I'm currently building a simple application on Gjs, which should change the background-image of my gnome-shell. A solution on how this can be done using the gsettings-tool can be found here.
Since I want to build a desktop-application around it, I want to change the org.gnome.desktop.background.picture-uri-key by using Gio's GSettings-class. But using the set_X()-method does not change the value of the key.
This is my code to change the gsettings value:
var gio = imports.gi.Gio;
// Get the GSettings-object for the background-schema:
var background = new gio.Settings({schema: "org.gnome.desktop.background"});
// Read the current Background-Image:
print( "Current Background-Image: "+background.get_string("picture-uri") );
if (background.is_writable("picture-uri")){
// Set a new Background-Image (should show up immediately):
if (background.set_string("picture-uri", "file:///path/to/some/pic.jpg")){
print("Success!");
}
else throw "Couldn't set the key!";
} else throw "The key is not writable";
Reading the value does work as expected, the is_writable()-method returns true and the set_string()-method also returns true.
I have checked that I'm not in "delay-apply" mode and the key has a GVariantType of string, so the set_string()-method should work.
Using the normal gsettings command-line tool (as explained in the linked post) works just fine.
I can't figure out what the problem is, is there any place I can look for logs or something?
After not getting any responses here I asked the same question on the gjs-mailing list.
It turned out that the writes to dconf were not yet on the disk when my script exited, so they were never really applied.
The solution was to call the g_settings_sync() function (JsDoc) right after the set_string() function, to ensure that all writes had finished.
if (background.set_string("picture-uri", "file:///path/to/some/pic.jpg")){
gio.Settings.sync()
print("Success!");
}
Thanks to Johan Dahlin and his answer.
Related
I have an if statement that I am trying to use to attack a problem with async functions, everything works great when it works however that take multiple refreshes. The page errors out several times then finally displays the color i need. Below is just an example but on the server side once the client connects, the server is dodging my if statement and goes straight for function current(). Here is example of what its doing. I'd like to update the clients color based on colors from the server so if they chose the color green their choice comes back to the server, goes through a function and spits out a different color which then is sent back over to them, when it works. My issue is, Im completely dodging the if statement.
function ijoined() {
do this();
do that();
after doing this and that();
decide();
}
Decideds what color to display
function decide() {
if (yellow !== null) {
start();
console.log('I started');
} else {
current();
console.log('I already started');
}
}
First color displayed for client
function start() {
yellow = 545;
}
Current color
function current() {
var color id = clients color;
var time = current time;
}
I summarize what I understand you want to do:
Have the client javascript generate a (random?) color and send it to the server
Have the server modify the color, send it back to the client
I see a couple of problems here. Posting the entire codebase (client & server) you actually use would help tremendously with giving an answer.
First, you never seem to define the variable yellow, so when you get to
if (yellow !== null) {
// ...
}
you run into a reference error.
Also, your variable names are invalid, they must not contain spaces.
color id
is not a valid variable name, as opposed to
color_id
// or
colorId
Refer to https://mathiasbynens.be/notes/javascript-identifiers or https://www.w3schools.com/js/js_variables.asp for a quick reference on valid variable names.
Also, your comments aren't really comments. You have to either prefix them with a double slash as such:
// This is a comment
This is a syntax error
or wrap them in /**/ as such:
/*
This is also a comment
that can span multiple lines
*/
Where does the communication with the server happen?
Unless you give me more to work with, unfortunately I can't help you.
I have recreated a blueprint, which has 60+ rooms, as an inline SVG.
There are functions that display information, such as pictures, when you select or hover a room. I'm using one div container to display the pictures by setting its background property to url('path-of-image.ext'), as can be seen below.
var cla = document.getElementsByClassName('cla');
for (i = 0; i < cla.length; i++) {
cla[i].addEventListener('mouseenter', fun);
}
function fun(){
var str = 'url("media/' + this.id.slice(4) + '.jpg")';
pictureFrame.style.background = str;
pictureFrame.style.backgroundSize = 'cover';
pictureFrame.style.backgroundPosition = 'center'
}
The reason I'm not using the background property's shorthand is because I plan on animating the background-position property with a transition.
However, not all rooms have pictures. Hence console throws the following error, GET ... net::ERR_FILE_NOT_FOUND, when you select or hover said rooms. The error doesn't cause the script to break, but I would prefer not to run that code every single time a room is hovered, even when a given room doesn't have pictures.
Even though I know this can be done imperatively with if/else statements, I'm trying to do this programmatically since there are so many individual rooms.
I've tried using try/catch, but this doesn't seem to detect this sort of error.
