src/hid.h

   1 #ifndef _HID_H_
   2 #define _HID_H_
   3
   4 #include <stdarg.h>
   5
   6 /* Human Interface Device */
   7
   8 /*
   9
  10 The way the HID layer works is that you instantiate a HID device
  11 structure, and invoke functions through its members.  Code in the
  12 common part of PCB may *not* rely on *anything* other than what's
  13 defined in this file.  Code in the HID layers *may* rely on data and
  14 functions in the common code (like, board size and such) but it's
  15 considered bad form to do so when not needed.
  16
  17 Coordinates are ALWAYS in pcb's default resolution (1/100 mil at the
  18 moment).  Positive X is right, positive Y is down.  Angles are
  19 degrees, with 0 being right (positive X) and 90 being up (negative Y).
  20 All zoom, scaling, panning, and conversions are hidden inside the HID
  21 layers.
  22
  23 The main structure is at the end of this file.
  24
  25 Data structures passed to the HIDs will be copied if the HID needs to
  26 save them.  Data structures retured from the HIDs must not be freed,
  27 and may be changed by the HID in response to new information.
  28
  29 */
  30
  31 #if defined(__cplusplus) && __cplusplus
  32 extern "C"
  33 {
  34 #endif
  35
  36 /* Like end cap styles.  The cap *always* extends beyond the
  37    coordinates given, by half the width of the line.  Beveled ends can
  38    used to make octagonal pads by giving the same x,y coordinate
  39    twice.  */
  40   typedef enum
  41   {
  42     Trace_Cap,                  /* This means we're drawing a trace, which has round caps.  */
  43     Square_Cap,                 /* Square pins or pads. */
  44     Round_Cap,                  /* Round pins or round-ended pads, thermals.  */
  45     Beveled_Cap                 /* Octagon pins or bevel-cornered pads.  */
  46   } EndCapStyle;
  47
  48 /* The HID may need something more than an "int" for colors, timers,
  49    etc.  So it passes/returns one of these, which is castable to a
  50    variety of things.  */
  51   typedef union
  52   {
  53     long lval;
  54     void *ptr;
  55   } hidval;
  56
  57 /* This graphics context is an opaque pointer defined by the HID.  GCs
  58    are HID-specific; attempts to use one HID's GC for a different HID
  59    will result in a fatal error.  */
  60   typedef struct hid_gc_struct *hidGC;
  61
  62 #define HIDCONCAT(a,b) a##b
  63
  64 /* This is used to register the action callbacks (for menus and
  65    whatnot).  HID assumes the following actions are available for its
  66    use:
  67         SaveAs(filename);
  68         Quit();
  69 */
  70   typedef struct
  71   {
  72     /* This is matched against action names in the GUI configuration */
  73     char *name;
  74     /* If this string is non-NULL, the action needs to know the X,Y
  75        coordinates to act on, and this string may be used to prompt
  76        the user to select a coordinate.  If NULL, the coordinates may
  77        be 0,0 if none are known.  */
  78     const char *need_coord_msg;
  79     /* Called when the action is triggered.  If this function returns
  80        non-zero, no further actions will be invoked for this key/mouse
  81        event.  */
  82     int (*trigger_cb) (int argc, char **argv, int x, int y);
  83     /* Short description that sometimes accompanies the name.  */
  84     const char *description;
  85     /* Full allowed syntax; use \n to separate lines.  */
  86     const char *syntax;
  87   } HID_Action;
  88
  89   extern void hid_register_action (HID_Action *);
  90
  91   extern void hid_register_actions (HID_Action *, int);
  92 #define REGISTER_ACTIONS(a) HIDCONCAT(void register_,a) ()\
  93 { hid_register_actions(a, sizeof(a)/sizeof(a[0])); }
  94
  95   /* Note that PCB expects the gui to provide the following actions:
  96
  97      PCBChanged();
  98      RouteStylesChanged()
  99      NetlistChanged()  (but core should call "void NetlistChanged(int);" in netlist.c)
