Any guide on creating DPI-aware apps?

[hua]

Hi guys,

Anyone has any tips, gotchas to share in regards of creating FWH apps that are dpi-aware?

I only realize the problem after a couple of our customers complained that they can't navigate to the end of my scrollable dialog. I've bookmarked http://msdn.microsoft.com/en-us/library ... 60(v=vs.85).aspx for reading later but for now I need to solve the scrollable dialog part first.

Using fwh\samples\testdscr_.prg, this is what I get after I changed to 120dpi and trying to navigate using the scrollbar to the bottom:


This is what should be seen:


So how should testdscr_.prg be modified to make it behave correctly irregardless what's the dpi (user can set the dpi to other than 96 or 120)?

TIA

[hua]

Got another interface issue. When user run our program on a more recent notebook pre-installed with Win7, the placement of controls on dialogs went crazy.

After some googling I suspect this is due to Win7's so called dpi-virtualization.

Read something about preparing a manifest that tell Win7 that an exe is already dpi-aware so don't auto-scale it. Will let you guys know the outcome once I could get my hand on a Win7 notebook

[Antonio Linares]

Hua,

Thanks for your feedback!

[Antonio Linares]

Hua,

Have you tried to automatically calculate it based on the oDlg:nHeight value ?

I think that in these lines:

Code: Select all  Expand view

  ACTIVATE DIALOG oDlg ;
      ON INIT ( oScrDlg := TScrDlg():New( oDlg, 1, 65, 1, 70), oDlg:SetSize( 560, 550 ), oDlg:Center() )
 

550 + 65 should be equal to oDlg:nHeight

[RAMESHBABU]

Hi,

Out of curiosity, I just tested TESTDSCR_.PRG.

I set the DPI to 120 and changed D_HEIGHT to 18 from 13

Code: Select all  Expand view

#define D_HEIGHT          18 //13
 

Then it worked perfectly.

To automatically calculate D_HEIGHT define, we need to know what is the current DPI Setting.
Based on that we can set the correct D_HEIGHT, which enables correct display of Scrollable Dialog.

Mr.Antonio,
Is there any such function to know the current DPI Setting ?

Regards,

- Ramesh Babu P

[Antonio Linares]

Ramesh,

http://msdn.microsoft.com/en-us/library/ms701681(v=vs.85).aspx

To get the system dpi setting, use the CDC::GetDeviceCaps function with the LOGPIXELSX flag. If you do not cancel dpi scaling, this call returns the default value of 96 dpi.

So it should be:

#define LOGPIXELSX 88

local hDC := GetDC( 0 )
MsgInfo( GetDeviceCaps( hDC, LOGPIXELSX ) )
ReleaseDC( 0, hDC )

[RAMESHBABU]

Mr.Antonio,

Thanks for your valuable suggestion,

I have tested the following code not only with 96 and 120 DPIs but also with
various DPIs and found to be working well.

Code: Select all  Expand view

// Testing how to scroll a dialog with its contents

#include "FiveWin.ch"

*#define d_width           4
*#define d_height         18

#define LOGPIXELSX        88

STATIC d_width := 4, d_height := 13

FUNCTION Main()

   LOCAL oDlg, oScrDlg

   local hDC  := GetDC( 0 )

   DEFINE DIALOG oDlg RESOURCE "dlgComScroll" ;  
         TITLE "Scroll dialog"            ;
         STYLE nOR( WS_VSCROLL, WS_HSCROLL )

   oDlg:bMouseWheel = { | nKey, nDelta, nXPos, nYPos | MouseWheel( nKey, nDelta, nXPos, nYPos, oScrDlg ) }

   ACTIVATE DIALOG oDlg ;
      ON INIT ( Set_D_Height(), oScrDlg := TScrDlg():New( oDlg, 1, 65, 1, 70), oDlg:SetSize( 560, 550 ), oDlg:Center() )

RETURN( NIL )



function MouseWheel( nKey, nDelta, nXPos, nYPos, oScrDlg )

   local oVScroll := oScrDlg:oDlg:oVScroll

   if nDelta < 0
      oVScroll:GoDown()
   else
      oVScroll:GoUp()
   endif      

   oScrDlg:VScroll()

return nil

//============================================================================
// FUNCTION : Set_D_Height()
// Purpose  : To Set new d_height for the Scroll bar
//============================================================================