Any ideas?
Is it even possible to detect this kind of error?
You could attempt to read it using FileReader and catch/handle NotFoundError error.
If it were to error, you could assign it to an object or array which you would first check upon hover. If the file was in that array, you could avoid attempting to read it again and just handle however you like.
Here is a good article by Nicholas Zakas on using FileReader
First off I would see if there is a way of checking if the file exists before the document even loads so that you don't make unnecessary requests. If you have a database on the backend which can manage this that would serve you very well in the long term
Since you make it sound like the way you only know a file exists is by requesting it, here's a method that will allow you to try this:
function UrlExists(url)
{
var http = new XMLHttpRequest();
http.open('HEAD', url, false);
http.send();
return http.status!=404;
}
This won't request the image twice because of browser caching. As you can see that method is itself being depricated and overall the best way you can remedy this problem is checking before the page even loads; if you have a database or datastructure of any sort, add a class or property to the element if the image exists or not. Then, in your existing method, you can call something like document.getElementsByClassName('cla-with-image') to get only records that you've determined has an image (much more efficient than trying to load images that don't exist).
If you end up using that UrlExists method, then you can just modify your existing method to be
function fun(){
var url = "media/' + this.id.slice(4) + '.jpg";
if (UrlExists(url)) {
var str = 'url(' + url + ')';
pictureFrame.style.background = str;
pictureFrame.style.backgroundSize = 'cover';
pictureFrame.style.backgroundPosition = 'center'
}
}
I am debugging a javascript/html5 web app that uses a lot of memory. Occasionally I get an error message in the console window saying
"uncaught exception: out of memory".
Is there a way for me to gracefully handle this error inside the app?
Ultimately I need to re-write parts of this to prevent this from happening in the first place.
You should calclulate size of your localStorage,
window.localStorage is full
as a solution is to try to add something
var localStorageSpace = function(){
var allStrings = '';
for(var key in window.localStorage){
if(window.localStorage.hasOwnProperty(key)){
allStrings += window.localStorage[key];
}
}
return allStrings ? 3 + ((allStrings.length*16)/(8*1024)) + ' KB' : 'Empty (0 KB)';
};
var storageIsFull = function () {
var size = localStorageSpace(); // old size
// try to add data
var er;
try {
window.localStorage.setItem("test-size", "1");
} catch(er) {}
// check if data added
var isFull = (size === localStorageSpace());
window.localStorage.removeItem("test-size");
return isFull;
}
I also got the same error message recently when working on a project having lots of JS and sending Json, but the solution which I found was to update input type="submit" attribute to input type="button". I know there are limitations of using input type="button"..> and the solution looks weird, but if your application has ajax with JS,Json data, you can give it a try. Thanks.
Faced the same problem in Firefox then later I came to know I was trying to reload a HTML page even before setting up some data into local-storage inside if loop. So you need to take care of that one and also check somewhere ID is repeating or not.
But same thing was working great in Chrome. Maybe Chrome is more Intelligent.
I have a not too big grid (30x20) with numbers in cells. I have to display all, calculate them in different ways (by columns, rows, some cells, etc.) and write values to some cells. This data is also written and read from db table fields. Everything is working, excluding simple (theoretically) mask tools.
In time of e.g. writing data to the field in the table I try to start mask and close it on finish. I used such a “masks” very often but only in this situation I have a problem and can’t solve it.
I prepare this mask the following way:
msk = new Ext.LoadMask(Ext.getBody(), { msg: "data loading ..." });
msk.show();
[writing data loops]
msk.hide();
msk.destroy();
I also tried to use grid obiect in place of Ext.getBody(), but without result.
I found also that the program behaves in a special way – loops which I use to write data to the table field are "omitted" by this mask, and it looks like loops are working in the background (asynchronously).
Would you be so kind as to suggest something?
No, no, no, sorry guys but my description isn’t very precise. It isn’t problem of loading or writing data to the database. Let’s say stores are in the memory but my problem is to calculate something and write into the grid. Just to see this values on the screen. Let me use my example once again:
msk = new Ext.LoadMask(Ext.getBody(), { msg: "data loading ..." });
msk.show();
Ext.each(dataX.getRange(), function (X) {
Ext.each(dataY.getRange(), function (Y) {
…
X.set('aaa', 10);
…
}
msk.hide();
msk.destroy();
And in such a situation this mask isn’t visible or is too fast to see it.