 100      LayersChanged()
 101      LibraryChanged()
 102      Busy()
 103    */
 104
 105   extern const char pcbchanged_help[];
 106   extern const char pcbchanged_syntax[];
 107   extern const char routestyleschanged_help[];
 108   extern const char routestyleschanged_syntax[];
 109   extern const char netlistchanged_help[];
 110   extern const char netlistchanged_syntax[];
 111   extern const char layerschanged_help[];
 112   extern const char layerschanged_syntax[];
 113   extern const char librarychanged_help[];
 114   extern const char librarychanged_syntax[];
 115
 116   int hid_action (const char *action_);
 117   int hid_actionl (const char *action_, ...);   /* NULL terminated */
 118   int hid_actionv (const char *action_, int argc_, char **argv_);
 119   void hid_save_settings (int);
 120   void hid_load_settings (void);
 121
 122 /* Parse the given command string into action calls, and call
 123    hid_actionv for each action found.  Accepts both "action(arg1,
 124    arg2)" and command-style "action arg1 arg2", allowing only one
 125    action in the later case.  Returns nonzero if the action handler(s)
 126    return nonzero. */
 127   int hid_parse_command (const char *str_);
 128
 129 /* Parse the given string into action calls, and call
 130    hid_actionv for each action found.  Accepts only
 131    "action(arg1, arg2)" */
 132   int hid_parse_actions (const char *str_);
 133
 134   typedef struct
 135   {
 136     /* Name of the flag */
 137     char *name;
 138     /* Function to call to get the value of the flag.  */
 139     int (*function) (int);
 140     /* Additional parameter to pass to that function.  */
 141     int parm;
 142   } HID_Flag;
 143
 144   extern void hid_register_flags (HID_Flag *, int);
 145 #define REGISTER_FLAGS(a) HIDCONCAT(void register_,a) ()\
 146 { hid_register_flags(a, sizeof(a)/sizeof(a[0])); }
 147
 148 /* Looks up one of the flags registered above.  If the flag is
 149    unknown, returns zero.  */
 150   int hid_get_flag (const char *name_);
 151
 152 /* Used for HID attributes (exporting and printing, mostly).
 153    HA_boolean uses int_value, HA_enum sets int_value to the index and
 154    str_value to the enumeration string.  HID_Label just shows the
 155    default str_value.  HID_Mixed is a real_value followed by an enum,
 156    like 0.5in or 100mm. */
 157   typedef struct
 158   {
 159     int int_value;
 160     char *str_value;
 161     double real_value;
 162   } HID_Attr_Val;
 163
 164   typedef struct
 165   {
 166     char *name;
 167     /* If the help_text is this, usage() won't show this option */
 168 #define ATTR_UNDOCUMENTED ((char *)(1))
 169     char *help_text;
 170     enum
 171     { HID_Label, HID_Integer, HID_Real, HID_String,
 172       HID_Boolean, HID_Enum, HID_Mixed, HID_Path
 173     } type;
 174     int min_val, max_val;       /* for integer and real */
 175     HID_Attr_Val default_val;   /* Also actual value for global attributes.  */
 176     const char **enumerations;
 177     /* If set, this is used for global attributes (i.e. those set
 178        statically with REGISTER_ATTRIBUTES below) instead of changing
 179        the default_val.  Note that a HID_Mixed attribute must specify a
 180        pointer to HID_Attr_Val here, and HID_Boolean assumes this is
 181        "char *" so the value should be initialized to zero, and may be
 182        set to non-zero (not always one).  */
 183     void *value;
 184     int hash; /* for detecting changes. */
 185   } HID_Attribute;
 186
 187   extern void hid_register_attributes (HID_Attribute *, int);
 188 #define REGISTER_ATTRIBUTES(a) HIDCONCAT(void register_,a) ()\
 189 { hid_register_attributes(a, sizeof(a)/sizeof(a[0])); }
 190
 191 /* These three are set by hid_parse_command_line().  */
 192   extern char *program_name;
 193   extern char *program_directory;
 194   extern char *program_basename;
 195
