1 /* VCG description handler for Bison. 
   3    Copyright (C) 2001, 2002 Free Software Foundation, Inc. 
   5    This file is part of Bison, the GNU Compiler Compiler. 
   7    Bison is free software; you can redistribute it and/or modify 
   8    it under the terms of the GNU General Public License as published by 
   9    the Free Software Foundation; either version 2, or (at your option) 
  12    Bison is distributed in the hope that it will be useful, 
  13    but WITHOUT ANY WARRANTY; without even the implied warranty of 
  14    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
  15    GNU General Public License for more details. 
  17    You should have received a copy of the GNU General Public License 
  18    along with Bison; see the file COPYING.  If not, write to 
  19    the Free Software Foundation, Inc., 59 Temple Place - Suite 330, 
  20    Boston, MA 02111-1307, USA.  */ 
  25 /* VCG color map. The 32 prime predefined colors. */ 
  62 /* VCG textmode. Specify the adjustement of the text within the border of a summary node. */ 
  70 /* VCG shapes. Used for nodes shapes. */ 
  79 /* Structure for colorentries.  */ 
  86   struct colorentry 
*next
; 
  89 /* Structure to construct lists of classnames. */ 
  92   int no
; /* Class number */ 
  93   const char *name
; /* Name associated to the class no. */ 
  94   struct classname 
*next
; /* next name class association. */ 
  97 /* Structure is in infoname.  */ 
 102   struct infoname 
*next
; 
 105 /* Layout Algorithms which can be found in VCG. 
 106    Details about each algoithm can be found below. */ 
 125 /* VCG decision yes/no. */ 
 132 /* VCG graph orientation. */ 
 141 /* VCG alignment for node alignement. */ 
 149 /* VCG arrow mode. */ 
 156 /* VCG crossing weight type. */ 
 175 /*------------------------------------------------------. 
 176 | Node attributs list. structure that describes a node. | 
 177 `------------------------------------------------------*/ 
 181   /* Title the unique string identifying the node. This attribute is 
 185   /* Label the text displayed inside the node. If no label is specified 
 186      then the title of the node will be used. Note that this text may 
 187      contain control characters like NEWLINE that influences the size of 
 191   /* loc is the location as x, y position relatively to the system of 
 192      coordinates of the graph. Locations are specified in the form 
 193      loc: - x: xpos y: ypos "". The locations of nodes are only valid, 
 194      if the whole graph is fully specified with locations and no part is 
 195      folded. The layout algorithm of the tool calculates appropriate x, y 
 196      positions, if at least one node that must be drawn (i.e., is not 
 197      hidden by folding or edge classes) does not have fixed specified 
 203   /* vertical order is the level position (rank) of the node. We can also 
 204      specify level: int. Level specifications are only valid, if the 
 205      layout is calculated, i.e. if at least one node does not have a 
 206      fixed location specification. The layout algorithm partitioned all 
 207      nodes into levels 0...maxlevel. Nodes at the level 0 are on the 
 208      upper corner. The algorithm is able to calculate appropriate levels 
 209      for the nodes automatically, if no fixed levels are given. 
 210      Specifications of levels are additional constraints, that may be 
 211      ignored, if they are in conflict with near edge specifications. 
 212      Default values are unspecified. */ 
 215   /* horizontal order is the horizontal position of the node within a 
 216      level. The nodes which are specified with horizontal positions are 
 217      ordered according to these positions within the levels. The nodes 
 218      which do not have this attribute are inserted into this ordering by 
 219      the crossing reduction mechanism. Note that connected components are 
 220      handled separately, thus it is not possible to intermix such 
 221      components by specifying a horizontal order. If the algorithm for 
 222      downward laid out trees is used, the horizontal order influences 
 223      only the order of the child nodes at a node, but not the order of 
 225      Default is unspecified. */ 
 226   int horizontal_order
; 
 228   /* width, height is the width and height of a node including the border. 
 229      If no value (in pixels) is given then width and height are 
 230      calculated from the size of the label. 
