tkCanvas.h

/*
 * tkCanvas.h --
 *
 *	Declarations shared among all the files that implement
 *	canvas widgets.
 *
 * Copyright (c) 1991-1994 The Regents of the University of California.
 * Copyright (c) 1994-1995 Sun Microsystems, Inc.
 *
 * See the file "license.terms" for information on usage and redistribution
 * of this file, and for a DISCLAIMER OF ALL WARRANTIES.
 *
 * SCCS: @(#) tkCanvas.h 1.41 96/02/15 18:51:28
 */

#ifndef _TKCANVAS
#define _TKCANVAS

#ifndef _TK
#include "tk.h"
#endif

/*
 * The record below describes a canvas widget.  It is made available
 * to the item procedures so they can access certain shared fields such
 * as the overall displacement and scale factor for the canvas.
 */

typedef struct TkCanvas {
    Tk_Window tkwin;		/* Window that embodies the canvas.  NULL
				 * means that the window has been destroyed
				 * but the data structures haven't yet been
				 * cleaned up.*/
    Display *display;		/* Display containing widget;  needed, among
				 * other things, to release resources after
				 * tkwin has already gone away. */
    Tcl_Interp *interp;		/* Interpreter associated with canvas. */
    Tcl_Command widgetCmd;	/* Token for canvas's widget command. */
    Tk_Item *firstItemPtr;	/* First in list of all items in canvas,
				 * or NULL if canvas empty. */
    Tk_Item *lastItemPtr;	/* Last in list of all items in canvas,
				 * or NULL if canvas empty. */

    /*
     * Information used when displaying widget:
     */

    int borderWidth;		/* Width of 3-D border around window. */
    Tk_3DBorder bgBorder;	/* Used for canvas background. */
    int relief;			/* Indicates whether window as a whole is
				 * raised, sunken, or flat. */
    int highlightWidth;		/* Width in pixels of highlight to draw
				 * around widget when it has the focus.
				 * <= 0 means don't draw a highlight. */
    XColor *highlightBgColorPtr;
				/* Color for drawing traversal highlight
				 * area when highlight is off. */
    XColor *highlightColorPtr;	/* Color for drawing traversal highlight. */
    int inset;			/* Total width of all borders, including
				 * traversal highlight and 3-D border.
				 * Indicates how much interior stuff must
				 * be offset from outside edges to leave
				 * room for borders. */
    GC pixmapGC;		/* Used to copy bits from a pixmap to the
				 * screen and also to clear the pixmap. */
    int width, height;		/* Dimensions to request for canvas window,
				 * specified in pixels. */
    int redrawX1, redrawY1;	/* Upper left corner of area to redraw,
				 * in pixel coordinates.  Border pixels
				 * are included.  Only valid if
				 * REDRAW_PENDING flag is set. */
    int redrawX2, redrawY2;	/* Lower right corner of area to redraw,
				 * in integer canvas coordinates.  Border
				 * pixels will *not* be redrawn. */
    int confine;		/* Non-zero means constrain view to keep
				 * as much of canvas visible as possible. */

    /*
     * Information used to manage the selection and insertion cursor:
     */

    Tk_CanvasTextInfo textInfo; /* Contains lots of fields;  see tk.h for
				 * details.  This structure is shared with
				 * the code that implements individual items. */
    int insertOnTime;		/* Number of milliseconds cursor should spend
				 * in "on" state for each blink. */
    int insertOffTime;		/* Number of milliseconds cursor should spend
				 * in "off" state for each blink. */
    Tcl_TimerToken insertBlinkHandler;
				/* Timer handler used to blink cursor on and
				 * off. */

    /*
     * Transformation applied to canvas as a whole:  to compute screen
     * coordinates (X,Y) from canvas coordinates (x,y), do the following:
     *
     * X = x - xOrigin;
     * Y = y - yOrigin;
     */

    int xOrigin, yOrigin;	/* Canvas coordinates corresponding to
				 * upper-left corner of window, given in
				 * canvas pixel units. */
    int drawableXOrigin, drawableYOrigin;
				/* During redisplay, these fields give the
				 * canvas coordinates corresponding to
				 * the upper-left corner of the drawable
				 * where items are actually being drawn
				 * (typically a pixmap smaller than the
				 * whole window). */

    /*
     * Information used for event bindings associated with items.
     */

    Tk_BindingTable bindingTable;
				/* Table of all bindings currently defined
				 * for this canvas.  NULL means that no
				 * bindings exist, so the table hasn't been
				 * created.  Each "object" used for this
				 * table is either a Tk_Uid for a tag or
				 * the address of an item named by id. */
    Tk_Item *currentItemPtr;	/* The item currently containing the mouse
				 * pointer, or NULL if none. */
    Tk_Item *newCurrentPtr;	/* The item that is about to become the
				 * current one, or NULL.  This field is
				 * used to detect deletions  of the new
				 * current item pointer that occur during
				 * Leave processing of the previous current
				 * item.  */
    double closeEnough;		/* The mouse is assumed to be inside an
				 * item if it is this close to it. */
    XEvent pickEvent;		/* The event upon which the current choice
				 * of currentItem is based.  Must be saved
				 * so that if the currentItem is deleted,
				 * can pick another. */
    int state;			/* Last known modifier state.  Used to
				 * defer picking a new current object
				 * while buttons are down. */