 196 #define SL_0_SIDE       0x0000
 197 #define SL_TOP_SIDE     0x0001
 198 #define SL_BOTTOM_SIDE  0x0002
 199 #define SL_SILK         0x0010
 200 #define SL_MASK         0x0020
 201 #define SL_PDRILL       0x0030
 202 #define SL_UDRILL       0x0040
 203 #define SL_PASTE        0x0050
 204 #define SL_INVISIBLE    0x0060
 205 #define SL_FAB          0x0070
 206 #define SL_ASSY         0x0080
 207 #define SL_RATS         0x0090
 208 /* Callers should use this.  */
 209 #define SL(type,side) (~0xfff | SL_##type | SL_##side##_SIDE)
 210
 211 /* File Watch flags */
 212 /* Based upon those in dbus/dbus-connection.h */
 213 typedef enum
 214 {
 215   PCB_WATCH_READABLE = 1 << 0, /**< As in POLLIN */
 216   PCB_WATCH_WRITABLE = 1 << 1, /**< As in POLLOUT */
 217   PCB_WATCH_ERROR    = 1 << 2, /**< As in POLLERR */
 218   PCB_WATCH_HANGUP   = 1 << 3  /**< As in POLLHUP */
 219 } PCBWatchFlags;
 220
 221 /* DRC GUI Hooks */
 222   typedef struct
 223   {
 224     int log_drc_overview;
 225     int log_drc_violations;
 226     void (*reset_drc_dialog_message) (void);
 227     void (*append_drc_violation) (DrcViolationType *violation);
 228     int (*throw_drc_dialog) (void);
 229   } HID_DRC_GUI;
 230
 231
 232 /* This is the main HID structure.  */
 233   typedef struct
 234   {
 235     /* The size of this structure.  We use this as a compatibility
 236        check; a HID built with a different hid.h than we're expecting
 237        should have a different size here.  */
 238     int struct_size;
 239
 240     /* The name of this HID.  This should be suitable for
 241        command line options, multi-selection menus, file names,
 242        etc. */
 243     const char *name;
 244
 245     /* Likewise, but allowed to be longer and more descriptive.  */
 246     const char *description;
 247
 248     /* If set, this is the GUI HID.  Exactly one of these three flags
 249        must be set; setting "gui" lets the expose callback optimize and
 250        coordinate itself.  */
 251     char gui:1;
 252
 253     /* If set, this is the printer-class HID.  The common part of PCB
 254        may use this to do command-line printing, without having
 255        instantiated any GUI HIDs.  Only one printer HID is normally
 256        defined at a time.  */
 257     char printer:1;
 258
 259     /* If set, this HID provides an export option, and should be used as
 260        part of the File->Export menu option.  Examples are PNG, Gerber,
 261        and EPS exporters.  */
 262     char exporter:1;
 263
 264     /* If set, the redraw code will draw polygons before erasing the
 265        clearances.  */
 266     char poly_before:1;
 267
 268     /* If set, the redraw code will draw polygons after erasing the
 269        clearances.  Note that HIDs may set both of these, in which case
 270        polygons will be drawn twice.  */
 271     char poly_after:1;
 272
 273     /* If set, the redraw code will dice the polygons, so that there
 274        are no clearances in any polygons.  */
 275     char poly_dicer:1;
 276
 277     /* Returns a set of resources describing options the export or print
 278        HID supports.  In GUI mode, the print/export dialogs use this to
 279        set up the selectable options.  In command line mode, these are
 280        used to interpret command line options.  If n_ret is non-NULL,
 281        the number of attributes is stored there.  */
 282     HID_Attribute *(*get_export_options) (int *n_ret_);
 283
 284     /* Export (or print) the current PCB.  The options given represent
 285        the choices made from the options returned from
 286        get_export_options.  Call with options == NULL to start the
 287        primary GUI (create a main window, print, export, etc)  */
 288     void (*do_export) (HID_Attr_Val * options_);
 289
 290     /* Parse the command line.  Call this early for whatever HID will be
 291        the primary HID, as it will set all the registered attributes.