 231      Default are width and height of the label. */ 
 235   /* shrink, expand gives the shrinking and expanding factor of the 
 236      node. The values of the attributes width, height, borderwidth and 
 237      the size of the label text is scaled by ((expand=shrink) \Lambda 
 238      100) percent. Note that the actual scale value is determined by the 
 239      scale value of a node relatively to a scale value of the graph, 
 240      i.e. if (expand,shrink) = (2,1) for the graph and (expand,shrink) 
 241      = (2,1) for the node of the graph, then the node is scaled by the 
 242      factor 4 compared to the normal size. The scale value can also be 
 243      specified by scaling: float. 
 248   /* folding specifies the default folding of the nodes. The folding k 
 249      (with k ? 0) means that the graph part that is reachable via edges 
 250      of a class less or equal to k is folded and displayed as one node. 
 251      There are commands to unfold such summary nodes, see section 5. If 
 252      no folding is specified for a node, then the node may be folded if 
 253      it is in the region of another node that starts the folding. If 
 254      folding 0 is specified, then the node is never folded. In this case 
 255      the folding stops at the predecessors of this node, if it is 
 256      reachable from another folding node. The summary node inherits some 
 257      attributes from the original node which starts the folding (all 
 258      color attributes, textmode and label, but not the location). A 
 259      folded region may contain folded regions with smaller folding class 
 260      values (nested foldings). If there is more than one node that start 
 261      the folding of the same region (this implies that the folding class 
 262      values are equal) then the attributes are inherited by one of these 
 263      nodes nondeterministically. If foldnode attributes are specified, 
 264      then the summary node attributes are inherited from these attributes. 
 268   /* shape specifies the visual appearance of a node: box, rhomb, ellipse, 
 269      and triangle. The drawing of ellipses is much slower than the drawing 
 274   /* textmode specifies the adjustment of the text within the border of a 
 275      node. The possibilities are center, left.justify and right.justify. 
 276      Default is center. */ 
 277   enum textmode textmode
; 
 279   /* borderwidth specifies the thickness of the node's border in pixels. 
 280      color is the background color of the node. If none is given, the 
 281      node is white. For the possibilities, see the attribute color for 
 287      Default is white or transparent, */ 
 290   /* textcolor is the color for the label text. bordercolor is the color 
 291      of the border. Default color is the textcolor. info1, info2, info3 
 292      combines additional text labels with a node or a folded graph. info1, 
 294   enum color textcolor
; 
 296   /* info2, info3 can be selected from the menu. The corresponding text 
 297      labels can be shown by mouse clicks on nodes.\f 
 298      Default are null strings. */ 
 299   const char *infos
[3]; 
 301   /* Node border color. 
 302      Default is textcolor. */ 
 303   enum color bordercolor
; 
 305   /* Next node node... */ 
 310 typedef struct node node
; 
 312 /*-------------------------------------------------------. 
 313 | Edge attributs list. Structure that describes an edge. | 
 314 `-------------------------------------------------------*/ 
 325 /* Structs enum definitions for edges. */ 
 341 /* The struct edge itself. */ 
 346      Default is normal edge. */ 
 349   /* Sourcename is the title of the source node of the edge. 
 351   const char *sourcename
; /* Mandatory. */ 
 353   /* Targetname is the title of the target node of the edge. 
 355   const char *targetname
; /* Mandatory. */ 
 357   /* Label specifies the label of the edge. It is drawn if 
 358      display.edge.labels is set to yes. 
 359      Default: no label. */ 
 362   /* Linestyle specifies the style the edge is drawn. Possibilities are: 
 363      ffl continuous a solid line is drawn ( -- ) ffl dashed the edge 
 364      consists of single dashes ( - - - ) ffl dotted the edge is made of 
 365      single dots ( \Delta  \Delta  \Delta  ) ffl invisible the edge is not 
 366      drawn. The attributes of its shape (color, thickness) are ignored. 
 367      To draw a dashed or dotted line needs more time than solid lines. 
 368      Default is continuous. */ 
 369   enum linestyle linestyle
; 
 371   /* Thickness is the thickness of an edge. 
 375   /* Class specifies the folding class of the edge. Nodes reachable by 
 376      edges of a class less or equal to a constant k specify folding 
 377      regions of k. See the node attribute folding and the folding commands. 
 381   /* color is the color of the edge. 
