Help with scrolling repaint

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I need a repainting scheme that cah handle a display that is a mixture of text and graphics.

I can handle repaint after scrolling if the display matter is either text or graphics, but once it is a mixture of both it becomes a challenge to me.

I handle text display by wiping the window clean, scanning through the buffer that holds the text and displaying the text that fit into the current page considering the scroll position.

I handle display of graphics by directing all out put to a memory dc and then using BitBlt to copy from the memory DC to the window DC.

My application hanles varied type of display with pre-determined format of which users cannot edit. Texts have varying sizes and style.

Seeing internet explorer, I just wander how it is able to handle a misture of text and bitmap seamlessly.

I once developed a formular to handle this display, but it produces some kind of wied display on scroll up.

Using the memory dc would hav been a perfect solution save for the fact that windows those not allow the size of the bitmap selected into it to exceed a certain limit.

Please, I need a after scroll repainting scheme that will handle a mixure of text and graphics seamlessly.

By graphics I meean JPEGS and .bmp bitmaps.

I use native programming and not MFC.

Posted 31-Jul-11 12:30pm

Gbenbam

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mbue · Answer 1 · 2011-07-31T13:50:00

You must use

SetWindowOrgEx

to adjust your memory dc to the scroll position. This is the offset of the scrolling position and the update rect.
i.e.:

// scroll = 0,-100; rcclipbox = 20,20,100,100
// orgpos = -20,-120
SetWindowOrgEx(memdc,orgpos.x,orgpos.y,0);
// dib = 80x80 pixel
BitBlt(hdc,20,20,80,80,memdc,0,0,SRCCOPY);
// ...

Regards.