我想创建一个图片幻灯片。图片来自json上的数据(如下所示)。 我尝试使用以下代码:
DispatcherTimer playlistTimer1a = null;
List<string> Images1a = new List<string>();
protected override void OnNavigatedTo(NavigationEventArgs e)
{
ImageSource1a();
}
private async void ImageSource1a()
{
try
{
var httpClientHandler = new HttpClientHandler();
httpClientHandler.Credentials = new System.Net.NetworkCredential("username", "password");
var httpClient = new HttpClient(httpClientHandler);
string urlPath = "http://";
var values = new List<KeyValuePair<string, string>>
{
new KeyValuePair<string, string>("platform","win"),
};
HttpResponseMessage response = await httpClient.PostAsync(urlPath, new FormUrlEncodedContent(values));
response.EnsureSuccessStatusCode();
string jsonText = await response.Content.ReadAsStringAsync();
JsonObject jsonObject = JsonObject.Parse(jsonText);
//JsonObject jsonData1 = jsonObject["data"].GetObject();
JsonArray jsonData1 = jsonObject["data"].GetArray();
foreach (JsonValue groupValue1 in jsonData1)
{
JsonObject groupObject1 = groupValue1.GetObject();
string image = groupObject1["image"].GetString();
string url = groupObject1["url"].GetString();
Banner file1 = new Banner();
file1.Image = image;
file1.URL = url;
Images1a.Add(file1.Image);
playlistTimer1a = new DispatcherTimer();
playlistTimer1a.Interval = new TimeSpan(0, 0, 6);
playlistTimer1a.Tick += playlistTimer_Tick1a;
topBanner.Source = new BitmapImage(new Uri(file1.Image));
playlistTimer1a.Start();
}
}
catch (HttpRequestException ex)
{
RequestException();
}
}
int count1a = 0;
void playlistTimer_Tick1a(object sender, object e)
{
if (Images1a != null)
{
if (count1a < Images1a.Count)
count1a++;
if (count1a >= Images1a.Count)
count1a = 0;
ImageRotation1a();
}
}
private async void ImageRotation1a()
{
OpacityTrans1.Begin();
}
问题只是幻灯片显示图像索引为0,无法更改图片。我怎样才能克服这个问题?
答案 0 :(得分:0)
问题只是幻灯片显示图像索引为0,无法更改图片。
foreach
循环会破坏所有内容。如果您想制作幻灯片显示图片,请不要在DispatcherTimer
循环中包含foreach
,您可以按照以下步骤修改代码:
修改您的ImageSource1a
方法,如下所示:
private async void ImageSource1a()
{
try
{
...
foreach (JsonValue groupValue1 in jsonData1)
{
JsonObject groupObject1 = groupValue1.GetObject();
string image = groupObject1["image"].GetString();
string url = groupObject1["url"].GetString();
Images1a.Add(image);
}
//I don't know what is Banner object used for but for this piece of codes, a banner object is not necessary.
//Banner file1 = new Banner();
//file1.Image = image;
//file1.URL = url;
playlistTimer1a = new DispatcherTimer();
playlistTimer1a.Interval = new TimeSpan(0, 0, 6);
playlistTimer1a.Tick += playlistTimer_Tick1a;
topBanner.Source = new BitmapImage(new Uri(Images1a[0]));//set the current image to the first one
playlistTimer1a.Start();
}
catch (HttpRequestException ex)
{
RequestException();
}
}
修改您的playlistTimer_Tick1a
方法,如下所示:
private void playlistTimer_Tick1a(object sender, object e)
{
if (Images1a != null)
{
if (count1a < Images1a.Count)
count1a++;
if (count1a >= Images1a.Count)
count1a = 0;
topBanner.Source = new BitmapImage(new Uri(Images1a[count1a]));
ImageRotation1a();
}
}
更新:这是我的基本演示:SlideShowSample。