private void loadImagefromfilename(string filename)
{
IPresentation pptxDoc = Presentation.Open(filename);
pptxDoc.ChartToImageConverter = new ChartToImageConverter();
pptxDoc.ChartToImageConverter.ScalingMode = Syncfusion.OfficeChart.ScalingMode.Best;
_images = pptxDoc.RenderAsImages(Syncfusion.Drawing.ImageType.Metafile);
_currentslide = 0;
loadImagetoUi(_currentslide);
}