbottom = gMousePt.Y
        end if
        skey = ""
        graphic inkey$ to skey
        if skey$ = $esc then exit loop
        lastpt = gMousePt
        sleep 50
    loop

    SetWindowLong(hGW, %GWL_WNDPROC, GrOldProc) ' remove subclassing
    graphic window end

end function