 385   /* textcolor is the color of the label of the edge. arrowcolor, 
 386      backarrowcolor is the color of the arrow head and of the backarrow 
 387      head. priority The positions of the nodes are mainly determined by 
 388      the incoming and outgoing edges. One can think of rubberbands instead 
 389      of edges that pull a node into its position. The priority of an edges 
 390      corresponds to the strength of the rubberband. 
 392   enum color textcolor
; 
 396   enum color arrowcolor
; 
 400   enum color backarrowcolor
; 
 402   /* arrowsize, backarrowsize The arrow head is a right-angled, isosceles 
 403      triangle and the cathetuses have length arrowsize. 
 411   /* arrowstyle, backarrowstyle Each edge has two arrow heads: the one 
 412      appears at the target node (the normal arrow head), the other appears 
 413      at the source node (the backarrow head). Normal edges only have the 
 414      normal solid arrow head, while the backarrow head is not drawn, i.e. 
 415      it is none. Arrowstyle is the style of the normal arrow head, and 
 416      backarrowstyle is the style of the backarrow head. Styles are none, 
 417      i.e. no arrow head, solid, and line. 
 419   enum arrowstyle arrowstyle
; 
 421   /* Default is none. */ 
 422   enum arrowstyle backarrowstyle
; 
 427   /* Anchor. An anchor point describes the vertical position in a node 
 428      where an edge goes out. This is useful, if node labels are several 
 429      lines long, and outgoing edges are related to label lines. (E.g., 
 430      this allows a nice visualization of structs containing pointers as 
 435   /* Horizontal order is the horizontal position the edge. This is of 
 436      interest only if the edge crosses several levels because it specifies 
 437      the point where the edge crosses the level. within a level. The nodes 
 438      which are specified with horizontal positions are ordered according 
 439      to these positions within a level. The horizontal position of a long 
 440      edge that crosses the level specifies between which two node of that 
 441      level the edge has to be drawn. Other edges which do not have this 
 442      attribute are inserted into this ordering by the crossing reduction 
 443      mechanism. Note that connected components are handled separately, 
 444      thus it is not possible to intermix such components by specifying a 
 446      Default is unspcified. */ 
 447   int horizontal_order
; 
 459 typedef struct edge edge
; 
 461 /*--------------------------------------------------------. 
 462 | Graph attributs list. Structure that describes a graph. | 
 463 `--------------------------------------------------------*/ 
 467   /* Graph title or name. 
 468      Title specifies the name (a string) associated with the graph. The 
 469      default name of a subgraph is the name of the outer graph, and the 
 470      name of the outmost graph is the name of the specification input 
 471      file. The name of a graph is used to identify this graph, e.g., if 
 472      we want to express that an edge points to a subgraph. Such edges 
 473      point to the root of the graph, i.e. the first node of the graph or 
 474      the root of the first subgraph in the graph, if the subgraph is 
 475      visualized explicitly. 
 476      By default, it's the name of the vcg graph file description. */ 
 480      Label the text displayed inside the node, when the graph is folded 
 481      to a node. If no label is specified then the title of the graph will 
 482      be used. Note that this text may contain control characters like 
 483      NEWLINE that influences the size of the node. 
 484      By default, it takes the title value */ 
 488      Info1, info2, info3 combines additional text labels with a node or a 
 489      folded graph. info1, info2, info3 can be selected from the menu 
 490      interactively. The corresponding text labels can be shown by mouse 
 492      Default values are empty strings (here NULL pointers) */ 
 493   const char *infos
[3]; 
 495   /* Background color and summary node colors 
 496      Color specifies the background color for the outermost graph, or the 
 497      color of the summary node for subgraphs. Colors are given in the enum 
 498      declared above. If more than these default colors are needed, a 
 499      color map with maximal 256 entries can be used. The first 32 entries 
 500      correspond to the colors just listed. A color of the color map can 
 501      selected by the color map index, an integer, for instance red has 
 502      index 2, green has index 3, etc. 
 503      Default is white for background and white or transparent for summary 
 508      need explanations ??? 
 509      default is black for summary nodes. */ 
 510   enum color textcolor
; 
 512   /* Bordercolor is the color of the summary node's border. Default color 
 513      is the textcolor. width, height are width and height of the 
 514      displayed part of the window of the outermost graph in pixels, or 
 515      width and height of the summary node of inner subgraphs. 
