Fit Nodes in the Scene on Initialization

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@cosmograph/cosmos",
-  "version": "1.4.2",
+  "version": "1.5.1",
   "description": "GPU-based force graph layout and rendering",
   "main": "dist/index.js",
   "types": "dist/index.d.ts",

src/config.ts

@@ -363,6 +363,23 @@ export interface GraphConfigInterface<N extends CosmosInputNode, L extends Cosmo
    * Default: `false`
    */
   disableZoom?: boolean;
+  /**
+   * Whether to center and zoom the view to fit all nodes in the scene on initialization or not.
+   * Default: `true`
+   */
+  fitViewOnInit?: boolean;
+  /**
+   * Delay in milliseconds before fitting the view.
+   * Useful if you want the layout to stabilize a bit before fitting.
+   * Default: `250`
+   */
+  fitViewDelay?: number;
+  /**
+   * When `fitViewOnInit` is set to `true`, fits the view to show the nodes within a rectangle
+   * defined by its two corner coordinates `[[left, bottom], [right, top]]` in the scene space.
+   * Default: `undefined`
+   */
+  fitViewByNodesInRect?: [[number, number], [number, number]] | [number, number][];
   /**
    * Providing a `randomSeed` value allows you to control
    * the randomness of the layout across different simulation runs.
@@ -444,6 +461,9 @@ export class GraphConfig<N extends CosmosInputNode, L extends CosmosInputLink> i
   public scaleNodesOnZoom = defaultConfigValues.scaleNodesOnZoom
   public initialZoomLevel = defaultConfigValues.initialZoomLevel
   public disableZoom = defaultConfigValues.disableZoom
+  public fitViewOnInit = defaultConfigValues.fitViewOnInit
+  public fitViewDelay = defaultConfigValues.fitViewDelay
+  public fitViewByNodesInRect = undefined
 
   public randomSeed = undefined
   public nodeSamplingDistance = defaultConfigValues.nodeSamplingDistance

src/index.ts

@@ -51,6 +51,11 @@ export class Graph<N extends CosmosInputNode, L extends CosmosInputLink> {
    * If the mouse is not on the Canvas, the `findHoveredPoint` method will not be executed.
    */
   private _isMouseOnCanvas = false
+  /**
+   * After setting data at a first time, the fit logic will run
+   * */
+  private _isFirstDataAfterInit = true
+  private _fitViewOnInitTimeoutID: number | undefined
 
   public constructor (canvas: HTMLCanvasElement, config?: GraphConfigInterface<N, L>) {
     if (config) this.config.init(config)
@@ -212,6 +217,7 @@ export class Graph<N extends CosmosInputNode, L extends CosmosInputLink> {
    * @param runSimulation When set to `false`, the simulation won't be started automatically (`true` by default).
    */
   public setData (nodes: N[], links: L[], runSimulation = true): void {
+    const { fitViewOnInit, fitViewDelay, fitViewByNodesInRect } = this.config
     if (!nodes.length && !links.length) {
       this.destroyParticleSystem()
       this.reglInstance.clear({
@@ -222,6 +228,14 @@ export class Graph<N extends CosmosInputNode, L extends CosmosInputLink> {
       return
     }
     this.graph.setData(nodes, links)
+    if (this._isFirstDataAfterInit && fitViewOnInit) {
+      this._fitViewOnInitTimeoutID = window.setTimeout(() => {
+        if (fitViewByNodesInRect) this.setZoomTransformByNodePositions(fitViewByNodesInRect, undefined, undefined, 0)
+        else this.fitView()
+      }, fitViewDelay)
+    }
+    this._isFirstDataAfterInit = false
+
     this.update(runSimulation)
   }
 
@@ -608,6 +622,7 @@ export class Graph<N extends CosmosInputNode, L extends CosmosInputLink> {
    * Destroy this Cosmos instance.
    */
   public destroy (): void {
+    window.clearTimeout(this._fitViewOnInitTimeoutID)
     this.stopFrames()
     this.destroyParticleSystem()
     this.fpsMonitor?.destroy()
@@ -803,9 +818,9 @@ export class Graph<N extends CosmosInputNode, L extends CosmosInputLink> {
     }
   }
 
-  private setZoomTransformByNodePositions (positions: [number, number][], duration = 250, scale?: number): void {
+  private setZoomTransformByNodePositions (positions: [number, number][], duration = 250, scale?: number, padding?: number): void {
     this.resizeCanvas()
-    const transform = this.zoomInstance.getTransform(positions, scale)
+    const transform = this.zoomInstance.getTransform(positions, scale, padding)
     this.canvasD3Selection
       .transition()
       .ease(easeQuadInOut)

src/modules/Zoom/index.ts

@@ -46,17 +46,18 @@ export class Zoom <N extends CosmosInputNode, L extends CosmosInputLink> {
     this.config = config
   }
 
-  public getTransform (positions: [number, number][], scale?: number): ZoomTransform {
+  public getTransform (positions: [number, number][], scale?: number, padding = this.store.maxPointSize / 2): ZoomTransform {
     if (positions.length === 0) return this.eventTransform
-    const { store: { screenSize, maxPointSize } } = this
+    const { store: { screenSize } } = this
     const width = screenSize[0]
     const height = screenSize[1]
     const xExtent = extent(positions.map(d => d[0])) as [number, number]
     const yExtent = extent(positions.map(d => d[1])) as [number, number]
-    xExtent[0] = this.store.scaleX(xExtent[0] - maxPointSize / 2)
-    xExtent[1] = this.store.scaleX(xExtent[1] + maxPointSize / 2)
-    yExtent[0] = this.store.scaleY(yExtent[0] - maxPointSize / 2)
-    yExtent[1] = this.store.scaleY(yExtent[1] + maxPointSize / 2)
+    xExtent[0] = this.store.scaleX(xExtent[0] - padding)
+    xExtent[1] = this.store.scaleX(xExtent[1] + padding)
+    yExtent[0] = this.store.scaleY(yExtent[0] - padding)
+    yExtent[1] = this.store.scaleY(yExtent[1] + padding)
+
     const xScale = width / (xExtent[1] - xExtent[0])
     const yScale = height / (yExtent[0] - yExtent[1])
     const clampedScale = clamp(scale ?? Math.min(xScale, yScale), ...this.behavior.scaleExtent())

src/variables.ts

@@ -41,6 +41,8 @@ export const defaultConfigValues = {
   scaleNodesOnZoom: true,
   initialZoomLevel: 1,
   disableZoom: false,
+  fitViewOnInit: true,
+  fitViewDelay: 250,
   nodeSamplingDistance: 150,
 }