PROCEDURE Set_D_Height()

LOCAL nDpi := GetCurrentDpi()

d_height := (nDpi * 13 / 96)

RETURN

//============================================================================
// FUNCTION : GetCurrentDpi()
// Purpose  : To Get the Windows Current DPI Setting
//============================================================================

FUNCTION GetCurrentDpi()

local hDc  := GetDc(0)
local nDpi := GetDeviceCaps( hDC, LOGPIXELSX )

nDpi := GetDeviceCaps( hDC, LOGPIXELSX )
MsgInfo( LTRIM(STR(nDpi))+" DPI" )

ReleaseDC( 0, hDC )

RETURN nDpi

//============================================================================
// FileName : SCROLL.PRG
// Purpose  :  dialog Scroll Class
// Author   : Eric Yang
// Update History :
//      Date     Contents
//    ---------- ---------------------------------------------------------------
//    1997.02.01
//    2006.29.12 By Rossini - Brasil
//============================================================================
#include "FiveWin.ch"

#ifndef TRUE
   #define TRUE              .T.
   #define FALSE             .F.
#endif

CLASS TScrDlg

   DATA oDlg
   DATA nVPos, nHPos

   METHOD New( oDlg,nV1,nV2,nH1,nH2 ) CONSTRUCTOR
   METHOD SetScroll( nV1,nV2,nH1,nH2 )

   //-*------------------------------------------------------------
   METHOD VScroll()
   METHOD VScrollThumb()
   METHOD VScrollTrack()
   METHOD VScrollPgDown()
   METHOD VScrollPgUp()

   //-*-----------------------------
   METHOD HScroll()
   METHOD HScrollThumb()
   METHOD HScrollTrack()
   METHOD HScrollPgDown()
   METHOD HScrollPgUp()

ENDCLASS

METHOD New( oDlg,nV1,nV2,nH1,nH2 ) CLASS TScrDlg
   ::nVPos := 0
   ::nHPos := 0
   ::oDlg  := oDlg
   ::SetScroll( nV1,nV2,nH1,nH2 )
RETURN Self

METHOD SetScroll( nV1,nV2,nH1,nH2 ) CLASS TScrDlg
LOCAL aCoors1:={},aCoors2:={}
   //--------------------------------------------------
   //-* Vertical Scroll Bar
   if ::oDlg:oVScroll != NIL
      ::oDlg:oVScroll:SetRange( nV1,nV2 )
      ::nVPos := ::oDlg:oVScroll:GetPos()
      ::oDlg:oVScroll:bGoDown   := {|| ::VScroll() }
      ::oDlg:oVScroll:bGoUp     := {|| ::VScroll() }
      ::oDlg:oVScroll:bPageUp   := {|| ::VScrollPgUp() }
      ::oDlg:oVScroll:bPageDown := {|| ::VScrollPgDown() }
      ::oDlg:oVScroll:bGoTop    := {|| ::VScroll() }
      ::oDlg:oVScroll:bGoBottom := {|| ::VScroll() }
      ::oDlg:oVScroll:nPgStep   := 10
      //::oDlg:oVScroll:lReDraw := TRUE
      ::oDlg:oVScroll:bPos      := {|nPos| ::VScrollThumb(nPos) }
      ::oDlg:oVScroll:bTrack    := {|nPos| ::VScrollTrack(nPos) }
   endif
   //--------------------------------------------------
   //-* Horizontal Scroll Bar
   if ::oDlg:oHScroll != NIL
      ::oDlg:oHScroll:SetRange( nH1,nH2 )
      ::nHPos := ::oDlg:oHScroll:GetPos()
      ::oDlg:oHScroll:bGoDown   := {|| ::HScroll() }
      ::oDlg:oHScroll:bGoUp     := {|| ::HScroll() }
      ::oDlg:oHScroll:bPageUp   := {|| ::HScrollPgUp() }
      ::oDlg:oHScroll:bPageDown := {|| ::HScrollPgDown() }
      ::oDlg:oHScroll:bGoTop    := {|| ::HScroll() }
      ::oDlg:oHScroll:bGoBottom := {|| ::HScroll() }
      ::oDlg:oHScroll:nPgStep   := 10
    //::oDlg:oHScroll:lReDraw   := TRUE
      ::oDlg:oHScroll:bPos      := {|nPos| ::HScrollThumb(nPos) }
      ::oDlg:oHScroll:bTrack    := {|nPos| ::HScrollTrack(nPos) }
   endif
*   ::oDlg:bKeyChar := {|nKey,nFlags| ScrollKey(nKey) }
   //--------------------------------------------------
RETURN( NIL )
/*
STATIC FUNCTION ScrollKey(nKey)

