path: root/fake-w32-gdi.c

/* See LICENSE file for copyright and license details. */
#define IN_LIBGAMMA_W32_GDI
#include "common.h"

/* This file very sloppily translates Windows GDI calls to X RandR calls.
 * It should by no means be used, without additional modification, as a
 * part of a compatibility layer. The purpose of this file is only to make
 * it possible to test for logical errors in Windows specific code on
 * a Linux system under X.
 */



#ifndef HAVE_LIBGAMMA_METHOD_X_RANDR
/* Use dummy translation */


/**
 * Get the device context for a window or the entire screen
 * 
 * @param   hWnd  The windows, `NULL` for the entire screen
 * @return        The device context
 * @see           http://msdn.microsoft.com/en-us/library/windows/desktop/dd144871(v=vs.85).aspx
 */
HDC
GetDC(HWND hWnd)
{
	/* Just a non-NULL value */
	(void) hWnd;
	return (HDC *)16;
}


/**
 * Free a device context
 * 
 * @param   hWnd  The window whose device context is `hDC`, `NULL` for the entire screen
 * @param   hDC   The device context to free
 * @return        Whether the call was successful
 * @see           http://msdn.microsoft.com/en-us/library/windows/desktop/dd162920(v=vs.85).aspx
 */
int
ReleaseDC(HWND hWnd, HDC hDC)
{
	/* Always successful */
	(void) hWnd;
	(void) hDC;
	return 1;
}


/**
 * Get information (capabilities) for a device context
 * 
 * @param   hDC     The device context
 * @param   nIndex  The information to retrieve, may be `COLORMGMTCAPS`
 * @return          The details of the queried information, can return `CM_GAMMA_RAMP`
 *                  if `nIndex` is `COLORMGMTCAPS`
 * @see             http://msdn.microsoft.com/en-us/library/windows/desktop/dd144877(v=vs.85).aspx
 */
int
GetDeviceCaps(HDC hDC, int nIndex)
{
	/* We have gamma ramps if the user asks for colour management capabilities */
	(void) hDC;
	return CM_GAMMA_RAMP + nIndex - COLORMGMTCAPS;
}


/**
 * Set the gamma ramps for a device
 * 
 * @param   hDC     The device context
 * @param   lpRamp  The gamma ramps joined in the order: red, green, blue
 *                  This is a `WORD*` casted to `void*`
 * @return          Whether the call was successful
 * @see             http://msdn.microsoft.com/en-us/library/windows/desktop/dd372194(v=vs.85).aspx
 */
BOOL
SetDeviceGammaRamp(HDC hDC, LPVOID restrict lpRamp)
{
	/* Always successful */
	(void) hDC;
	(void) lpRamp;
	return TRUE;
}


/**
 * Get the current gamma ramps for a device
 * 
 * @param   hDC     The device context
 * @param   lpRamp  The output for the gamma ramps joined in the order: red, green, blue
 *                  This is a `WORD *` casted to `void *`
 * @return          Whether the call was successful
 * @see             http://msdn.microsoft.com/en-us/library/windows/desktop/dd316946(v=vs.85).aspx
 */
BOOL
GetDeviceGammaRamp(HDC hDC, LPVOID restrict lpRamp)
{
	/* Always successful */
	(void) hDC;
	(void) lpRamp;
	return TRUE;
}


/**
 * Get the context for a device
 * 
 * @param   lpszDriver  The driver or a display device, use "DISPLAY" if you want a display
 * @param   lpszDevice  The name of the device. If you want a display use can use the member
 *                      name `DeviceName` in the third parameter, an output parameter, of
 *                      `EnumDisplayDevices`
 * @param   lpszOutput  We will always use `NULL` here
 * @param   lpInitData  We will always use `NULL` here; this should actually by a `const DEVMODE *`
 * @return              The context for the device
 * @see                 http://msdn.microsoft.com/en-us/library/windows/desktop/dd183490(v=vs.85).aspx
 */
HDC
CreateDC(LPCTSTR restrict lpszDriver, LPCTSTR restrict lpszDevice, LPCTSTR restrict lpszOutput, const void *restrict lpInitData)
{
	/* `NULL` if not asking for a CRTC, otherwise a non-NULL value */
	(void) lpszOutput;
	(void) lpInitData;
	(void) lpszDevice;
	return !strcmp(lpszDriver, "DISPLAY") ? (HDC *)16 : NULL;
}


