BitBlting multiple images to buffer

Posted by Anonymous on Stack Overflow See other posts from Stack Overflow or by Anonymous
Published on 2010-05-05T11:34:33Z Indexed on 2010/05/05 11:38 UTC
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bitblt

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hdc

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bitmaps

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buffer

So I've made a class which draws a transparant image to a buffer. the buffer is a HDC which has been used blackness on. What I am trying to do is draw three images to this buffer. Which means I am using this function three times. After that's done, I output it to the screen (using SRCCOPYing the buffer). But what I get to see is just the third image and blackness.

void draw_buffer(HDC buffer, int draw_x, int draw_y) { BitBlt(this->main, draw_x, draw_y, this->img_width, this->img_height, this->image, this->mask_x, this->mask_y, SRCAND); BitBlt(this->main, draw_x, draw_y, this->img_width, this->img_height, this->image, this->img_x, this->img_y, SRCPAINT); BitBlt(buffer, 0, 0, 800, 600, this->main, 0, 0, SRCCOPY); }

At initiation, this->main becomes this:

this->main = CreateCompatibleDC(GetDC(0));
this->bitmap = CreateCompatibleBitmap(GetDC(0),800,600);
SelectObject(this->main, this->bitmap);

What is wrong with my code?

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