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Added a hint SDL_HINT_MOUSE_RELATIVE_SYSTEM_SCALE to control whether …
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…to use system mouse acceleration on raw relative motion.

This is currently only implemented on Windows, and "Enhanced pointer
precision" mode is not quite correct.
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@slouken
slouken committed Aug 22, 2022
1 parent 3ce3594 commit 92b3c53
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Showing 6 changed files with 249 additions and 8 deletions.
11 changes: 11 additions & 0 deletions include/SDL_hints.h
View file
Expand Up @@ -1106,6 +1106,17 @@ extern "C" {
*/
#define SDL_HINT_MOUSE_RELATIVE_SPEED_SCALE "SDL_MOUSE_RELATIVE_SPEED_SCALE"

/**
* \brief A variable controlling whether the system mouse acceleration curve is used for relative mouse motion.
*
* This variable can be set to the following values:
* "0" - Relative mouse motion will be unscaled (the default)
* "1" - Relative mouse motion will be scaled using the system mouse acceleration curve.
*
* If SDL_HINT_MOUSE_RELATIVE_SPEED_SCALE is set, that will override the system speed scale.
*/
#define SDL_HINT_MOUSE_RELATIVE_SYSTEM_SCALE "SDL_MOUSE_RELATIVE_SYSTEM_SCALE"

/**
* \brief A variable controlling whether a motion event should be generated for mouse warping in relative mode.
*
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125 changes: 117 additions & 8 deletions src/events/SDL_mouse.c
View file
Expand Up @@ -83,8 +83,10 @@ SDL_MouseNormalSpeedScaleChanged(void *userdata, const char *name, const char *o
SDL_Mouse *mouse = (SDL_Mouse *)userdata;

if (hint && *hint) {
mouse->enable_normal_speed_scale = SDL_TRUE;
mouse->normal_speed_scale = (float)SDL_atof(hint);
} else {
mouse->enable_normal_speed_scale = SDL_FALSE;
mouse->normal_speed_scale = 1.0f;
}
}
Expand All @@ -95,12 +97,22 @@ SDL_MouseRelativeSpeedScaleChanged(void *userdata, const char *name, const char
SDL_Mouse *mouse = (SDL_Mouse *)userdata;

if (hint && *hint) {
mouse->enable_relative_speed_scale = SDL_TRUE;
mouse->relative_speed_scale = (float)SDL_atof(hint);
} else {
mouse->enable_relative_speed_scale = SDL_FALSE;
mouse->relative_speed_scale = 1.0f;
}
}

static void SDLCALL
SDL_MouseRelativeSystemScaleChanged(void *userdata, const char *name, const char *oldValue, const char *hint)
{
SDL_Mouse *mouse = (SDL_Mouse *)userdata;

mouse->enable_relative_system_scale = SDL_GetStringBoolean(hint, SDL_FALSE);
}

static void SDLCALL
SDL_TouchMouseEventsChanged(void *userdata, const char *name, const char *oldValue, const char *hint)
{
Expand Down Expand Up @@ -189,6 +201,9 @@ SDL_MouseInit(void)
SDL_AddHintCallback(SDL_HINT_MOUSE_RELATIVE_SPEED_SCALE,
SDL_MouseRelativeSpeedScaleChanged, mouse);

SDL_AddHintCallback(SDL_HINT_MOUSE_RELATIVE_SYSTEM_SCALE,
SDL_MouseRelativeSystemScaleChanged, mouse);

SDL_AddHintCallback(SDL_HINT_TOUCH_MOUSE_EVENTS,
SDL_TouchMouseEventsChanged, mouse);

Expand Down Expand Up @@ -344,7 +359,10 @@ SDL_SendMouseMotion(SDL_Window * window, SDL_MouseID mouseID, int relative, int
static int
GetScaledMouseDelta(float scale, int value, float *accum)
{
if (scale != 1.0f) {
if (value && scale != 1.0f) {
if ((value > 0) != (*accum > 0)) {
*accum = 0.0f;
}
*accum += scale * value;
if (*accum >= 0.0f) {
value = (int)SDL_floor(*accum);
Expand All @@ -356,6 +374,100 @@ GetScaledMouseDelta(float scale, int value, float *accum)
return value;
}

static float
CalculateSystemScale(SDL_Mouse *mouse, int *x, int *y)
{
int i;
int n = mouse->num_system_scale_values;
float *v = mouse->system_scale_values;
float speed, coef, scale;

/* If we're using a single scale value, return that */
if (n == 1) {
return v[0];
}

speed = SDL_sqrtf((float)(*x * *x) + (*y * *y));
for (i = 0; i < (n - 2); i += 2) {
if (speed < v[i + 2]) {
break;
}
}
if (i == (n - 2)) {
scale = v[n - 1];
} else if (speed <= v[i]) {
scale = v[i + 1];
} else {
coef = (speed - v[i]) / (v[i + 2] - v[i]);
scale = v[i + 1] + (coef * (v[i + 3] - v[i + 1]));
}
SDL_Log("speed = %.2f, scale = %.2f\n", speed, scale);
return scale;
}

