package boswars tags 559615 + patch quit Kalle Olavi Niemitalo <k...@iki.fi> writes:
> I see these ways to fix or work around this bug:
>
> (a) putenv("SDL_MOUSE_RELATIVE=0") in boswars before SDL
> initialization. AFAICT boswars does not care about relative
> mouse motion.
This works fine; patch attached.
From 5c740e3a68150346323c70f9141014d44a91dbcc Mon Sep 17 00:00:00 2001
From: Kalle Olavi Niemitalo <k...@iki.fi>
Date: Fri, 15 Jan 2010 02:08:34 +0200
Subject: [PATCH] Fix tablet input in full-screen mode
Work around an SDL 1.2 misfeature that makes Bos Wars in full-screen
mode unplayable with tablet devices that report absolute coordinates.
Fixes Debian bug 559615.
---
engine/video/sdl.cpp | 42 ++++++++++++++++++++++++++++++++++++++++++
1 files changed, 42 insertions(+), 0 deletions(-)
diff --git a/engine/video/sdl.cpp b/engine/video/sdl.cpp
index c8cfc01..ccaeb57 100644
--- a/engine/video/sdl.cpp
+++ b/engine/video/sdl.cpp
@@ -381,6 +381,48 @@ void InitVideoSdl(void)
Uint32 flags;
if (SDL_WasInit(SDL_INIT_VIDEO) == 0) {
+#ifdef HAVE_X
+ // Fix tablet input in full-screen mode.
+ //
+ // By default, SDL 1.2 on X11 uses mouse relative mode
+ // if the mouse cursor is hidden and input is grabbed.
+ // In this mode, SDL attempts to report the direction
+ // in which the mouse is moving. SDL computes this
+ // from the mouse-cursor coordinates it gets from X.
+ // If the mouse cursor of X were to hit an edge of the
+ // screen, SDL would not know whether the user keeps
+ // moving the mouse in that direction. To prevent
+ // that, SDL warps the mouse cursor of X back to the
+ // center of the screen whenever it gets too far.
+ // SDL then compensates for this warping in its
+ // relative-motion computations, and uses the relative
+ // coordinates to maintain its own idea of the mouse
+ // cursor location, separately from what X thinks.
+ //
+ // All of the above works great with mice but fails
+ // horribly with tablet or touch-screen devices, where
+ // the coordinates reported by X depend only on the
+ // position of the stylus and not at all on where SDL
+ // previously warped the pointer. Because Bos Wars
+ // doesn't actually care about relative mouse motion,
+ // let's just disable that whole feature in SDL. The
+ // easiest way to do that is by setting an environment
+ // variable. Do this before SDL_Init in case that
+ // caches the value.
+ //
+ // SDL 1.2 documentation warns that environment
+ // variables are mostly for debugging and might not be
+ // supported in future SDL releases. In that event,
+ // Bos Wars can instead use the same trick as Barrage
+ // does: tell SDL to show the mouse cursor, but make
+ // all of its pixels transparent, so it's actually
+ // invisible. However, SDL 1.3 is apparently going to
+ // support tablet devices natively, so this might not
+ // be needed then.
+ static char MouseRelative0[] = "SDL_MOUSE_RELATIVE=0";
+ SDL_putenv(MouseRelative0); // doesn't want const
+#endif
+
if (SDL_Init(
#ifdef DEBUG
SDL_INIT_NOPARACHUTE |
--
1.6.6
> (e) Make SDL explicitly support tablet devices (perhaps via > XInput) and pass their coordinates through unmolested. The unreleased SDL 1.3 has some native support for tablets but I don't know whether it fixes this bug.
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