 516      Default is the default of the textcolor. */ 
 517   enum color bordercolor
; 
 519   /* Width, height are width and height of the displayed part of the 
 520      window of the outermost graph in pixels, or width and height of the 
 521      summary node of inner subgraphs. 
 522      Default value is 100. */ 
 526   /* Specify the thickness if summary node's border in pixels. 
 527      default value is 2. */ 
 530   /* x, y are the x-position and y-position of the graph's window in 
 531      pixels, relatively to the root screen, if it is the outermost graph. 
 532      The origin of the window is upper, left hand. For inner subgraphs, 
 533      it is the position of the folded summary node. The position can also 
 534      be specified in the form loc: fx:int y:intg. 
 535      The default value is 0. */ 
 539   /* folding of a subgraph is 1, if the subgraph is fused, and 0, if the 
 540      subgraph is visualized explicitly. There are commands to unfold such 
 542      Default value is 0 */ 
 545   /* Shrink, expand gives the shrinking and expanding factor for the 
 546      graph's representation (default is 1, 1). ((expand=shrink) \Lambda 
 547      100) is the scaling of the graph in percentage, e.g., 
 548      (expand,shrink) = (1,1) or (2,2) or (3,3) : : : is normal size, 
 549      (expand,shrink) = (1,2) is half size, (expand,shrink) = (2,1) is 
 550      double size. For subgraphs, it is also the scaling factor of the 
 551      summary node. The scaling factor can also be specified by scaling: 
 552      float (here, scaling 1.0 means normal size). */ 
 556   /* textmode specifies the adjustment of the text within the border of a 
 557      summary node. The possibilities are center, left.justify and 
 559      Default value is center.*/ 
 560   enum textmode textmode
; 
 562   /* Shape can be specified for subgraphs only. It is the shape of the 
 563      subgraph summary node that appears if the subgraph is folded: box, 
 564      rhomb, ellipse, and triangle. vertical order is the level position 
 565      (rank) of the summary node of an inner subgraph, if this subgraph is 
 566      folded. We can also specify level: int. The level is only 
 567      recognized, if an automatical layout is calculated. horizontal order 
 568      is the horizontal position of the summary node within a level. The 
 569      nodes which are specified with horizontal positions are ordered 
 570      according to these positions within the levels. The nodes which do 
 571      not have this attribute are inserted into this ordering by the 
 572      crossing reduction mechanism. Note that connected 
 573      components are handled separately, thus it is not possible to 
 574      intermix such components by specifying a horizontal order. If the 
 575      algorithm for downward laid out trees is used, the horizontal order 
 576      influences only the order of the child nodes at a node, but not the 
 577      order of the whole level. 
 578      Default is box, other: rhomb, ellipse, triangle. */ 
 581   /* Vertical order is the level position (rank) of the summary node of an  
 582      inner subgraph, if this subgraph is folded. We can also specify  
 583      level: int. The level is only recognized, if an automatical layout is  
 587   /* Horizontal order is the horizontal position of the summary node within  
 588      a level. The nodes which are specified with horizontal positions are  
 589      ordered according to these positions within the levels. The nodes which  
 590      do not have this attribute are inserted into this ordering by the  
 591      crossing reduction mechanism. Note that connected components are  
 592      handled separately, thus it is not possible to intermix such components  
 593      by specifying a horizontal order. If the algorithm for downward laid  
 594      out trees is used, the horizontal order influences only the order of  
 595      the child nodes at a node, but not the order of the whole level.  */ 
 596   int horizontal_order
; 
 598   /* xmax, ymax specify the maximal size of the virtual window that is 
 599      used to display the graph. This is usually larger than the displayed 
 600      part, thus the width and height of the displayed part cannot be 
 601      greater than xmax and ymax. Only those parts of the graph are drawn 
 602      that are inside the virtual window. The virtual window can be moved 
 603      over the potential infinite system of coordinates by special 
 604      positioning commands. 
 605      Defaults are 90 and 90. */ 
 609   /* xy-base: specify the upper left corner coordinates of the graph 
 610      relatively to the root window. 
 611      Defaults are 5, 5. */ 
 615   /* xspace, yspace the minimum horizontal and vertical distance between 
 616      nodes. xlspace is the horizontal distance between lines at the 
 617      points where they cross the levels. (At these points, dummy nodes 
 618      are used. In fact, this is the horizontal distance between dummy 
 619      nodes.) It is recommended to set xlspace to a larger value, if 
 620      splines are used to draw edges, to prevent sharp bendings. 
