Implement a JavaScript API for document scanning

chrome/common/extensions/docs/examples/api/document_scan/scan.js

+var requestButton = document.getElementById("requestButton");
+var scanButton = document.getElementById('scanButton');
+var scannedImages = document.getElementById('scannedImages');
+var waitAnimation = document.getElementById('waitAnimation');
+var imageMimeType;
+
+function setOnlyChild(parent, child) {
+  while (parent.firstChild) {
+    parent.removeChild(parent.firstChild);
+  }
+  parent.appendChild(child);
+}
+
+var gotPermission = function(result) {
+  waitAnimation.style.display = 'block';
+  requestButton.style.display = 'none';
+  scanButton.style.display = 'block';
+  console.log('App was granted the "documentScan" permission.');
+  waitAnimation.style.display = 'none';
+};
+
+var permissionObj = {permissions: ['documentScan']};
+
+requestButton.addEventListener('click', function() {
+  waitAnimation.style.display = 'block';
+  chrome.permissions.request( permissionObj, function(result) {
+    if (result) {
+      gotPermission();
+    } else {
+      console.log('App was not granted the "documentScan" permission.');
+      console.log(chrome.runtime.lastError);
+    }
+  });
+});
+
+var onScanCompleted = function(scan_results) {
+  waitAnimation.style.display = 'none';
+  if (chrome.runtime.lastError) {
+    console.log('Scan failed: ' + chrome.runtime.lastError.message);
+    return;
+  }
+  numImages = scan_results.dataUrls.length;
+  console.log('Scan completed with ' + numImages + ' images.');
+  for (var i = 0; i < numImages; i++) {
+    urlData = scan_results.dataUrls[i]
+    console.log('Scan ' + i + ' data length ' +
+                urlData.length + '.');
+    console.log('URL is ' + urlData);
+    var scannedImage = document.createElement('img');
+    scannedImage.src = urlData;
+    scannedImages.insertBefore(scannedImage, scannedImages.firstChild);
+  }
+};
+
+scanButton.addEventListener('click', function() {
+  var scanProperties = {};
+  waitAnimation.style.display = 'block';
+  chrome.documentScan.scan(scanProperties, onScanCompleted);
+});
+
+chrome.permissions.contains(permissionObj, function(result) {
+  if (result) {
+    gotPermission();
+  }
+});