1 files changed, 107 insertions, 0 deletions
diff --git a/dom/browser-element/mochitest/browserElement_GetScreenshotDppx.js b/dom/browser-element/mochitest/browserElement_GetScreenshotDppx.js
new file mode 100644
index 000000000..1d61f6afc
--- /dev/null
+++ b/dom/browser-element/mochitest/browserElement_GetScreenshotDppx.js
@@ -0,0 +1,107 @@
+/* Any copyright is dedicated to the public domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+// Test the getScreenshot property for mozbrowser
+"use strict";
+
+SimpleTest.waitForExplicitFinish();
+browserElementTestHelpers.setEnabledPref(true);
+
+function runTest() {
+  var dppxPref = 'layout.css.devPixelsPerPx';
+  var cssPixelWidth = 600;
+  var cssPixelHeight = 400;
+
+  var iframe1 = document.createElement('iframe');
+  iframe1.setAttribute('width', cssPixelWidth);
+  iframe1.setAttribute('height', cssPixelHeight);
+  iframe1.setAttribute('mozbrowser', 'true');
+
+  iframe1.src = 'data:text/html,<html><body>hello</body></html>';
+  document.body.appendChild(iframe1);
+
+  var images = [];
+
+  function screenshotTaken(image) {
+    images.push(image);
+    if (images.length === 1) {
+      ok(true, 'Got initial non blank screenshot');
+
+      if (image.width !== cssPixelWidth || image.height !== cssPixelHeight) {
+        ok(false, 'The pixel width of the image received is not correct');
+        SimpleTest.finish();
+        return;
+      }
+      ok(true, 'The pixel width of the image received is correct');
+
+      SpecialPowers.pushPrefEnv(
+        {'set': [['layout.css.devPixelsPerPx', 2]]}, takeScreenshot);
+    }
+    else if (images.length === 2) {
+      ok(true, 'Got updated screenshot after source page changed');
+
+      if (image.width !== cssPixelWidth * 2 ||
+          image.height !== cssPixelHeight * 2) {
+        ok(false, 'The pixel width of the 2dppx image received is not correct');
+        SimpleTest.finish();
+        return;
+      }
+      ok(true, 'The pixel width of the 2dppx image received is correct');
+      SimpleTest.finish();
+    }
+  }
+
+  function takeScreenshot() {
+    function gotImage(e) {
+      // |this| is the Image.
+
+      URL.revokeObjectURL(this.src);
+
+      if (e.type === 'error' || !this.width || !this.height) {
+        tryAgain();
+
+        return;
+      }
+
+      screenshotTaken(this);
+    }
+
+    function tryAgain() {
+      if (--attempts === 0) {
+        ok(false, 'Timed out waiting for correct screenshot');
+        SimpleTest.finish();
+      } else {
+        setTimeout(function() {
+          iframe1.getScreenshot(cssPixelWidth, cssPixelHeight).onsuccess =
+            getScreenshotImageData;
+        }, 200);
+      }
+    }
+
+    function getScreenshotImageData(e) {
+      var blob = e.target.result;
+      if (blob.size === 0) {
+        tryAgain();
+
+        return;
+      }
+
+      var img = new Image();
+      img.src = URL.createObjectURL(blob);
+      img.onload = img.onerror = gotImage;
+    }
+
+    var attempts = 10;
+    iframe1.getScreenshot(cssPixelWidth, cssPixelHeight).onsuccess =
+      getScreenshotImageData;
+  }
+
+  function iframeLoadedHandler() {
+    SpecialPowers.pushPrefEnv(
+      {'set': [['layout.css.devPixelsPerPx', 1]]}, takeScreenshot);
+  }
+
+  iframe1.addEventListener('mozbrowserloadend', iframeLoadedHandler);
+}
+
+addEventListener('testready', runTest);