Deck

Deck is a class that takes deck.gl layer instances and viewport parameters, renders those layers as a transparent overlay, and handles events.

If you are using React, you should not use this class directly. Instead you should be rendering the DeckGL React component.

Usage

// Basic standalone use
import {Deck} from '@deck.gl/core';
import {ScatterplotLayer} from '@deck.gl/layers';

const deck = new Deck({
  initialViewState: {
    longitude: -122.45,
    latitude: 37.78,
    zoom: 12
  },
  controller: true,
  layers: [
    new ScatterplotLayer({data})
  ]
});

Constructor

Creates a new Deck instance.

const deck = new Deck(props);

Parameters:

See the Properties section.

Properties

Initialization Settings

The following properties are used to initialize a Deck instance. Any custom value should always be provided to the Deck constructor. Changing them with setProps afterwards will have no effect.

canvas (HTMLCanvasElement | String, optional)

The canvas to render into. Can be either a HTMLCanvasElement or the element id. Will be auto-created if not supplied.

gl (WebGLContext)

WebGL context. Will be auto-created if not supplied.

glOptions (Object)

Additional options used when creating the WebGLContext. See WebGL context attributes.

id (String)

• Default: 'deckgl-overlay'

ID assigned to the canvas that is created by this Deck instance, to allow style customization in CSS.

parent (HTMLElement)

• Default: document.body

The container to append the auto-created canvas to.

debug (Boolean)

• Default: false

Flag to enable WebGL debug mode. Also requires an extra luma.gl import:

import '@luma.gl/debug';
import {Deck} from '@deck.gl/core';

new Deck({
  // ...
  debug: true
})

Notes:

• Debug mode is slower as it will use synchronous operations to keep track of GPU state.

_typedArrayManagerProps (Object)

• Default: {}

(Experimental) May contain the following fields:

• overAlloc (Number) - Default 2. By default, attributes are allocated twice the memory than they actually need (on both CPU and GPU). Must be larger than 1.
• poolSize (Number) - Default 100. When memory reallocation is needed, old chunks are held on to and recycled. Smaller number uses less CPU memory. Can be any number >=0.

The above default settings make data updates faster, at the price of using more memory. If the app does not anticipate frequent data changes, they may be aggressively reduced:

new Deck({
  // ...
  _typedArrayManagerProps: isMobile ? {overAlloc: 1, poolSize: 0} : null
})

Rendering Configuration

width (Number|String)

• Default: '100%'

Width of the canvas, a number in pixels or a valid CSS string.

height (Number|String)

• Default: '100%'

Height of the canvas, a number in pixels or a valid CSS string.

style (Object)

Additional CSS styles for the canvas.

useDevicePixels (Boolean|Number)

• Default: true

Controls the resolution of drawing buffer used for rendering.

• true: Device (physical) pixels resolution is used for rendering, this resolution is defined by window.devicePixelRatio. On Retina/HD systems this resolution is usually twice as big as CSS pixels resolution.
• false: CSS pixels resolution (equal to the canvas size) is used for rendering.
• Number (Experimental): Specified Number is used as a custom ratio (drawing buffer resolution to CSS pixel resolution) to determine drawing buffer size, a value less than one uses resolution smaller than CSS pixels, gives better performance but produces blurry images, a value greater than one uses resolution bigger than CSS pixels resolution (canvas size), produces sharp images but at a lower performance.

