Question

Why does the line of code below, cause an {“InvalidCastException”}

((RotateTransform)image.RenderTransform).Angle = 90; 

The whole code in the method is

void loadImage()
        {
            // The image will be read from isolated storage into the following byte array

        byte[] data;

        // Read the entire image in one go into a byte array

        using (IsolatedStorageFile isf = IsolatedStorageFile.GetUserStoreForApplication())
        {

            // Open the file - error handling omitted for brevity

            // Note: If the image does not exist in isolated storage the following exception will be generated:

            // System.IO.IsolatedStorage.IsolatedStorageException was unhandled 

            // Message=Operation not permitted on IsolatedStorageFileStream 

            using (IsolatedStorageFileStream isfs = isf.OpenFile("0.jpg", FileMode.Open, FileAccess.Read))
            {

                // Allocate an array large enough for the entire file

                data = new byte[isfs.Length];



                // Read the entire file and then close it

                isfs.Read(data, 0, data.Length);

                isfs.Close();

            }
        }



        // Create memory stream and bitmap

        MemoryStream ms = new MemoryStream(data);

        BitmapImage bi = new BitmapImage();

        // Set bitmap source to memory stream

        bi.SetSource(ms);

        // Create an image UI element – Note: this could be declared in the XAML instead

        Image image = new Image();

        // Set size of image to bitmap size for this demonstration

        image.Height = bi.PixelHeight;

        image.Width = bi.PixelWidth;

        // Assign the bitmap image to the image’s source

        image.Source = bi;

        ((RotateTransform)image.RenderTransform).Angle += 90; 

        // Add the image to the grid in order to display the bit map

        ContentPanelx.Children.Add(image);

    }

EDIT

Having changed the following code like so, it does not crash but no image is drawn.

        image.Height = bi.PixelHeight;

        image.Width = bi.PixelWidth;

        // Assign the bitmap image to the image’s source

        image.Source = bi;
        image.RenderTransform = new RotateTransform() { Angle = 90 };

        ContentPanelx.Children.Add(image);

Is there a step I am missing?

Many Thanks,
-Code

Answer 1

You have just created an image object. Its RenderTransform property doesn’t reference a RotateTransform instance. Try: image.RenderTransform = new RotateTransform(){Angle=90};