打印 优化， 没有页时 提示不可以打印。

XHWK.WKTool/PrintWindow.xaml.cs

             {
                 imgPri.Source = new BitmapImage(new Uri(_imgPath));
             }
+            else
+            {
+                imgPri.Source = null;
+            }
             I = 0;
             if (t == null)
             {

XHWK.WKTool/XHMicroLessonSystemWindow.xaml

                     <RowDefinition Height="50"/>
                 </Grid.RowDefinitions>
                 <Label x:Name="lblVideoMess" Grid.Row="0" Content="暂无微课录制信息，请录制并等待保存完成后重试！" HorizontalAlignment="Center" Margin="0,0,0,100" VerticalAlignment="Center" FontSize="20" Visibility="Hidden"/>
-                <Button x:Name="BtnVideoUpPage" Content="上一页" HorizontalAlignment="Center" Margin="0,0,150,10" Grid.Row="1" VerticalAlignment="Bottom" Width="60" Background="{x:Null}" BorderBrush="{x:Null}" FontSize="16" Foreground="#FF333333" Click="BtnVideoUpPage_Click"/>
+                <Button  Cursor="Hand" x:Name="BtnVideoUpPage" Content="上一页" HorizontalAlignment="Center" Margin="0,0,150,10" Grid.Row="1" VerticalAlignment="Bottom" Width="60" Background="{x:Null}" BorderBrush="{x:Null}" FontSize="16" Foreground="#FF333333"  Click="BtnVideoUpPage_Click"/>
                 <Label x:Name="lblVideoPageNum" Grid.Row="1" FontSize="14" Content="100/100" HorizontalAlignment="Center" VerticalAlignment="Bottom" Margin="0,0,0,10" Foreground="#FF333333" />
-                <Button x:Name="BtnVideoDownPage" Content="下一页" HorizontalAlignment="Center" Margin="150,0,0,10" Grid.Row="1" VerticalAlignment="Bottom" Width="60" Background="{x:Null}" BorderBrush="{x:Null}" FontSize="16" Foreground="#FF333333" Click="BtnVideoDownPage_Click"/>
+                <Button  Cursor="Hand" x:Name="BtnVideoDownPage" Content="下一页" HorizontalAlignment="Center" Margin="150,0,0,10" Grid.Row="1" VerticalAlignment="Bottom" Width="60" Background="{x:Null}" BorderBrush="{x:Null}" FontSize="16" Foreground="#FF333333" Click="BtnVideoDownPage_Click"/>
             </Grid>
 
             <Grid Grid.Row="2" Background="#EFF1F8" Margin="0,0,0,0">

XHWK.WKTool/XHMicroLessonSystemWindow.xaml.cs

                     gridSetUp.Visibility = Visibility.Visible;
                     gridUpload.Visibility = Visibility.Collapsed;
                     txbStoragePath.Content = APP.WKData.WkPath;
-
+                    GridMyVideo.Visibility = Visibility.Collapsed;
                     #region 读取用户配置
                     //接口地址
                     if (!File.Exists(APP.dataPath + "interfaceAddress.txt")) //若为空
                 ofd = new System.Windows.Forms.OpenFileDialog
                 {
                     //Filter = "文档|*.docx;*.doc;*.ppt;*.pptx",
-                    Filter = "文档|*.docx;*.doc;*.ppt;*.pptx;*.pdf",
+                    Filter = "文档|*.docx;*.doc;*.ppt;*.pptx",
                     InitialDirectory = desktopPath,
                     Multiselect = false,
                     AddExtension = true,
                 PageNum = APP.pageData.currpage
             };
             APP.PageDrawList.Add(model_DrawData);
+             ImgPrint.Visibility = Visibility.Visible;//可打印
+                                ImgPrintTwo.Visibility = Visibility.Collapsed;
+                                btnPrint.IsEnabled = true;
             //APP.SaveDraw();
             if (btnImport.IsEnabled == true)
             {
             try
             {
                 //3种情况  1.文档图片 2.截图图片 3.没有图片
-
+                if(APP.PageDrawList.Count==0)
+                {
+                    MessageWindow.Show("没有可打印的页，您可以新增、截图或导入来增加页！");
+                    return;
+                }
 
 
                 iTextSharp.text.Document document = new iTextSharp.text.Document(iTextSharp.text.PageSize.A4, 25, 25, 25, 25);
             GridMain.Visibility = Visibility.Visible;
             gridSetUp.Visibility = Visibility.Collapsed;
             gridUpload.Visibility = Visibility.Collapsed;
+            GridMyVideo.Visibility = Visibility.Collapsed;
             if (APP.pageData.pagenum > 0)
             {
                 gridPage.Visibility = Visibility.Visible;