From 6605a16ca8392b6a1b8cb15934f2a79532135b2a Mon Sep 17 00:00:00 2001
From: Cameron Gutman <[EMAIL REDACTED]>
Date: Mon, 31 Mar 2025 15:58:13 -0500
Subject: [PATCH] Use SDL3's integer mouse mode hint (#403)
---
src/sdl2_compat.c | 65 +++++++++++++++++------------------------------
1 file changed, 23 insertions(+), 42 deletions(-)
diff --git a/src/sdl2_compat.c b/src/sdl2_compat.c
index 6f97b8f..9b2256b 100644
--- a/src/sdl2_compat.c
+++ b/src/sdl2_compat.c
@@ -481,9 +481,12 @@ static QuirkEntryType quirks[] = {
{ "hl.exe", SDL_HINT_MOUSE_EMULATE_WARP_WITH_RELATIVE, "0" },
#endif
- /* Moonlight supports high DPI properly under Wayland */
+ /* Moonlight supports high DPI properly under Wayland.
+ It also reads fractional values in wheel events. */
{ "moonlight", SDL_HINT_VIDEO_WAYLAND_SCALE_TO_DISPLAY, "0" },
{ "moonlight-qt", SDL_HINT_VIDEO_WAYLAND_SCALE_TO_DISPLAY, "0" },
+ { "moonlight", "SDL_MOUSE_INTEGER_MODE", "1" },
+ { "moonlight-qt", "SDL_MOUSE_INTEGER_MODE", "1" },
/* Pragtical code editor supports high DPI properly under Wayland */
{ "pragtical", SDL_HINT_VIDEO_WAYLAND_SCALE_TO_DISPLAY, "0" },
@@ -498,6 +501,13 @@ static QuirkEntryType quirks[] = {
/* Stylus Labs Write does its own X11 input handling */
{ "Write", "SDL_VIDEO_X11_XINPUT2", "0" },
+ /* PPSSPP reads fractional values in wheel events */
+ { "PPSSPP", "SDL_MOUSE_INTEGER_MODE", "1" },
+ { "PPSSPPSDL", "SDL_MOUSE_INTEGER_MODE", "1" },
+
+ /* Lite-XL reads fractional values in wheel events */
+ { "lite-xl", "SDL_MOUSE_INTEGER_MODE", "1" },
+
/* The UE5 editor has input issues and broken toast notification positioning on Wayland */
{ "UnrealEditor", SDL_HINT_VIDEO_DRIVER, "x11" },
};
@@ -1173,12 +1183,6 @@ static SDL_mutex *EventWatchListMutex = NULL;
static SDL2_LogOutputFunction LogOutputFunction2 = NULL;
static EventFilterWrapperData *EventWatchers2 = NULL;
static SDL2_bool relative_mouse_mode = SDL2_FALSE;
-static float relative_mouse_state_x_frac = 0.0f;
-static float relative_mouse_state_y_frac = 0.0f;
-static float relative_mouse_event_x_frac = 0.0f;
-static float relative_mouse_event_y_frac = 0.0f;
-static float mouse_wheel_event_x_frac = 0.0f;
-static float mouse_wheel_event_y_frac = 0.0f;
static SDL_JoystickID *joystick_instance_list = NULL;
static int num_joystick_instances = 0;
static SDL_JoystickID *joystick_list = NULL;
@@ -1315,6 +1319,10 @@ SDL2Compat_InitOnStartupInternal(void)
SDL3_SetHint("SDL_VIDEO_SYNC_WINDOW_OPERATIONS", "1");
SDL3_SetHint("SDL_VIDEO_X11_EXTERNAL_WINDOW_INPUT", "0");
+ /* Emulate both integer mouse coordinates and integer mouse wheel deltas for maximum compatibility.
+ Apps that use preciseX/Y for smooth scrolling can be quirked to get fractional wheel deltas. */
+ SDL3_SetHint("SDL_MOUSE_INTEGER_MODE", "3");
+
// Pretend Wayland doesn't have fractional scaling by default.
// This is more compatible with applications that have only been tested under X11 without high DPI support.
// For apps that support high DPI on Wayland, add a SDL_HINT_VIDEO_WAYLAND_SCALE_TO_DISPLAY=0 quirk for them.
