Strip Bitmaps - lose resolution

[Barry Gordon]

Hi,

I'm trying to use a strip bitmap to provide a graphics knob on a form that can be turned e.g. (like a volume control).  I have the a test bitmap and have put together a test program to use it and it works perfectly (ish).

The only problem is that the strip bitmap is clearly grayscale (others could be colour)  when I start; whereas when I use it within the program the graphics knob loses resolution (i.e I assume it goes to monochrome [b&w]).  I have searched the web and the forum but can find no advice on what might be wrong.

Below is the test program and I have attached it as a zip:-

Its bound to be something obvious on my part - but I cannot see it - so any advice would be greatly appreciated.

Many thanks
Barry
-------
Global gindex As Integer
Global gHandle As Dword 
'--------------------------------------------------------------------------------
Function FORM1_COMMAND1_BN_CLICKED ( _
                                   ControlIndex     As Long,  _  ' index in Control Array
                                   hWndForm         As Dword, _  ' handle of Form
                                   hWndControl      As Dword, _  ' handle of Control
                                   idButtonControl  As Long   _  ' identifier of button
                                   ) As Long

gIndex = gIndex + 1
FF_Control_Redraw( HWND_FORM1_PICTURE1 )

End Function
'--------------------------------------------------------------------------------
Function FORM1_WM_CREATE ( _
                         hWndForm As Dword, _      ' handle of Form
                         ByVal UserData As Long _  ' optional user defined Long value
                         ) As Long

gHandle = ImageList_LoadImage( App.hInstance, "barrytest.bmp",0 , 1, %CLR_NONE ,%IMAGE_BITMAP ,%LR_LOADFROMFILE Or %LR_DEFAULTCOLOR     )

gIndex = 0

End Function
'--------------------------------------------------------------------------------
Function FORM1_PICTURE1_WM_PAINT ( _
                                 ControlIndex  As Long,  _  ' index in Control Array
                                 hWndForm      As Dword, _  ' handle of Form
                                 hWndControl   As Dword  _  ' handle of Control
                                 ) As Long
   Local hdc      As Dword
   Local nSavedDC As Dword

   Local hBitMap As Dword 
   Local hDCBitMap As Dword

   Local ps As paintstruct
   
   If ( gIndex = 0 ) Then Exit Function                'Lets see what the original looks like by missing the first pass
   
    hDC = BeginPaint( hWndControl, ps )
    nSavedDC = SaveDC( hDC ) 

    hDCBitMap = CreateCompatibleDC(hDC)
    hBitMap = CreateCompatibleBitmap(hDC, ps.rcpaint.nRight, ps.rcpaint.nBottom )
    SelectObject ( hDCBitMap, hBitMap )
   
   ImageList_DrawEx( gHandle, gIndex, hDCBitMap, 0, 0, 0, 0,%CLR_NONE,%CLR_NONE,%ILD_NORMAL )   

   BitBlt  ( hDC, 0, 0, 67, 67, hDCBitMap, 0, 0, %srccopy )

   RestoreDC ( hDC, nSavedDC  )

   If hBitMap       Then DeleteObject hBitMap               
   If hDCBitMap     Then DeleteObject hDCBitMap               
   If hDC           Then DeleteObject hDC   
     
End Function

[Barry Gordon]

Hi,

I think I have found the answer to my problem myself - see below - as it now works.

I've also included/attached the modfiied FireFly project in case it helps anyone in the future.

Obviously if anyone knows a better way then I would always be pleased to be told.

Cheers
Barry
---

Global gindex As Integer
Global gHandle As Dword 
'--------------------------------------------------------------------------------
Function FORM1_COMMAND1_BN_CLICKED ( _
                                   ControlIndex     As Long,  _  ' index in Control Array
                                   hWndForm         As Dword, _  ' handle of Form
                                   hWndControl      As Dword, _  ' handle of Control
                                   idButtonControl  As Long   _  ' identifier of button
                                   ) As Long

gIndex = gIndex + 1
FF_Control_Redraw( HWND_FORM1_PICTURE1 )

End Function
'--------------------------------------------------------------------------------
Function FORM1_WM_CREATE ( _
                         hWndForm As Dword, _      ' handle of Form
                         ByVal UserData As Long _  ' optional user defined Long value
                         ) As Long
'------------------------------                         
' REPLACE THIS .....
   
'gHandle = ImageList_LoadImage( App.hInstance, "barrytest.bmp",0 , 1, %CLR_NONE ,%IMAGE_BITMAP ,%LR_LOADFROMFILE Or %LR_DEFAULTCOLOR     )

'  WITH THIS ....
'
'=====
Local hScrBM As Dword

gHandle = ImageList_Create(67, 67, %ILC_COLOR24, 0, 1)
hScrBM = LoadImage(App.hInstance,  "barrytest.bmp", %IMAGE_BITMAP, 0, 0, %LR_LOADFROMFILE    )
ImageList_Add(gHandle, hScrBM, %Null)
DeleteObject(hScrBM)
'======
gIndex = 0

End Function
'--------------------------------------------------------------------------------
Function FORM1_PICTURE1_WM_PAINT ( _
                                 ControlIndex  As Long,  _  ' index in Control Array
                                 hWndForm      As Dword, _  ' handle of Form
                                 hWndControl   As Dword  _  ' handle of Control
                                 ) As Long
   Local hdc      As Dword
   Local nSavedDC As Dword

   Local hBitMap As Dword 
   Local hDCBitMap As Dword

   Local ps As paintstruct
   
   If ( gIndex = 0 ) Then Exit Function                'Lets see what the original looks like by missing the first pass
   
    hDC = BeginPaint( hWndControl, ps )
    nSavedDC = SaveDC( hDC ) 

    hDCBitMap = CreateCompatibleDC(%Null)
    hBitMap = CreateCompatibleBitmap(hDC, ps.rcpaint.nRight, ps.rcpaint.nBottom )
    SelectObject ( hDCBitMap, hBitMap )
   
   ImageList_Draw  ( gHandle, gIndex, hDCBitMap,0,0,%ILD_NORMAL)

   BitBlt  ( hDC, 0, 0, 67, 67, hDCBitMap, 0, 0, %srccopy )

   RestoreDC ( hDC, nSavedDC  )

   If hBitMap       Then DeleteObject hBitMap               
   If hDCBitMap     Then DeleteObject hDCBitMap               
   If hDC           Then DeleteObject hDC   
     
End Function

[Robert Eaton]

I looked at your sample and was a little puzzled myself. It looked like the palette was getting changed to 4-bit (16 color). After you posted your solution I looked up ImageList_Create in the WinAPI help and see this for the ILC_COLOR flag:

"Use the default behavior if none of the other ILC_COLOR* flags is specified. Typically, the default is ILC_COLOR4"

So it sounds like if you don't use ImageList_Create you will likely get 4-bit color?

[Barry Gordon]

Hi Robert,

Thanks - yes that explains it.  I had read the help on LoadImage - but had missed that vital line. 

I like to know why solutions work - rather than they just do - as thats how you learn.  And now I know....

Cheers
Barry