Is a dashed border around a selected text/image element possible in Silverlight? - wpf

Question

I have an image editor I'm developing in silverlight which has multiple text and image elements on one canvas, that are draggable etc. I need feedback for the user to highlight the selected element when it is clicked on by the user and highlight a different element instead if another is clicked. I think I should do this with a dashed border around the element, but I don't know if it's possible.
Below is my code relating to the elements -
Project.cs
namespace ImageEditor.Client.BLL
{
public class Project : INotifyPropertyChanged
{
private int numberOfElements;
#region Properties
private ObservableCollection<FrameworkElement> elements;
public ObservableCollection<FrameworkElement> Elements
{
get { return elements; }
set
{
elements = value;
NotifyPropertyChanged("Elements");
}
}
private FrameworkElement selectedElement;
public FrameworkElement SelectedElement
{
get { return selectedElement; }
set
{
selectedElement = value;
NotifyPropertyChanged("SelectedElement");
}
}
private TextBlock selectedTextElement;
public TextBlock SelectedTextElement
{
get { return selectedTextElement; }
set
{
selectedTextElement = value;
NotifyPropertyChanged("SelectedTextElement");
}
}
private Image selectedImageElement;
public Image SelectedImageElement
{
get { return selectedImageElement; }
set
{
selectedImageElement = value;
NotifyPropertyChanged("SelectedImageElement");
}
}
#endregion
#region Methods
private void AddTextElement(object param)
{
TextBlock textBlock = new TextBlock();
textBlock.Text = "New Text";
textBlock.Foreground = new SolidColorBrush(Colors.Gray);
textBlock.FontSize = 25;
textBlock.FontFamily = new FontFamily("Arial");
textBlock.Cursor = Cursors.Hand;
textBlock.Tag = null;
AddDraggingBehavior(textBlock);
textBlock.MouseLeftButtonUp += element_MouseLeftButtonUp;
this.Elements.Add(textBlock);
numberOfElements++;
this.SelectedElement = textBlock;
this.selectedTextElement = textBlock;
}
private BitmapImage GetImageFromLocalMachine(out bool? success, out string fileName)
{
OpenFileDialog dialog = new OpenFileDialog()
{
Filter = "Image Files (*.bmp;*.jpg;*.gif;*.png;)|*.bmp;*.jpg;*.gif;*.png;",
Multiselect = false
};
success = dialog.ShowDialog();
if (success == true)
{
fileName = dialog.File.Name;
FileStream stream = dialog.File.OpenRead();
byte[] data;
BitmapImage imageSource = new BitmapImage();
using (FileStream fileStream = stream)
{
imageSource.SetSource(fileStream);
data = new byte[fileStream.Length];
fileStream.Read(data, 0, data.Length);
fileStream.Flush();
fileStream.Close();
}
return imageSource;
}
else
{
fileName = string.Empty;
return new BitmapImage();
}
}
private void AddImageElement(object param)
{
bool? gotImage;
string fileName;
BitmapImage imageSource = GetImageFromLocalMachine(out gotImage, out fileName);
if (gotImage == true)
{
Image image = new Image();
image.Name = fileName;
image.Source = imageSource;
image.Height = imageSource.PixelHeight;
image.Width = imageSource.PixelWidth;
image.MaxHeight = imageSource.PixelHeight;
image.MaxWidth = imageSource.PixelWidth;
image.Cursor = Cursors.Hand;
image.Tag = null;
AddDraggingBehavior(image);
image.MouseLeftButtonUp += element_MouseLeftButtonUp;
this.Elements.Add(image);
numberOfElements++;
this.SelectedElement = image;
this.SelectedImageElement = image;
}
}
private void OrderElements()
{
var elList = (from element in this.Elements
orderby element.GetValue(Canvas.ZIndexProperty)
select element).ToList<FrameworkElement>();
for (int i = 0; i < elList.Count; i++)
{
FrameworkElement fe = elList[i];
fe.SetValue(Canvas.ZIndexProperty, i);
}
this.Elements = new ObservableCollection<FrameworkElement>(elList);
}
public void element_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
this.SelectedElement = sender as FrameworkElement;
if (sender is TextBlock)
{
this.SelectedTextElement = sender as TextBlock;
FadeOut(this.SelectedTextElement);
}
else if (sender is Image)
{
this.SelectedImageElement = sender as Image;
FadeOut(this.SelectedImageElement);
}
}
#endregion
More than needed there but you get a good idea of how it all works from that. How might I go about it? I'm still pretty new to silverlight
Edit:
This is my start attempt at a DashBorder Method, wherein I'm trying to make a rectangle the same dimensions as the selected element which will go around the element
public static void DashBorder(FrameworkElement element)
{
Rectangle rect = new Rectangle();
rect.Stroke = new SolidColorBrush(Colors.Black);
rect.Width=element.Width;
rect.Height=element.Height;
rect.StrokeDashArray = new DoubleCollection() { 2, 2 };
}
It appears to do nothing and isn't what I want to do anyway. Is there no way to make a dash border on a FrameworkElement directly?

Answer 1

I don't know how, but google does.
You can use the StrokeDashArray to achieve the desired effect,
example:
<Rectangle Canvas.Left="10" Canvas.Top="10" Width="100" Height="100"
Stroke="Black" StrokeDashArray="10, 2"/>
The first number in StrokeDashArray is the length of the dash, the
second number is the length of the gap. You can repeat the dash gap
pairs to generate different patterns.
Edit:
To do this in code create a rectangle and set it's StrokeDashArray property like this (code untested):
Rectangle rect = new Rectangle();
rect.StrokeThickness = 1;
double[] dashArray = new double[2];
dashArray[0] = 2;
dashArray[1] = 4;
rect.StrokeDashArray = dashArray;