GraphWin Layout Operations
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The Layout Operations of GraphWin manipulate the positions and sizes of nodes and the sequences of bends of the edges. Such operations are, for example, used to realize the functions in the layout menu of the interactive interface. See also Graph Drawing Algorithms for an application of layout operations. On the right you see a screenshot of a GraphWin with an orthogonal drawing of a planar graph. The screenshot is taken from the Example ORTHO_DRAW() from Section Graph Drawing Algorithms. Clicking on the picture shows the Graphwin in original size. |
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Some OperationsIn most layout operations the new node positions can be specified
as points or as pairs
of void gw.set_positions(const node_array<double>& xpos,
const node_array<double>& ypos);
void gw.set_positions(const node_array<point>& pos);
move every node v of gw from its old position
to (xpos[v],ypos[v]) or pos[v], respectively.
The bends of all edges are left unchanged. The operation
void gw.set_layout(const node_array<point>& pos,
const edge_array<list<point> > bends);
moves every node v to position pos[v] and
sets the bend sequence of every edge e to bends[e].
The operation
void gw.set_layout(const node_array<point>& pos);moves every node v to position pos[v] and
removes all edge bends from the layout. The operation
void gw.remove_bends();removes all edge bends from the layout and leaves the node positions unchanged. The operation void gw.place_into_box(double x0, double y0,
double x1, double y1);
moves the graph into the rectangular
box (x0,y0,x1,y1) by scaling and translating the layout,
and
void gw.place_into_win();moves the graph into the drawing window by scaling and translating. There are many more layout operations available. For a complete list have a look at the Manual Page GraphWin Animation of Layout ChangesGraphWin animates changes in the layout by linear interpolation. The parameter animation_steps controls this animation. If animation_steps is zero, the layout change is performed instantaneously. The operationint gw.set_animation_steps(int s);allows to change the parameter. Layout Coordinate ComputationConsider the following situation. Given aGraphWin gw
and the associated graph
G. We have computed a new layout for G, but the
new layout does not conform the coordinate space of gw
(see also pixel
and user coordinates). We want to adjust the layout data before
applying it. The following operations are a combination of a stretch
or shrink transformation with a translation of the window, that is,
they do not actually change the layout of the current graph.
GraphWin provides operations for this situation. They apply the
transformations void gw.adjust_coords_to_box(node_array<double>& xpos,
node_array<double>& ypos,
edge_array<list<double> >& xbends,
edge_array<list<double> >& ybends,
double x0, double y0, double x1, double y1);
moves and stretches the graph to fill the given rectangular box (x0,
y0, x1, y1) by appropriate scaling and translating operations.
void gw.adjust_coords_to_win(node_array<double>& xpos,
node_array<double>& ypos,
edge_array<list<double> >& xbends,
edge_array<list<double> >& ybends);
moves and stretches the graph to fill the entire window by appropriate
scaling and translating operations. For examples of how to use the
layout coordinate computation see Edit
and Run: A Simple Recipe for Interactive Demos or A
Recipe for Online Demos of Network Algorithms. |
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See also:
Edit and Run: A Simple Recipe for Interactive Demos
A Recipe for Online Demos of Network Algorithms
Basic Data Types for 2D Geometry