C / C++ / MFC

23-Jan-20 7:25

Hi
I read some articles on how to make a win32 prog DPI aware. I want to make a dialog which has
windows controls, bitmaps and gdiplus objects combined.
I am using VS2019 and started a MFC app from scratch.
What would be the right way to get a DPI aware app, because I set DPI to high in the MFC app setting and used GetDeviceCaps to draw the lines. But when DPI is set to HIGH the lines do not match with the controls anymore. When I switch it off, the graphics look blurry, but are on the right position.
I made some screenshots to show what I mean:

Windows 100%, DPI aware to HIGH

Windows 150%, DPI aware to HIGH

Windows 150%, DPI aware to NO

What would be the right approach, so windows controls and graphics match on all resolutions?

thanks
regards
Erich

Gerry Schmitz23-Jan-20 7:37

Gerry Schmitz

23-Jan-20 7:37

In Windows 10 you make your apps "fluent" and don't worry about that stuff. The user controls text size through "Ease of Access" in the control panel.

Stick to Segoe UI fonts; use the "standard resources" for headings and body; size everything divisible by 4; stick to PNGs, using transparent backgrounds when necessary to reduce size.

It was only in wine that he laid down no limit for himself, but he did not allow himself to be confused by it.
― Confucian Analects: Rules of Confucius about his food

Erich Jarz23-Jan-20 8:27

23-Jan-20 8:27

Hi
Thanks, but that didnt answer my question. How should I draw Gdiplus graphics and controls so that they are always drawn correctly (same position) on all Dpi settings?
The code that I use can be seen in the first screenshot.
Regards
Erich

leon de boer24-Jan-20 7:05

leon de boer

24-Jan-20 7:05

Short answer you scale everything long answer you scale everything

Okay to get scale factor you need the DPI of the screen which you use Win32 API

HDC Dc = GetDC(GetDesktopWindow());       // Get Screen DC
int DpiX = GetDeviceCaps(Dc, LOGPIXELSX); // X DPI for this DC (96 for normal screen)
int DpiY = GetDeviceCaps(Dc, LOGPIXELSY); // Y DPI for this DC (96 for normal screen)
ReleaseDC(GetDesktopWindow(), Dc);	      // Release screen DC finished with it now
if (DpiX != 96 || DpiY != 96)	          // High DPI mode active
{
    /* calculate scale */
    double ScaleX = (double)DpiX/96;
    double ScaleY = (double)DpiY/96; 
}

In vino veritas

Erich Jarz24-Jan-20 7:42

24-Jan-20 7:42

Hi
Thanks for your reply. I already tried to calculate the coord with GetDeviceCaps, but that does not work correctly! When I set 150% font size in windows I get a ratio of 144/96=1.5 as expected, but the controls and the dialog itself do not scale that way!

Here a different example:

I have drawn two red rectangles, one with the size of the dialog and an inner one which is the size of a group box. For the size of the dialog rectangle I use GetClientRect. It works on all font sizes (DPI scalings) correct.
For the inner rectangle inside the group box I tried to recalculate the coords with GetDeviceCaps, but that does not work. If I change scaling in windows the inner rectangle is completely off.
So I tried to figure out the correct coords for the inner rectangle by trial and error. Below are the coords which draw the correct rectangles in relation to the group box.
But how can I calculate them, I get some weird values? In the x axis I would get a factor of 1.3328 and on the y axis a factor of 1.62 with 150% scaling, not 1.5 as expected!?

Screenshot at 100%

// coords at 100%
Dialog rectangle coord = 0/0 - 1445/832
group box rectangle coord = 624/9 - 1247/581

Screenshot at 125%

// coords at 125%
Dialog rectangle coord = 0/0 - 1685/1088
group box rectangle coord = 728/11 - 1456/761

Screenshot at 150%

// coords at 150%
Dialog rectangle coord = 0/0 - 1926/1344
group box rectangle coord = 831/13 - 1664/941

How can I calculate the right coordinates for these elements ?

thanks
regards
Erich

leon de boer24-Jan-20 19:41

leon de boer

24-Jan-20 19:41

You are obviously loading the dialog from a resource file or template.
Those have a normal DPI scale of 48 and yes it gets messy.

