annotate README @ 3485:e77a69aae239

Mason Wheeler to sdl I updated SDL, and suddenly my SDL frames stopped working. They'd "initialize" full of gibberish, and I couldn't render anything to them. After a bit of digging, I found a problem: the renderer initialization routine in my SDL frame code wasn't getting called anymore. procedure TSdlFrame.Paint; begin if SDL_SelectRenderer(FWindowID) = -1 then CreateRenderer; SDL_RenderPresent; end; function TSdlFrame.CreateRenderer: boolean; const pf: tagPIXELFORMATDESCRIPTOR = (nSize: sizeof(pf); nVersion: 1; dwFlags: PFD_DRAW_TO_WINDOW or PFD_SUPPORT_OPENGL or PFD_DOUBLEBUFFER; iPixelType: PFD_TYPE_RGBA; cColorBits: 24; cAlphaBits: 8; iLayerType: PFD_MAIN_PLANE); RENDERERS: array[TRendererType] of AnsiString = ('software', 'gdi', 'opengl', 'd3d'); var pFormat: integer; begin if (SDL_SelectRenderer(FWindowID) = 0) then begin result := true; Exit; end; if FRendererType = rtOpenGL then begin pFormat := ChoosePixelFormat(canvas.Handle, @pf); if not SetPixelFormat(canvas.Handle, pFormat, @pf) then outputDebugString(PChar(SysErrorMessage(GetLastError))); if wglCreateContext(canvas.Handle) = 0 then outputDebugString(PChar(SysErrorMessage(GetLastError))); end; if (SDL_CreateRenderer(FWindowID, SDL_RendererIndex(RENDERERS[FRendererType]), [sdlrPresentFlip3, sdlrAccelerated]) = 0) then begin SDL_ShowWindow(FWindowID); assert(SDL_SetRenderDrawColor(0, 0, 0, 255) = 0); FFlags := SDL_GetWindowFlags(FWindowID); if assigned(FOnAvailable) then FOnAvailable(self); end else outputDebugString(pChar(format('SDL_CreateRenderer failed: %s', [sdl_GetError]))); result := SDL_SelectRenderer(FWindowID) = 0; end; This is a critical issue. The Paint method gets called when the control receives a WM_PAINT message from Windows. I can't create the renderer before then, or it will fail and cause trouble. And when I do create it, it needs to be created with certain parameters. So imagine my surprise when I started debugging into the DLL and found that SDL_SelectRenderer was trying to be "helpful" by creating the renderer for me if it didn't already exist! Now not only does my initialization code not get called, I end up with the wrong renderer and so things don't render as expected when I try to use the window.
author Sam Lantinga <slouken@libsdl.org>
date Tue, 24 Nov 2009 04:48:12 +0000
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2 Simple DirectMedia Layer
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4 (SDL)
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6 Version 1.2
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8 ---
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9 http://www.libsdl.org/
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11 This is the Simple DirectMedia Layer, a general API that provides low
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12 level access to audio, keyboard, mouse, joystick, 3D hardware via OpenGL,
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13 and 2D framebuffer across multiple platforms.
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15 The current version supports Linux, Windows, Windows CE, BeOS, MacOS,
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16 Mac OS X, FreeBSD, NetBSD, OpenBSD, BSD/OS, Solaris, IRIX, and QNX.
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17 The code contains support for AIX, OSF/Tru64, RISC OS, and SymbianOS,
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18 but these are not officially supported.
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20 SDL is written in C, but works with C++ natively, and has bindings to
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21 several other languages, including Ada, C#, Eiffel, Erlang, Euphoria,
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22 Guile, Haskell, Java, Lisp, Lua, ML, Objective C, Pascal, Perl, PHP,
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23 Pike, Pliant, Python, Ruby, and Smalltalk.
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25 This library is distributed under GNU LGPL version 2, which can be
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26 found in the file "COPYING". This license allows you to use SDL
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27 freely in commercial programs as long as you link with the dynamic
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28 library.
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29
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30 The best way to learn how to use SDL is to check out the header files in
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31 the "include" subdirectory and the programs in the "test" subdirectory.
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32 The header files and test programs are well commented and always up to date.
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33 More documentation is available in HTML format in "docs/index.html", and
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34 a documentation wiki is available online at:
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35 http://www.libsdl.org/cgi/docwiki.cgi
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37 The test programs in the "test" subdirectory are in the public domain.
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38
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39 Frequently asked questions are answered online:
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40 http://www.libsdl.org/faq.php
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42 If you need help with the library, or just want to discuss SDL related
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43 issues, you can join the developers mailing list:
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44 http://www.libsdl.org/mailing-list.php
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46 Enjoy!
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47 Sam Lantinga (slouken@libsdl.org)
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