 292        The HID should remove all arguments, leaving any possible file
 293        names behind.  */
 294     void (*parse_arguments) (int *argc_, char ***argv_);
 295
 296     /* This may be called to ask the GUI to force a redraw of a given area */
 297     void (*invalidate_lr) (int left_, int right_, int top_, int bottom_);
 298     void (*invalidate_all) (void);
 299
 300     /* During redraw or print/export cycles, this is called once per
 301        layer (or layer group, for copper layers).  If it returns false
 302        (zero), the HID does not want that layer, and none of the drawing
 303        functions should be called.  If it returns true (nonzero), the
 304        items in that layer [group] should be drawn using the various
 305        drawing functions.  In addition to the MAX_LAYERS copper layer
 306        groups, you may select layers indicated by the macros SL_*
 307        defined above, or any others with an index of -1.  For copper
 308        layer groups, you may pass NULL for name to have a name fetched
 309        from the PCB struct.  The EMPTY argument is a hint - if set, the
 310        layer is empty, if zero it may be non-empty.  */
 311     int (*set_layer) (const char *name_, int group_, int _empty);
 312
 313     /* Drawing Functions.  Coordinates and distances are ALWAYS in PCB's
 314        default coordinates (1/100 mil at the time this comment was
 315        written).  Angles are always in degrees, with 0 being "right"
 316        (positive X) and 90 being "up" (positive Y).  */
 317
 318     /* Make an empty graphics context.  */
 319       hidGC (*make_gc) (void);
 320     void (*destroy_gc) (hidGC gc_);
 321
 322     /* Special note about the "erase" color: To use this color, you must
 323        use this function to tell the HID when you're using it.  At the
 324        beginning of a layer redraw cycle (i.e. after set_layer), call
 325        use_mask() to redirect output to a buffer.  Draw to the buffer
 326        (using regular HID calls) using regular and "erase" colors.  Then
 327        call use_mask(HID_MASK_OFF) to flush the buffer to the HID.  If
 328        you use the "erase" color when use_mask is disabled, it simply
 329        draws in the background color.  */
 330     void (*use_mask) (int use_it_);
 331     /* Flush the buffer and return to non-mask operation.  */
 332 #define HID_MASK_OFF 0
 333     /* Polygons being drawn before clears.  */
 334 #define HID_MASK_BEFORE 1
 335     /* Clearances being drawn.  */
 336 #define HID_MASK_CLEAR 2
 337     /* Polygons being drawn after clears.  */
 338 #define HID_MASK_AFTER 3
 339     /* Set to do live drawing on the screen   */
 340 #define HID_LIVE_DRAWING 4
 341     /* stop live drawing on the screen   */
 342 #define HID_LIVE_DRAWING_OFF 5
 343     /* flush any queued drawing   */
 344 #define HID_FLUSH_DRAW_Q 6
 345
 346     /* Set a color.  Names can be like "red" or "#rrggbb" or special
 347        names like "erase".  *Always* use the "erase" color for removing
 348        ink (like polygon reliefs or thermals), as you cannot rely on
 349        knowing the background color or special needs of the HID.  Always
 350        use the "drill" color to draw holes.  You may assume this is
 351        cheap enough to call inside the redraw callback, but not cheap
 352        enough to call for each item drawn. */
 353     void (*set_color) (hidGC gc_, const char *name_);
 354
 355     /* Set the line style.  While calling this is cheap, calling it with
 356        different values each time may be expensive, so grouping items by
 357        line style is helpful.  */
 358     void (*set_line_cap) (hidGC gc_, EndCapStyle style_);