 621      Default are 20 and 70. */ 
 625   /* The horizontal space between lines at the point where they cross 
 627      defaults value is 1/2 xspace (polygone) and 4/5 xspace (splines)*/ 
 630   /* xraster, yraster specifies the raster distance for the position of 
 631      the nodes. The center of a node is aligned to this raster. xlraster 
 632      is the horizontal raster for the positions of the line control 
 633      points (the dummy nodes). It should be a divisor of xraster. 
 638   /* xlraster is the horizontal raster for the positions of the line 
 639      control points (the dummy nodes). It should be a divisor of xraster. 
 643   /* hidden specifies the classes of edges that are hidden. 
 644      Edges that are within such a class are not laid out nor drawn. 
 645      Nodes that are only reachable (forward or backward) by edges of an 
 646      hidden class are not drawn. However, nodes that are not reachable 
 647      at all are drawn. (But see attribute ignore.singles.) Specification 
 648      of classes of hidden edges allows to hide parts of a graph, e.g., 
 649      annotations of a syntax tree. This attribute is only allowed at the 
 650      outermost level. More than one settings are possible to specify 
 651      exactly the set of classes that are hidden. Note the important 
 652      difference between hiding of edges and the edge line style invisible. 
 653      Hidden edges are not existent in the layout. Edges with line style 
 654      invisible are existent in the layout; they need space and may 
 655      produce crossings and influence the layout, but you cannot see 
 660   /* Classname allows to introduce names for the edge classes. The names 
 661      are used in the menus. infoname allows to introduce names for the 
 662      additional text labels. The names are used in the menus. 
 663      defaults are 1,2,3... 
 664      By default, no class names. */ 
 665   struct classname 
*classname
; 
 667   /* Infoname allows to introduce names for the additional text labels.  
 668      The names are used in the menus.   
 669      Infoname is given by an integer and a string.   
 670      The default value is NULL.  */ 
 671   struct infoname 
*infoname
; 
 673   /* Colorentry allows to fill the color map. A color is a triplet of integer  
 674      values for the red/green/blue-part. Each integer is between 0 (off) and  
 675      255 (on), e.g., 0 0 0 is black and 255 255 255 is white. For instance  
 676      colorentry 75 : 70 130 180 sets the map entry 75 to steel blue. This  
 677      color can be used by specifying just the number 75. 
 679   struct colorentry 
*colorentry
; 