/**
 * Get a display device by its name or index
 * 
 * @param   lpDevice         The name of the device, use `NULL` to base the call on `iDevNum` instead
 * @param   iDevNum          The index of the device
 * @param   lpDisplayDevice  Output for the found device
 * @param   dwFlags          Flags, we will always use zero
 * @return                   Whether the call was successful; zero is also returned if `iDevNum`
 *                           is greater than the largest device index on the system
 * @see                      http://msdn.microsoft.com/en-us/library/windows/desktop/dd162609(v=vs.85).aspx
 */
BOOL
EnumDisplayDevices(LPCTSTR lpDevice, restrict DWORD iDevNum, PDISPLAY_DEVICE restrict lpDisplayDevice, DWORD dwFlags)
{
	(void) dwFlags;
	/* Check correctness of `lpDevice` */
	if (lpDevice) {
		fprintf(stderr, "lpDevice (argument 1) for EnumDisplayDevices should be NULL\n");
		abort();
		return FALSE;
	}
	/* Pretend that we have two CRTC:s */
	if (iDevNum >= 2)
		return FALSE;
	/* Check correctness of `lpDisplayDevice` */
	if (lpDisplayDevice->cb != sizeof(DISPLAY_DEVICE)) {
		fprintf(stderr, "lpDisplayDevice->cb for EnumDisplayDevices is not sizeof(DISPLAY_DEVICE)\n");
		abort();
		return FALSE;
	}
	/* Store an arbitrary name for the monitor */
	strcmp(lpDisplayDevice->DeviceName, "some monitor");
	/* The connector is always enabled */
	lpDisplayDevice->StateFlags = DISPLAY_DEVICE_ACTIVE;
	return TRUE;
}


#else
/* Use translation to X RandR */


#include <xcb/xcb.h>
#include <xcb/randr.h>


/**
 * The gamma ramp size that devices will
 * always have in Windows GDI
 */
#define GAMMA_RAMP_SIZE 256


/**
 * Connection to the X RandR display
 */
static xcb_connection_t *restrict connection = NULL;

/**
 * Resouces for the screen
 * 
 * We only have one screen, again this
 * is a very sloppy compatibility layer
 */
static xcb_randr_get_screen_resources_current_reply_t *restrict res_reply = NULL;

/**
 * The number of available CRTC:s, -1 if not known yet
 */
static ssize_t crtc_count = -1;

/**
 * List of X RandR CRTC:s
 */
static xcb_randr_crtc_t *restrict crtcs = NULL;

/**
 * The number of opened CRTC:s
 */
static size_t dc_count = 0;



/**
 * Get the device context for a window or the entire screen
 * 
 * @param   hWnd  The windows, `NULL` for the entire screen
 * @return        The device context
 * @see           http://msdn.microsoft.com/en-us/library/windows/desktop/dd144871(v=vs.85).aspx
 */
HDC
GetDC(HWND hWnd)
{
	/* Return the primary CRTC */
	(void) hWnd;
	return CreateDC(TEXT("DISPLAY"), "0", NULL, NULL);
}


/**
 * Free a device context
 * 
 * @param   hWnd  The window whose device context is `hDC`, `NULL` for the entire screen
 * @param   hDC   The device context to free
 * @return        Whether the call was successful
 * @see           http://msdn.microsoft.com/en-us/library/windows/desktop/dd162920(v=vs.85).aspx
 */
int
ReleaseDC(HWND hWnd, HDC hDC)
{
	/* Disconnect from the RandR display when all monitors have been closed */
	(void) hWnd;
	(void) hDC;
	if (!dc_count--) {
		if (connection) {
			xcb_disconnect(connection);
			connection = NULL;
		}
		free(res_reply);
		res_reply = NULL;
	}
	return 1;
}