 359     void (*set_line_width) (hidGC gc_, int width_);
 360     void (*set_draw_xor) (hidGC gc_, int xor_);
 361     /* Blends 20% or so color with 80% background.  Only used for
 362        assembly drawings so far. */
 363     void (*set_draw_faded) (hidGC gc_, int faded_);
 364
 365     /* When you pass the same x,y twice to draw_line, the end caps are
 366        drawn as if the "line" were parallel to the line defined by these
 367        coordinates.  Use this for rotating non-round pads.  */
 368     void (*set_line_cap_angle) (hidGC gc_, int x1_, int y1_, int x2_, int y2_);
 369
 370     /* The usual drawing functions.  "draw" means to use segments of the
 371        given width, whereas "fill" means to fill to a zero-width
 372        outline.  */
 373     void (*draw_line) (hidGC gc_, int x1_, int y1_, int x2_, int y2_);
 374     void (*draw_arc) (hidGC gc_, int cx_, int cy_, int xradius_, int yradius_,
 375                       int start_angle_, int delta_angle_);
 376     void (*draw_rect) (hidGC gc_, int x1_, int y1_, int x2_, int y2_);
 377     void (*fill_circle) (hidGC gc_, int cx_, int cy_, int radius_);
 378     void (*fill_polygon) (hidGC gc_, int n_coords_, int *x_, int *y_);
 379     void (*fill_pcb_polygon) (hidGC gc_, PolygonType *poly,
 380                               const BoxType *clip_box);
 381     void (*thindraw_pcb_polygon) (hidGC gc_, PolygonType *poly,
 382                                   const BoxType *clip_box);
 383     void (*fill_rect) (hidGC gc_, int x1_, int y1_, int x2_, int y2_);
 384
 385
 386     /* This is for the printer.  If you call this for the GUI, xval and
 387        yval are ignored, and a dialog pops up to lead you through the
 388        calibration procedure.  For the printer, if xval and yval are
 389        zero, a calibration page is printed with instructions for
 390        calibrating your printer.  After calibrating, nonzero xval and
 391        yval are passed according to the instructions.  Metric is nonzero
 392        if the user prefers metric units, else inches are used. */
 393     void (*calibrate) (double xval_, double yval_);
 394
 395
 396     /* GUI layout functions.  Not used or defined for print/export
 397        HIDs.  */
 398
 399     /* Temporary */
 400     int (*shift_is_pressed) (void);
 401     int (*control_is_pressed) (void);
 402         int (*mod1_is_pressed) (void);
 403     void (*get_coords) (const char *msg_, int *x_, int *y_);
 404
 405     /* Sets the crosshair, which may differ from the pointer depending
 406        on grid and pad snap.  Note that the HID is responsible for
 407        hiding, showing, redrawing, etc.  The core just tells it what
 408        coordinates it's actually using.  Note that this routine may
 409        need to know what "pcb units" are so it can display them in mm
 410        or mils accordingly.  If cursor_action is set, the cursor or
 411        screen may be adjusted so that the cursor and the crosshair are
 412        at the same point on the screen.  */
 413     void (*set_crosshair) (int x_, int y_, int cursor_action_);
 414 #define HID_SC_DO_NOTHING       0
 415 #define HID_SC_WARP_POINTER     1
 416 #define HID_SC_PAN_VIEWPORT     2
 417
 418     /* Causes func to be called at some point in the future.  Timers are
 419        only good for *one* call; if you want it to repeat, add another
 420        timer during the callback for the first.  user_data can be
 421        anything, it's just passed to func.  Times are not guaranteed to
 422        be accurate.  */
 423       hidval (*add_timer) (void (*func) (hidval user_data_),
 424                            unsigned long milliseconds_, hidval user_data_);
