Graphics Reference
In-Depth Information
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<StackPanel DockPanel.Dock =
"Left"
Orientation=
"Vertical"
Background=
"#ECE9D8"
>
<TextBlock Margin=
"3"
Text=
"Controls"
/>
<Button Margin="3,5" HorizontalAlignment="Left"
Click="b1Click">Subdivide </Button>
<Button Margin="3,5" HorizontalAlignment="Left"
Click="b2Click">Clear</Button>
</StackPanel>
Now we modify the C# code in
Window1.xaml.cs
. We start by initializing both
polygons to be empty:
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public partial class Window1 : Window
{
Polygon myPolygon = new Polygon();
Polygon mySubdivPolygon = new Polygon();
bool isSubdivided = false;
GraphPaper gp = null;
[...]
public Window1()
{
[...]
initPoly(myPolygon, Brushes.Black);
initPoly(mySubdivPolygon, Brushes.Firebrick);
gp.Children.Add(myPolygon);
gp.Children.Add(mySubdivPolygon);
ready = true;
// Now we're ready to have sliders
// and buttons influence the display.
}
The polygon initialization procedure also sets the polygons to have different
colors and a standard line thickness, and to make sure that when two edges meet
at a sharp angle they are truncated, as shown at the bottom of Figure 4.4, instead
of having the joint extended in a long miter as shown in the middle.
Figure 4.4: When we thicken the
vertex join at the top, we must
miter it, as shown in the middle.
At the bottom, the miter is limited.
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private void initPoly(Polygon p, SolidColorBrush b)
{
p.Stroke = b;
p.StrokeThickness = 0.5;
// 0.5 mm thick line
p.StrokeMiterLimit = 1;
// no long pointy bits
p.Fill = null;
// at vertices
}
Handling a click on the Clear button is straightforward: We simply remove all
points from each polygon and set the
isSubdivided
flag back to
false
:
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// Clear button
public void b2Click(object sender, RoutedEventArgs e)
{
myPolygon.Points.Clear();
mySubdivPolygon.Points.Clear();
isSubdivided = false;
e.Handled = true;
// don't propagate click further
}
The Subdivide button is more complex. First, if the polygon is already subdi-
vided, we want to replace
myPolygon
's points with those of the subdivided poly-
gon. Then we can subdivide
myPolygon
and put the result into
mySubdivPolygon
.