/**
 * Get information (capabilities) for a device context
 * 
 * @param   hDC     The device context
 * @param   nIndex  The information to retrieve, may be `COLORMGMTCAPS`
 * @return          The details of the queried information, can return `CM_GAMMA_RAMP`
 *                  if `nIndex` is `COLORMGMTCAPS`
 * @see             http://msdn.microsoft.com/en-us/library/windows/desktop/dd144877(v=vs.85).aspx
 */
int
GetDeviceCaps(HDC hDC, int nIndex)
{
	/* We have gamma ramps if the user asks for colour management capabilities */
	(void) hDC;
	return CM_GAMMA_RAMP + nIndex - COLORMGMTCAPS;
}


/* xcb violates the rule to never return `struct`:s */
#ifdef __GNUC__
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Waggregate-return"
#endif


/**
 * Set the gamma ramps for a device
 * 
 * @param   hDC     The device context
 * @param   lpRamp  The gamma ramps joined in the order: red, green, blue
 *                  This is a `WORD *` casted to `void *`
 * @return          Whether the call was successful
 * @see             http://msdn.microsoft.com/en-us/library/windows/desktop/dd372194(v=vs.85).aspx
 */
BOOL
SetDeviceGammaRamp(HDC hDC, LPVOID restrict lpRamp)
{
	/* We assume that our gamma ramps are of the same size
	 * as used by Windows GDI (we are so sloppy) */
	uint16_t *ramp = lpRamp;
	xcb_void_cookie_t gamma_cookie = xcb_randr_set_crtc_gamma_checked(connection, *(xcb_randr_crtc_t *)hDC, GAMMA_RAMP_SIZE,
	                                                                  &ramp[0 * GAMMA_RAMP_SIZE], &ramp[1 * GAMMA_RAMP_SIZE],
	                                                                  &ramp[2 * GAMMA_RAMP_SIZE]);
	xcb_generic_error_t *error = xcb_request_check(connection, gamma_cookie);
	return !error ? TRUE : FALSE;
}


/**
 * Get the current gamma ramps for a device
 * 
 * @param   hDC     The device context
 * @param   lpRamp  The output for the gamma ramps joined in the order: red, green, blue
 *                  This is a `WORD *` casted to `void *`
 * @return          Whether the call was successful
 * @see             http://msdn.microsoft.com/en-us/library/windows/desktop/dd316946(v=vs.85).aspx
 */
BOOL
GetDeviceGammaRamp(HDC hDC, LPVOID restrict lpRamp)
{
	xcb_randr_get_crtc_gamma_cookie_t gamma_cookie;
	xcb_randr_get_crtc_gamma_reply_t *restrict gamma_reply;
	xcb_generic_error_t *error;
	uint16_t *restrict ramp = lpRamp;

	/* Read current gamma ramps */
	gamma_cookie = xcb_randr_get_crtc_gamma(connection, *(xcb_randr_crtc_t *)hDC);
	gamma_reply = xcb_randr_get_crtc_gamma_reply(connection, gamma_cookie, &error);
	if (error)
		return FALSE;

	/* Copy the ramps into the output parameter (coalesced) */
	memcpy(&ramp[0 * GAMMA_RAMP_SIZE], xcb_randr_get_crtc_gamma_red(gamma_reply),   GAMMA_RAMP_SIZE * sizeof(*ramp));
	memcpy(&ramp[1 * GAMMA_RAMP_SIZE], xcb_randr_get_crtc_gamma_green(gamma_reply), GAMMA_RAMP_SIZE * sizeof(*ramp));
	memcpy(&ramp[2 * GAMMA_RAMP_SIZE], xcb_randr_get_crtc_gamma_blue(gamma_reply),  GAMMA_RAMP_SIZE * sizeof(*ramp));

	free(gamma_reply);
	return TRUE;
}


/**
 * Get the context for a device
 * 
 * @param   lpszDriver  The driver or a display device, use "DISPLAY" if you want a display
 * @param   lpszDevice  The name of the device. If you want a display use can use the member
 *                      name `DeviceName` in the third parameter, an output parameter, of
 *                      `EnumDisplayDevices`
 * @param   lpszOutput  We will always use `NULL` here
 * @param   lpInitData  We will always use `NULL` here; this should actually by a `const DEVMODE *`
 * @return              The context for the device
 * @see                 http://msdn.microsoft.com/en-us/library/windows/desktop/dd183490(v=vs.85).aspx
 */
HDC
CreateDC(LPCTSTR restrict lpszDriver, LPCTSTR restrict lpszDevice, LPCTSTR restrict lpszOutput, const void *restrict lpInitData)
{
	int crtc_index = atoi(lpszDevice);
	xcb_generic_error_t *error;
	xcb_screen_iterator_t iter;
	xcb_randr_get_screen_resources_current_cookie_t res_cookie;

