planning

node_modules/ol/src/ImageCanvas.js

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+/**
+ * @module ol/ImageCanvas
+ */
+import ImageBase from './ImageBase.js';
+import ImageState from './ImageState.js';
+
+/**
+ * A function that is called to trigger asynchronous canvas drawing.  It is
+ * called with a "done" callback that should be called when drawing is done.
+ * If any error occurs during drawing, the "done" callback should be called with
+ * that error.
+ *
+ * @typedef {function(function(Error=): void): void} Loader
+ */
+
+class ImageCanvas extends ImageBase {
+  /**
+   * @param {import("./extent.js").Extent} extent Extent.
+   * @param {number} resolution Resolution.
+   * @param {number} pixelRatio Pixel ratio.
+   * @param {HTMLCanvasElement} canvas Canvas.
+   * @param {Loader} [opt_loader] Optional loader function to
+   *     support asynchronous canvas drawing.
+   */
+  constructor(extent, resolution, pixelRatio, canvas, opt_loader) {
+    const state =
+      opt_loader !== undefined ? ImageState.IDLE : ImageState.LOADED;
+
+    super(extent, resolution, pixelRatio, state);
+
+    /**
+     * Optional canvas loader function.
+     * @type {?Loader}
+     * @private
+     */
+    this.loader_ = opt_loader !== undefined ? opt_loader : null;
+
+    /**
+     * @private
+     * @type {HTMLCanvasElement}
+     */
+    this.canvas_ = canvas;
+
+    /**
+     * @private
+     * @type {?Error}
+     */
+    this.error_ = null;
+  }
+
+  /**
+   * Get any error associated with asynchronous rendering.
+   * @return {?Error} Any error that occurred during rendering.
+   */
+  getError() {
+    return this.error_;
+  }
+
+  /**
+   * Handle async drawing complete.
+   * @param {Error} [err] Any error during drawing.
+   * @private
+   */
+  handleLoad_(err) {
+    if (err) {
+      this.error_ = err;
+      this.state = ImageState.ERROR;
+    } else {
+      this.state = ImageState.LOADED;
+    }
+    this.changed();
+  }
+
+  /**
+   * Load not yet loaded URI.
+   */
+  load() {
+    if (this.state == ImageState.IDLE) {
+      this.state = ImageState.LOADING;
+      this.changed();
+      this.loader_(this.handleLoad_.bind(this));
+    }
+  }
+
+  /**
+   * @return {HTMLCanvasElement} Canvas element.
+   */
+  getImage() {
+    return this.canvas_;
+  }
+}
+
+export default ImageCanvas;