How to Change the LockScreen back ground (find windows.system.UserProfile.dll)?

Question

I started a windows form application which imports images from files and store them and specify a radio button to each one.

it have a button with the name 'Lock' so if user select one radio button and then press the button the app should change the lock screen image and then Lock the screen.

But I don't know how to set the image and lock the screen.

I googled later and the answer about the LockScreen.blabla didn't work for me because I can't do using windows.system.userprofile;

If some one get me the assembly i will do the thing.

there is the events:

private void rB_CheckedChanged(object sender, EventArgs e)
        {
            MyRadioButton radioButton = sender as MyRadioButton;
            pictureBox1.Image = radioButton.Image;
        }

        private void btnBrowse_Click(object sender, EventArgs e)
        {
            if (openFileDialog1.ShowDialog() == DialogResult.OK)
            {
                pictureBox1.Image = Image.FromFile(openFileDialog1.FileName);
                foreach (Control control in FindForm().Controls)
                {
                    if (control.GetType() == typeof(MyRadioButton))
                    {
                        MyRadioButton mrb = control as MyRadioButton;
                        if (mrb.Checked == true)
                        {
                            mrb.Image = pictureBox1.Image;
                        }
                    }
                }
            }
        }

        private void btnLock_Click(object sender, EventArgs e)
        {
            //should set the lock screen background

            LockScreen.LockScreen.SetImageFileAsync(imagefile);//shows error 'the name lock screen does not exist
        }

Answer 1

I have made a UWP application to use the LockScreen class provided by windows.userProfile.dll And the event's changed to:

        private Dictionary<string, string> Images = new Dictionary<string, string>();
        private async void btnLock_Click(object sender, RoutedEventArgs e)
        {
            string path;
            if (Images.TryGetValue(selectedRadioButton.Name, out path))
            {
                StorageFile file = await StorageFile.GetFileFromPathAsync(path);
                await LockScreen.SetImageFileAsync(file);
                try
                {
                    HttpClient httpClient = new HttpClient();
                    Uri uri = new Uri("http://localhost:8080/lock/");

                    HttpStringContent content = new HttpStringContent(
                        "{ \"pass\": \"theMorteza@1378App\" }",
                        UnicodeEncoding.Utf8,
                        "application/json");

                    HttpResponseMessage httpResponseMessage = await httpClient.PostAsync(
                        uri,
                        content);

                    httpResponseMessage.EnsureSuccessStatusCode();
                    var httpResponseBody = await httpResponseMessage.Content.ReadAsStringAsync();
                }
                catch (Exception ex)
                {
                    throw ex;
                }
            }
        }

private async void btnBrowse_Click(object sender, RoutedEventArgs e)
        {
            var picker = new Windows.Storage.Pickers.FileOpenPicker();
            picker.ViewMode = Windows.Storage.Pickers.PickerViewMode.Thumbnail;
            picker.SuggestedStartLocation = Windows.Storage.Pickers.PickerLocationId.Desktop;
            picker.FileTypeFilter.Add(".jpg");
            picker.FileTypeFilter.Add(".jpeg");
            picker.FileTypeFilter.Add(".png");

            StorageFile file = await picker.PickSingleFileAsync();
            if (file != null)
            {
                using (var imageStream = await file.OpenReadAsync())
                {
                    var bitmapImage = new BitmapImage();
                    await bitmapImage.SetSourceAsync(imageStream);
                    image.Source = bitmapImage;
                }
                StorageFolder storageFolder = ApplicationData.Current.LocalFolder;
                await file.CopyAsync(storageFolder, selectedRadioButton.Name+file.FileType,NameCollisionOption.ReplaceExisting);
                addOrUpdate(selectedRadioButton.Name, Path.Combine(storageFolder.Path, selectedRadioButton.Name + file.FileType));
                save();
            }
        }
        private async void rb_Checked(object sender, RoutedEventArgs e)
        {
            RadioButton rb = sender as RadioButton;
            selectedRadioButton = rb;
            btnBrowse.IsEnabled = true;
            string path;
            if (Images.TryGetValue(rb.Name, out path))
            {
                StorageFile file = await StorageFile.GetFileFromPathAsync(path);
                using (var imageStream = await file.OpenReadAsync())
                {
                    var bitmapImage = new BitmapImage();
                    await bitmapImage.SetSourceAsync(imageStream);
                    image.Source = bitmapImage;
                }
            }
        }
        private void addOrUpdate(string key, string image)
        {
            if (Images.Keys.Contains(key))
            {
                Images.Remove(key);
                Images.Add(key, image);
            }
            else
            {
                Images.Add(key, image);
            }
        }

        private async void save()
        {
            StorageFolder storageFolder = ApplicationData.Current.LocalFolder;
            StorageFile file = await storageFolder.CreateFileAsync("sample.txt", CreationCollisionOption.ReplaceExisting);
            await FileIO.WriteTextAsync(file, JsonConvert.SerializeObject(Images));
        }

        private async void load()
        {
            StorageFolder storageFolder = ApplicationData.Current.LocalFolder;
            StorageFile sampleFile = await storageFolder.GetFileAsync("sample.txt");
            string fileText = await FileIO.ReadTextAsync(sampleFile);
            try
            {
                Images = JsonConvert.DeserializeObject<Dictionary<string, string>>(fileText);
            }
            catch (Exception)
            {
            }
        }

and you can see in the lock button click event there is a request to a web server cause you cannot directly lock the screen in a UWP app and you can follow the rest of your question in my next answer to the question "why I can't directly lock screen in UWP app?and how to do so?".