/*
 * File: xdisplay.h
 * Last modified on Fri Jul 22 12:24:59 1994 by eroberts
 * -----------------------------------------------------
 * This interface is responsible for the actual display operations
 * of the X manager phase of the graphics.c implementation.  In many
 * cases, the functions in this interface are similar to those in
 * the client interface to the graphics library.  The graphics.h
 * interface, for example, contains DrawLine and DrawArc; this
 * interface exports DisplayLine and DisplayArc.  The difference
 * is that the graphics.h functions simply send commands down a
 * communication channel, while the xdisplay.h functions actually
 * perform the rendering operations for the X window manager.
 */

#ifndef _xdisplay_h
#define _xdisplay_h

#include "genlib.h"

/*
 * Function: OpenDisplay
 * Usage: OpenDisplay(title);
 * --------------------------
 * This function creates a display window and performs all the
 * necessary initialization for the X system.  The title string
 * is displayed in the title bar.
 */

void OpenDisplay(string title);

/*
 * Function: CloseDisplay
 * Usage: CloseDisplay();
 * ----------------------
 * This function closes the graphics window and frees all of the
 * X storage.
 */

void CloseDisplay(void);

/*
 * Function: DisplayFD
 * Usage: fd = DisplayFD();
 * ------------------------
 * This function returns the Unix file descriptor of the X
 * connection to the graphics window display.
 */

int DisplayFD(void);

/*
 * Function: ProcessXEvent
 * Usage: if (ProcessXEvent()) . . .
 * ---------------------------------
 * This function checks to see if there is a pending X event
 * and, if so, processes that event.  The function returns
 * TRUE if an event was detected and FALSE if no events were
 * pending so that the client can set a timeout before testing
 * again for another event.
 */

bool ProcessXEvent(void);

/*
 * Function: CheckForRedraw
 * Usage: CheckForRedraw();
 * ------------------------
 * This function checks to see if the window needs redrawing and,
 * if so, issues the X commands to update the screen.
 */

void CheckForRedraw(void);

/*
 * Function: SetRedrawFlag
 * Usage: SetRedrawFlag();
 * -----------------------
 * This function informs the X display module that the screen needs
 * to be redrawn.
 */

void SetRedrawFlag(void);

/*
 * Function: ClearDisplay
 * Usage: ClearDisplay();
 * ----------------------
 * ClearDisplay erases the entire contents of the graphics window.
 */

void ClearDisplay(void);

/*
 * Function: DisplayLine
 * Usage: DisplayLine(x, y, dx, dy);
 * ---------------------------------
 * This function draws a line from (x, y) to (x+dx, y+dy).
 */

void DisplayLine(double x, double y, double dx, double dy);

/*
 * Function: DisplayArc
 * Usage: DisplayArc(x, y, rx, ry, start, sweep);
 * ----------------------------------------------
 * This function draws an elliptical arc segment centered at
 * (x, y) with cartesian radii rx and ry.  Note that the
 * interpretation of (x, y) is not the current point as
 * it is in the DrawArc call.  The start and sweep parameters
 * are interpreted as they are in DrawArc.
 */

void DisplayArc(double x, double y, double rx, double ry,
                double start, double sweep);

/*
 * Function: DisplayText
 * Usage: DisplayText(x, y, text);
 * -------------------------------
 * This function displays the string text at (x, y) using the
 * current font and size.
 */

void DisplayText(double x, double y, string text);

/*
 * Function: DisplayTextWidth
 * Usage: width = DisplayTextWidth(text);
 * --------------------------------------
 * This function returns the width of the text string at the
 * current font and size.
 */

double DisplayTextWidth(string text);

/*
 * Function: DisplaySetFont
 * Usage: str = DisplaySetFont(font, size);
 * ----------------------------------------
 * This function finds the appropriate font and size to use based
 * on the users request and returns a string consisting of the size
 * and font name separated by a space.
 */

string DisplaySetFont(string font, int size);

/*
 * Function: DisplaySetTitle
 * Usage: DisplaySetTitle(title);
 * ------------------------------
 * This function sets the title bar for the window.
 */

void DisplaySetTitle(string title);

/*
 * Function: DisplaySetEraseMode
 * Usage: DisplaySetEraseMode(flag);
 * ---------------------------------
 * This function sets the erase mode setting according to the
 * Boolean flag.
 */

void DisplaySetEraseMode(bool flag);

/*
 * Function: DisplayStartRegion
 * Usage: DisplayStartRegion(grayScale);
 * -------------------------------------
 * The DisplayStartRegion function sets the internal state so
 * that subsequent calls to DisplayLine and DisplayArc (which
 * have already been checked by the client to ensure that they
 * form a connected path) are used to create a fillable polygon.
 * The region is displayed by the corresponding DisplayEndRegion.
 */

void DisplayStartRegion(double grayScale);

/*
 * Function: DisplayEndRegion
 * Usage: DisplayEndRegion();
 * --------------------------
 * This function closes the region opened by DisplayStartRegion.
 */

void DisplayEndRegion(void);

/*
 * Functions: DisplayGetWidth, DisplayGetHeight
 * Usage: width = DisplayGetWidth();
 *        height = DisplayGetHeight();
 * -----------------------------------
 * These functions return the width and height of the X display.
 */

double DisplayGetWidth(void);
double DisplayGetHeight(void);

#endif