【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。

原文
2 N0 c4 s: k% ]4 m" rhttp://www.gamedev.net/community/forums/topic.asp?topic_id=359319

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.

, y. \! E# F8 eBack to the sample. The files of interest are:
Overlay.cpp: Window creation (auto-generated, nothing interesting) and the main loop (important).
overlay_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:
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dwAlignSizeSrc
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5 y7 E1 w1 U2 R4 ~% P4 X8 CdwAlignStrideAlign
. Z5 J: m6 _5 B" hdwMinOverlayStretch
dwMaxOverlayStretch
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# K, W) D: F' uThe 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.

! S( q, h# w. ~0 e# d, XThe limitations (and overlays in general) are documented under “DirectDraw->DirectDraw Essentials->Surfaces->Overlay Surfaces” in the DX7 documentation. It’s available at icarusIndie.
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2 g- d3 N9 y. h' BI might write a managed port, if someone’s interested. All feedback’s welcome.