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/* See LICENSE file for copyright and license details. */
#ifndef HAVE_LIBGAMMA_METHOD_W32_GDI
# error Compiling gamma-w32-gdi.c without HAVE_LIBGAMMA_METHOD_W32_GDI
#endif

#include "gamma-w32-gdi.h"

#include "libgamma-error.h"

#ifndef WINVER
# define WINVER 0x0500
#endif
#ifdef FAKE_LIBGAMMA_METHOD_W32_GDI
# include "fake-w32-gdi.h"
#else
# include <windows.h>
# include <wingdi.h>
#endif

#include <errno.h>


/**
 * The gamma ramp size that devices will always have in Windows GDI
 * 
 * @see  http://msdn.microsoft.com/en-us/library/windows/desktop/dd372194(v=vs.85).aspx
 */
#define GAMMA_RAMP_SIZE 256


/**
 * Return the capabilities of the adjustment method
 * 
 * @param  this  The data structure to fill with the method's capabilities
 */
void
libgamma_w32_gdi_method_capabilities(libgamma_method_capabilities_t *restrict this)
{
	/* Gamma ramps size, depth and support can be queried */
	this->crtc_information = LIBGAMMA_CRTC_INFO_GAMMA_SIZE | LIBGAMMA_CRTC_INFO_GAMMA_DEPTH;
	/* Windows GDI does not support sites or partitions */
	this->default_site_known = 1;
	this->multiple_sites = 0;
	this->multiple_partitions = 0;
	/* Windows GDI does support CRTC:s */
	this->multiple_crtcs = 1;
	/* Partitions are not supported... */
	this->partitions_are_graphics_cards = 0;
	/* Windows GDI does not have system restore capabilities */
	this->site_restore = 0;
	this->partition_restore = 0;
	this->crtc_restore = 0;
	/* Ramps sizes are fixed and identical and ramp depth is too */
	this->identical_gamma_sizes = 1;
	this->fixed_gamma_size = 1;
	this->fixed_gamma_depth = 1;
	/* Windows GDI is a real adjustment method that can be faked */
#ifdef FAKE_LIBGAMMA_METHOD_W32_GDI
	/* It is considered real but fake if it is translated to X RandR */
	this->fake = 1;
# ifdef HAVE_LIBGAMMA_METHOD_X_RANDR
	this->real = 1;
# else
	this->real = 0;
# endif
#else
	/* It is real and not fake if we are running on Windows */
	this->fake = 0;
	this->real = 1;
#endif
	/* Gamma ramp adjustments are persistent */
	this->auto_restore = 0;
}


/**
 * Initialise an allocated site state
 * 
 * @param   this    The site state to initialise
 * @param   site    The site identifier, unless it is `NULL` it must a
 *                  `free`:able. Once the state is destroyed the library
 *                  will attempt to free it. There you should not free
 *                  it yourself, and it must not be a string constant
 *                  or allocate on the stack. Note however that it will
 *                  not be free:d if this function fails.
 * @return          Zero on success, otherwise (negative) the value of an
 *                  error identifier provided by this library
 */
int
libgamma_w32_gdi_site_initialise(libgamma_site_state_t *restrict this, char* restrict site)
{
	this->partitions_available = 1;
	return !site ? 0 : LIBGAMMA_NO_SUCH_SITE;
}


/**
 * Release all resources held by a site state
 * 
 * @param  this  The site state
 */
void
libgamma_w32_gdi_site_destroy(libgamma_site_state_t *restrict this)
{
	(void) this;
}


/**
 * Restore the gamma ramps all CRTC:s with a site to the system settings
 * 
 * @param   this  The site state
 * @return        Zero on success, otherwise (negative) the value of an
 *                error identifier provided by this library
 */
int
libgamma_w32_gdi_site_restore(libgamma_site_state_t *restrict this)
{
	(void) this;
	errno = ENOTSUP;
	return LIBGAMMA_ERRNO_SET;
}



/**
 * Initialise an allocated partition state
 * 
 * @param   this       The partition state to initialise
 * @param   site       The site state for the site that the partition belongs to
 * @param   partition  The the index of the partition within the site
 * @return             Zero on success, otherwise (negative) the value of an
 *                     error identifier provided by this library
 */
int
libgamma_w32_gdi_partition_initialise(libgamma_partition_state_t *restrict this,
                                      libgamma_site_state_t *restrict site, size_t partition)
{
	DWORD n = 0;
	DISPLAY_DEVICE display;