   MsgInfo( "Key : "+str(nKey,10) )

   //if nKey == K_ENTER
   //   goMainDlg:End()
   //   lRetVal := TRUE
   //endif
RETURN( NIL )
*/

//=================================================================
//-* Vertical Scroll Bar
METHOD VScroll() CLASS TScrDlg
LOCAL nNewPos

   if ::nVPos >= ::oDlg:oVScroll:nMin   ;
      .and. ::nVPos <= ::oDlg:oVScroll:nMax
      nNewPos := ::oDlg:oVScroll:GetPos()
      SysRefresh()

      ScrollWindow( ::oDlg:hWnd, 0,  ;
         (  ::nVPos-nNewPos )*d_height,    ;
         0 , GetClientRect(::oDlg:hWnd) )
      ::nVPos := nNewPos
   endif
RETURN( NIL )

METHOD VScrollThumb(nNewPos) CLASS TScrDlg
   if ::nVPos >= ::oDlg:oVScroll:nMin   ;
      .and. ::nVPos <= ::oDlg:oVScroll:nMax
      ::oDlg:oVScroll:SetPos(nNewPos)
      SysRefresh()
      ScrollWindow( ::oDlg:hWnd, 0,  ;
         (::nVPos - nNewPos )*d_height,    ;
         0 , GetClientRect(::oDlg:hWnd) )
      ::nVPos := nNewPos
   endif
RETURN( NIL )

METHOD VScrollTrack(nNewPos) CLASS TScrDlg
   if ::nVPos >= ::oDlg:oVScroll:nMin   ;
      .and. ::nVPos <= ::oDlg:oVScroll:nMax
      ::oDlg:oVScroll:SetPos(nNewPos)
      SysRefresh()
      ScrollWindow( ::oDlg:hWnd, 0,  ;
         (::nVPos - nNewPos )*d_height,    ;
         0 , GetClientRect(::oDlg:hWnd) )
      ::nVPos := nNewPos
   endif
RETURN( NIL )

METHOD VScrollPgDown() CLASS TScrDlg
LOCAL nNewPos
   if ::nVPos < ::oDlg:oVScroll:nMax
      nNewPos := ::nVPos + ::oDlg:oVScroll:nPgStep
      nNewPos := iif(nNewPos > ::oDlg:oVScroll:nMax, ::oDlg:oVScroll:nMax, nNewPos)
      SysRefresh()
      ScrollWindow( ::oDlg:hWnd, 0,  ;
         ( ::nVPos - nNewPos )*d_height,    ;
         0 , GetClientRect(::oDlg:hWnd) )
      ::nVPos := nNewPos
   endif
RETURN( NIL )

METHOD VScrollPgUp() CLASS TScrDlg
LOCAL nNewPos
   if ::nVPos > ::oDlg:oVScroll:nMin
      nNewPos := ::nVPos - ::oDlg:oVScroll:nPgStep
      nNewPos := iif(nNewPos < ::oDlg:oVScroll:nMin,::oDlg:oVScroll:nMin,nNewPos)
      SysRefresh()
      ScrollWindow( ::oDlg:hWnd, 0,  ;
         ( ::nVPos - nNewPos )*d_height,    ;
         0 , GetClientRect(::oDlg:hWnd) )
      ::nVPos := nNewPos
   endif
RETURN( NIL )