@@ -2165,22 +2173,6 @@ static SDL_AudioDeviceID AudioDeviceID3to2(SDL_AudioDeviceID id)
return 0;
}
-static int AccumulateFloatValueToInteger(float *frac, float value)
-{
- float intval;
-
- /* Reset the accumulated fractional value if the sign changes */
- if ((*frac < 0.0f && value > 0.0f) || (*frac > 0.0f && value < 0.0f)) {
- *frac = 0.0f;
- }
-
- /* Accumulate the fractional portion that is truncated by integer conversion */
- *frac += value;
- *frac = SDL3_modff(*frac, &intval);
-
- return (int)intval;
-}
-
/* (current) strategy for SDL_Events:
in sdl12-compat, we built our own event queue, so when the SDL2 queue is pumped, we
took the events we cared about and added them to the sdl12-compat queue, and otherwise
@@ -2246,13 +2238,6 @@ static SDL2_Event *Event3to2(const SDL_Event *event3, SDL2_Event *event2)
case SDL_EVENT_DROP_COMPLETE:
event2->drop.windowID = event3->drop.windowID;
break;
- case SDL_EVENT_WINDOW_MOUSE_ENTER:
- /* Reset accumulated fractional mouse data when mouse focus changes */
- relative_mouse_event_x_frac = 0.0f;
- relative_mouse_event_y_frac = 0.0f;
- mouse_wheel_event_x_frac = 0.0f;
- mouse_wheel_event_y_frac = 0.0f;
- break;
case SDL_EVENT_MOUSE_MOTION:
renderer = SDL3_GetRenderer(SDL3_GetWindowFromID(event3->motion.windowID));
if (renderer) {
@@ -2274,14 +2259,14 @@ static SDL2_Event *Event3to2(const SDL_Event *event3, SDL2_Event *event2)
motion->state = (Uint8)event3->motion.state;
motion->x = (Sint32)event3->motion.x;
motion->y = (Sint32)event3->motion.y;
- motion->xrel = AccumulateFloatValueToInteger(&relative_mouse_event_x_frac, event3->motion.xrel);
- motion->yrel = AccumulateFloatValueToInteger(&relative_mouse_event_y_frac, event3->motion.yrel);
+ motion->xrel = (Sint32)event3->motion.xrel;
+ motion->yrel = (Sint32)event3->motion.yrel;
} else {
SDL2_MouseMotionEvent *motion = &event2->motion;
motion->x = (Sint32)event3->motion.x;
motion->y = (Sint32)event3->motion.y;
- motion->xrel = AccumulateFloatValueToInteger(&relative_mouse_event_x_frac, event3->motion.xrel);
- motion->yrel = AccumulateFloatValueToInteger(&relative_mouse_event_y_frac, event3->motion.yrel);
+ motion->xrel = (Sint32)event3->motion.xrel;
+ motion->yrel = (Sint32)event3->motion.yrel;
}
break;
case SDL_EVENT_MOUSE_BUTTON_DOWN:
@@ -2327,8 +2312,8 @@ static SDL2_Event *Event3to2(const SDL_Event *event3, SDL2_Event *event2)
wheel->y = (Sint32)(event3->wheel.x * 120);
} else {
SDL2_MouseWheelEvent *wheel = &event2->wheel;
- wheel->x = AccumulateFloatValueToInteger(&mouse_wheel_event_x_frac, event3->wheel.x);
- wheel->y = AccumulateFloatValueToInteger(&mouse_wheel_event_y_frac, event3->wheel.y);
+ wheel->x = (Sint32)event3->wheel.x;
+ wheel->y = (Sint32)event3->wheel.y;
wheel->preciseX = event3->wheel.x;
wheel->preciseY = event3->wheel.y;
wheel->mouseX = (Sint32)event3->wheel.mouse_x;
@@ -3310,8 +3295,8 @@ SDL_GetRelativeMouseState(int *x, int *y)
{
float fx, fy;
Uint32 ret = SDL3_GetRelativeMouseState(&fx, &fy);
- if (x) *x = AccumulateFloatValueToInteger(&relative_mouse_state_x_frac, fx);
- if (y) *y = AccumulateFloatValueToInteger(&relative_mouse_state_y_frac, fy);
+ if (x) *x = (int)fx;
+ if (y) *y = (int)fy;
return ret;
}
@@ -6807,10 +6792,6 @@ static void PostInitSubsystem(SDL_InitFlags new_flags)
/* These are potentially noisy and have no SDL2 equivalent */
SDL3_SetEventEnabled(SDL_EVENT_JOYSTICK_UPDATE_COMPLETE, false);
SDL3_SetEventEnabled(SDL_EVENT_GAMEPAD_UPDATE_COMPLETE, false);
-
- /* SDL_GetRelativeMouseState() resets when the event subsystem initializes */
- relative_mouse_state_x_frac = 0.0f;
- relative_mouse_state_y_frac = 0.0f;
}
if (new_flags & SDL_INIT_VIDEO) {