 681   /* layoutalgorithm chooses different graph layout algorithms 
 682      Possibilities are maxdepth, mindepth, maxdepthslow, mindepthslow, 
 683      maxdegree, mindegree, maxindegree, minindegree, maxoutdegree, 
 684      minoutdegree, minbackward, dfs and tree. The default algorithm tries 
 685      to give all edges the same orientation and is based on the 
 686      calculation of strongly connected components. The algorithms that 
 687      are based on depth first search are faster. While the simple dfs 
 688      does not enforce additionally constraints, the algorithm maxdepth 
 689      tries to increase the depth of the layout and the algorithm mindepth 
 690      tries to increase the wide of the layout. These algorithms are fast 
 691      heuristics. If they are not appropriate, the algorithms maxdepthslow 
 692      or mindepthslow also increase the depth or wide, but they are very 
 693      slow. The algorithm maxindegree lays out the nodes by scheduling the 
 694      nodes with the maximum of incoming edges first, and minindegree lays 
 695      out the nodes by scheduling the nodes with the minimum of incoming 
 696      edges first. In the same manner work the algorithms maxoutdegree and 
 697      minoutdegree for outgoing edges, and maxdegree and mindegree for the 
 698      sum of incoming and outgoing edges. These algorithms may have various 
 699      effects, and can sometimes be used as replacements of maxdepthslow 
 702      The algorithm minbackward can be used if the graph is acyclic. 
 703      The algorithm tree is a specialized method for downward laid out 
 704      trees. It is much faster on such tree-like graphs and results in a 
 706      Default is normal. */ 
 707   enum layoutalgorithm layoutalgorithm
; 
 709   /* Layout downfactor, layout upfactor, layout nearfactor The layout 
 710      algorithm partitions the set of edges into edges pointing upward, 
 711      edges pointing downward, and edges pointing sidewards. The last type 
 712      of edges is also called near edges. If the layout.downfactor is 
 713      large compared to the layout.upfactor and the layout.nearfactor, 
 714      then the positions of the nodes is mainly determined by the edges 
 715      pointing downwards. If the layout.upfactor is large compared to the 
 716      layout.downfactor and the layout.nearfactor, then the positions of 
 717      the nodes is mainly determined by the edges pointing upwards. If the 
 718      layout.nearfactor is large, then the positions of the nodes is 
 719      mainly determined by the edges pointing sidewards. These attributes 
 720      have no effect, if the method for downward laid out trees is used. 
 721      Default is normal. */ 
 722   int layout_downfactor
; 
 724   int layout_nearfactor
; 
 725   /* Layout splinefactor determines the bending at splines. The factor 
 726      100 indicates a very sharp bending, a factor 1 indicates a very flat 
 727      bending. Useful values are 30 : : : 80. */ 
 728   int layout_splinefactor
; 
 730   /* Late edge labels yes means that the graph is first partitioned and 
 731      then, labels are introduced. The default algorithm first creates 
 732      labels and then partitions the graph, which yield a more compact 
 733      layout, but may have more crossings. 
 735   enum decision late_edge_labels
; 
 737   /* Display edge labels yes means display labels and no means don't 
 739      Default vaule is no. */ 
 740   enum decision display_edge_labels
; 
 742   /* Dirty edge labels yes enforces a fast layout of edge labels, which 
 743      may very ugly because several labels may be drawn at the same place. 
 744      Dirty edge labels cannot be used if splines are used. 
 747   enum decision dirty_edge_labels
; 
 749   /* Finetuning no switches the fine tuning phase of the graph layout 
 750      algorithm off, while it is on as default. The fine tuning phase 
 751      tries to give all edges the same length. 
 753   enum decision finetuning
; 
 755   /* Ignore singles yes hides all nodes which would appear single and 
 756      unconnected from the remaining graph. Such nodes have no edge at all 
 757      and are sometimes very ugly. Default is to show all nodes. 
 759   enum decision ignore_singles
; 
 761   /* Long straight phase yes initiates an additional phase that tries to avoid 
 762      bendings in long edges. 
 763      Long edges are laid out by long straight vertical lines with 
 764      gradient 90 degree. Thus, this phase is not very appropriate for 
 765      normal layout, but it is recommended, if an orthogonal layout is 
 766      selected (see manhattan.edges). 
 768   enum decision long_straight_phase
; 
 770   /* priority phase yes replaces the normal pendulum method by a 
 771      specialized method: It forces straight long edges with 90 degree, 
 772      just as the straight phase. In fact, the straight phase is a fine 
 773      tune phase of the priority method. This phase is also recommended, 
 774      if an orthogonal layout is selected (see manhattan.edges). 
 776   enum decision priority_phase
; 
 778   /* manhattan edges yes switches the orthogonal layout on. Orthogonal 
 779      layout (or manhattan layout) means that all edges consist of line 
 780      segments with gradient 0 or 90 degree. Vertical edge segments might 
 781      by shared by several edges, while horizontal edge segments are never 
 782      shared. This results in very aesthetical layouts just for flowcharts. 
 783      If the orthogonal layout is used, then the priority phase and 
 784      straight phase should be used. Thus, these both phases are switched 
 785      on, too, unless priority layout and straight line tuning are 
 786      switched off explicitly. 
 788   enum decision manhattan_edges
; 
 790   /* Smanhattan edges yes switches a specialized orthogonal layout on: 
 791      Here, all horizontal edge segments between two levels share the same 
 792      horizontal line, i.e. not only vertical edge segments are shared, 
 793      but horizontal edge segments are shared by several edges, too. This 
 794      looks nice for trees but might be too confusing in general, because 
 795      the location of an edge might be ambiguously. 