Note:

• Consider setting to false or to a number <=1 if better rendering performance is needed.
• When it is set to a high Number (like, 4 or more), it is possible to hit the system limit for allocating drawing buffer, such cases will log a warning and fallback to system allowed resolution.

parameters (Object)

Expects an object with WebGL settings. Before each frame is rendered, this object will be passed to luma.gl's setParameters function to reset the WebGL context parameters, e.g. to disable depth testing, change blending modes etc. The default parameters set by Deck on initialization are the following:

{
  blend: true,
  blendFunc: [GL.SRC_ALPHA, GL.ONE_MINUS_SRC_ALPHA, GL.ONE, GL.ONE_MINUS_SRC_ALPHA],
  polygonOffsetFill: true,
  depthTest: true,
  depthFunc: GL.LEQUAL
}

Refer to the luma.gl setParameters API for documentation on supported parameters and values.

import GL from '@luma.gl/constants';
new Deck({
  // ...
  parameters: {
    blendFunc: [GL.ONE, GL.ONE, GL.ONE, GL.ONE],
    depthTest: false
  }
});

Notes:

• Any WebGL parameters prop supplied to individual layers will still override the global parameters when that layer is rendered.
• An alternative way to set parameters is to instead define the onWebGLInitialized callback (it receives the gl context as parameter) and call the luma.gl setParameters method inside it.

layers (Array)

• Default: []

The array of Layer instances to be rendered.

Nested arrays are accepted, as well as falsy values (null, false, undefined). This allows applications to do something like:

new Deck({
  // ...
  layers: dataSource.map((item, index) => item && [
    new ScatterplotLayer({id: `scatterplot-${index}`, ...}),
    new PolygonLayer({id: `polygon-${index}`, ...})
  ])
});
// layers is in the shape of [[<layer>, <layer>], null, [<layer>, <layer>], ...]

layerFilter (Function)

• Default: null

If supplied, will be called before a layer is drawn to determine whether it should be rendered. This gives the application an opportunity to filter out layers from the layer list during either rendering or picking. Filtering can be done per viewport or per layer or both. This enables techniques like adding helper layers that work as masks during picking but do not show up during rendering.

new Deck({
  // ...
  layerFilter: ({layer, viewport}) => {
    if (viewport.id !== 'minimap' && layer.id === 'geofence') {
      // only display geofence in the minimap
      return false;
    }
    return true;
  }
}

Receives arguments:

• layer (Layer) - the layer to be drawn
• viewport (Viewport) - the current viewport
• isPicking (Boolean) - whether this is a picking pass
• renderPass (String) - the name of the current render pass. Some standard passes are:
  • 'screen' - drawing to screen
  • 'picking:hover' - drawing to offscreen picking buffer due to pointer move
  • 'picking:query' - drawing to offscreen picking buffer due to user-initiated query, e.g. calling deck.pickObject.
  • 'shadow' - drawing to shadow map

Returns:

true if the layer should be drawn.

Notes:

• layerFilter does not override the visibility if the layer is disabled via visible: false or pickable: false props.
• All the lifecycle methods other than draw are still triggered even a if a layer is filtered out using this method.

views (Object|Array)

• Default: new MapView()

A single View instance, or an array of View instances.

Views represent the "camera(s)" (essentially viewport dimensions and projection matrices) that you look at your data with. deck.gl offers multiple view types for both geospatial and non-geospatial use cases. Read the Views and Projections guide for the concept and examples.

viewState (Object)

An object that describes the view state for each view in the views prop. For example, the default view's view state is described here:

new Deck({
  // ...
  viewState: {
    longitude: -122.45,
    latitude: 37.78,
    zoom: 12,
    pitch: 30,
    bearing: 0
  }
})

When using multiple views, the viewState is a map from each view id to its respective view state object. See example.

Transitions between two viewState objects can also be achieved by providing set of fields to viewState prop, for more details check ViewState Transitions).

Notes:

• If you supply this prop, you are responsible of managing the changes to the view state upon user interaction. This prop is therefore usually used together with the onViewStateChange callback (example). For Deck to update view states automatically, use the initialViewState prop instead.

initialViewState (Object)

If initialViewState is provided, the Deck component will track view state changes from any attached controller using internal state, with initialViewState as its initial view state. This is the easiest way to control the camera.

If the initialViewState prop changes, the internally tracked view state will be updated to match the new "initial" view state.

