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7.34 flowchart

This package provides routines to assist in drawing flowcharts. The primary structure is a block, which represents a single block on the flowchart. The following eight functions return a position on the appropriate edge of the block, given picture transform t: 

pair block.top(transform t=identity());
pair block.left(transform t=identity());
pair block.right(transform t=identity());
pair block.bottom(transform t=identity());
pair block.topleft(transform t=identity());
pair block.topright(transform t=identity());
pair block.bottomleft(transform t=identity());
pair block.bottomright(transform t=identity());
To obtain an arbitrary position along the boundary of the block in user coordinates, use: 
pair block.position(real x, transform t=identity());
The center of the block in user coordinates is stored in block.center and the block size in PostScript coordinates is given by block.size.

A frame containing the block is returned by 

frame block.draw(pen p=currentpen);
The following block generation routines accept a Label, string, or frame for their object argument:
rectangular block with an optional header (and padding dx around header and body):
     
     block rectangle(object header, object body, pair center=(0,0),
                     pen headerpen=mediumgray, pen bodypen=invisible,
                     pen drawpen=currentpen,
                     real dx=3, real minheaderwidth=0, real minheaderheight=0,
                     real minbodywidth=0, real minbodyheight=0);
     block rectangle(object body, pair center=(0,0), pen fillpen=invisible,
                     pen drawpen=currentpen, real dx=3, real minwidth=0,
                     real minheight=0);

diamond-shaped flowchart block:
     
     block diamond(object body, pair center=(0,0),
                   pen fillpen=invisible, pen drawpen=currentpen,
                   real ds=5, real dw=1,
                   real height=20, real minwidth=0, real minheight=0);

circular flowchart block:
     
     block circle(object body, pair center=(0,0), pen fillpen=invisible,
                  pen drawpen=currentpen, real dr=3, real mindiameter=0);

rectangular flowchart block with rounded corners:
     
     block roundrectangle(object body, pair center=(0,0),
                          pen fillpen=invisible, pen drawpen=currentpen,
                          real ds=5, real dw=0, real minwidth=0,
                          real minheight=0);

rectangular flowchart block with beveled edges:
     
     block bevel(object body, pair center=(0,0), pen fillpen=invisible,
                 pen drawpen=currentpen, real dh=5,
                 real dw=5, real minwidth=0, real minheight=0);

To draw paths joining the pairs in point with right-angled lines, use the routine: 

path path(pair point[] ... bool horizontal[]);
The entries in horizontal identify whether successive segments between the pairs specified by point should be drawn horizontal (true) or vertical (false).

Here is a simple flowchart example: 

size(0,300);

import flowchart;

block block1=rectangle(Label("Example",magenta),
		       pack(Label("Start:",heavygreen),"",Label("$A:=0$",blue),
			    "$B:=1$"),(-0.5,3),palegreen,paleblue,red);
block block2=diamond(Label("Choice?",blue),(0,2),palegreen,red);
block block3=roundrectangle("Do something",(-1,1));
block block4=bevel("Don't do something",(1,1));
block block5=circle("End",(0,0));

draw(block1);
draw(block2);
draw(block3);
draw(block4);
draw(block5);

add(new void(frame f, transform t) {
    picture pic;
    draw(pic,path(new pair[]{block1.right(t),block2.top(t)},Horizontal),
         Arrow,PenMargin);
    draw(pic,Label("Yes",0.5),path(new pair[]{block2.left(t),block3.top(t)},
                                   Horizontal),Arrow,PenMargin);
    draw(pic,Label("No",0.5,N),path(new pair[]{block2.right(t),block4.top(t)},
                                    Horizontal),Arrow,PenMargin);
    draw(pic,path(new pair[]{block3.bottom(t),block5.left(t)},Vertical),
         Arrow,PenMargin);
    draw(pic,path(new pair[]{block4.bottom(t),block5.right(t)},Vertical),
         Arrow,PenMargin);

    add(f,pic.fit());
  });
flowchartdemo.png