# Class PackedLayout

GoJS® Diagramming Components
version 3.0.13
by Northwoods Software®

This is an extension and not part of the main GoJS library. Note that the API for this class may change at any time. If you intend to use an extension in production, you should copy the code to your own source directory. See the Extensions intro page for more information.

#### Hierarchy

- Layout
  - PackedLayout

Custom layout which attempts to pack nodes as close together as possible without overlap. Each node is assumed to be either rectangular or circular (dictated by the hasCircularNodes property). This layout supports packing nodes into either a rectangle or an ellipse, with the shape determined by the packShape property and the aspect ratio determined by either the aspectRatio property or the specified width and height (depending on the packMode).

Nodes with 0 width or height cannot be packed, so they are treated by this layout as having a width or height of 0.1 instead.

If you want to experiment with this extension, try the PackedLayout sample.

#####
Index

### Constructors

constructor

### Accessors

actualBounds
actualSpacing
arrangesToOrigin
aspectRatio
comparer
enclosingCircle
hasCircularNodes
packMode
packShape
size
sortMode
sortOrder
spacing

### Methods

commitLayout
doLayout

#####
Inherited Index

### Accessors

Layout.arrangementOrigin
Layout.boundsComputation
Layout.diagram
Layout.group
Layout.isInitial
Layout.isOngoing
Layout.isRealtime
Layout.isRouting
Layout.isValidLayout
Layout.isViewportSized
Layout.network

### Methods

Layout.collectParts
Layout.copy
Layout.createNetwork
Layout.getLayoutBounds
Layout.initialOrigin
Layout.invalidateLayout
Layout.makeNetwork
Layout.updateParts

## Constructors

### constructor

- new PackedLayout(init?: Partial<PackedLayout>): PackedLayout

- #### Parameters

  - ##### `Optional` init: Partial<PackedLayout>

  #### Returns PackedLayout

## Accessors

### `Readonly` actualBounds
: Rect

- This read-only property returns the actual rectangular bounds occupied by the packed nodes. This property does not take into account any kind of spacing around the packed nodes.

  Note that this property will only return a valid value after a layout has been performed. Before then, its behavior is undefined.

### `Readonly` actualSpacing
: number

- This read-only property is the effective spacing calculated after doLayout.

  If the packMode is PackMode.AspectOnly, this will simply be the spacing property. However, in the PackMode.Fit and PackMode.ExpandToFit modes, this property will include the forced spacing added by the modes themselves.

  Note that this property will only return a valid value after a layout has been performed. Before then, its behavior is undefined.

### arrangesToOrigin
: boolean

- Gets or sets whether or not to use the go.Layout.arrangementOrigin property when placing nodes.

  The default value is true.

### aspectRatio
: number

- Gets or sets the aspect ratio for the shape that nodes will be packed into. The provided aspect ratio should be a nonzero postive number.

  Note that this only applies if the packMode is PackMode.AspectOnly. Otherwise, the size will determine the aspect ratio of the packed shape.

  The default value is 1.

### comparer
: ((a: Node, b: Node) => number)

- Gets or sets the comparison function used for sorting nodes.

  By default, the comparison function is set according to the values of sortMode and sortOrder.

  Whether this comparison function is used is determined by the value of sortMode. Any value except SortMode.None will result in the comparison function being used.

        new PackedLayout({
            sortMode: SortMode.Area,
            comparer: (na, nb) => {
              const na = na.data;
              const nb = nb.data;
              if (da.someProperty < db.someProperty) return -1;
              if (da.someProperty > db.someProperty) return 1;
              return 0;
            }
          })

### `Readonly` enclosingCircle
: Rect

- This read-only property returns the smallest enclosing circle around the packed nodes. It makes use of the hasCircularNodes property to determine whether or not to make enclosing circle calculations for rectangles or for circles. This property does not take into account any kind of spacing around the packed nodes. The enclosing circle calculation is performed the first time this property is retrieved, and then cached to prevent slow accesses in the future.

  Note that this property will only return a valid value after a layout has been performed. Before then, its behavior is undefined.

  This property is included as it may be useful for some data visualizations.

### hasCircularNodes
: boolean

- Gets or sets whether or not to assume that nodes are circular. This changes the packing algorithm to one that is much more efficient for circular nodes.

  As this algorithm expects circles, it is assumed that if this property is set to true that the given nodes will all have the same height and width. All calculations are done using the width of the given nodes, so unexpected results may occur if the height differs from the width.

  The default value is false.

### packMode
: PackMode

- Gets or sets the mode that the layout will use to determine its size. Valid values are PackMode values.

  The default value is PackMode.AspectOnly. In this mode, the layout will simply grow as needed, attempting to keep the aspect ratio defined by aspectRatio.

### packShape
: PackShape

- Gets or sets the shape that nodes will be packed into. Valid values are PackShape values.

  In PackShape.Spiral mode, nodes are not packed into a particular shape, but rather packed consecutively one after another in a spiral fashion. The aspectRatio property is ignored in this mode, and the size property (if provided) is expected to be square. If it is not square, the largest dimension given will be used. This mode currently only works with circular nodes, so setting it cause the assume that layout to assume that hasCircularNodes is true.

  Note that this property sets only the shape, not the aspect ratio. The aspect ratio of this shape is determined by either aspectRatio or size, depending on the packMode.

  When the packMode is PackMode.Fit or PackMode.ExpandToFit and this property is set to true, the layout will attempt to make the diameter of the enclosing circle of the layout approximately equal to the greater dimension of the given size property.

  The default value is PackShape.Elliptical.

### size
: Size

- Gets or sets the size for the shape that nodes will be packed into. To fill the viewport, set a size with a width and height of NaN. Size values of 0 are considered for layout purposes to instead be 1.

  If the width and height are set to NaN (to fill the viewport), but this layout has no diagram associated with it, the default value of size will be used instead.

  Note that this only applies if the packMode is PackMode.Fit or PackMode.ExpandToFit.

  The default value is 500x500.

### sortMode
: SortMode

- Gets or sets the method by which nodes will be sorted before being packed. To change the order, see sortOrder.

  The default value is SortMode.None, in which nodes will not be sorted at all.

### sortOrder
: SortOrder

- Gets or sets the order that nodes will be sorted in before being packed. To change the sort method, see sortMode.

  The default value is SortOrder.Descending

### spacing
: number

- Gets or sets the spacing between nodes. This value can be set to any real number (a negative spacing will compress nodes together, and a positive spacing will leave space between them).

  Note that the spacing value is only respected in the PackMode.Fit packMode if it does not cause the layout to grow outside of the specified bounds. In the PackMode.ExpandToFit packMode, this property does not do anything.

  The default value is 0.

## Methods

### `Virtual` `Override` commitLayout

- commitLayout(): void

- This method is called at the end of doLayout, but before the layout transaction is committed. It can be overriden and used to customize layout behavior. By default, the method does nothing.

  #### Returns void

### `Override` doLayout

- doLayout(coll: Diagram | Iterable<Part> | Group): void

- Performs the PackedLayout.

  #### Parameters

  - ##### coll: Diagram | Iterable<Part> | Group

    A go.Diagram or a go.Group or a collection of go.Parts.

  #### Returns void

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