🐛 Fix image ArrayBuffer recovery

CHANGELOG.md

@@ -1,5 +1,9 @@
 # Changelogs
 
+## Unreleased
+
+* [feat] Add new method `Aladin#getViewImageBuffer` to get the current view as a PNG buffer
+
 ## 3.3.3
 
 * [feat] UI: add HiPS basic filter that filters the `hipsList` given
@@ -353,4 +357,4 @@ New in the API:
 ### Fin 2013
 
 * ajout catalogue progressif
-* ajout on select, objectClicked, objectHovered
+* ajout on select, objectClicked, objectHovered

src/js/Aladin.js

@@ -26,6 +26,7 @@
  * Author: Thomas Boch[CDS], Matthieu Baumann[CDS]
  *
  *****************************************************************************/
+
 import { version } from "./../../package.json";
 import { View } from "./View.js";
 import { Utils } from "./Utils";
@@ -2159,6 +2160,7 @@ aladin.on("positionChanged", ({ra, dec}) => {
      *     * format (optional): 'image/png' or 'image/jpeg'
      *     * width: width in pixels of the image to output
      *     * height: height in pixels of the image to output
+     *     * logo (optional): boolean to display the Aladin Lite logo
      *
      * @API
      */
@@ -2172,11 +2174,16 @@ aladin.on("positionChanged", ({ra, dec}) => {
         const canvasDataURL = await this.view.getCanvasDataURL(
             options.format,
             options.width,
-            options.height
+            options.height,
+            options.logo
         );
         return canvasDataURL;
     };
 
+    Aladin.prototype.getViewImageBuffer = async function (withLogo) {
+        return await this.view.getCanvasBuffer("image/png", null, null, withLogo);
+    }
+
     /**
      * Return the current view WCS as a key-value dictionary
      * Can be useful in coordination with getViewDataURL

src/js/View.js

@@ -446,42 +446,65 @@ export let View = (function () {
         this.catalogCanvas.style.cursor = cursor;
     };
 
-    /**
-     * return dataURL string corresponding to the current view
-     */
-    View.prototype.getCanvasDataURL = async function (imgType, width, height) {
+    View.prototype.getCanvasContext = async function (imgType, width, height, withLogo=true) {
         const loadImage = function (url) {
             return new Promise((resolve, reject) => {
-                var image = new Image()
+                const image = new Image()
                 image.src = url
                 image.onload = () => resolve(image)
                 image.onerror = () => reject(new Error('could not load image'))
             })
         }
 
-        return loadImage("data:image/png;base64,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")
-            .then((img) => {
-                imgType = imgType || "image/png";
+        imgType = imgType || "image/png";
 
-                const canvas = this.wasm.canvas();
+        const canvas = this.wasm.canvas();
 
-                var c = document.createElement('canvas');
-                c.width = width || (this.width * window.devicePixelRatio);
-                c.height = height || (this.height * window.devicePixelRatio);
+        const c = document.createElement('canvas');
+        c.width = width || (this.width * window.devicePixelRatio);
+        c.height = height || (this.height * window.devicePixelRatio);
 
-                var ctx = c.getContext('2d');
+        const ctx = c.getContext('2d');
 
-                ctx.drawImage(canvas, 0, 0, c.width, c.height);
-                ctx.drawImage(this.catalogCanvas, 0, 0, c.width, c.height);
+        ctx.drawImage(canvas, 0, 0, c.width, c.height);
+        ctx.drawImage(this.catalogCanvas, 0, 0, c.width, c.height);
 
-                const offX = c.width - img.width;
-                const offY = c.height - img.height;
-                ctx.drawImage(img, offX, offY);
+        if(withLogo) {
+            const logo = await loadImage("data:image/png;base64,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");
+            const offX = c.width - logo.width;
+            const offY = c.height - logo.height;
+            ctx.drawImage(logo, offX, offY);
+        }
 
-                return c.toDataURL(imgType);
-            });
+        return c;
+    }
+
+    /**
+     * return dataURL string corresponding to the current view
+     */
+    View.prototype.getCanvasDataURL = async function (imgType, width, height, withLogo=true) {
+        const c = await this.getCanvasContext(imgType, width, height, withLogo);
+        return c.toDataURL(imgType);
     };
 
+    /**
+     * return ArrayBuffer corresponding to the current view
+     */
+    View.prototype.getCanvasBuffer = async function (imgType, width, height, withLogo=true) {
+        const c = await this.getCanvasContext(imgType, width, height, withLogo);
+        return new Promise((resolve, reject) => {
+            c.toBlob(blob => {
+                if (blob) {
+                    const reader = new FileReader();
+                    reader.onloadend = () => resolve(reader.result);
+                    reader.onerror = () => reject(new Error('Error reading blob as ArrayBuffer'));
+                    reader.readAsArrayBuffer(blob);
+                } else {
+                    reject(new Error('Canvas toBlob failed'));
+                }
+            }, imgType);
+        });
+    }
 
     View.prototype.selectLayer = function (layer) {
         if (!this.imageLayers.has(layer)) {