	(void) lpszOutput;
	(void) lpInitData;

	/* Check correctness of input */
	if (strcmp(lpszDriver, "DISPLAY"))
		return NULL;

	/* Connect to the display and get screen data if not already done so */
	if (!dc_count) {
		/* Connect to the display */
		connection = xcb_connect(NULL, NULL);
		/* Get the first screen */
		iter = xcb_setup_roots_iterator(xcb_get_setup(connection));
		/* Get the resources of the screen */
		res_cookie = xcb_randr_get_screen_resources_current(connection, iter.data->root);
		res_reply = xcb_randr_get_screen_resources_current_reply(connection, res_cookie, &error);
		if (error) {
			fprintf(stderr, "Failed to open X connection\n");
			xcb_disconnect(connection);
			crtc_count = -1;
			return NULL;
		}

		/* Get the number of CRTC:s */
		crtc_count = res_reply->num_crtcs;
		/* Get the CRTC ID:s */
		crtcs = xcb_randr_get_screen_resources_current_crtcs(res_reply);
	}

	/* Was the index too high */
	if (crtc_index >= crtc_count) {
		/* Disconnect and release resouces and mark that
		 * we do not know the number of available CRTC:s
		 * if we have not opened any monitors yet */
		if (!dc_count) {
			xcb_disconnect(connection);
			free(res_reply);
			res_reply = NULL;
			crtc_count = -1;
		}
		return NULL;
	}

	/* We have opened a new CRTC */
	dc_count++;
	/* Return the ID of the CRTC */
	return &crtcs[crtc_index];
}


#ifdef __GNUC__
# pragma GCC diagnostic pop
#endif


/**
 * Get a display device by its name or index
 * 
 * @param   lpDevice         The name of the device, use `NULL` to base the call on `iDevNum` instead
 * @param   iDevNum          The index of the device
 * @param   lpDisplayDevice  Output for the found device
 * @param   dwFlags          Flags, we will always use zero
 * @return                   Whether the call was successful; zero is also returned if `iDevNum`
 *                           is greater than the largest device index on the system
 * @see                      http://msdn.microsoft.com/en-us/library/windows/desktop/dd162609(v=vs.85).aspx
 */
BOOL
EnumDisplayDevices(LPCTSTR restrict lpDevice, DWORD iDevNum, PDISPLAY_DEVICE restrict lpDisplayDevice, DWORD dwFlags)
{
	size_t count = (size_t)crtc_count;

	(void) dwFlags;

	/* Check the correctness of the input */
	if (lpDevice) {
		fprintf(stderr, "lpDevice (argument 1) for EnumDisplayDevices should be NULL\n");
		abort();
		return FALSE;
	}
	/* Do we know how many CRTC:s are available? */
	if (crtc_count < 0) {
		/* If not open the first CRTC so that will be figured out */
		if (!GetDC(NULL))
			return FALSE;
		count = (size_t)crtc_count;
		/* Close the primary monitor that we just closed */
		ReleaseDC(NULL, NULL);
	}
	/* Check that the request CRTC exists */
	if (iDevNum >= count)
		return FALSE;
	/* Check the correctness of the input */
	if (lpDisplayDevice->cb != sizeof(DISPLAY_DEVICE)) {
		fprintf(stderr, "lpDisplayDevice->cb for EnumDisplayDevices is not sizeof(DISPLAY_DEVICE)\n");
		abort();
		return FALSE;
	}
	/* Store name for the CRTC */
	sprintf(lpDisplayDevice->DeviceName, "%lu", (unsigned long int)iDevNum);
	/* The connector that the CRTC belongs to is enabled */
	lpDisplayDevice->StateFlags = DISPLAY_DEVICE_ACTIVE;
	return TRUE;
}


#endif