Date: Tue, 15 Feb 2005 21:28:48 +0900 (JST) From: "Michael Leonhard" Subject: [SDL] resize bug on Win32 and patch This is my first post to this mailing list. In this email I will detail a bug in the behavior of resizable SDL windows on Win32. Then I will explain the solution and provide a patch. Symptoms: Under Windows, an SDL display created with the SDL_RESIZABLE flag exhibits quirky behavior when being maximized. The window is resized to the proper size, but it is shifted upwards about half the height of the title bar. Similarly, a window whose origin is above the top of the screen will spontaneously move its upper-left origin upon being resized. After two such resize-induced moves, the title bar will be entirely off the top edge of the screen. Subsequently, when the mouse is clicked and released on the window border, the window will shrink its height spontaneously. This height shrinkage occurs even if the user did not resize the border. To observe this curious situation, please invoke: SDL-1.2.8/test/testwm.exe -resize Cause: A pair of integers, SDL_windowX and SDL_windowY, are defined in video/wincommon/SDL_sysevents.c. They are used by the DirectX video driver and the DIB video driver: video/windx5/SDL_dx5video.c video/windib/SDL_dibvideo.c As I understand the source code, the primary use of these variables is to create a rectangle that represents the surface area in CLIENT SPACE. Client space refers to a coordinate system that originates at the upper left corner of a Win32 Window's drawable area. This is just inside the window border and title bar. This client space rectangle, called bounds, is subsequently converted to screen space with a call to AdjustWindowRectEx. The problem is found in SDL's handling of the WM_WINDOWPOSCHANGED message. According to MSDN, "The WM_WINDOWPOSCHANGED message is sent to a window whose size, position, or place in the Z order has changed as a result of a call to the SetWindowPos function or another window-management function." I have confirmed that this message is indeed being sent to the SDL window when the mouse is clicked on the window border, even if the window border is not dragged. In video/wincommon/SDL_sysevents.c, on line 464, in response to the WM_WINDOWPOSCHANGED message, the (potentially) new client rectangle is obtained. This rectangle is translated into screen coordinates and THEN assigned to the SDL_windowX and Y variables. Thus screen coordinates are being assigned to client coordinate variables. Once this is understood, the solution is apparent: assign SDL_windowX and Y before translating the rectangle to screen coordinates. This is accomplished by the following patch. -Mike_L

Project files for embedded Visual C++ 3.0, 4.0 and 
Visual Studio 2005 can be found in VisualCE.zip

SDL supports GAPI and WinDib output for Windows CE.

GAPI driver supports:

- all possible WinCE devices (Pocket PC, Smartphones, HPC)
  with different orientations of video memory and resolutions.
- 4, 8 and 16 bpp devices
- special handling of 8bpp on 8bpp devices
- VGA mode, you can even switch between VGA and GAPI in runtime
  (between 240x320 and 480x640 for example). On VGA devices you can
  use either GAPI or VGA.
- Landscape mode and automatic rotation of buttons and stylus coordinates.
  To enable landscape mode make width of video screen bigger than height.
  For example: 
    SDL_SetVideoMode(320,240,16,SDL_FULLSCREEN)
- WM2005
- SDL_ListModes

NOTE:
There are several SDL features not available in the WinCE port of SDL.

- DirectX is not yet available
- Semaphores are not available
- Joystick support is not available
- CD-ROM control is not available

In addition, there are several features that run in "degraded" mode:

Preprocessor Symbol		Effect
===================		=================================

SDL_systimer.c:
USE_GETTICKCOUNT		Less accurate values for SDL time functions
USE_SETTIMER			Use only a single marginally accurate timer

SDL_syswm.c:
DISABLE_ICON_SUPPORT		Can't set the runtime window icon

SDL_sysmouse.c:
USE_STATIC_CURSOR		Only the arrow cursor is available

SDL_sysevents.c:
NO_GETKEYBOARDSTATE		Can't get modifier state on keyboard focus

SDL_dibevents.c:
NO_GETKEYBOARDSTATE		Very limited keycode translation

SDL_dibvideo.c:
NO_GETDIBITS			Can't distinguish between 15 bpp and 16 bpp
NO_CHANGEDISPLAYSETTINGS	No fullscreen support
NO_GAMMA_SUPPORT		Gamma correction not available