The Tor Browser: image/test/browser/browser

     1 waitForExplicitFinish();

     3 let pageSource =

     4   '<html><body>' +

     5     '<img id="testImg" src="' + TESTROOT + 'big.png">' +

     6   '</body></html>';

     8 let oldDiscardingPref, oldTab, newTab;

     9 let prefBranch = Cc["@mozilla.org/preferences-service;1"]

    10                    .getService(Ci.nsIPrefService)

    11                    .getBranch('image.mem.');

    13 function isImgDecoded() {

    14   let img = gBrowser.getBrowserForTab(newTab).contentWindow

    15             .document.getElementById('testImg');

    16   img.QueryInterface(Ci.nsIImageLoadingContent);

    17   let request = img.getRequest(Ci.nsIImageLoadingContent.CURRENT_REQUEST);

    18   return request.imageStatus & Ci.imgIRequest.STATUS_FRAME_COMPLETE ? true : false;

    19 }

    21 // Ensure that the image is decoded by drawing it to a canvas.

    22 function forceDecodeImg() {

    23   let doc = gBrowser.getBrowserForTab(newTab).contentWindow.document;

    24   let img = doc.getElementById('testImg');

    25   let canvas = doc.createElement('canvas');

    26   let ctx = canvas.getContext('2d');

    27   ctx.drawImage(img, 0, 0);

    28 }

    30 function test() {

    31   // Enable the discarding pref.

    32   oldDiscardingPref = prefBranch.getBoolPref('discardable');

    33   prefBranch.setBoolPref('discardable', true);

    35   // Create and focus a new tab.

    36   oldTab = gBrowser.selectedTab;

    37   newTab = gBrowser.addTab('data:text/html,' + pageSource);

    38   gBrowser.selectedTab = newTab;

    40   // Run step2 after the tab loads.

    41   gBrowser.getBrowserForTab(newTab)

    42           .addEventListener("pageshow", step2 );

    43 }

    45 function step2() {

    46   // Check that the image is decoded.

    47   forceDecodeImg();

    48   ok(isImgDecoded(), 'Image should initially be decoded.');

    50   // Focus the old tab, then fire a memory-pressure notification.  This should

    51   // cause the decoded image in the new tab to be discarded.

    52   gBrowser.selectedTab = oldTab;

    53   var os = Cc["@mozilla.org/observer-service;1"]

    54              .getService(Ci.nsIObserverService);

    55   os.notifyObservers(null, 'memory-pressure', 'heap-minimize');

    56   ok(!isImgDecoded(), 'Image should be discarded.');

    58   // And we're done.

    59   gBrowser.removeTab(newTab);

    60   prefBranch.setBoolPref('discardable', oldDiscardingPref);

    61   finish();

    62 }

The Tor Browser / file revision