<MudDialog>
    <DialogContent>
        <div class="d-flex flex-column py-1">
            <MudTextField @bind-Value="_url" InputType="InputType.Url" Label="图片地址" Variant="Variant.Text"></MudTextField>
        </div>
    </DialogContent>
    <DialogActions>
        <MudButton OnClick="Cancel">取消</MudButton>
        <MudButton Color="Color.Primary" OnClick="Submit">确定</MudButton>
    </DialogActions>
</MudDialog>

@code {

    [CascadingParameter]
    MudDialogInstance MudDialog { get; set; }

    [Inject]
    private IDialogService DialogService { get; set; }

    string _url = "";

    void Submit()
    {
        if (!_url.StartsWith("https", StringComparison.OrdinalIgnoreCase))
        {
            DialogService.ShowMessageBox("提示", "只支持https协议的图片", "确定");
            return;
        }

        var markdown = $"![]({_url})";
        MudDialog.Close(DialogResult.Ok(markdown));
    }

    void Cancel() => MudDialog.Cancel();
}