Graphviz wrapper
lazarus / 39-Graphics

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iLya2IK · 2022-01-29 09:15

Hello! Sorry if this question has already been asked, but I didn't
find anything suitable on the forum. Tell me please if there is a
pascal header for Graphvis library.

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iLya2IK · 2022-02-14 14:25

Out of desperation, I had to write my own wrapper  . Who is
interested, I invite you to the project page.

Here is a code example of how to use the wrapper
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i (* Create
and draw finite state machine example     *)(*
<https://graphviz.org/Gallery/directed/fsm.html> *) program
simpletest; uses Classes, OGLGraphvizWrapper; var  // wrapper  Cntx :
TGVContext;  Gv  : IGVCntxGraph;  Nv : Array [0..8] of IGVNode;  Ev :
IGVEdge;  Av : TGVAttrId;  NI, EI : IGVIterator;  FS :
TFileStream;begin  if TGVContext.GVLibsLoad then // initalize gvc and
cgraph libs  begin    Cntx := TGVContext.Create;    try      Gv :=
Cntx.NewGraph('finite_state_machine', [gvoDirected]);      try       
Gv.GraphAttr('rankdir', 'LR');        Gv.GraphAttr('size', '8, 5');  
    Gv.NodeAttr('shape', 'doublecircle');        Nv[0] :=
Gv.Node('0');        Nv[3] := Gv.Node('3');        Nv[4] :=
Gv.Node('4');        Nv[8] := Gv.Node('8');       
Gv.NodeAttr('shape', 'circle');        Nv[2] := Gv.Node('2');       
Nv[1] := Gv.Node('1');        Nv[6] := Gv.Node('6');        Nv[5] :=
Gv.Node('5');        Nv[7] := Gv.Node('7');         Av :=
Gv.EdgeAttr('label', '');        Ev := Gv.Edge(Gv.FindNode('0'),
Gv.FindNode('2'));        Ev.SetExAttr(Av, 'SS(B)');       
Gv.Edge(Nv[0], Nv[1]).SetExAttr(Av, 'SS(S)');        Gv.Edge(Nv[1],
Nv[3]).SetExAttr(Av, 'S($end)');        Gv.Edge(Nv[2],
Nv[6]).SetExAttr(Av, 'SS(b)');        Gv.Edge(Nv[2],
Nv[5]).SetExAttr(Av, 'SS(a)');        Gv.Edge(Nv[2],
Nv[4]).SetExAttr(Av, 'S(A)');        Gv.Edge(Nv[5],
Nv[7]).SetExAttr(Av, 'S(b)');        Gv.Edge(Nv[5],
Nv[5]).SetExAttr(Av, 'S(a)');        Gv.Edge(Nv[6],
Nv[6]).SetExAttr(Av, 'S(b)');        Gv.Edge(Nv[6],
Nv[5]).SetExAttr(Av, 'S(a)');        Gv.Edge(Nv[7],
Nv[8]).SetExAttr(Av, 'S(b)');        Gv.Edge(Nv[7],
Nv[5]).SetExAttr(Av, 'S(a)');        Gv.Edge(Nv[8],
Nv[6]).SetExAttr(Av, 'S(b)');        Gv.Edge(Nv[8],
Nv[5]).SetExAttr(Av, 'S(a)');         // place the graph in a
contextual layout to initialize         // drawing interfaces using a
specific engine (dot)        Gv.Layout(Cntx, 'dot');                 
// iterating through all nodes and edges of the graph        NI :=
Gv.GetNodeIterator;        while NI.HasNext do        begin         
Nv[0] := NI.Next as IGVNode;          WriteLn('Node ', Nv[0].Name);  
      EI := Gv.GetEdgeIterator(Nv[0]);          while EI.HasNext do  
      begin            Ev := EI.Next as IGVEdge;            WriteLn('
 Edge ', Ev.GetExAttr(Av).AsString);          end;        end;       
// draw the graph in an SVG file        Gv.RenderFilename('svg',
'out3.svg');                        // example of drawing the graph
into a stream        FS := TFileStream.Create('out4.bmp', fmCreate or
fmOpenWrite);        try          Gv.RenderStream('bmp', FS);       
finally          FS.Free;        end;       finally        Gv.Close; 
   end;    finally      Cntx.Free;    end;    
TGVContext.GVLibsUnLoad;  end else begin    WriteLn('Cant initialize
Graphviz');  end;  Readln;end.

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avra · 2022-02-15 01:13

Thanks! I will have a need for this in the future...