planning

node_modules/ol/src/source/ImageCanvas.js

@@ -0,0 +1,146 @@
+/**
+ * @module ol/source/ImageCanvas
+ */
+
+import ImageCanvas from '../ImageCanvas.js';
+import ImageSource from './Image.js';
+import {
+  containsExtent,
+  getHeight,
+  getWidth,
+  scaleFromCenter,
+} from '../extent.js';
+
+/**
+ * A function returning the canvas element (`{HTMLCanvasElement}`)
+ * used by the source as an image. The arguments passed to the function are:
+ * {@link module:ol/extent~Extent} the image extent, `{number}` the image resolution,
+ * `{number}` the pixel ratio of the map, {@link module:ol/size~Size} the image size,
+ * and {@link module:ol/proj/Projection~Projection} the image projection. The canvas returned by
+ * this function is cached by the source. The this keyword inside the function
+ * references the {@link module:ol/source/ImageCanvas~ImageCanvasSource}.
+ *
+ * @typedef {function(this:import("../ImageCanvas.js").default, import("../extent.js").Extent, number,
+ *     number, import("../size.js").Size, import("../proj/Projection.js").default): HTMLCanvasElement} FunctionType
+ */
+
+/**
+ * @typedef {Object} Options
+ * @property {import("./Source.js").AttributionLike} [attributions] Attributions.
+ * @property {FunctionType} [canvasFunction] Canvas function.
+ * The function returning the canvas element used by the source
+ * as an image. The arguments passed to the function are: {@link import("../extent.js").Extent} the
+ * image extent, `{number}` the image resolution, `{number}` the pixel ratio of the map,
+ * {@link import("../size.js").Size} the image size, and {@link import("../proj/Projection.js").default} the image
+ * projection. The canvas returned by this function is cached by the source. If
+ * the value returned by the function is later changed then
+ * `changed` should be called on the source for the source to
+ * invalidate the current cached image. See: {@link module:ol/Observable~Observable#changed}
+ * @property {boolean} [imageSmoothing=true] Deprecated.  Use the `interpolate` option instead.
+ * @property {boolean} [interpolate=true] Use interpolated values when resampling.  By default,
+ * linear interpolation is used when resampling.  Set to false to use the nearest neighbor instead.
+ * @property {import("../proj.js").ProjectionLike} [projection] Projection. Default is the view projection.
+ * @property {number} [ratio=1.5] Ratio. 1 means canvases are the size of the map viewport, 2 means twice the
+ * width and height of the map viewport, and so on. Must be `1` or higher.
+ * @property {Array<number>} [resolutions] Resolutions.
+ * If specified, new canvases will be created for these resolutions
+ * @property {import("./Source.js").State} [state] Source state.
+ */
+
+/**
+ * @classdesc
+ * Base class for image sources where a canvas element is the image.
+ * @api
+ */
+class ImageCanvasSource extends ImageSource {
+  /**
+   * @param {Options} [opt_options] ImageCanvas options.
+   */
+  constructor(opt_options) {
+    const options = opt_options ? opt_options : {};
+
+    let interpolate =
+      options.imageSmoothing !== undefined ? options.imageSmoothing : true;
+    if (options.interpolate !== undefined) {
+      interpolate = options.interpolate;
+    }
+
+    super({
+      attributions: options.attributions,
+      interpolate: interpolate,
+      projection: options.projection,
+      resolutions: options.resolutions,
+      state: options.state,
+    });
+
+    /**
+     * @private
+     * @type {FunctionType}
+     */
+    this.canvasFunction_ = options.canvasFunction;
+
+    /**
+     * @private
+     * @type {import("../ImageCanvas.js").default}
+     */
+    this.canvas_ = null;
+
+    /**
+     * @private
+     * @type {number}
+     */
+    this.renderedRevision_ = 0;
+
+    /**
+     * @private
+     * @type {number}
+     */
+    this.ratio_ = options.ratio !== undefined ? options.ratio : 1.5;
+  }
+
+  /**
+   * @param {import("../extent.js").Extent} extent Extent.
+   * @param {number} resolution Resolution.
+   * @param {number} pixelRatio Pixel ratio.
+   * @param {import("../proj/Projection.js").default} projection Projection.
+   * @return {import("../ImageCanvas.js").default} Single image.
+   */
+  getImageInternal(extent, resolution, pixelRatio, projection) {
+    resolution = this.findNearestResolution(resolution);
+
+    let canvas = this.canvas_;
+    if (
+      canvas &&
+      this.renderedRevision_ == this.getRevision() &&
+      canvas.getResolution() == resolution &&
+      canvas.getPixelRatio() == pixelRatio &&
+      containsExtent(canvas.getExtent(), extent)
+    ) {
+      return canvas;
+    }
+
+    extent = extent.slice();
+    scaleFromCenter(extent, this.ratio_);
+    const width = getWidth(extent) / resolution;
+    const height = getHeight(extent) / resolution;
+    const size = [width * pixelRatio, height * pixelRatio];
+
+    const canvasElement = this.canvasFunction_.call(
+      this,
+      extent,
+      resolution,
+      pixelRatio,
+      size,
+      projection
+    );
+    if (canvasElement) {
+      canvas = new ImageCanvas(extent, resolution, pixelRatio, canvasElement);
+    }
+    this.canvas_ = canvas;
+    this.renderedRevision_ = this.getRevision();
+
+    return canvas;
+  }
+}
+
+export default ImageCanvasSource;