Question

我需要将图像（从Web服务获取）转换为base64String，以将它们存储在SQLite数据库中。

编辑：我使用ImageOpened以便在将图像转换为base64String但ImageOpened doest运行之前加载/下载图像。我该如何完成这项任务？我的意思是将图像数组转换为base64。

这是我的代码：

public async void LoadData()
    {
       //get Json
       string str = await Helper.getJSON(); 

       //Deserialize json
       MainClass apiData = JsonConvert.DeserializeObject<MainClass>(str);

       //the problem loop
       for (int i = 0; i < apiData.Categories.Count;i++ ) 
       {
           //apiData.Categoriesp[i].icon_image is the url of the image
           BitmapImage image = new BitmapImage(new Uri(apiData.Categories[i].icon_image,UriKind.RelativeOrAbsolute));


         //it never runs
           image.ImageOpened += (s, e) =>
           {
             //code for conversion of image into memory stream
               image.CreateOptions = BitmapCreateOptions.None;
               WriteableBitmap wb = new WriteableBitmap(image);
               MemoryStream ms = new MemoryStream();
               wb.SaveJpeg(ms, image.PixelWidth, image.PixelHeight, 0, 100);
               byte[] imageBytes = ms.ToArray();  

               string base64String = Convert.ToBase64String(imageBytes);

             //setting imageInSql property of the list (but it never runs)
               apiData.Categories[i].imageInSql = base64String;
           }; 

       } 

        //Inserting into database
        using(var db= new SQLiteConnection(App.dbPath)){
                //geting null in imageinSql property.
                db.InsertAll(apiData.Categories,typeof(Category));  
        } 
    }

提前致谢。

Answer 1

对我来说，它看起来像是在事件处理程序中设置CreateOptions属性。

image.ImageOpened += (s, e) =>
{
     //code for conversion of image into memory stream
     image.CreateOptions = BitmapCreateOptions.None;

你应该这样做 -

image.CreateOptions = BitmapCreateOptions.None;
image.ImageOpened += (s, e) =>
{

尝试以下代码。

public async void LoadData()
{
   //get Json
   string str = await Helper.getJSON(); 

   //Deserialize json
   MainClass apiData = JsonConvert.DeserializeObject<MainClass>(str);

   //the problem loop
   for (int i = 0; i < apiData.Categories.Count;i++ ) 
   {
       //apiData.Categoriesp[i].icon_image is the url of the image
       BitmapImage image = new BitmapImage(new Uri(apiData.Categories[i].icon_image,UriKind.RelativeOrAbsolute));

      image.CreateOptions = BitmapCreateOptions.None
     //it never runs
       image.ImageOpened += (s, e) =>
       {
         //code for conversion of image into memory stream

           WriteableBitmap wb = new WriteableBitmap(image);
           MemoryStream ms = new MemoryStream();
           wb.SaveJpeg(ms, image.PixelWidth, image.PixelHeight, 0, 100);
           byte[] imageBytes = ms.ToArray();  

           string base64String = Convert.ToBase64String(imageBytes);

         //setting imageInSql property of the list (but it never runs)
           apiData.Categories[i].imageInSql = base64String;
       }; 

   } 

    //Inserting into database
    using(var db= new SQLiteConnection(App.dbPath)){
            //geting null in imageinSql property.
            db.InsertAll(apiData.Categories,typeof(Category));  
    } 
}

从Web链接获取图像并将其转换为循环中的base64string

1 个答案: