Image scaling problem

Question

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Hi
This is probably a simple mistake. However, I have been working on this for hours and can't see what is wrong.

I want to scale and image by a scaling factor. Look at the following code.

XML

 <StackPanel>
    <StackPanel Name="StackDesktop" Width="Auto" Height="Auto" >
        <Label Name="LabSlideName" Width="Auto" Content="Slide Name" Height="25" Foreground="White"/>
        <Grid Name="GridPreview" Width="640" Height="480" HorizontalAlignment="Center" VerticalAlignment="Center" removed="DarkBlue" >
            <Grid Name="GridImage">
                <Viewbox Name="ViewBoxPreview" Stretch="None" StretchDirection="Both" />
            </Grid>
        </Grid>
    </StackPanel>
</StackPanel>

Code Behind

SlideShow.SlideShow node = ExperimentLibrary.Experiment.Instance.GetSlideShow().GetNodeByID(id);
            System.Windows.Controls.Image img = new System.Windows.Controls.Image();
            Bitmap bmp = new Bitmap((int)node.Slide.PresentationSize.Width, (int)node.Slide.PresentationSize.Height);
             
            Graphics g = System.Drawing.Graphics.FromImage(bmp);
            node.Slide.Draw(g);
            IntPtr hBitmap = bmp.GetHbitmap();
            System.Windows.Media.ImageSource WpfBitmap = System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap(hBitmap, IntPtr.Zero, Int32Rect.Empty, BitmapSizeOptions.FromEmptyOptions());
            img.Source = WpfBitmap;

            double scale = GridPreview.Width / System.Windows.SystemParameters.PrimaryScreenWidth;
            GridImage.Width = (int)(WpfBitmap.Width * scale);
            GridImage.Height = (int)(WpfBitmap.Height * scale);
            ViewBoxPreview.Stretch = Stretch.UniformToFill; ;
            ViewBoxPreview.Child = img;

The original image size is 640*480. The final displayed image is 234*135. As scale is 0.4685, and GridImage.Width = 299 and GridImage.Height = 224, I was expecting the final image to be 299*224.

Can someone please help as I am stuck...

Cheers....

Posted 18-Apr-13 13:17pm

FlurryKnox

Updated 18-Apr-13 13:23pm

v2

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Comments

Sergey Alexandrovich Kryukov 19-Apr-13 0:34am

WPF? Tag it.
—SA

FlurryKnox 19-Apr-13 3:00am

Yes, that's what I tried first. E.g. Change Width and Height and then Stretch to UniformToFill and StretchDirection to Both. The resulting image is still 234*135. E.g. the results are the same.???? I've tried about everything I can think of.

Sergey Alexandrovich Kryukov 19-Apr-13 12:09pm

No. I did not ask you for clarification.

This question has tags. Add "WPF". Use "Improve question" above. You are the one who is interested in that.
—SA

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FlurryKnox · Answer 1 · 2013-04-18T21:11:00

[This is not an answer and should be removed. OP should move it to the question using "Improve question" —SA]

Look here,

XML

<StackPanel>
                        <StackPanel Name="StackDesktop" Width="Auto" Height="Auto" >
                            <Label Name="LabSlideName" Width="Auto" Content="Slide Name" Height="25" Foreground="White"/>
                            <Grid Name="GridPreview" Width="640" Height="480" HorizontalAlignment="Center" VerticalAlignment="Center" Background="DarkBlue" Margin="26,0,34,0" >
                                <Grid Name="GridImage">

                                </Grid>
                            </Grid>
                        </StackPanel>
                    </StackPanel>

SlideShow.SlideShow node = ExperimentLibrary.Experiment.Instance.GetSlideShow().GetNodeByID(id);
            System.Windows.Controls.Image img = new System.Windows.Controls.Image();
            Bitmap bmp = new Bitmap((int)node.Slide.PresentationSize.Width, (int)node.Slide.PresentationSize.Height);
             
            Graphics g = System.Drawing.Graphics.FromImage(bmp);
            node.Slide.Draw(g);
            IntPtr hBitmap = bmp.GetHbitmap();
            System.Windows.Media.ImageSource WpfBitmap = System.Windows.Interop.Imaging.CreateBitmapSourceFromHBitmap(hBitmap, IntPtr.Zero, Int32Rect.Empty, BitmapSizeOptions.FromEmptyOptions());
            img.Source = WpfBitmap;

            
                double scale = GridPreview.Width / System.Windows.SystemParameters.PrimaryScreenWidth;
                img.Width = (int)(WpfBitmap.Width * scale);
                img.Height = (int)(WpfBitmap.Height * scale);
                img.Stretch = Stretch.UniformToFill; ;
                img.StretchDirection = StretchDirection.Both;
                GridImage.Children.Add(img);

Image is still 234*135...Any ideas why???