Properly determine checkbox state for custom draw - c++

Question

INTRODUCTION AND RELEVANT INFORMATION:
I need to have themed common controls but with different text color, and transparent background. I have ran into a problem that is well documented in this question.
I have made some progress by handling NM_CUSTOMDRAW and have decided to finish the checkbox first.
PROBLEM:
I got stuck with determining the state of the checkbox, so I can not pass the correct parameter for DrawThemeBackground().
Code speaks more than words, so here is the snippet:
case WM_NOTIFY:
{
if( ((LPNMHDR)lParam)->code == NM_CUSTOMDRAW )
{
switch( ((LPNMHDR)lParam)->idFrom )
{
case IDC_CHECK1:
{
switch( ((LPNMCUSTOMDRAW)lParam)->dwDrawStage )
{
case CDDS_PREERASE:
{
HRESULT hr = DrawThemeParentBackground(
((LPNMCUSTOMDRAW)lParam)->hdr.hwndFrom
((LPNMCUSTOMDRAW)lParam)->hdc,
&((LPNMCUSTOMDRAW)lParam)->rc );
if( FAILED(hr) ) // if failed draw without theme
{
SetWindowLongPtr( hDlg, DWLP_MSGRESULT
(LONG_PTR)CDRF_DODEFAULT );
return TRUE;
}
HTHEME hTheme = OpenThemeData(
((LPNMCUSTOMDRAW)lParam)->hdr.hwndFrom,
L"BUTTON" );
if( ! hTheme ) // if failed draw without theme
{
CloseThemeData(hTheme);
SetWindowLongPtr( hDlg, DWLP_MSGRESULT
(LONG_PTR)CDRF_DODEFAULT );
return TRUE;
}
// draw the state-->this is the problem part
// I thought this might be useful
LRESULT state = SendMessage(
((LPNMCUSTOMDRAW)lParam)->hdr.hwndFrom,
BM_GETSTATE, 0, 0 );
int stateID; // parameter for DrawThemeBackground
switch( ((LPNMCUSTOMDRAW)lParam)->uItemState )
{
case CDIS_HOT:
{
if( IsDlgButtonChecked( hDlg, ((LPNMCUSTOMDRAW)lParam)->hdr.idFrom ) )
stateID = CBS_CHECKEDHOT;
else
stateID = CBS_UNCHECKEDHOT;
break;
}
case CDIS_DEFAULT:
{
if( IsDlgButtonChecked( hDlg, ((LPNMCUSTOMDRAW)lParam)->hdr.idFrom ) )
stateID = CBS_CHECKEDNORMAL;
else
stateID = CBS_UNCHECKEDNORMAL;
break;
}
case CDIS_FOCUS:
{
if( IsDlgButtonChecked( hDlg, ((LPNMCUSTOMDRAW)lParam)->hdr.idFrom ) )
stateID = CBS_CHECKEDNORMAL;
else
stateID = CBS_UNCHECKEDNORMAL;
break;
}
case CDIS_SELECTED:
{
if( IsDlgButtonChecked( hDlg, ((LPNMCUSTOMDRAW)lParam)->hdr.idFrom ) )
stateID = CBS_CHECKEDPRESSED;
else
stateID = CBS_UNCHECKEDPRESSED;
break;
}
}
RECT r;
SIZE s;
// get check box dimensions so we can calculate
// rectangle dimensions for text
GetThemePartSize( hTheme,
((LPNMCUSTOMDRAW)lParam)->hdc,
BP_CHECKBOX, stateID, NULL,
TS_TRUE ,&s );
r.left = ((LPNMCUSTOMDRAW)lParam)->rc.left;
r.top = ((LPNMCUSTOMDRAW)lParam)->rc.top;
r.right = ((LPNMCUSTOMDRAW)lParam)->rc.left + s.cx;
r.bottom = ((LPNMCUSTOMDRAW)lParam)->rc.top + s.cy;
DrawThemeBackground( hTheme, ((LPNMCUSTOMDRAW)lParam)->hdc,
BP_CHECKBOX, stateID, &r, NULL );
// adjust rectangle for text drawing
((LPNMCUSTOMDRAW)lParam)->rc.left += 2 + s.cx;
DrawText( ((LPNMCUSTOMDRAW)lParam)->hdc,
L"Example text", -1,
&((LPNMCUSTOMDRAW)lParam)->rc,
DT_SINGLELINE | DT_VCENTER );
CloseThemeData(hTheme);
SetWindowLongPtr( hDlg, DWLP_MSGRESULT
(LONG_PTR)CDRF_SKIPDEFAULT );
return TRUE;
}
}
}
}
}
}
break;
The text color and text background are set in the WM_CTLCOLORSTATIC handler:
case WM_CTLCOLORSTATIC:
{
SetTextColor( (HDC)wParam, RGB( 255, 0, 0 ) );
SetBkMode( (HDC)wParam, TRANSPARENT );
}
return (INT_PTR)( (HBRUSH)GetStockObject(NULL_BRUSH) );
I have included common controls 6 with the #pragma comment and InitCommonControlsEx().
QUESTION:
All I need for now is to pass proper state for the DrawThemeBackground. Can someone help me with this?
Thank you.
Best regards.

Answer 1

NM_CUSTOMDRAW gives you state information about the control being drawn. The NMCUSTOMDRAW::uItemState field is a bitmask that can hold multiple values at a time, but you are not taking that into account. You need to use the & bitwise operator to check for the presence of specific values.
Change this:
// I thought this might be useful
LRESULT state = SendMessage(
((LPNMCUSTOMDRAW)lParam)->hdr.hwndFrom,
BM_GETSTATE, 0, 0 );
int stateID; // parameter for DrawThemeBackground
switch( ((LPNMCUSTOMDRAW)lParam)->uItemState )
{
case CDIS_HOT:
{
if( IsDlgButtonChecked( hDlg, ((LPNMCUSTOMDRAW)lParam)->hdr.idFrom ) )
stateID = CBS_CHECKEDHOT;
else
stateID = CBS_UNCHECKEDHOT;
break;
}
case CDIS_DEFAULT:
{
if( IsDlgButtonChecked( hDlg, ((LPNMCUSTOMDRAW)lParam)->hdr.idFrom ) )
stateID = CBS_CHECKEDNORMAL;
else
stateID = CBS_UNCHECKEDNORMAL;
break;
}
case CDIS_FOCUS:
{
if( IsDlgButtonChecked( hDlg, ((LPNMCUSTOMDRAW)lParam)->hdr.idFrom ) )
stateID = CBS_CHECKEDNORMAL;
else
stateID = CBS_UNCHECKEDNORMAL;
break;
}
case CDIS_SELECTED:
{
if( IsDlgButtonChecked( hDlg, ((LPNMCUSTOMDRAW)lParam)->hdr.idFrom ) )
stateID = CBS_CHECKEDPRESSED;
else
stateID = CBS_UNCHECKEDPRESSED;
break;
}
}
To something more like this instead:
int stateID; // parameter for DrawThemeBackground
UINT uiItemState = ((LPNMCUSTOMDRAW)lParam)->uItemState;
bool bChecked = (uiItemState & CDIS_CHECKED);
if (uiItemState & CDIS_HOT)
stateID = bChecked ? CBS_CHECKEDHOT : CBS_UNCHECKEDHOT;
else if (uiItemState & CDIS_SELECTED)
stateID = bChecked ? CBS_CHECKEDPRESSED : CBS_UNCHECKEDPRESSED;
else
stateID = bChecked ? CBS_CHECKEDNORMAL : CBS_UNCHECKEDNORMAL;