    /*
     * Information used for managing scrollbars:
     */

    char *xScrollCmd;		/* Command prefix for communicating with
				 * horizontal scrollbar.  NULL means no
				 * horizontal scrollbar.  Malloc'ed*/
    char *yScrollCmd;		/* Command prefix for communicating with
				 * vertical scrollbar.  NULL means no
				 * vertical scrollbar.  Malloc'ed*/
    int scrollX1, scrollY1, scrollX2, scrollY2;
				/* These four coordinates define the region
				 * that is the 100% area for scrolling (i.e.
				 * these numbers determine the size and
				 * location of the sliders on scrollbars).
				 * Units are pixels in canvas coords. */
    char *regionString;		/* The option string from which scrollX1
				 * etc. are derived.  Malloc'ed. */
    int xScrollIncrement;	/* If >0, defines a grid for horizontal
				 * scrolling.  This is the size of the "unit",
				 * and the left edge of the screen will always
				 * lie on an even unit boundary. */
    int yScrollIncrement;	/* If >0, defines a grid for horizontal
				 * scrolling.  This is the size of the "unit",
				 * and the left edge of the screen will always
				 * lie on an even unit boundary. */

    /*
     * Information used for scanning:
     */

    int scanX;			/* X-position at which scan started (e.g.
				 * button was pressed here). */
    int scanXOrigin;		/* Value of xOrigin field when scan started. */
    int scanY;			/* Y-position at which scan started (e.g.
				 * button was pressed here). */
    int scanYOrigin;		/* Value of yOrigin field when scan started. */

    /*
     * Information used to speed up searches by remembering the last item
     * created or found with an item id search.
     */

    Tk_Item *hotPtr;		/* Pointer to "hot" item (one that's been
				 * recently used.  NULL means there's no
				 * hot item. */
    Tk_Item *hotPrevPtr;	/* Pointer to predecessor to hotPtr (NULL
				 * means item is first in list).  This is
				 * only a hint and may not really be hotPtr's
				 * predecessor. */

    /*
     * Miscellaneous information:
     */

    Tk_Cursor cursor;		/* Current cursor for window, or None. */
    char *takeFocus;		/* Value of -takefocus option;  not used in
				 * the C code, but used by keyboard traversal
				 * scripts.  Malloc'ed, but may be NULL. */
    double pixelsPerMM;		/* Scale factor between MM and pixels;
				 * used when converting coordinates. */
    int flags;			/* Various flags;  see below for
				 * definitions. */
    int nextId;			/* Number to use as id for next item
				 * created in widget. */
    struct TkPostscriptInfo *psInfoPtr;
				/* Pointer to information used for generating
				 * Postscript for the canvas.  NULL means
				 * no Postscript is currently being
				 * generated. */
} TkCanvas;

/*
 * Flag bits for canvases:
 *
 * REDRAW_PENDING -		1 means a DoWhenIdle handler has already
 *				been created to redraw some or all of the
 *				canvas.
 * REDRAW_BORDERS - 		1 means that the borders need to be redrawn
 *				during the next redisplay operation.
 * REPICK_NEEDED -		1 means DisplayCanvas should pick a new
 *				current item before redrawing the canvas.
 * GOT_FOCUS -			1 means the focus is currently in this
 *				widget, so should draw the insertion cursor
 *				and traversal highlight.
 * CURSOR_ON -			1 means the insertion cursor is in the "on"
 *				phase of its blink cycle.  0 means either
 *				we don't have the focus or the cursor is in
 *				the "off" phase of its cycle.
 * UPDATE_SCROLLBARS -		1 means the scrollbars should get updated
 *				as part of the next display operation.
 * LEFT_GRABBED_ITEM -		1 means that the mouse left the current
 *				item while a grab was in effect, so we
 *				didn't change canvasPtr->currentItemPtr.
 * REPICK_IN_PROGRESS -		1 means PickCurrentItem is currently
 *				executing.  If it should be called recursively,
 *				it should simply return immediately.
 */

#define REDRAW_PENDING		1
#define REDRAW_BORDERS		2
#define REPICK_NEEDED		4
#define GOT_FOCUS		8
#define CURSOR_ON		0x10
#define UPDATE_SCROLLBARS	0x20
#define LEFT_GRABBED_ITEM	0x40
#define REPICK_IN_PROGRESS	0x100

/*
 * Canvas-related procedures that are shared among Tk modules but not
 * exported to the outside world:
 */

extern int		TkCanvPostscriptCmd _ANSI_ARGS_((TkCanvas *canvasPtr,
			    Tcl_Interp *interp, int argc, char **argv));

#endif /* _TKCANVAS */