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 /* -*- Mode: Java; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */

 // Helper file for shared image functionality

 // 

 // Note that this is use by tests elsewhere in the source tree. When in doubt,

 // check mxr before removing or changing functionality.

 // Helper function to clear the image cache of content images

 function clearImageCache()

 {

   var tools = SpecialPowers.Cc["@mozilla.org/image/tools;1"]

                              .getService(SpecialPowers.Ci.imgITools);

   var imageCache = tools.getImgCacheForDocument(window.document);

   imageCache.clearCache(false); // true=chrome, false=content

 }

 // Helper function to determine if the frame is decoded for a given image id

 function isFrameDecoded(id)

 {

   return (getImageStatus(id) &

           SpecialPowers.Ci.imgIRequest.STATUS_FRAME_COMPLETE)

          ? true : false;

 }

 // Helper function to determine if the image is loaded for a given image id

 function isImageLoaded(id)

 {

   return (getImageStatus(id) &

           SpecialPowers.Ci.imgIRequest.STATUS_LOAD_COMPLETE)

          ? true : false;

 }

 // Helper function to get the status flags of an image

 function getImageStatus(id)

 {

   // Get the image

   var img = SpecialPowers.wrap(document.getElementById(id));

   // QI the image to nsImageLoadingContent

   img.QueryInterface(SpecialPowers.Ci.nsIImageLoadingContent);

   // Get the request

   var request = img.getRequest(SpecialPowers.Ci

                                          .nsIImageLoadingContent

                                          .CURRENT_REQUEST);

   // Return the status

   return request.imageStatus;

 }

 // Forces a synchronous decode of an image by drawing it to a canvas. Only

 // really meaningful if the image is fully loaded first

 function forceDecode(id)

 {

   // Get the image

   var img = document.getElementById(id);

   // Make a new canvas

   var canvas = document.createElement("canvas");

   // Draw the image to the canvas. This forces a synchronous decode

   var ctx = canvas.getContext("2d");

   ctx.drawImage(img, 0, 0);

 }

 // Functions to facilitate getting/setting various image-related prefs

 //

 // If you change a pref in a mochitest, Don't forget to reset it to its 

 // original value!

 //

 // Null indicates no pref set

 const DISCARD_ENABLED_PREF = {name: "discardable", branch: "image.mem.", type: "bool"};

 const DECODEONDRAW_ENABLED_PREF = {name: "decodeondraw", branch: "image.mem.", type: "bool"};

 const DISCARD_TIMEOUT_PREF = {name: "min_discard_timeout_ms", branch: "image.mem.", type: "int"};

 function setImagePref(pref, val)

 {

   var prefService = SpecialPowers.Cc["@mozilla.org/preferences-service;1"]

                                  .getService(SpecialPowers.Ci.nsIPrefService);

   var branch = prefService.getBranch(pref.branch);

   if (val != null) {

     switch(pref.type) {

       case "bool":

         branch.setBoolPref(pref.name, val);

         break;

       case "int":

         branch.setIntPref(pref.name, val);

         break;

       default:

         throw new Error("Unknown pref type");

     }

   }

   else if (branch.prefHasUserValue(pref.name))

     branch.clearUserPref(pref.name);

 }

 function getImagePref(pref)

 {

   var prefService = SpecialPowers.Cc["@mozilla.org/preferences-service;1"]

                                  .getService(SpecialPowers.Ci.nsIPrefService);

   var branch = prefService.getBranch(pref.branch);

   if (branch.prefHasUserValue(pref.name)) {

     switch (pref.type) {

       case "bool":

         return branch.getBoolPref(pref.name);

       case "int":

         return branch.getIntPref(pref.name);

       default:

         throw new Error("Unknown pref type");

     }

   }

   else

     return null;

 }

 // JS implementation of imgIScriptedNotificationObserver with stubs for all of its methods.

 function ImageDecoderObserverStub()

 {

   this.sizeAvailable = function sizeAvailable(aRequest)   {}

   this.frameComplete = function frameComplete(aRequest)   {}

   this.decodeComplete = function decodeComplete(aRequest) {}

   this.loadComplete = function loadComplete(aRequest)     {}

   this.frameUpdate = function frameUpdate(aRequest)       {}

   this.discard = function discard(aRequest)               {}

   this.isAnimated = function isAnimated(aRequest)         {}

 }