public static SlidePreview CreateFromSlide(Slide slide, string presentationId, string text = null)
{
var preview = new SlidePreview();
preview.slideText = text ?? (slide != null ? ("" + slide.SlideNumber) : "1");
preview.presentationId = presentationId;
preview.slideImage = new BitmapImage();
byte[] buffer;
if (slide == null || slide.ImageData == null) {
var bitmap = new Bitmap(1024, 768);
var g = Graphics.FromImage(bitmap);
g.Clear(Color.Transparent);
using (var memory = new MemoryStream()) {
bitmap.Save(memory, ImageFormat.Png);
memory.Position = 0;
using (var br = new BinaryReader(memory)) {
buffer = br.ReadBytes((Int32) memory.Length);
}
}
if (slide != null) slide.ImageData = buffer;
} else {
buffer = slide.ImageData;
}
preview.slideImage.BeginInit();
preview.slideImage.StreamSource = new MemoryStream(buffer);
preview.slideImage.EndInit();
return preview;
}
public bool UpdateSlide(string clientId, string presentationId, Slide slide)
{
if (string.IsNullOrEmpty(clientId)) return false;
if (string.IsNullOrEmpty(presentationId) || !presentations.ContainsKey(presentationId)) return false;
if (presentations[presentationId].Owner != clientId) return false;
if (presentations[presentationId].Slides == null) return false;
if (slide == null) return false;
var slides = presentations[presentationId].Slides.ToList();
if (slides.Count <= (slide.SlideNumber - 1)) return false;
// update slide
slides[slide.SlideNumber - 1] = slide;
presentations[presentationId].Slides = slides;
return true;
}