Notes:

• The onViewStateChange callback will still be called, if provided.
• If the viewState prop is supplied by the application, the supplied viewState will always be used, overriding the Deck component's internal view state.
• In simple applications, use of the initialViewState prop can avoid the need to track the view state in the application.
• One drawback of using initialViewState for reactive/functional applications is that the Deck component becomes more stateful.

effects (Array)

The array of effects to be rendered. A lighting effect will be added if an empty array is supplied. Refer to effect's documentation to see details:

• LightingEffect
• PostProcessEffect

_framebuffer (Object)

(Experimental) Render to a custom frame buffer other than to screen.

_animate (Boolean)

• Default: false

(Experimental) Forces deck.gl to redraw layers every animation frame. Normally deck.gl layers are only redrawn if any change is detected.

Interaction Settings

controller (Function | Boolean | Object)

• Default: null

Options for viewport interactivity, e.g. pan, rotate and zoom with mouse, touch and keyboard. This is a shorthand for defining interaction with the views prop if you are using the default view (i.e. a single MapView).

new Deck({
  // ...
  views: [
    new MapView({
      controller: {touchRotate: true, doubleClickZoom: false}
    })
  ]
})

is equivalent to:

new Deck({
  // ...
  // views: undefined
  controller: {touchRotate: true, doubleClickZoom: false}
})

controller can be one of the following types:

• null or false: the viewport is not interactive.
• true: initiates the default controller of the default view - e.g. a MapController if MapView is used.
• Controller class (not instance): initiates the provided controller with default options. Must be a subclass of Controller.
• Object: controller options. This will be merged with the default controller options.
  • controller.type: the controller class, must be a subclass of Controller.
  • Other options supported by the controller type. Consult the documentation of Controller.

getCursor (Function)

• Default: ({isDragging}) => isDragging ? 'grabbing' : 'grab'

A custom callback to retrieve the cursor type.

Receives arguments:

• interactiveState (Object)
  • isDragging (Boolean) - whether the pointer is down and moving
  • isHovering (Boolean) - whether the pointer is over a pickable object

Returns:

A valid CSS cursor string.

Remarks:

• It is worth noting that when supplying a custom image for the cursor icon, Chrome requires a fallback option to be supplied, otherwise the custom image will not be loaded; e.g. getCursor={() => 'url(images/custom.png), auto'}

getTooltip (Function)

Callback that takes a hovered-over point and renders a tooltip. If the prop is not specified, the tooltip is always hidden.

Receives arguments:

• info - the picking info describing the object being hovered.

Returns one of the following:

• null - the tooltip is hidden, with the CSS display property set to none.
• A string - the string is rendered in a tooltip with the default CSS styling described below.
• An object with the following fields:
  • text (String, optional) - Specifies the innerText attribute of the tooltip.
  • html (String, optional) - Specifies the innerHTML attribute of the tooltip. Note that this will override the specified innerText.
  • className (String, optional) - Class name to attach to the tooltip element. The element has the default class name of deck-tooltip.
  • style (Object, optional) - An object of CSS styles to apply to the tooltip element, which can override the default styling.

By default, the tooltip has the following CSS style:

z-index: 1;
position: absolute;
color: #a0a7b4;
background-color: #29323c;
padding: 10px;

pickingRadius (Number)

Extra pixels around the pointer to include while picking. This is helpful when rendered objects are difficult to target, for example irregularly shaped icons, small moving circles or interaction by touch. Default 0.

touchAction (String)

• Default: none.

Allow browser default touch actions. See hammer.js documentation.

By default, the deck canvas captures all touch interactions. This prop is useful for mobile applications to unblock default scrolling behavior. For example, use the combination controller: {dragPan: false} and touchAction: 'pan-y' to allow vertical page scroll when dragging over the canvas.

eventRecognizerOptions (Object)

• default: {}

Set options for gesture recognition. May contain the following fields:

• pan - an object that is Hammer.Pan options. This gesture is used for drag events.
• pinch - an object that is Hammer.Pinch options This gesture is used for two-finger touch events.
• tripan - an object that is Hammer.Pan options. This gesture is used for three-finger touch events.
• tap - an object that is Hammer.Tap options. This gesture is used for the onClick callback.
• doubletap - an object that is Hammer.Tap options. This gesture is used for double click events.