/* You can set either a single scale, or a set of {speed, scale} values in ascending order */
int
SDL_SetMouseSystemScale(int num_values, const float *values)
{
SDL_Mouse *mouse = SDL_GetMouse();
float *v;

if (num_values == mouse->num_system_scale_values &&
SDL_memcmp(values, mouse->system_scale_values, num_values * sizeof(*values)) == 0) {
/* Nothing has changed */
return 0;
}

if (num_values < 1) {
return SDL_SetError("You must have at least one scale value");
}

if (num_values > 1) {
/* Validate the values */
int i;

if (num_values < 4 || (num_values % 2) != 0) {
return SDL_SetError("You must pass a set of {speed, scale} values");
}

for (i = 0; i < (num_values - 2); i += 2) {
if (values[i] >= values[i + 2]) {
return SDL_SetError("Speed values must be in ascending order");
}
}
}

v = (float *)SDL_realloc(mouse->system_scale_values, num_values * sizeof(*values));
if (!v) {
return SDL_OutOfMemory();
}
SDL_memcpy(v, values, num_values * sizeof(*values));

mouse->num_system_scale_values = num_values;
mouse->system_scale_values = v;
return 0;
}

static void
GetScaledMouseDeltas(SDL_Mouse *mouse, int *x, int *y)
{
if (mouse->relative_mode) {
if (mouse->enable_relative_speed_scale) {
*x = GetScaledMouseDelta(mouse->relative_speed_scale, *x, &mouse->scale_accum_x);
*y = GetScaledMouseDelta(mouse->relative_speed_scale, *y, &mouse->scale_accum_y);
} else if (mouse->enable_relative_system_scale && mouse->num_system_scale_values > 0) {
float relative_system_scale = CalculateSystemScale(mouse, x, y);
*x = GetScaledMouseDelta(relative_system_scale, *x, &mouse->scale_accum_x);
*y = GetScaledMouseDelta(relative_system_scale, *y, &mouse->scale_accum_y);
}
} else {
if (mouse->enable_normal_speed_scale) {
*x = GetScaledMouseDelta(mouse->normal_speed_scale, *x, &mouse->scale_accum_x);
*y = GetScaledMouseDelta(mouse->normal_speed_scale, *y, &mouse->scale_accum_y);
}
}
}

static int
SDL_PrivateSendMouseMotion(SDL_Window * window, SDL_MouseID mouseID, int relative, int x, int y)
{
Expand Down Expand Up @@ -405,13 +517,7 @@ SDL_PrivateSendMouseMotion(SDL_Window * window, SDL_MouseID mouseID, int relativ
}

if (relative) {
if (mouse->relative_mode) {
x = GetScaledMouseDelta(mouse->relative_speed_scale, x, &mouse->scale_accum_x);
y = GetScaledMouseDelta(mouse->relative_speed_scale, y, &mouse->scale_accum_y);
} else {
x = GetScaledMouseDelta(mouse->normal_speed_scale, x, &mouse->scale_accum_x);
y = GetScaledMouseDelta(mouse->normal_speed_scale, y, &mouse->scale_accum_y);
}
GetScaledMouseDeltas(mouse, &x, &y);
xrel = x;
yrel = y;
x = (mouse->last_x + xrel);
Expand Down Expand Up @@ -818,6 +924,9 @@ SDL_MouseQuit(void)
SDL_DelHintCallback(SDL_HINT_MOUSE_RELATIVE_SPEED_SCALE,
SDL_MouseRelativeSpeedScaleChanged, mouse);

SDL_DelHintCallback(SDL_HINT_MOUSE_RELATIVE_SYSTEM_SCALE,
SDL_MouseRelativeSystemScaleChanged, mouse);

SDL_DelHintCallback(SDL_HINT_TOUCH_MOUSE_EVENTS,
SDL_TouchMouseEventsChanged, mouse);

Expand Down
8 changes: 8 additions & 0 deletions src/events/SDL_mouse_c.h
View file
Expand Up @@ -92,8 +92,13 @@ typedef struct
SDL_bool relative_mode;
SDL_bool relative_mode_warp;
SDL_bool relative_mode_warp_motion;
SDL_bool enable_normal_speed_scale;
float normal_speed_scale;
SDL_bool enable_relative_speed_scale;
float relative_speed_scale;
SDL_bool enable_relative_system_scale;
int num_system_scale_values;
float *system_scale_values;
float scale_accum_x;
float scale_accum_y;
Uint32 double_click_time;
Expand Down Expand Up @@ -141,6 +146,9 @@ extern void SDL_SetMouseFocus(SDL_Window * window);
/* Update the mouse capture window */
extern int SDL_UpdateMouseCapture(SDL_bool force_release);

/* You can set either a single scale, or a set of {speed, scale} values in sorted order */
extern int SDL_SetMouseSystemScale(int num_values, const float *values);

/* Send a mouse motion event */
extern int SDL_SendMouseMotion(SDL_Window * window, SDL_MouseID mouseID, int relative, int x, int y);

