Class: CanvasRenderer

renderer.CanvasRenderer

Base Class to render layer on HTMLCanvasElement

(abstract, protected) new renderer.CanvasRenderer(layer) [source]

Parameter Type Description
layer Layer the layer to render
Extends:

Methods

  • render() [source]

    • Render the layer. Call checkResources

  • (abstract) checkResources() [source]

    • Check if has any external resources to load If yes, load the resources before calling draw method
    Returns:
    Array.<Array>: an array of resource arrays [ [url1, width, height], [url2, width, height], [url3, width, height] .. ]

  • (abstract) draw() [source]

    • a required abstract method to implement draw the layer when map is not interacting

  • (abstract) drawOnInteracting(eventParam) [source]

    • an optional abstract method to implement draw the layer when map is interacting (moving/zooming/dragrotating)
    Parameter Type Description
    eventParam Object event parameters

  • needToRedraw() [source]

    • Ask whether the layer renderer needs to redraw
    Returns:
    Boolean:

  • onSkipDrawOnInteracting() [source]

    • A callback for overriding when drawOnInteracting is skipped due to low fps

  • mustRenderOnInteracting() [source]

    • Whether must call render instead of drawOnInteracting when map is interacting

  • setToRedraw() [source]

    • Set to redraw, ask map to call draw/drawOnInteracting to redraw the layer

  • setCanvasUpdated() [source]

    • Mark layer's canvas updated

  • (protected) isCanvasUpdated() [source]

    • Only called by map's renderer to check whether the layer's canvas is updated
    Returns:
    Boolean:

  • remove() [source]

    • Remove the renderer, will be called when layer is removed

  • getMap() [source]

    • Get map
    Returns:
    Map:

  • getCanvasImage() [source]

    • Get renderer's Canvas image object
    Returns:
    HTMLCanvasElement:

  • clear() [source]

    • Clear canvas

  • isBlank() [source]

    • A method to help improve performance. If you are sure that layer's canvas is blank, returns true to save unnecessary layer works of maps.
    Returns:
    Boolean:

  • show() [source]

    • Show the layer

  • hide() [source]

    • Hide the layer

  • setZIndex() [source]

    • Set z-index of layer

  • hitDetect(point) [source]

    • Detect if there is anything painted on the given point
    Parameter Type Description
    point Point containerPoint
    Returns:
    Boolean:

  • loadResources(resourceUrls, onComplete, context) [source]

    • loadResource from resourceUrls
    Parameter Type Description
    resourceUrls Array.<String> Array of urls to load
    onComplete function callback after loading complete
    context Object callback's context
    Returns:
    Array.<Promise>:

  • createCanvas() [source]

    • Create renderer's Canvas

  • resizeCanvas(canvasSize) [source]

    • Resize the canvas
    Parameter Type Description
    canvasSize Size the size resizing to

  • clearCanvas() [source]

    • Clear the canvas to blank

  • prepareCanvas() [source]

    • Prepare the canvas for rendering.
    1. Clear the canvas to blank.
    2. Clip the canvas by mask if there is any and return the mask's extent
    Returns:
    PointExtent: mask's extent of current zoom's 2d point.

  • getViewExtent() [source]

    • Get renderer's current view extent in 2d point
    Returns:
    Object: view.extent, view.maskExtent, view.zoom, view.middleWest

  • completeRender() [source]

    • call when rendering completes, this will fire necessary events and call setCanvasUpdated

  • getEvents() [source]

    • Get renderer's event map registered on the map
    Returns:
    Object: events

  • onZoomStart(param) [source]

    • /** onZoomStart
    Parameter Type Description
    param Object event parameters

  • onZoomEnd(param) [source]

    • onZoomEnd
    Parameter Type Description
    param Object event parameters

  • onZooming(param) [source]

    • onZooming
    Parameter Type Description
    param Object event parameters

  • onMoveStart(param) [source]

    • onMoveStart
    Parameter Type Description
    param Object event parameters

  • onMoving(param) [source]

    • onMoving
    Parameter Type Description
    param Object event parameters

  • onMoveEnd(param) [source]

    • onMoveEnd
    Parameter Type Description
    param Object event parameters

  • onResize(param) [source]

    • onResize
    Parameter Type Description
    param Object event parameters

  • onDragRotateStart(param) [source]

    • onDragRotateStart
    Parameter Type Description
    param Object event parameters

  • onDragRotating(param) [source]

    • onDragRotating
    Parameter Type Description
    param Object event parameters

  • onDragRotateEnd(param) [source]

    • onDragRotateEnd
    Parameter Type Description
    param Object event parameters

  • onSpatialReferenceChange(param) [source]

    • onSpatialReferenceChange
    Parameter Type Description
    param Object event parameters

  • getDrawTime() [source]

    • Get ellapsed time of previous drawing
    Returns:
    Number:

  • (inherited) callInitHooks() [source]

    • Visit and call all the init hooks defined on Class and its parents.
    Returns:
    Class: this

  • (inherited) setOptions(options) [source]

    • Merges options with the default options of the object.
    Parameter Type Description
    options Object options to set
    Returns:
    Class: this

  • (inherited) config(conf) [source]

    • 1. Return object's options if no parameter is provided.
    2. update an option and enable/disable the handler if a handler with the same name existed. 
    // Get marker's options;
var options = marker.config();
// Set map's option "draggable" to false and disable map's draggable handler.
map.config('draggable', false);
// You can update more than one options like this:
map.config({
    'scrollWheelZoom' : false,
    'doubleClickZoom' : false
});
    Parameter Type Description
    conf Object config to update
    Returns:
    Class: this

  • (inherited) onConfig() [source]

    • Default callback when config is called