BaseLayerView2D
require(["esri/views/2d/layers/BaseLayerView2D"], function(BaseLayerView2D) { /* code goes here */ });
esri/views/2d/layers/BaseLayerView2D
var TileBorderLayerView2D = BaseLayerView2D.createSubclass({
// Example of a render implementation that draws tile boundaries
render(renderParameters) {
var tileSize = this.layer.tileInfo.size[0];
var state = renderParameters.state;
var pixelRatio = state.pixelRatio;
var width = state.size[0];
var height = state.size[1];
var context = renderParameters.context;
var coords = [0, 0];
context.fillStyle = "rgba(0,0,0,0.25)";
context.fillRect(0, 0, width * pixelRatio, height * pixelRatio);
// apply rotation for everything that will be applied to the canvas
if (state.rotation !== 0) {
context.translate(width * pixelRatio * 0.5, height * pixelRatio * 0.5);
context.rotate((state.rotation * Math.PI) / 180);
context.translate(- width * pixelRatio * 0.5, -height * pixelRatio * 0.5);
}
// Set the style for all the text.
context.font = "24px monospace";
context.fillStyle = "black";
context.shadowBlur = 1;
for (const tile of this.tiles) {
var screenScale = tile.resolution / state.resolution * pixelRatio;
state.toScreenNoRotation(coords, tile.coords);
// Draw the tile boundaries
context.strokeRect(coords[0], coords[1], tileSize * screenScale, tileSize * screenScale);
// Draw the tile information
context.shadowColor = "white";
context.fillText(
tile.level + "/" + tile.row + "/" + tile.col + "/" + tile.world,
coords[0] + 12,
coords[1] + 24,
tileSize * screenScale
);
context.shadowColor = "transparent";
}
}
});
var CustomTileLayer = Layer.createSubclass({
tileInfo: TileInfo.create({ spatialReference: { wkid: 3857 }}),
createLayerView(view) {
if (view.type === "2d") {
return new TileBorderLayerView2D({
view: view,
layer: this
});
}
}
});
Property Overview
Name | Type | Summary | Object | |
---|---|---|---|---|
Layer | References the layer this LayerView represents. more details | more details | BaseLayerView2D | |
Tile[] | The array of Tile objects computed to cover the MapView's visible area. more details | more details | BaseLayerView2D | |
MapView | References the MapView this LayerView belongs to. more details | more details | BaseLayerView2D |
Property Details
- tilesTile[]
The array of Tile objects computed to cover the MapView's visible area. This array is updated when the view is animating or the user is interacting with it. Then if tiles have been added or removed, tilesChanged() is called.
- See also:
- viewMapView
Method Overview
Name | Return Type | Summary | Object | |
---|---|---|---|---|
Method called when after the LayerView is created and right before it's asked to draw the layer's content. more details | more details | BaseLayerView2D | ||
Method called after the layer is removed and the LayerView is about to be removed. more details | more details | BaseLayerView2D | ||
Promise<Graphic> | Method to implement that is responsible for providing objects hit at the specified screen coordinates. more details | more details | BaseLayerView2D | |
The method to implement that is responsible of drawing the content of the layer. more details | more details | BaseLayerView2D | ||
The LayerView can call this method to ask the MapView to schedule a new rendering frame. more details | more details | BaseLayerView2D | ||
Method to implement, which notifies of tiles being added or removed for the current view state. more details | more details | BaseLayerView2D |
Method Details
- attach()
Method called when after the LayerView is created and right before it's asked to draw the layer's content. Typically this method is implemented to start watching property changes on the layer for example.
- See also:
Example:attach() { this._propertyHandle = this.layer.watch("opacity", function() { this.requestRender(); }); }
- detach()
Method called after the layer is removed and the LayerView is about to be removed. Typically, this method is implemented to free resources like watchers.
- See also:
Example:// remove the watchers on the layer that are added in attach() detach() { this._propertyHandle.remove(); this._propertyHandle = null; }
Method to implement that is responsible for providing objects hit at the specified screen coordinates. This method is called internally by the MapView each time its hitTest() method is called.
Parameters:x NumberThe x-coordinate in screen space of the desired hit.
y NumberThe y-coordinate in screen space of the desired hit.
Returns:Type Description Promise<Graphic> A Promise that can resolve with a hit graphic instance.
- render(renderParameters)
The method to implement that is responsible of drawing the content of the layer. This method is called every time the MapView's state changes, or if requestRender() has been called.
Parameters:Specification:renderParameters ObjectSpecification:context CanvasRenderingContext2DThe canvas 2D context in which to draw content.
stationary BooleanThe stationary state of the
MapView
.state ViewStateThe object that describes view state.
Example:// Example of a render implementation that draws tile boundaries render(renderParameters) {var tileSize = this.layer.tileInfo.size[0]; var state = renderParameters.state; var pixelRatio = state.pixelRatio; var width = state.size[0]; var height = state.size[1]; var context = renderParameters.context; var coords = [0, 0]; context.fillStyle = "rgba(0,0,0,0.25)"; context.fillRect(0, 0, width * pixelRatio, height * pixelRatio); // apply rotation for everything that will be applied to the canvas if (state.rotation !== 0) { context.translate(width * pixelRatio * 0.5, height * pixelRatio * 0.5); context.rotate((state.rotation * Math.PI) / 180); context.translate(- width * pixelRatio * 0.5, -height * pixelRatio * 0.5); } // Set the style for all the text. context.font = "24px monospace"; context.fillStyle = "black"; context.shadowBlur = 1; for (const tile of this.tiles) { var screenScale = tile.resolution / state.resolution * pixelRatio; state.toScreenNoRotation(coords, tile.coords); // Draw the tile boundaries context.strokeRect(coords[0], coords[1], tileSize * screenScale, tileSize * screenScale); // Draw the tile information context.shadowColor = "white"; context.fillText( tile.level + "/" + tile.row + "/" + tile.col + "/" + tile.world, coords[0] + 12, coords[1] + 24, tileSize * screenScale ); context.shadowColor = "transparent"; } }
- requestRender()
The LayerView can call this method to ask the MapView to schedule a new rendering frame.
Example:// Call requestRender whenever the layer opacity has changed. attach() { this._propertyHandle = this.layer.watch("opacity", function() { this.requestRender(); }); }
- tilesChanged(added, removed)
Method to implement, which notifies of tiles being added or removed for the current view state. This function can be implemented to start and stop fetching new data, or allocate and dispose resources.
Parameters:added Tile[]The tile objects added for the current view viewport.
removed Tile[]The tile objects removed from the view viewport.
Type Definitions
- TileObject
Represents a tile reference.
- Properties:
- id String
The tile string identifier in the format
level/row/col/world
level NumberThe level identifier of the LOD to which the tile belongs
row NumberThe row identifier.
col NumberThe column identifier.
world NumberWhen the projection allows world wrapping (e.g. Web Mercator), identifies the instance of the world this tile's
level
/row
/col
.resolution NumberThe number of map units per pixel in the tile.
scale NumberThe map scale at the tile's level.
coords Number[]The coordinates of the top-left corner of the tile as an array of two numbers. The coordinates are in un-normalized map units.
bounds Number[]The bounds of the tile as an array of four numbers that be readily converted to an Extent object.