 425     /* Use this to stop a timer that hasn't triggered yet.  */
 426     void (*stop_timer) (hidval timer_);
 427
 428     /* Causes func to be called when some condition occurs on the file
 429        descriptor passed. Conditions include data for reading, writing,
 430        hangup, and errors. user_data can be anything, it's just passed
 431        to func. */
 432       hidval (*watch_file) (int fd_, unsigned int condition_, void (*func_) (hidval watch_, int fd_, unsigned int condition_, hidval user_data_),
 433         hidval user_data);
 434     /* Use this to stop a file watch. */
 435     void (*unwatch_file) (hidval watch_);
 436
 437     /* Causes func to be called in the mainloop prior to blocking */
 438       hidval (*add_block_hook) (void (*func_) (hidval data_), hidval data_);
 439     /* Use this to stop a mainloop block hook. */
 440     void (*stop_block_hook) (hidval block_hook_);
 441
 442     /* Various dialogs */
 443
 444     /* Log a message to the log window.  */
 445     void (*log) (const char *fmt_, ...);
 446     void (*logv) (const char *fmt_, va_list args_);
 447
 448     /* A generic yes/no dialog.  Returns zero if the cancel button is
 449        pressed, one for the ok button.  If you specify alternate labels
 450        for ..., they are used instead of the default OK/Cancel ones, and
 451        the return value is the index of the label chosen.  You MUST pass
 452        NULL as the last parameter to this.  */
 453     int (*confirm_dialog) (char *msg_, ...);
 454
 455     /* A close confirmation dialog for unsaved pages, for example, with
 456        options "Close without saving", "Cancel" and "Save". Returns zero
 457        if the close is cancelled, or one if it should proceed. The HID
 458        is responsible for any "Save" action the user may wish before
 459        confirming the close.
 460        */
 461     int (*close_confirm_dialog) ();
 462 #define HID_CLOSE_CONFIRM_CANCEL 0
 463 #define HID_CLOSE_CONFIRM_OK     1
 464
 465     /* Just prints text.  */
 466     void (*report_dialog) (char *title_, char *msg_);
 467
 468     /* Prompts the user to enter a string, returns the string.  If
 469        default_string isn't NULL, the form is pre-filled with this
 470        value.  "msg" is like "Enter value:".  */
 471     char *(*prompt_for) (char *msg_, char *default_string_);
 472
 473     /* Prompts the user for a filename or directory name.  For GUI
 474        HID's this would mean a file select dialog box.  The 'flags'
 475        argument is the bitwise OR of the following values.  */
 476 #define HID_FILESELECT_READ  0x01
 477
 478     /* The function calling hid->fileselect will deal with the case
 479        where the selected file already exists.  If not given, then the
 480        gui will prompt with an "overwrite?" prompt.  Only used when
 481        writing.
 482     */
 483 #define HID_FILESELECT_MAY_NOT_EXIST 0x02
 484
 485     /* The call is supposed to return a file template (for gerber
 486        output for example) instead of an actual file.  Only used when
 487        writing.
 488     */
 489 #define HID_FILESELECT_IS_TEMPLATE 0x04
 490
 491     /* title may be used as a dialog box title.  Ignored if NULL.
 492      *
 493      * descr is a longer help string.  Ignored if NULL.
 494      *
 495      * default_file is the default file name.  Ignored if NULL.
 496      *
 497      * default_ext is the default file extension, like ".pdf".
 498      * Ignored if NULL.
 499      *
 500      * history_tag may be used by the GUI to keep track of file
 501      * history.  Examples would be "board", "vendor", "renumber",
 502      * etc.  If NULL, no specific history is kept.
