hbrBackground

[Jules Marchildon]

Today, I'm not the sharpest tool in the shed, ...I cannot recall why +1 is required
...this +1 automatically converts it to an HBRUSH ???

hbrBackground

Identifies the class background brush. This member can be a handle to the physical brush to be 
used for painting the background, or it can be a color value. A color value must be one of the 
following standard system colors (the value 1 must be added to the chosen color). If a color value is 
given, you must convert it to one of the following HBRUSH types: 

COLOR_ACTIVEBORDER
COLOR_ACTIVECAPTION
COLOR_APPWORKSPACE
COLOR_BACKGROUND
COLOR_BTNFACE
COLOR_BTNSHADOW
COLOR_BTNTEXT
COLOR_CAPTIONTEXT
COLOR_GRAYTEXT
COLOR_HIGHLIGHT
COLOR_HIGHLIGHTTEXT
COLOR_INACTIVEBORDER
COLOR_INACTIVECAPTION
COLOR_MENU
COLOR_MENUTEXT
COLOR_SCROLLBAR
COLOR_WINDOW
COLOR_WINDOWFRAME
COLOR_WINDOWTEXT

[Kev Peel]

Jules,

Basically using "0" tells Windows to not paint the background, but since the color constants also cover 0 you need to +1 to other values (you use a COLOR_ value).

The background can be a brush handle, color constant+1 (what they call a "HBRUSH type" above), or 0 if you draw it yourself.

[Jules Marchildon]

Thanks Kev,

So if to use %COLOR_SCROLLBAR = 0 , then +1 to assure its not a %NULL brush.
I recall if I use a %NULL Brush, I paint myself or supply my own created brush.

but if I use %COLOR_BTNFACE = 15 or any other non-zero constant...

i.e. twcx.hbrBackground = %COLOR_BTNFACE gives me the wrong color?

and

twcx.hbrBackground = %COLOR_BTNFACE+1 gives to me the correct color.

sorry, I'm still a little fuzzy.

-----
OK... only logic I can find...
There's a set of color constants for various parts of Windows interface.
Those constants start at zero (ie. %COLOR_SCROLLBAR has numeric value 0),
and so you have to add one to the constant when using it in place of
hBrush in WndClassEx: otherwise, %COLOR_SCROLLBAR would be
indistinguishable from %NULL handle.
Guess one could use GetSysColorBrush(%COLOR_xxxx) to avoid the +1 logic.
Now I understand more ways to skin a carrot...

[Kev Peel]

Jules,

You have three choices:

1. hbrBackground = %NULL (no background)
2. hbrBackground = %COLOR_XXX + 1 (color value, ALWAYS add 1)
3. hbrBackground = hBrush (use specified brush)

Hope that's clearer