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Memory DC's

shalom · 2001-08-02T18:13:08

Hi: I''m writing a game in Visual Basic. VB isn''t very good with graphics, so everyone bypasses the VB graphics and uses the GDI. For some reason, though, no-one makes their own device contexts. Everyone uses invisible PictureBox controls (a simple VB control that displays pictures) because they have a DC property. For example, if someone wanted to blit a transparent picture on to the window, they would have three PictureBox controls, let''s say Pic1, Pic2, and Pic3. They would load the picture they want to blit onto in Pic1, the picture they want to blit in Pic2, and a mask in Pic3. They would import the GDI BitBlt function and use the following VB code: BitBlt Pic1.hDC, 0, 0, 100, 100, Pic3.hDC, 0, 0, SRCAND BitBlt Pic1.hDC, 0, 0, 100, 100, Pic2.hDC, 0, 0, SRCPAINT BitBlt Me.hDC, 0, 0, 100, 100, Pic1.hDC, 0, 0, SRCCOPY. This is all fine if your doing a little animation or something, but if I want to make a full game, perhaps using independant classes that may not have access to windows and their PictureBoxes, how do I use the GDI to make memory DC''s? I can''t find it anywhere. How do C programmers, who don''t have access to PictureBox controls, make memory DCs that can be used to temporarily Blt on to and off again? Thanx in advance, Shalom

General and Gameplay Programming Programming

Started by shalom July 31, 2001 04:18 PM

19 comments, last by shalom 22 years, 8 months ago

Mr Ekted

122

August 02, 2001 06:13 PM

Saving and restoring the BITMAP alone is not sufficient in all cases. You need to restore PEN, BRUSH, PALETTE, FONT, and REGION. If you know you are only calling SelectObject() on the BITMAP, then what you have is fine. However, I really recommend making your class use "int SaveDC(HDC)" and "BOOL RestoreDC(HDC, int)" to make it generic.

Memory DC's

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Memory DC's

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