For example, the following setting makes panning less sensitive and clicking easier on mobile:

new Deck({
  // ...
  eventRecognizerOptions: isMobile ? {
    pan: {threshold: 10},
    tap: {threshold: 5}
  } : {}
})

_pickable (Boolean)

• Default: true

(Experimental) If set to false, force disables all picking features, disregarding the pickable prop set in any layer.

Event Callbacks

onWebGLInitialized (Function)

Called once the WebGL context has been initiated.

Receives arguments:

• gl - the WebGL context.

onViewStateChange (Function)

Called when the user has interacted with the deck.gl canvas, e.g. using mouse, touch or keyboard.

onViewStateChange({viewState, interactionState, oldViewState})

Receives arguments:

• viewState - An updated view state object.
• interactionState - Describes the interaction that invoked the view state change. May include the following fields:
  • inTransition (Boolean)
  • isDragging (Boolean)
  • isPanning (Boolean)
  • isRotating (Boolean)
  • isZooming (Boolean)
• oldViewState - The previous view state object.

Returns:

A view state object that is used to update Deck's internally tracked view state (see initialViewState). This can be used to intercept and modify the view state before the camera updates, see add constraints to view state example.

If no value is returned, it's equivalent to (viewState) => viewState.

onInteractionStateChange (Function)

Called when the user has interacted with the deck.gl canvas, e.g. using mouse, touch or keyboard.

onInteractionStateChange(interactionState)

Receives arguments:

• interactionState - Describes the current interaction. May include the following fields:
  • inTransition (Boolean)
  • isDragging (Boolean)
  • isPanning (Boolean)
  • isRotating (Boolean)
  • isZooming (Boolean)

Note:

• onInteractionStateChange may be fired without onViewStateChange. For example, when the pointer is released at the end of a drag-pan, isDragging is reset to false, without the viewport's longitude and latitude changing.

onHover (Function)

Called when the pointer moves over the canvas.

Receives arguments:

• info - the picking info describing the object being hovered.
• event - the original gesture event

onClick (Function)

Called when clicking on the canvas.

Receives arguments:

• info - the picking info describing the object being clicked.
• event - the original gesture event

onDragStart (Function)

Called when the user starts dragging on the canvas.

Receives arguments:

• info - the picking info describing the object being dragged.
• event - the original gesture event

onDrag (Function)

Called when dragging the canvas.

Receives arguments:

• info - the picking info describing the object being dragged.
• event - the original gesture event

onDragEnd (Function)

Called when the user releases from dragging the canvas.

Receives arguments:

• info - the picking info describing the object being dragged.
• event - the original gesture event

onLoad (Function)

Called once after gl context and Deck components (ViewManager, LayerManager, etc) are created. It is safe to trigger viewport transitions after this event.

onResize (Function)

Called when the canvas resizes.

Receives arguments:

• size
  • width (Number) - the new width of the deck canvas, in client pixels
  • height (Number) - the new height of the deck canvas, in client pixels

onBeforeRender (Function)

Called just before the canvas rerenders.

Receives arguments:

• gl - the WebGL context.

onAfterRender (Function)

Called right after the canvas rerenders.

Receives arguments:

• gl - the WebGL context.

onError (Function)

• Default: console.error

Called if deck.gl encounters an error. By default, deck logs the error to console and attempt to continue rendering the rest of the scene. If this callback is set to null, errors are silently ignored.

Receives arguments:

• error (Error)
• layer (Layer?) - the layer where the error is originated, if applicable

_onMetrics (Function)

(Experimental) Called once every second with performance metrics.