1.) Don't do it .... manually create the dialog and insert the items.

or

2.) If you don't want to do it manually on window entries that draw on the WM_CREATE grab the size and scale of the window just like you did. Which is basically what Gerry is saying below and contain your draws to windows. That means if you want to draw something on the dialog background make an transparent invisible window in the resource so it scales with the rest of the dialog and draw on it.

You are sort of creating a mountain out of a molehill.

In vino veritas

modified 25-Jan-20 1:50am.

Erich Jarz26-Jan-20 20:22

26-Jan-20 20:22

Hi
Thanks for your replies. I drew the controls with the MFC resource editor, so the scaling doesnt match as you said.
So, I started a Win32 desktop application from scratch without MFC or other wrappers. I will do all drawings and scalings myself for all elements. I hope this will solve my DPI problems. I know that this is much work, but I only have experience with VisualStudio and MFC and I have to learn the basic WIN32 stuff first. I wanted to know the underlying win32 basics anyway.

Thanks for your help!
regards
Erich

Gerry Schmitz24-Jan-20 8:27

Gerry Schmitz

24-Jan-20 8:27

My "answer" was, why bother when the OS / framework will do it for you.

Besides dimensions, you have to scale positions (top, left), fonts, pixel fiddling.

With a "ViewBox" (as one example) one can do in 1 minute what you'll be spending the next month on.

Your graphics are "Border" elements within a Grid, inside a viewbox, with whatever relative dimensions you want.

It was only in wine that he laid down no limit for himself, but he did not allow himself to be confused by it.
― Confucian Analects: Rules of Confucius about his food

modified 24-Jan-20 14:34pm.

win32 Radio button doesn't show when is checked

Richard MacCutchan23-Jan-20 9:59

Richard MacCutchan

23-Jan-20 9:59

I am not sure how you are drawing that button, but using the same co-ordinates as you use for the red lines should get it to the right place.

See Writing DPI Aware Applications | Windows Vista | Microsoft Windows[^]

modified 23-Jan-20 16:29pm.

coco24319-Jan-20 6:53

Re: win32 Radio button doesn't show when is checked

19-Jan-20 6:53

Hi,

I am covering a book tutorial about programming win32 and when I am compiling the code provided,
radio buttons doesn't show when are checked, instead the checkbox that is in the same dialog window
shows when it is checked.

I will attach the code if you can help me:

resource code:

C++

TESTDIALOG DIALOG DISCARDABLE  20, 20, 180, 70
STYLE DS_MODALFRAME | WS_POPUP | WS_VISIBLE | WS_CAPTION | WS_SYSMENU
CAPTION "Test Dialog"
FONT 8, "MS Sans Serif"
BEGIN
    CHECKBOX        "Check box control.",IDC_CHECKBOX,9,7,70,10
    GROUPBOX        "Radio Buttons",-1,7,21,86,39
    RADIOBUTTON     "First", IDC_RADIO1,13,32,37,10,WS_GROUP | WS_TABSTOP
    RADIOBUTTON     "Second",IDC_RADIO2,13,45,39,10
    PUSHBUTTON      "Done",IDCANCEL,116,8,50,14,WS_GROUP
END

cpp code:

LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
	int wmId, wmEvent;
	PAINTSTRUCT ps;
	HDC hdc;

	switch (message)
	{
	case WM_COMMAND:
		wmId    = LOWORD(wParam);
		wmEvent = HIWORD(wParam);
		// Parse the menu selections:
		switch (wmId)
		{
		case ID_FILE_TEST:                        // adaugat de mine
			// ShowWindow(hWnd,SW_SHOWMAXIMIZED);   // maximizeaza fereastra
		 if ( !hDlgModeless )
                           hDlgModeless = CreateDialog( hInst,  MAKEINTRESOURCE(32767), 
                                                hWnd, (DLGPROC)TestDlgProc );
			 break;
		case IDM_ABOUT:
			DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About);
			break;
		case IDM_EXIT:
			DestroyWindow(hWnd);
			break;
		default:
			return DefWindowProc(hWnd, message, wParam, lParam);
		}
		break;
	case WM_PAINT:
		hdc = BeginPaint(hWnd, &ps);
		// TODO: Add any drawing code here...
		EndPaint(hWnd, &ps);
		break;
	case WM_DESTROY:
		PostQuitMessage(0);
		break;
	default:
		return DefWindowProc(hWnd, message, wParam, lParam);
	}
	return 0;
}

