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/* gamma-w32gdi.c -- Windows GDI gamma adjustment source
This file is part of Redshift.
Redshift is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
Redshift is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with Redshift. If not, see <http://www.gnu.org/licenses/>.
Copyright (c) 2010-2014 Jon Lund Steffensen <jonlst@gmail.com>
*/
#include <stdio.h>
#include <stdlib.h>
#ifndef WINVER
# define WINVER 0x0500
#endif
#include <windows.h>
#include <wingdi.h>
#ifdef ENABLE_NLS
# include <libintl.h>
# define _(s) gettext(s)
#else
# define _(s) s
#endif
#include "gamma-w32gdi.h"
#include "colorramp.h"
#define GAMMA_RAMP_SIZE 256
int
w32gdi_init(w32gdi_state_t *state)
{
state->saved_ramps = NULL;
state->preserve = 0;
return 0;
}
int
w32gdi_start(w32gdi_state_t *state)
{
BOOL r;
/* Open device context */
HDC hDC = GetDC(NULL);
if (hDC == NULL) {
fputs(_("Unable to open device context.\n"), stderr);
return -1;
}
/* Check support for gamma ramps */
int cmcap = GetDeviceCaps(hDC, COLORMGMTCAPS);
if (cmcap != CM_GAMMA_RAMP) {
fputs(_("Display device does not support gamma ramps.\n"),
stderr);
return -1;
}
/* Allocate space for saved gamma ramps */
state->saved_ramps = malloc(3*GAMMA_RAMP_SIZE*sizeof(WORD));
if (state->saved_ramps == NULL) {
perror("malloc");
ReleaseDC(NULL, hDC);
return -1;
}
/* Save current gamma ramps so we can restore them at program exit */
r = GetDeviceGammaRamp(hDC, state->saved_ramps);
if (!r) {
fputs(_("Unable to save current gamma ramp.\n"), stderr);
ReleaseDC(NULL, hDC);
return -1;
}
/* Release device context */
ReleaseDC(NULL, hDC);
return 0;
}
void
w32gdi_free(w32gdi_state_t *state)
{
/* Free saved ramps */
free(state->saved_ramps);
}
void
w32gdi_print_help(FILE *f)
{
fputs(_("Adjust gamma ramps with the Windows GDI.\n"), f);
fputs("\n", f);
/* TRANSLATORS: Windows GDI help output
left column must not be translated */
fputs(_(" preserve={0,1}\tWhether existing gamma should be"
" preserved\n"),
f);
fputs("\n", f);
}
int
w32gdi_set_option(w32gdi_state_t *state, const char *key, const char *value)
{
if (strcasecmp(key, "preserve") == 0) {
state->preserve = atoi(value);
} else {
fprintf(stderr, _("Unknown method parameter: `%s'.\n"), key);
return -1;
}
return 0;
}
void
w32gdi_restore(w32gdi_state_t *state)
{
/* Open device context */
HDC hDC = GetDC(NULL);
if (hDC == NULL) {
fputs(_("Unable to open device context.\n"), stderr);
return;
}
/* Restore gamma ramps */
BOOL r = SetDeviceGammaRamp(hDC, state->saved_ramps);
if (!r) fputs(_("Unable to restore gamma ramps.\n"), stderr);
/* Release device context */
ReleaseDC(NULL, hDC);
}
int
w32gdi_set_temperature(w32gdi_state_t *state,
const color_setting_t *setting)
{
BOOL r;
/* Open device context */
HDC hDC = GetDC(NULL);
if (hDC == NULL) {
fputs(_("Unable to open device context.\n"), stderr);
return -1;
}
/* Create new gamma ramps */
WORD *gamma_ramps = malloc(3*GAMMA_RAMP_SIZE*sizeof(WORD));
if (gamma_ramps == NULL) {
perror("malloc");
ReleaseDC(NULL, hDC);
return -1;
}
WORD *gamma_r = &gamma_ramps[0*GAMMA_RAMP_SIZE];
WORD *gamma_g = &gamma_ramps[1*GAMMA_RAMP_SIZE];
WORD *gamma_b = &gamma_ramps[2*GAMMA_RAMP_SIZE];
if (state->preserve) {
/* Initialize gamma ramps from saved state */
memcpy(gamma_ramps, state->saved_ramps,
3*GAMMA_RAMP_SIZE*sizeof(WORD));
} else {
/* Initialize gamma ramps to pure state */
for (int i = 0; i < GAMMA_RAMP_SIZE; i++) {
WORD value = (double)i/GAMMA_RAMP_SIZE *
(UINT16_MAX+1);
gamma_r[i] = value;
gamma_g[i] = value;
gamma_b[i] = value;
}
}
colorramp_fill(gamma_r, gamma_g, gamma_b, GAMMA_RAMP_SIZE,
setting);
/* Set new gamma ramps */
r = SetDeviceGammaRamp(hDC, gamma_ramps);
if (!r) {
/* TODO it happens that SetDeviceGammaRamp returns FALSE on
occasions where the adjustment seems to be successful.
Does this only happen with multiple monitors connected? */
fputs(_("Unable to set gamma ramps.\n"), stderr);
free(gamma_ramps);
ReleaseDC(NULL, hDC);
return -1;
}
free(gamma_ramps);
/* Release device context */
ReleaseDC(NULL, hDC);
return 0;
}
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