CODEWITHSUNDEEP
c#wpfdrag-and-drop
shampoo
shampoo

Reputation: 1281

GetManifestResourceStream - how can it help caching?

i searched for embedding custom drag and drop cursor in my wpf app. i ended up with an article which i have no idea of ONE LINE in the code suggested in (it is highlighted with the comments):

   private void textBlock2_MouseLeftButtonDown(object sender, MouseButtonEventArgs e)
    {
        TextBlock btn = (TextBlock)sender;

        GiveFeedbackEventHandler handler = new GiveFeedbackEventHandler(DragSource_GiveFeedback);
        btn.GiveFeedback += handler;


        DataObject dataObj = new DataObject(btn.Text);
        DragDrop.DoDragDrop(btn, dataObj, DragDropEffects.Move);
        btn.GiveFeedback -= handler;

    }

    void DragSource_GiveFeedback(object sender, GiveFeedbackEventArgs e)
    {
        try
        {
            if (_allOpsCursor == null)
            {

                ////////////////////////////////////////THE UNKOWN ONE LINE STARTS HERE
                using (Stream cursorStream = System.Reflection.Assembly.GetExecutingAssembly().GetManifestResourceStream("SimplestDragDrop.DDIcon.cur")) // AND ENDS HERE
                {
                    _allOpsCursor = new Cursor(cursorStream);
                }
            }
            Mouse.SetCursor(_allOpsCursor);

            e.UseDefaultCursors = false;
            e.Handled = true;
        }
        finally { }
    }

i checked GetManifestResourceStream, but i still have no idea what a mainfest resource is how could it be handled and where to start to get this caching idea (mentioned in the main article) to work.

Upvotes: 2

Views: 1083

Answers (1)

cfeduke
cfeduke

Reputation: 23236

Your assembly is loaded into memory as part of the AppDomain executing under the CLR. Because of this, if the resource is embedded into the assembly as part of the compilation process, using a stream to read an in-memory byte array is faster than having to go to disk to open a file, read its contents, close the file.

Alternatives are to store a byte array representing the resource within the source code, though more or less you're arriving at the same place using GetManifestResourceStream.

Upvotes: 1

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