In the mean time I find (I think) a good description of my problem but still can’t find a solution for me. When I use e.g. alert() function I see this mask, when I use delay anyway, mask is too fast. Explanation is the following:
The reason for that is quite simple - JS is single threaded. If you modify DOM (for example by turning mask on) the actual change is made immediately after current execution path is finished. Because you turn mask on in beginning of some time-consuming task, browser waits with DOM changes until it finishes. Because you turn mask off at the end of method, it might not show at all. Solution is simple - invoke store rebuild after some delay.*
I have no idea how is your code looks in general but this is some tip that you could actually use.
First of all loading operations are asynchronously so you need to make that mask show and then somehow destroy when data are loaded.
First of all check if in your store configuration you have autoLoad: false
If yes then we can make next step:
Since Extjs is strongly about MVC design pattern you should have your controller somewhere in your project.
I suppose you are loading your data on afterrender or on button click event so we can make this:
In function for example loadImportantData
loadImportantData: function(){
var controller = this;
var store = controller.getStore('YourStore'); //or Ext.getStore('YourStore'); depends on your configuration in controller
var myMask = new Ext.LoadMask(Ext.getBody(), {msg:"Please wait..."});
myMask.show();
store.load({
callback: function (records, operation, success) {
//this callback is fired when your store load all data.
//then hide mask.
myMask.hide();
}
});
}
When data is loaded your mask will disappear.
If you have a reference to the grid, you can simply call grid.setLoading(true) to display a loading mask over the grid at any time.
I have two jQuery mobile pages (#list and #show). There are several items on the #list page with different IDs. If I click on item no.5, the ID no5 will be stored in localStorage and I will be redirected to page #show
Now the problem:
Storing the ID in localStorage works, but the next page shows me not the item no.5, but it shows me an old item, that was in the localStorage before.
script from page #list
localStorage.setItem("garageID", $(this).attr('id'));
window.location.replace("#show");
I encountered this problem too (and not on a mobile : on Chromium/linux).
As there doesn't seem to be a callback based API, I "fixed" it with a timeout which "prevents" the page to be closed before the setItem action is done :
localStorage.setItem(name, value);
setTimeout(function(){
// change location
}, 50);
A timeout of 0 might be enough but as I didn't find any specification (it's probably in the realm of bugs) and the problem isn't consistently reproduced I didn't take any chance. If you want you might test in a loop :
function setLocalStorageAndLeave(name, value, newLocation){
value = value.toString(); // to prevent infinite loops
localStorage.setItem(name, value);
(function one(){
if (localStorage.getItem(name) === value) {
window.location = newLocation;
} else {
setTimeout(one, 30);
}
})();
}
But I don't see how the fact that localStorage.getItem returns the right value would guarantee it's really written in a permanent way as there's no specification of the interruptable behavior, I don't know if the following part of the spec can be legitimately interpreted as meaning the browser is allowed to forget about dumping on disk when it leaves the page :
This specification does not require that the above methods wait until
the data has been physically written to disk. Only consistency in what
different scripts accessing the same underlying list of key/value
pairs see is required.
In your precise case, a solution might be to simply scroll to the element with that given name to avoid changing page.
Note on the presumed bug :
I didn't find nor fill any bug report as I find it hard to reproduce. In the cases I observed on Chromium/linux it happened with the delete operation.
Disclaimer: This solution isn't official and only tested for demo, not for production.
You can pass data between pages using $.mobile.changePage("target", { data: "anything" });. However, it only works when target is a URL (aka single page model).
Nevertheless, you still can pass data between pages - even if you're using Multi-page model - but you need to retrieve it manually.
When page is changed, it goes through several stages, one of them is pagebeforechange. That event carries two objects event and data. The latter object holds all details related to the page you're moving from and the page you're going to.
Since $.mobile.changePage() would ignore passed parameters on Multi-page model, you need to push your own property into data.options object through $.mobile.changePage("#", { options }) and then retrieve it when pagebeforechange is triggered. This way you won't need localstorage nor will you need callbacks or setTimeout.
Step one:
Pass data upon changing page. Use a unique property in order not to conflict with jQM ones. I have used stuff.
/* jQM <= v1.3.2 */
$.mobile.changePage("#page", { stuff: "id-123" });
/* jQM >= v1.4.0 */
$.mobile.pageContainer.pagecontainer("change", "#page", { stuff: "id-123" });
Step two:
Retrieve data when pagebeforechange is triggered on the page you're moving to, in your case #show.
$(document).on("pagebeforechange", function (event, data) {
/* check if page to be shown is #show */
if (data.toPage[0].id == "show") {
/* retrieve .stuff from data.options object */
var stuff = data.options.stuff;
/* returns id-123 */
console.log(stuff);
}
});
Demo