LRESULT CALLBACK TestDlgProc(HWND hDlg, UINT uMsg, WPARAM wParam, LPARAM lParam)
{
  switch (uMsg)
  {
  // Initially set the check box
  // and radio button states.
  //...........................
  case WM_INITDIALOG:
	  CheckDlgButton(hDlg,IDC_CHECKBOX, bChecked ? MF_CHECKED : MF_UNCHECKED);
	  CheckRadioButton(hDlg,IDC_RADIO1,IDC_RADIO2,bRadio1 ? IDC_RADIO1 : IDC_RADIO2);
	  break;
  case WM_COMMAND:
	  switch( LOWORD(wParam))
	  {
	  case IDC_CHECKBOX:
		  bChecked=!IsDlgButtonChecked(hDlg,IDC_CHECKBOX);
		  CheckDlgButton(hDlg,IDC_CHECKBOX, bChecked ? MF_CHECKED : MF_UNCHECKED);
		  break;
	  case IDC_RADIO1:
		  bRadio1=TRUE;
		  CheckRadioButton(hDlg,IDC_RADIO1,IDC_RADIO2, IDC_RADIO1);
		  break;
	  case IDC_RADIO2:
		  bRadio1=FALSE;
		  CheckRadioButton(hDlg,IDC_RADIO1,IDC_RADIO2,IDC_RADIO2);
		  break;
	  case IDCANCEL:
		  DestroyWindow(hDlg);
		  break;
	  }//end switch
	  break;
  case WM_DESTROY:
	  hDlgModeless=NULL;
	  break;
  default: 
	  return (FALSE);
  }// end switch


	return (TRUE);
}

If it's need it I will put all the code.

Thank you in advance.

Victor Nijegorodov19-Jan-20 7:32

Victor Nijegorodov

19-Jan-20 7:32

Did you debug this code?
Is this code:

C++

case IDC_CHECKBOX:
          bChecked=!IsDlgButtonChecked(hDlg,IDC_CHECKBOX);
          CheckDlgButton(hDlg,IDC_CHECKBOX, bChecked ? MF_CHECKED : MF_UNCHECKED);

executed?
Is this code:

C++

case IDC_RADIO1:
          bRadio1=TRUE;
          CheckRadioButton(hDlg,IDC_RADIO1,IDC_RADIO2, IDC_RADIO1);
          break;

executed?

Re: win32 Radio button doesn't show when is checked

coco24319-Jan-20 8:48

Re: win32 Radio button doesn't show when is checked

19-Jan-20 8:48

Yes, I attached a link to the result, but how I sayed, when I check the radio box nothing happens:
Dialog-Box — imgbb.com[^]

The checkbox instead is ok:

Dialog-Box1 — imgbb.com[^]

[url=https://imgbb.com/][img]https://i.ibb.co/SBV51Bm/Dialog-Box1.jpg[/img][/url]

Victor Nijegorodov19-Jan-20 9:29

Victor Nijegorodov

19-Jan-20 9:29

Again: did you set a break point to one of these lines:

<pre lang="c++">

case IDC_RADIO1:
bRadio1=TRUE;
CheckRadioButton(hDlg,IDC_RADIO1,IDC_RADIO2, IDC_RADIO1);
break;
and was sure that this

C++

CheckRadioButton(hDlg,IDC_RADIO1,IDC_RADIO2, IDC_RADIO1);

has been executed?

Re: win32 Radio button doesn't show when is checked

coco24319-Jan-20 10:05

Re: win32 Radio button doesn't show when is checked

19-Jan-20 10:05

Yes, I had placed a brakepoint after the CheckRadioButton RADIO1 function at the "break" statement.
When I press the Radio1 radio button the program goes and stops at the breakpoint, but what I had observed is that when a press play again to the compiler the program continues to execute and then it's comes back at the break point without to press again the radio button.
Thanks,

_Flaviu19-Jan-20 19:22

_Flaviu

19-Jan-20 19:22

Check in Resource.h file to see if those two radio buttons has consecutive values ... might be a problem if they are not.

Re: win32 Radio button doesn't show when is checked

coco24320-Jan-20 6:50