 797   enum decision smanhattan_edges
; 
 799   /* Near edges no suppresses near edges and bent near edges in the 
 802   enum decision near_edges
; 
 804   /* Orientation specifies the orientation of the graph: top.to.bottom, 
 805      bottom.to.top, left.to.right or right.to.left. Note: the normal 
 806      orientation is top.to.bottom. All explanations here are given 
 807      relatively to the normal orientation, i.e., e.g., if the orientation 
 808      is left to right, the attribute xlspace is not the horizontal but 
 809      the vertical distance between lines, etc. 
 810      Default is to_to_bottom. */ 
 811   enum orientation orientation
; 
 813   /* Node alignment specified the vertical alignment of nodes at the 
 814      horizontal reference line of the levels. If top is specified, the 
 815      tops of all nodes of a level have the same y-coordinate; on bottom, 
 816      the bottoms have the same y-coordinate, on center the nodes are 
 817      centered at the levels. 
 818      Default is center. */ 
 819   enum alignment node_alignment
; 
 821   /* Port sharing no suppresses the sharing of ports of edges at the 
 822      nodes. Normally, if multiple edges are adjacent to the same node, 
 823      and the arrow head of all these edges has the same visual appearance 
 824      (color, size, etc.), then these edges may share a port at a node, 
 825      i.e. only one arrow head is draw, and all edges are incoming into 
 826      this arrow head. This allows to have many edges adjacent to one node 
 827      without getting confused by too many arrow heads. If no port sharing 
 828      is used, each edge has its own port, i.e. its own place where it is 
 829      adjacent to the node. 
 831   enum decision port_sharing
; 
 833   /* Arrow mode fixed (default) should be used, if port sharing is used, 
 834      because then, only a fixed set of rotations for the arrow heads are 
 835      used. If the arrow mode is free, then each arrow head is rotated 
 836      individually to each edge. But this can yield to a black spot, where 
 837      nothing is recognizable, if port sharing is used, since all these 
 838      qdifferently rotated arrow heads are drawn at the same place. If the 
 839      arrow mode is fixed, then the arrow head is rotated only in steps of 
 840      45 degree, and only one arrow head occurs at each port. 
 842   enum arrow_mode arrow_mode
; 
 844   /* Treefactor The algorithm tree for downward laid out trees tries to 
 845      produce a medium dense, balanced tree-like layout. If the tree 
 846      factor is greater than 0.5, the tree edges are spread, i.e. they 
 847      get a larger gradient. This may improve the readability of the tree. 
 848      Note: it is not obvious whether spreading results in a more dense or 
 849      wide layout. For a tree, there is a tree factor such that the whole 
 850      tree is minimal wide. 
 854   /* Spreadlevel This parameter only influences the algorithm tree, too. 
 855      For large, balanced trees, spreading of the uppermost nodes would 
 856      enlarge the width of the tree too much, such that the tree does not 
 857      fit anymore in a window. Thus, the spreadlevel specifies the minimal 
 858      level (rank) where nodes are spread. Nodes of levels upper than 
 859      spreadlevel are not spread. 
 863   /* Crossing weight specifies the weight that is used for the crossing 
 864      reduction: bary (default), median, barymedian or medianbary. We 
 865      cannot give a general recommendation, which is the best method. For 
 866      graphs with very large average degree of edges (number of incoming 
 867      and outgoing edges at a node), the weight bary is the fastest 
 868      method. With the weights barymedian and medianbary, equal weights of 
 869      different nodes are not very probable, thus the crossing reduction 
 870      phase 2 might be very fast. 
 872   enum crossing_type crossing_weight
; 
 874   /* Crossing phase2 is the most time consuming phase of the crossing 
 875      reduction. In this phase, the nodes that happen to have equal 
 876      crossing weights are permuted. By specifying no, this phase is 
 879   enum decision crossing_phase2
; 
 881   /* Crossing optimization is a postprocessing phase after the normal 
 882      crossing reduction: we try to optimize locally, by exchanging pairs 
 883      of nodes to reduce the crossings. Although this phase is not very 
 884      time consuming, it can be suppressed by specifying no. 
