UWP - 在网格视图图像绑定上显示占位符，同时仍加载

Question

我在网格视图上有一个图像绑定，下面有 XAML：

<Border x:Name="coverBox" Grid.Row="0" Margin="5,10,0,0" Width="230" Height="170" VerticalAlignment="Top" HorizontalAlignment="Left" BorderBrush="Gray" BorderThickness="1" Background="{x:Null}">
<Image x:Name="cover" Source="{Binding Thumbnail}" HorizontalAlignment="Center" Stretch="Uniform" AutomationProperties.Name="{Binding Title}" Width="230" Height="170"/>
</Border>

法典：

string urlPath1 = "http://..../API/sekolah";
var httpClient1 = new HttpClient(new HttpClientHandler());
var values1 = new List<KeyValuePair<string, string>>
{
new KeyValuePair<string, string>("api_key", "...."),
new KeyValuePair<string, string>("limit", limit++.ToString()),
new KeyValuePair<string, string>("hal", noHal++.ToString())
};
var response1 = await httpClient1.PostAsync(urlPath1, new FormUrlEncodedContent(values1));
response1.EnsureSuccessStatusCode();
if (!response1.IsSuccessStatusCode)
{
busyIndicator.IsActive = false;
RequestException();
}
string jsonText1 = await response1.Content.ReadAsStringAsync();
JsonObject jsonObject1 = JsonObject.Parse(jsonText1);
JsonArray jsonData1 = jsonObject1["data"].GetArray();
foreach (JsonValue groupValue1 in jsonData1)
{
JsonObject groupObject2 = groupValue1.GetObject();
string thumbnail = groupObject2.ContainsKey("thumbnail") && groupObject2["thumbnail"] != null ? groupObject2["thumbnail"].GetString() : string.Empty;
ListingClass file1 = new ListingClass();
file1.Thumbnail = thumbnail;
listingDatasourceDetail.Add(file1);
}
listingGridView.ItemsSource = listingDatasourceDetail;

我想在仍然加载时从 JSON 获取图像数据，然后首先显示起搏器images/SEKOLAH-place-holder-600.png

如何在加载时添加占位符？

Answer 1

将cover图像包装在网格中，然后创建另一个图像以显示占位符 png 并将其放在cover后面。

Answer 2

尝试将Loading事件添加到图像：

private void myimage_Loading(FrameworkElement sender, object args)
{
Image myimage = (Image)sender;
myimage.Source = new BitmapImage(new Uri("ms-appx:///images/SEKOLAH-place-holder-600.png"));
}