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gdi32: Copy gamma ramp validation from winex11 to make it driver independent.

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André Hentschel 2013-04-17 00:38:37 +02:00 committed by Alexandre Julliard
parent 26b59bf8e5
commit 741f7b6f0c
1 changed files with 81 additions and 1 deletions
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82
dlls/gdi32/dc.c
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@ -1311,6 +1311,84 @@ BOOL WINAPI GetDeviceGammaRamp(HDC hDC, LPVOID ptr)
return ret;
}
static BOOL check_gamma_ramps(void *ptr)
{
WORD *ramp = ptr;
while (ramp < (WORD*)ptr + 3 * 256)
{
float r_x, r_y, r_lx, r_ly, r_d, r_v, r_e, g_avg, g_min, g_max;
unsigned i, f, l, g_n, c;
f = ramp[0];
l = ramp[255];
if (f >= l)
{
TRACE("inverted or flat gamma ramp (%d->%d), rejected\n", f, l);
return FALSE;
}
r_d = l - f;
g_min = g_max = g_avg = 0.0;
/* check gamma ramp entries to estimate the gamma */
TRACE("analyzing gamma ramp (%d->%d)\n", f, l);
for (i=1, g_n=0; i<255; i++)
{
if (ramp[i] < f || ramp[i] > l)
{
TRACE("strange gamma ramp ([%d]=%d for %d->%d), rejected\n", i, ramp[i], f, l);
return FALSE;
}
c = ramp[i] - f;
if (!c) continue; /* avoid log(0) */
/* normalize entry values into 0..1 range */
r_x = i/255.0; r_y = c / r_d;
/* compute logarithms of values */
r_lx = log(r_x); r_ly = log(r_y);
/* compute gamma for this entry */
r_v = r_ly / r_lx;
/* compute differential (error estimate) for this entry */
/* some games use table-based logarithms that magnifies the error by 128 */
r_e = -r_lx * 128 / (c * r_lx * r_lx);
/* compute min & max while compensating for estimated error */
if (!g_n || g_min > (r_v + r_e)) g_min = r_v + r_e;
if (!g_n || g_max < (r_v - r_e)) g_max = r_v - r_e;
/* add to average */
g_avg += r_v;
g_n++;
}
if (!g_n)
{
TRACE("no gamma data, shouldn't happen\n");
return FALSE;
}
g_avg /= g_n;
TRACE("low bias is %d, high is %d, gamma is %5.3f\n", f, 65535-l, g_avg);
/* check that the gamma is reasonably uniform across the ramp */
if (g_max - g_min > 12.8)
{
TRACE("ramp not uniform (max=%f, min=%f, avg=%f), rejected\n", g_max, g_min, g_avg);
return FALSE;
}
/* check that the gamma is not too bright */
if (g_avg < 0.2)
{
TRACE("too bright gamma ( %5.3f), rejected\n", g_avg);
return FALSE;
}
ramp += 256;
}
return TRUE;
}
/***********************************************************************
* SetDeviceGammaRamp (GDI32.@)
*/
@ -1325,7 +1403,9 @@ BOOL WINAPI SetDeviceGammaRamp(HDC hDC, LPVOID ptr)
if (GetObjectType( hDC ) != OBJ_MEMDC)
{
PHYSDEV physdev = GET_DC_PHYSDEV( dc, pSetDeviceGammaRamp );
ret = physdev->funcs->pSetDeviceGammaRamp( physdev, ptr );
if (check_gamma_ramps(ptr))
ret = physdev->funcs->pSetDeviceGammaRamp( physdev, ptr );
}
else SetLastError( ERROR_INVALID_PARAMETER );
release_dc_ptr( dc );