 503      *
 504      * flags are the bitwise or of the HID_FILESELECT defines above
 505      */
 506
 507     char *(*fileselect) (const char *title_, const char *descr_,
 508                          char *default_file_, char *default_ext_,
 509                          const char *history_tag_, int flags_);
 510
 511     /* A generic dialog to ask for a set of attributes.  If n_attrs is
 512        zero, attrs(.name) must be NULL terminated.  Returns non-zero if
 513        an error occurred (usually, this means the user cancelled the
 514        dialog or something). title is the title of the dialog box
 515        descr (if not NULL) can be a longer description of what the
 516        attributes are used for.  The HID may choose to ignore it or it
 517        may use it for a tooltip or text in a dialog box, or a help
 518        string.
 519     */
 520     int (*attribute_dialog) (HID_Attribute * attrs_,
 521                              int n_attrs_, HID_Attr_Val * results_,
 522                              const char * title_, const char * descr_);
 523
 524     /* This causes a second window to display, which only shows the
 525        selected item. The expose callback is called twice; once to size
 526        the extents of the item, and once to draw it.  To pass magic
 527        values, pass the address of a variable created for this
 528        purpose.  */
 529     void (*show_item) (void *item_);
 530
 531     /* Something to alert the user.  */
 532     void (*beep) (void);
 533
 534     /* Used by optimizers and autorouter to show progress to the user.
 535        Pass all zeros to flush display and remove any dialogs.
 536        Returns nonzero if the user wishes to cancel the operation.  */
 537     int (*progress) (int so_far_, int total_, const char *message_);
 538
 539     HID_DRC_GUI *drc_gui;
 540
 541     void (*edit_attributes) (char *owner, AttributeListType *attrlist_);
 542
 543   } HID;
 544
 545 /* Call this as soon as possible from main().  No other HID calls are
 546    valid until this is called.  */
 547   void hid_init (void);
 548
 549 /* When PCB runs in interactive mode, this is called to instantiate
 550    one GUI HID which happens to be the GUI.  This HID is the one that
 551    interacts with the mouse and keyboard.  */
 552   HID *hid_find_gui ();
 553
 554 /* Finds the one printer HID and instantiates it.  */
 555   HID *hid_find_printer (void);
 556
 557 /* Finds the indicated exporter HID and instantiates it.  */
 558   HID *hid_find_exporter (const char *);
 559
 560 /* This returns a NULL-terminated array of available HIDs.  The only
 561    real reason to use this is to locate all the export-style HIDs. */
 562   HID **hid_enumerate (void);
 563
 564 /* This function (in the common code) will be called whenever the GUI
 565    needs to redraw the screen, print the board, or export a layer.  If
 566    item is not NULL, only draw the given item.  Item is only non-NULL
 567    if the HID was created via show_item.
 568
 569    Each time func is called, it should do the following:
 570
 571    * allocate any colors needed, via get_color.
 572
 573    * cycle through the layers, calling set_layer for each layer to be
 574      drawn, and only drawing elements (all or specified) of desired
 575      layers.
 576
 577    Do *not* assume that the hid that is passed is the GUI hid.  This
 578    callback is also used for printing and exporting. */
 579   struct BoxType;
 580   void hid_expose_callback (HID * hid_, struct BoxType *region_, void *item_);
 581
 582 /* This is initially set to a "no-gui" gui, and later reset by
 583    main. hid_expose_callback also temporarily set it for drawing. */
 584   extern HID *gui;
 585
 586 /* This is either NULL or points to the current HID that is being called to
 587         do the exporting. The gui HIDs set and unset this var.*/
 588   extern HID *exporter;
 589
 590 /* This is either NULL or points to the current HID_Action that is being
 591    called. The action launcher sets and unsets this variable. */
 592   extern HID_Action *current_action;
 593
 594 /* The GUI may set this to be approximately the PCB size of a pixel,
 595    to allow for near-misses in selection and changes in drawing items
 596    smaller than a screen pixel.  */
 597   extern int pixel_slop;
 598
 599 #if defined(__cplusplus) && __cplusplus
 600 }
 601 #endif
 602
 603 #endif