【代理DLL汉化研究】 [C++] Overlay sample 覆盖代码实例

shane007

用于在全屏游戏上画东西，写字。
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原文
http://www.gamedev.net/community/forums/topic.asp?topic_id=359319
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A lot of people seem interested in knowing how to render content over full-screen applications, like XFire and Co, judging by the number of posts about it. Here’s an unmanaged overlaying sample. Visual Studio 2003 and 2005 solutions are included.
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The sample uses DirectDraw overlays to render a black 256x64 box to the top-left of the screen, with some text in it. I would’ve shown you a screenshot, but I can’t, due to the way overlays work. Overlays are displayed as the device is painting the monitor from the primary surface. If it’s painting a location where an overlay exists, it paints the monitor with its color instead of the primary surface. Consequently, you can’t capture that in an image.
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2 Q4 C. j+ J3 g% mBack to the sample. The files of interest are:
- q: z% }- P3 m) \$ Q9 w& @Overlay.cpp: Window creation (auto-generated, nothing interesting) and the main loop (important).
" Q& c: f1 ]/ K( _/ u0 Soverlay_renderer.h, overlay_renderer.cpp: The core of the sample. The code is fairly self-explanatory, though.
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One important thing to keep in mind is that overlay support comes with a set of limitations. The following limitations are not checked or accounted for in the sample:
dwAlignBoundarySrc
dwAlignSizeSrc
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dwAlignSizeDest
dwAlignStrideAlign
dwMinOverlayStretch
dwMaxOverlayStretch

/ _1 D9 n  G8 ~+ r! E, YThe limitations are hardware-dependent. For example, my X300 doesn’t impose any alignment restrictions for the source or destination overlay rectangles. In a product, however, you’d want to make sure you check for these and abide by them. Use CapsViewer to find out the limitations of your hardware quickly. I don’t know if the October SDK caps database includes DirectDraw caps or not, but consider checking it out.

3 ?* l; Y" w5 O/ pThe limitations (and overlays in general) are documented under “DirectDraw->DirectDraw Essentials->Surfaces->Overlay Surfaces” in the DX7 documentation. It’s available at icarusIndie.

+ @+ {$ |5 _5 g! M4 O( y. m3 ~I might write a managed port, if someone’s interested. All feedback’s welcome.