//=================================================================
//-* Horizontal Scroll Bar
METHOD HScroll() CLASS TScrDlg
LOCAL nNewPos

   if ::nHPos >= ::oDlg:oHScroll:nMin   ;
      .and. ::nHPos <= ::oDlg:oHScroll:nMax
      nNewPos := ::oDlg:oHScroll:GetPos()
      SysRefresh()
      ScrollWindow( ::oDlg:hWnd,           ;
         (::nHPos - nNewPos )*d_width,0,   ;
         0 , GetClientRect(::oDlg:hWnd) )
      ::nHPos := nNewPos
   endif
RETURN( NIL )

METHOD HScrollThumb(nNewPos) CLASS TScrDlg
   if ::nHPos >= ::oDlg:oHScroll:nMin   ;
      .and. ::nHPos <= ::oDlg:oHScroll:nMax
      ::oDlg:oHScroll:SetPos(nNewPos)
      SysRefresh()
      ScrollWindow( ::oDlg:hWnd,           ;
         (::nHPos - nNewPos )*d_width,0,   ;
         0 , GetClientRect(::oDlg:hWnd) )
      ::nHPos := nNewPos
   endif
RETURN( NIL )

METHOD HScrollTrack(nNewPos) CLASS TScrDlg
   if ::nHPos >= ::oDlg:oHScroll:nMin   ;
      .and. ::nHPos <= ::oDlg:oHScroll:nMax
      ::oDlg:oHScroll:SetPos(nNewPos)
      SysRefresh()
      ScrollWindow( ::oDlg:hWnd,           ;
         (::nHPos - nNewPos )*d_width,0,   ;
         0 , GetClientRect(::oDlg:hWnd) )
      ::nHPos := nNewPos
   endif
RETURN( NIL )

METHOD HScrollPgDown() CLASS TScrDlg

LOCAL nNewPos
   if ::nHPos < ::oDlg:oHScroll:nMax
      nNewPos := ::nHPos + ::oDlg:oHScroll:nPgStep
      nNewPos := iif(nNewPos > ::oDlg:oHScroll:nMax, ::oDlg:oHScroll:nMax, nNewPos)
      SysRefresh()
      ScrollWindow( ::oDlg:hWnd,           ;
         ( ::nHPos - nNewPos )*d_width,0,  ;
         0 , GetClientRect(::oDlg:hWnd) )
      ::nHPos := nNewPos
   endif
RETURN( NIL )

METHOD HScrollPgUp() CLASS TScrDlg
LOCAL nNewPos
   if ::nHPos > ::oDlg:oHScroll:nMin
      nNewPos := ::nHPos - ::oDlg:oHScroll:nPgStep
      nNewPos := iif(nNewPos < ::oDlg:oHScroll:nMin,::oDlg:oHScroll:nMin,nNewPos)
      SysRefresh()
      ScrollWindow( ::oDlg:hWnd,           ;
         ( ::nHPos - nNewPos )*d_width,0,  ;
         0 , GetClientRect(::oDlg:hWnd) )
      ::nHPos := nNewPos
   endif
RETURN( NIL )

//=* End of File =================================================

//#include "wndscrol.c"

 

I request our members to test it further, on different Windows OS environments.
I have tested this on Windows XP, Service Pack 2

Regards,

- Ramesh Babu P

[RAMESHBABU]

Hi Members,

It would be nice if the cursor is moved up/down based on pressing TAB or SHIFT+TAB or
ENTER key to go down, accordingly scroll bar automatically moved upwards or downwards
and the current get is visible.

I request the members who are all using this Scrollable Dialogue Class to try it.

Regards,

- Ramesh Babu P

[Antonio Linares]

Ramesh,

Very good! Thanks!

[hua]

Thank you for the prompt reply Antonio. Sorry for the late reply, was dragged to solve something that was deemed higher priority by management.

Ramesh, thank you! I'm gonna try your solution now.

It would be nice if the cursor is moved up/down based on pressing TAB or SHIFT+TAB or
ENTER key to go down, accordingly scroll bar automatically moved upwards or downwards
and the current get is visible.

I agree with you on this

[hua]

I find the following tutorial has been quite useful:
http://www.rw-designer.com/DPI-aware