从缩略图中的图库转换图像（xamarin表格）

Question

this is my code for pick an image from gallery in my pcl project (ios/android)

        protected async Task PickImage()
    {
        try
        {
            Stream stream = await DependencyService.Get<IPicturePicker>().GetImageStreamAsync();

            {
                Image image = new Image
                {
                    Source = ImageSource.FromStream(() => stream),
                    BackgroundColor = Color.Gray
                };

                byte[] ImageData = Utils.Base64Utils.ToByteArray(stream);
                _base64String = Convert.ToBase64String(ImageData);

                editar_foto_perfil.Source = ImageSource.FromStream(() => new MemoryStream(Convert.FromBase64String(_base64String)));

                user.trocaImage = _base64String;

                if (Device.OS == TargetPlatform.iOS)
                {
                    user.cont_datanascimento = editar_date_datanasc.Date.ToString("yyyyMMdd");

                    if (editar_entry_nome.Text != null)
                        user.cont_nome = editar_entry_nome.Text;

                    if (editar_picker_estado.SelectedIndex != -1)
                        user.cont_estado = editar_picker_estado.Items[editar_picker_estado.SelectedIndex].ToString();

                    if (editar_picker_cidade.SelectedIndex != -1)
                        user.cont_cidade = editar_picker_cidade.Items[editar_picker_cidade.SelectedIndex].ToString();

                    if (editar_entry_senha.Text != null)
                        user.usua_senha = editar_entry_senha.Text;

                    if (editar_entry_email.Text != null)
                        user.usua_login = editar_entry_email.Text;

                    menu.RecriaEditarIOS(user);
                }
            }
        }
        catch (Exception ex)
        {
            var s = ex.Message;
        }
    }

sometimes I can't send the image picked to the server. Normally, it happens when the image is big, so, I want to resize it to a small image and send it to the server. Some idea?

---

Update

I am trying the Crossmedia plugin as our friend suggested in the comments... then I changed my method:

protected async Task PickImage()
    {
        try
        {
            //Stream stream = await DependencyService.Get<IPicturePicker>().GetImageStreamAsync();
            await CrossMedia.Current.Initialize();

            if (!CrossMedia.Current.IsPickPhotoSupported)
            {
                DisplayAlert("Photos Not Supported", ":( Permission not granted to photos.", "OK");
                return;
            }
            else
            {
            var file = await Plugin.Media.CrossMedia.Current.PickPhotoAsync(new Plugin.Media.Abstractions.PickMediaOptions
            {
                PhotoSize = Plugin.Media.Abstractions.PhotoSize.Medium,
            });             
        }
      }
        catch (Exception ex)
        {
            var s = ex.Message;
        }
    }

But, file is always null

Answer 1

pick an image from the gallery in my PCL project and I want to resize it to a small image

You could use the MediaPlugin to implement this function, here is its simple usage :

pickPhoto.Clicked += async (sender, args) =>
{
    if (!CrossMedia.Current.IsPickPhotoSupported)
    {
      DisplayAlert("Photos Not Supported", ":( Permission not granted to photos.", "OK");
      return;
    }
     var file = await Plugin.Media.CrossMedia.Current.PickPhotoAsync(new Plugin.Media.Abstractions.PickMediaOptions
                  {
                      PhotoSize =  Plugin.Media.Abstractions.PhotoSize.Medium,
     });


    if (file == null)
      return;

    var stream = file.GetStream();
}

Class PickMediaOptions is used to resize the selected image, you could find the source code here .

Update:

Here is my code and it works fine on my side:

private async void button_Clicked(object sender, EventArgs e)
{
    await PickImage();
}

protected async Task PickImage()
{
    try
    {
        await CrossMedia.Current.Initialize();

        if (!CrossMedia.Current.IsPickPhotoSupported)
        {
            DisplayAlert("Photos Not Supported", ":( Permission not granted to photos.", "OK");
            return;
        }
        else
        {
            var file = await Plugin.Media.CrossMedia.Current.PickPhotoAsync(new Plugin.Media.Abstractions.PickMediaOptions
            {
                PhotoSize = Plugin.Media.Abstractions.PhotoSize.Medium,
            });

            if (file == null)
                return;

            image.Source = ImageSource.FromStream(() =>
            {
                var stream = file.GetStream();
                file.Dispose();
                return stream;
            });
        }
    }
    catch (Exception ex)
    {
        var s = ex.Message;
    }
}