Receives arguments:

• metrics - an object with fields specified here.

Methods

finalize

Frees all resources associated with this Deck instance.

deck.finalize()

setProps

Updates (partial) properties.

deck.setProps({...});

Parameters:

• One or more properties to update, as described in the "Properties" section on this page.

redraw

Attempt to draw immediately, rather than waiting for the next draw cycle. By default, deck flushes all changes to the canvas on each animation frame. This behavior might cause the deck canvas to fall out of sync with other components if synchronous updates are required.

Redrawing frequently outside of rAF may cause performance problems. Only use this method if the render cycle must be managed manually.

deck.redraw(true);

Parameters:

• force (Boolean) - if false, only redraw if necessary (e.g. changes have been made to views or layers). If true, skip the check. Default false.

pickObject

Get the closest pickable and visible object at the given screen coordinate.

deck.pickObject({x, y, radius, layerIds})

Parameters:

• x (Number) - x position in pixels
• y (Number) - y position in pixels
• radius (Number, optional) - radius of tolerance in pixels. Default 0.
• layerIds (Array, optional) - a list of layer ids to query from. If not specified, then all pickable and visible layers are queried.
• unproject3D (Boolean, optional) - if true, info.coordinate will be a 3D point by unprojecting the x, y screen coordinates onto the picked geometry. Default false.

Returns:

• a single info object, or null if nothing is found.

pickMultipleObjects

Performs deep picking. Finds all close pickable and visible object at the given screen coordinate, even if those objects are occluded by other objects.

deck.pickMultipleObjects({x, y, radius, layerIds, depth})

Parameters:

• x (Number) - x position in pixels
• y (Number) - y position in pixels
• radius=0 (Number, optional) - radius of tolerance in pixels.
• layerIds=null (Array, optional) - a list of layer ids to query from. If not specified, then all pickable and visible layers are queried.
• depth=10 - Specifies the max
• unproject3D (Boolean, optional) - if true, info.coordinate will be a 3D point by unprojecting the x, y screen coordinates onto the picked geometry. Default false.

Returns:

• An array of info objects. The array will be empty if no object was picked.

Notes:

• Deep picking is implemented as a sequence of simpler picking operations and can have a performance impact. Should this become a concern, you can use the depth parameter to limit the number of matches that can be returned, and thus the maximum number of picking operations.

pickObjects

Get all pickable and visible objects within a bounding box.

deck.pickObjects({x, y, width, height, layerIds})

Parameters:

• x (Number) - left of the bounding box in pixels
• y (Number) - top of the bouding box in pixels
• width (Number, optional) - width of the bouding box in pixels. Default 1.
• height (Number, optional) - height of the bouding box in pixels. Default 1.
• layerIds (Array, optional) - a list of layer ids to query from. If not specified, then all pickable and visible layers are queried.

Returns:

• an array of unique info objects

Notes:

• The query methods are designed to quickly find objects by utilizing the picking buffer.
• The query methods offer more flexibility for developers to handle events compared to the built-in hover and click callbacks.

Member Variables

metrics

A map of various performance statistics for the last 60 frames of rendering. Metrics gathered in deck.gl are the following:

• fps - average number of frames rendered per second
• updateAttributesTime - time spent updating layer attributes
• setPropsTime - time spent setting deck properties
• framesRedrawn - number of times the scene was rendered
• pickTime - total time spent on picking operations
• pickCount - number of times a pick operation was performed
• gpuTime - total time spent on GPU processing
• gpuTimePerFrame - average time spent on GPU processing per frame
• cpuTime - total time spent on CPU processing
• cpuTimePerFrame - average time spent on CPU processing per frame
• bufferMemory - total GPU memory allocated for buffers
• textureMemory - total GPU memory allocated for textures
• renderbufferMemory - total GPU memory allocated for renderbuffers
• gpuMemory - total allocated GPU memory

Source

modules/core/src/lib/deck.js