 886   enum decision crossing_optimization
; 
 888   /* View allows to select the fisheye views. Because 
 889      of the fixed size of the window that shows the graph, we normally 
 890      can only see a small amount of a large graph. If we shrink the graph 
 891      such that it fits into the window, we cannot recognize any detail 
 892      anymore. Fisheye views are coordinate transformations: the view onto 
 893      the graph is distort, to overcome this usage deficiency. The polar 
 894      fisheye is easy to explain: assume a projection of the plane that 
 895      contains the graph picture onto a spheric ball. If we now look onto 
 896      this ball in 3 D, we have a polar fisheye view. There is a focus 
 897      point which is magnified such that we see all details. Parts of the 
 898      plane that are far away from the focus point are demagnified very 
 899      much. Cartesian fisheye have a similar effect; only the formula for 
 900      the coordinate transformation is different. Selecting cfish means 
 901      the cartesian fisheye is used which demagnifies such that the whole 
 902      graph is visible (self adaptable cartesian fisheye). With fcfish, 
 903      the cartesian fisheye shows the region of a fixed radius around the 
 904      focus point (fixed radius cartesian fisheye). This region might be 
 905      smaller than the whole graph, but the demagnification needed to show 
 906      this region in the window is also not so large, thus more details 
 907      are recognizable. With pfish the self adaptable polar fisheye is 
 908      selected that shows the whole graph, and with fpfish the fixed 
 909      radius polar fisheye is selected. 
 910      Default is normal view.  */ 
 913   /* Edges no suppresses the drawing of edges. 
 917   /* Nodes no suppresses the drawing of nodes. 
 921   /* Splines specifies whether splines are used to draw edges (yes or no). 
 922      As default, polygon segments are used to draw edges, because this is 
 923      much faster. Note that the spline drawing routine is not fully 
 924      validated, and is very slow. Its use is mainly to prepare high 
 925      quality PostScript output for very small graphs. 
 927   enum decision splines
; 
 929   /* Bmax set the maximal number of iterations that are done for the 
 930      reduction of edge bendings. 
 934   /* Cmin set the minimal number of iterations that are done for the 
 935      crossing reduction with the crossing weights. The normal method 
 936      stops if two consecutive checks does not reduce the number of 
 937      crossings anymore. However, this increasing of the number of 
 938      crossings might be locally, such that after some more iterations, 
 939      the crossing number might decrease much more. 
 943   /* Cmax set the maximal number of interactions for crossing reduction. 
 944      This is helpful for speedup the layout process. 
 945      Default is infinite. */ 
 948   /* Pmin set the minimal number of iterations that is done with the 
 949      pendulum method. Similar to the crossing reduction, this method 
 950      stops if the `imbalancement weight' does not decreases anymore. 
 951      However, the increasing of the imbalancement weight might be locally, 
 952      such that after some more iterations, the imbalancement weight might 
 957   /* Pmax set the maximal number of iterations of the pendulum method. 
 958      This is helpful for speedup the layout process. 
 962   /* Rmin set the minimal number of iterations that is done with the 
 963      rubberband method. This is similar as for the pendulum method. 
 967   /* Rmax set the maximal number of iterations of the rubberband method. 
 968      This is helpful for speedup the layout process. 
 972   /* Smax set the maximal number of iterations of the straight line 
 973      recognition phase (useful only, if the straight line recognition 
 974      phase is switched on, see attribute straight.phase). 
 983   /* List of nodes declared. 
 987   /* List of edges declared. 
 993 /* Graph typedefs. */ 
 994 typedef struct graph graph
; 
 996 void new_graph (graph 
*g
); 
 997 void new_node (node 
*n
); 
 998 void new_edge (edge 
*e
); 
1000 void add_node (graph 
*g
, node 
*n
); 
1001 void add_edge (graph 
*g
, edge 
*e
); 
1003 void add_colorentry (graph 
*g
, int color_idx
, int red_cp
,  
1004                      int green_cp
, int blue_cp
); 
1005 void add_classname (graph 
*g
, int val
, const char *name
); 
1006 void add_infoname (graph 
*g
, int val
, const char *name
); 
1008 void open_node (FILE *fout
); 
1009 void output_node (node 
*n
, FILE *fout
); 
1010 void close_node (FILE *fout
); 
1012 void open_edge (edge 
*e
, FILE *fout
); 
1013 void output_edge (edge 
*e
, FILE *fout
); 
1014 void close_edge (FILE *fout
); 
1016 void open_graph (FILE *fout
); 
1017 void output_graph (graph 
*g
, FILE *fout
); 
1018 void close_graph (graph 
*g
, FILE *fout
);