	(void) site;

	if (partition)
		return LIBGAMMA_NO_SUCH_PARTITION;

	/* Count CRTC:s by iteration over all possible identifiers
	   until we reach on that does not exist */
	display.cb = sizeof(DISPLAY_DEVICE);
	while (EnumDisplayDevices(NULL, n, &display, 0))
		if (n++ == UINT32_MAX)
			return LIBGAMMA_IMPOSSIBLE_AMOUNT;
	this->crtcs_available = (size_t)n;
	return 0;
}


/**
 * Release all resources held by a partition state
 * 
 * @param  this  The partition state
 */
void
libgamma_w32_gdi_partition_destroy(libgamma_partition_state_t *restrict this)
{
	(void) this;
}


/**
 * Restore the gamma ramps all CRTC:s with a partition to the system settings
 * 
 * @param   this  The partition state
 * @return        Zero on success, otherwise (negative) the value of an
 *                error identifier provided by this library
 */
int
libgamma_w32_gdi_partition_restore(libgamma_partition_state_t *restrict this)
{
	(void) this;
	errno = ENOTSUP;
	return LIBGAMMA_ERRNO_SET;
}



/**
 * Initialise an allocated CRTC state
 * 
 * @param   this       The CRTC state to initialise
 * @param   partition  The partition state for the partition that the CRTC belongs to
 * @param   crtc       The the index of the CRTC within the site
 * @return             Zero on success, otherwise (negative) the value of an
 *                     error identifier provided by this library
 */
int
libgamma_w32_gdi_crtc_initialise(libgamma_crtc_state_t *restrict this,
                                 libgamma_partition_state_t *restrict partition, size_t crtc)
{
	DISPLAY_DEVICE display;
	HDC context;

	(void) partition;

	this->data = NULL;

	/* Windows's API mandates this... */
	display.cb = sizeof(DISPLAY_DEVICE);
	/* Get identifier for selected CRTC */
	if (!EnumDisplayDevices(NULL, (DWORD)crtc, &display, 0))
		return LIBGAMMA_NO_SUCH_CRTC;
	/* Check that the connector is enabled,
	 * newer versions of Windows will always pass.
	 * (According to w32's documentation, but that
	 * that is a load of crap) */
	if (!(display.StateFlags & DISPLAY_DEVICE_ACTIVE))
		return LIBGAMMA_CONNECTOR_DISABLED;
	/* Acquire CRTC connection. */
	context = CreateDC(TEXT("DISPLAY"), display.DeviceName, NULL, NULL);
	if (!context)
		return LIBGAMMA_OPEN_CRTC_FAILED;
	this->data = context;
	return 0;
}


/**
 * Release all resources held by a CRTC state
 * 
 * @param  this  The CRTC state
 */
void
libgamma_w32_gdi_crtc_destroy(libgamma_crtc_state_t *restrict this)
{
	if (this->data)
		ReleaseDC(NULL, this->data);
}


/**
 * Restore the gamma ramps for a CRTC to the system settings for that CRTC
 * 
 * @param   this  The CRTC state
 * @return        Zero on success, otherwise (negative) the value of an
 *                error identifier provided by this library
 */
int
libgamma_w32_gdi_crtc_restore(libgamma_crtc_state_t *restrict this)
{
	(void) this;
	errno = ENOTSUP;
	return LIBGAMMA_ERRNO_SET;
}



/**
 * Read information about a CRTC
 * 
 * @param   this    Instance of a data structure to fill with the information about the CRTC
 * @param   crtc    The state of the CRTC whose information should be read
 * @param   fields  OR:ed identifiers for the information about the CRTC that should be read
 * @return          Zero on success, -1 on error. On error refer to the error reports in `this`
 */
int
libgamma_w32_gdi_get_crtc_information(libgamma_crtc_information_t *restrict this,
                                      libgamma_crtc_state_t *restrict crtc, int32_t fields)
{
#define KNOWN_FIELDS (LIBGAMMA_CRTC_INFO_GAMMA_SIZE | LIBGAMMA_CRTC_INFO_GAMMA_DEPTH)
#define _E(FIELD)    ((fields & FIELD) ? LIBGAMMA_CRTC_INFO_NOT_SUPPORTED : 0)

	(void) crtc;

