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/*-
* redshift-ng - Automatically adjust display colour temperature according the Sun
*
* Copyright (c) 2009-2018 Jon Lund Steffensen <jonlst@gmail.com>
* Copyright (c) 2014-2016, 2025 Mattias Andrée <m@maandree.se>
*
* redshift-ng 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-ng 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-ng. If not, see <http://www.gnu.org/licenses/>.
*/
#ifndef WINVER
# define WINVER 0x0500
#endif
#include "common.h"
#include <wingdi.h>
#define GAMMA_RAMP_SIZE 256
#define MAX_ATTEMPTS 10
struct gamma_state {
WORD *saved_ramps;
};
static int
w32gdi_create(struct gamma_state **state_out)
{
*state_out = emalloc(sizeof(**state_out));
(*state_out)->saved_ramps = NULL;
return 0;
}
static int
w32gdi_start(struct gamma_state *state)
{
HDC hDC;
int cmcap;
/* Open device context */
hDC = GetDC(NULL);
if (!hDC) {
weprintf(_("Unable to open device context."));
return -1;
}
/* Check support for gamma ramps */
cmcap = GetDeviceCaps(hDC, COLORMGMTCAPS);
if (cmcap != CM_GAMMA_RAMP) {
weprintf(_("Display device does not support gamma ramps."));
return -1;
}
/* Allocate space for saved gamma ramps */
state->saved_ramps = emalloc(3 * GAMMA_RAMP_SIZE * sizeof(WORD));
/* Save current gamma ramps so we can restore them at program exit */
if (!GetDeviceGammaRamp(hDC, state->saved_ramps)) {
weprintf(_("Unable to save current gamma ramp."));
ReleaseDC(NULL, hDC);
return -1;
}
/* Release device context */
ReleaseDC(NULL, hDC);
return 0;
}
static void
w32gdi_free(struct gamma_state *state)
{
free(state->saved_ramps);
free(state);
}
static void
w32gdi_print_help(FILE *f)
{
fputs(_("Adjust gamma ramps with the Windows GDI.\n"), f);
fputs("\n", f);
}
static int
w32gdi_set_option(struct gamma_state *state, const char *key, const char *value)
{
if (!strcasecmp(key, "preserve")) {
weprintf(_("Parameter `%s' is now always on; use the `%s' command-line option to disable."), key, "-P");
} else {
weprintf(_("Unknown method parameter: `%s'."), key);
return -1;
}
return 0;
}
static void
w32gdi_restore(struct gamma_state *state)
{
HDC hDC;
int i;
/* Open device context */
hDC = GetDC(NULL);
if (!hDC) {
weprintf(_("Unable to open device context."));
return;
}
/* Restore gamma ramps */
for (i = 0; i < MAX_ATTEMPTS; i++) {
/* We retry a few times before giving up because some
buggy drivers fail on the first invocation of
SetDeviceGammaRamp just to succeed on the second. */
if (SetDeviceGammaRamp(hDC, state->saved_ramps))
goto done;
}
weprintf(_("Unable to restore gamma ramps."));
done:
/* Release device context */
ReleaseDC(NULL, hDC);
}
static int
w32gdi_apply(struct gamma_state *state, const colour_setting_t *setting, int preserve)
{
WORD *gamma_ramps, *gamma_r, *gamma_b, *gamma_g, value;
HDC hDC;
int i;
/* Open device context */
hDC = GetDC(NULL);
if (!hDC) {
weprintf(_("Unable to open device context."));
return -1;
}
/* Create new gamma ramps */
gamma_ramps = emalloc(3 * GAMMA_RAMP_SIZE * sizeof(WORD));
gamma_r = &gamma_ramps[0 * GAMMA_RAMP_SIZE];
gamma_g = &gamma_ramps[1 * GAMMA_RAMP_SIZE];
gamma_b = &gamma_ramps[2 * GAMMA_RAMP_SIZE];
if (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 (i = 0; i < GAMMA_RAMP_SIZE; i++) {
value = (double)i / (GAMMA_RAMP_SIZE - 1) * UINT16_MAX;
gamma_r[i] = value;
gamma_g[i] = value;
gamma_b[i] = value;
}
}
fill_ramps_u16(gamma_r, gamma_g, gamma_b, GAMMA_RAMP_SIZE, GAMMA_RAMP_SIZE, GAMMA_RAMP_SIZE, setting);
/* Set new gamma ramps */
for (i = 0; i < MAX_ATTEMPTS; i++) {
/* We retry a few times before giving up because some
buggy drivers fail on the first invocation of
SetDeviceGammaRamp just to succeed on the second. */
if (SetDeviceGammaRamp(hDC, gamma_ramps))
goto done;
}
weprintf(_("Unable to set gamma ramps."));
free(gamma_ramps);
ReleaseDC(NULL, hDC);
return -1;
done:
free(gamma_ramps);
/* Release device context */
ReleaseDC(NULL, hDC);
return 0;
}
const struct gamma_method w32gdi_gamma_method = GAMMA_METHOD_INIT("wingdi", 1, 0, w32gdi);
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