Re: MFC CPicture, CBitmap and CDC programming question

Tech-Archive recommends: Repair Windows Errors & Optimize Windows Performance

From: Louis Solomon [SteelBytes] (louis_at_steelbytes.spam-is-bad.com)
Date: 03/01/04 

Date: Mon, 1 Mar 2004 13:33:25 +1100

explore DIBSections ...
they are an easy an practical way to dirrectly manipulate and then draw
images
...
load the source image into a dib section (CreateDIBSection) in a memory dc
(created with CreateCompatibleDC), then directly manipulate the pixels using
the pointer returned by CreateDIBSection, then BitBlt it during a wm_paint
to the screen 

-- 
Louis Solomon
www.steelbytes.com
"Adam Messer" <amesser@mchsi.com> wrote in message 
news:8pe040lebddtgo4n8v57tcbh22efvj61ds@4ax.com...
> Hello all,
>
> I am a fairly new Windows programmer. I am writing a program
> to remote control some A/V equipment. The way I decided to implement
> my interface is to use a BMP image of a universal remote control. I am
> using Visual Studio 6 with C++ and MFC in a dialog application.
>
> I have gone through the trouble to get the coordinates of
> every button on the remote control. By capturing the left button click
> message I am able to determine which button was under the mouse when
> it is clicked. I want visual feedback when a button is clicked, and
> here is what I am doing to get it.
>
> 1) I find all the 'fairly white' pixels within the button region and
> paint them a bright yellow to make it look like the button lights when
> clicked.
>
> 1a) Many of my buttons are not rectangular and there is black writing
> on each button. That is why I can't simply paint all pixels in my
> rectangles.
>
> 2) After about 1/2 second I change the color of the yellow pixels back
> to a 'standard white' color.
>
> 3) I am using the SetPixelV method to set the colors of the buttons.
>
>
> When I say 'fairly white', I mean all pixels who's RGB values fall
> into a range that look white. SInce I took a picture of my remote
> control instead of drawing it within my application, the colors vary a
> lot, so I can't simply do a flood fill. The color of the buttons and
> the surrounding areas are not consistent.
>
> This is obviously a very inefficient way to accomplish my task. There
> is one button called 'light' on my remote. When I click on it the
> whole keypad is supposed to light up for a few seconds. It takes so
> long to write all the pixels, one by one, that it looks like a yellow
> wave slowly washes across my remote control.
>
> The way I see it I have two choices. 1) I can go into some sort of
> graphics program (i.e. Photoshop) and 'fix up' the remote control
> image file. 2) I can set all 'fairly white' pixels to a consistent
> white when my application initializes. I can then use a flood fill
> when a button is clicked which should be much faster.
>
> Here is my problem. The method I am using to write directly into the
> device context doesn't work if my application gets re-painted. All the
> colors revert back to their defaults. If some kind sole out there
> could clue me in on a way to change the colors that would remain
> changed after a re-paint, I would be forever grateful!
>
> Please forgive me if my terminology isn't very good, but I am an OS
> programmer, not a UI or graphics programmer. These Win32 and MFC
> concepts and terms are fairly new to me.
>
> TIA,
> Adam Messer
> amesser39@hotmail.com
>

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