	/* Windows GDI does not support EDID or monitor dimensions */
	this->edid_error = _E(LIBGAMMA_CRTC_INFO_EDID);
	this->width_mm_error = _E(LIBGAMMA_CRTC_INFO_WIDTH_MM);
	this->height_mm_error = _E(LIBGAMMA_CRTC_INFO_HEIGHT_MM);
	this->width_mm_edid_error = _E(LIBGAMMA_CRTC_INFO_WIDTH_MM_EDID);
	this->height_mm_edid_error = _E(LIBGAMMA_CRTC_INFO_HEIGHT_MM_EDID);
	/* Windows GDI have fixed gamma ramp sizes */
	this->red_gamma_size = GAMMA_RAMP_SIZE;
	this->green_gamma_size = GAMMA_RAMP_SIZE;
	this->blue_gamma_size = GAMMA_RAMP_SIZE;
	this->gamma_size_error = 0;
	/* Windows GDI have fixed gamma ramp depth */
	this->gamma_depth = 16;
	this->gamma_depth_error = 0;
	/* It is possible to query Windows GDI whether the device
	   have gamma ramp support. It cannot fail. However, I think
	   the result is incorrect if multiple monitors are active,
	   so we cannot include this. */
	/*
	if ((fields & LIBGAMMA_CRTC_INFO_GAMMA_SUPPORT))
		this->gamma_support = GetDeviceCaps(crtc->data, COLORMGMTCAPS) == CM_GAMMA_RAMP;
	this->gamma_support_error = 0;
	*/
	this->gamma_support_error = _E(LIBGAMMA_CRTC_INFO_GAMMA_SUPPORT);
	/* Windows GDI does not support EDID or connector information */
	this->subpixel_order_error = _E(LIBGAMMA_CRTC_INFO_SUBPIXEL_ORDER);
	this->active_error = _E(LIBGAMMA_CRTC_INFO_ACTIVE);
	this->connector_name_error = _E(LIBGAMMA_CRTC_INFO_CONNECTOR_NAME);
	this->connector_type_error = _E(LIBGAMMA_CRTC_INFO_CONNECTOR_TYPE);
	this->gamma_error = _E(LIBGAMMA_CRTC_INFO_GAMMA);

	/* There was a failure if and only if unsupport field was requested. */
	return (fields & ~KNOWN_FIELDS) ? -1 : 0;

#undef _E
#undef KNOWN_FIELDS
}


/**
 * Get the current gamma ramps for a CRTC, 16-bit gamma-depth version
 * 
 * @param   this   The CRTC state
 * @param   ramps  The gamma ramps to fill with the current values
 * @return         Zero on success, otherwise (negative) the value of an
 *                 error identifier provided by this library
 */
int
libgamma_w32_gdi_crtc_get_gamma_ramps16(libgamma_crtc_state_t *restrict this, libgamma_gamma_ramps16_t *restrict ramps)
{
#ifdef DEBUG
	/* Windows GDI have fixed gamma ramp sizes */
	if (ramps->  red_size != GAMMA_RAMP_SIZE ||
	    ramps->green_size != GAMMA_RAMP_SIZE ||
	    ramps-> blue_size != GAMMA_RAMP_SIZE)
		return LIBGAMMA_WRONG_GAMMA_RAMP_SIZE;
#endif
	/* Read current gamma ramps */
	if (!GetDeviceGammaRamp(this->data, ramps->red))
		return LIBGAMMA_GAMMA_RAMP_READ_FAILED;
	return 0;
}


/**
 * Set the gamma ramps for a CRTC, 16-bit gamma-depth version
 * 
 * @param   this   The CRTC state
 * @param   ramps  The gamma ramps to apply
 * @return         Zero on success, otherwise (negative) the value of an
 *                 error identifier provided by this library
 */
int
libgamma_w32_gdi_crtc_set_gamma_ramps16(libgamma_crtc_state_t *restrict this, libgamma_gamma_ramps16_t ramps)
{
#ifdef DEBUG
	/* Windows GDI have fixed gamma ramp sizes */
	if (ramps.  red_size != GAMMA_RAMP_SIZE ||
	    ramps.green_size != GAMMA_RAMP_SIZE ||
	    ramps. blue_size != GAMMA_RAMP_SIZE)
		return LIBGAMMA_WRONG_GAMMA_RAMP_SIZE;
#endif
	/* Apply gamma ramps */
	if (!SetDeviceGammaRamp(this->data, ramps.red))
		return LIBGAMMA_GAMMA_RAMP_WRITE_FAILED;
	return 0;
}