Expand Down
7 changes: 7 additions & 0 deletions src/video/windows/SDL_windowsevents.c
View file
Expand Up @@ -1628,6 +1628,13 @@ WIN_WindowProc(HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
return 0;
}
break;

case WM_SETTINGCHANGE:
if (wParam == SPI_SETMOUSE || wParam == SPI_SETMOUSESPEED) {
WIN_UpdateMouseSystemScale();
}
break;

#endif /*!defined(__XBOXONE__) && !defined(__XBOXSERIES__)*/
}

Expand Down
105 changes: 105 additions & 0 deletions src/video/windows/SDL_windowsmouse.c
View file
Expand Up @@ -363,6 +363,8 @@ WIN_InitMouse(_THIS)
SDL_SetDefaultCursor(WIN_CreateDefaultCursor());

SDL_blank_cursor = WIN_CreateBlankCursor();

WIN_UpdateMouseSystemScale();
}

void
Expand All @@ -379,6 +381,109 @@ WIN_QuitMouse(_THIS)
}
}

/* For a great description of how the enhanced mouse curve works, see:
* https://superuser.com/questions/278362/windows-mouse-acceleration-curve-smoothmousexcurve-and-smoothmouseycurve
* http://www.esreality.com/?a=post&id=1846538/
*/
static SDL_bool
LoadFiveFixedPointFloats(BYTE *bytes, float *values)
{
int i;

for (i = 0; i < 5; ++i) {
float fraction = (float)((Uint16) bytes[1] << 8 | bytes[0]) / 65535.0f;
float value = (float)(((Uint16)bytes[3] << 8) | bytes[2]) + fraction;
*values++ = value;
bytes += 8;
}
return SDL_TRUE;
}

static void
WIN_SetEnhancedMouseScale(int mouse_speed)
{
float scale = (float) mouse_speed / 10.0f;
HKEY hKey;
DWORD dwType = REG_BINARY;
BYTE value[40];
DWORD length = sizeof(value);
int i;
float xpoints[5];
float ypoints[5];
float scale_points[10];
const int dpi = 96; // FIXME, how do we handle different monitors with different DPI?
const float display_factor = 3.5f * (150.0f / dpi);

if (RegOpenKeyExW(HKEY_CURRENT_USER, L"Control Panel\\Mouse", 0, KEY_READ, &hKey) == ERROR_SUCCESS) {
if (RegQueryValueExW(hKey, L"SmoothMouseXCurve", 0, &dwType, value, &length) == ERROR_SUCCESS &&
LoadFiveFixedPointFloats(value, xpoints) &&
RegQueryValueExW(hKey, L"SmoothMouseYCurve", 0, &dwType, value, &length) == ERROR_SUCCESS &&
LoadFiveFixedPointFloats(value, ypoints)) {
for (i = 0; i < 5; ++i) {
float gain;
if (xpoints[i] > 0.0f) {
gain = (ypoints[i] / xpoints[i]) * scale;
} else {
gain = 0.0f;
}
scale_points[i * 2] = xpoints[i];
scale_points[i * 2 + 1] = gain / display_factor;
//SDL_Log("Point %d = %f,%f\n", i, scale_points[i * 2], scale_points[i * 2 + 1]);
}
SDL_SetMouseSystemScale(SDL_arraysize(scale_points), scale_points);
}
RegCloseKey(hKey);
}
}

static void
WIN_SetLinearMouseScale(int mouse_speed)
{
static float mouse_speed_scale[] = {
0.0f,
1 / 32.0f,
1 / 16.0f,
1 / 8.0f,
2 / 8.0f,
3 / 8.0f,
4 / 8.0f,
5 / 8.0f,
6 / 8.0f,
7 / 8.0f,
1.0f,
1.25f,
1.5f,
1.75f,
2.0f,
2.25f,
2.5f,
2.75f,
3.0f,
3.25f,
3.5f
};

if (mouse_speed > 0 && mouse_speed < SDL_arraysize(mouse_speed_scale)) {
SDL_SetMouseSystemScale(1, &mouse_speed_scale[mouse_speed]);
}
}

void
WIN_UpdateMouseSystemScale()
{
int mouse_speed;
int params[3] = { 0, 0, 0 };

if (SystemParametersInfo(SPI_GETMOUSESPEED, 0, &mouse_speed, 0) &&
SystemParametersInfo(SPI_GETMOUSE, 0, params, 0)) {
if (params[2]) {
WIN_SetEnhancedMouseScale(mouse_speed);
} else {
WIN_SetLinearMouseScale(mouse_speed);
}
}
}

#endif /* SDL_VIDEO_DRIVER_WINDOWS */

/* vi: set ts=4 sw=4 expandtab: */
1 change: 1 addition & 0 deletions src/video/windows/SDL_windowsmouse.h
View file
Expand Up @@ -29,6 +29,7 @@ extern HCURSOR SDL_cursor;
extern void WIN_InitMouse(_THIS);
extern void WIN_QuitMouse(_THIS);
extern void WIN_SetCursorPos(int x, int y);
extern void WIN_UpdateMouseSystemScale();

#endif /* SDL_windowsmouse_h_ */

Expand Down

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