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

This is the porting of 1.2.0 version of SDL (the latest stable one)
to AmigaOS/68k.

All the bugs known of the past version have been corrected. And I've
added all the new SDL features.

This version of SDL needs Cybergraphx V3 (r69+) or CyberGraphX V4
and AHI v3+. Probably it works also with P96 or CGXAga, but it's 
untested.

This version is available as linked library for SAS/C and GCC, only 68k this 
time, a powerup (ppcemu compatible) and a morphos version will be ready quite 
soon (i hope).

Implemented:

- 8/16/24/32bit video modes, both fullscreen and windowed.
- Hardware surfaces.
- CGX blitting acceleration.
- CGX colorkey blitting acceleration.
- AHI audio (8/16 bit, with any audio format), always uses unit 0 for now.
- Thread support (maybe not 100% compatible with other implementations)
- Semaphores 
- Window resizing and backdrop windows (NEW)
- Joystick/Joypad support.

To do:

- CDRom audio playing support
- OpenGL (A guy was working on it but I've lost his tracks :( )

The SAS/C library is distributed with debug info attached, to strip debug info 
simply add STRIPDEBUG argument to the linker.

NOTE: SDL includes debug output using kprintf, to disable it add to your 
project a function like this:

void kprintf(char *a,...)
{
}

Otherwise you can redirect the debug to a console window with sushi, sashimi or
similar tools (the default output is the internal serial port). 

For info, support, bugfix and other feel free to mail me:

Gabriele Greco (gabriele.greco@aruba.it)

You can find also a small SDL Amiga page at:
http://ggreco.interfree.it/sdl.html