Partial scaling of a composed elements in WPF

I am in the following situation: designing an interactive flow-chart GUI. I stuck with animating a scale down animation of the flow-chart. Composed elements of the flow-chart are minimized, but they keep being active.

I have something like this:

            <Canvas Canvas.Left="55" Canvas.Top="720" Height="100" Width="500" Tag="stepDown">
                <Line Stroke="#99CCFF" StrokeThickness="8" X1="0" X2="720" Y1="10" Y2="10">
                <Polygon Stroke="Black" StrokeThickness="2" Points="0,30 40,0 40,60" Canvas.Left="-20" Canvas.Top="-20" Fill="#99CCFF"></Polygon>
                <Polygon Stroke="Black" StrokeThickness="2" Points="0,0 0,60 40,30" Canvas.Left="720" Canvas.Top="-20" Fill="#99CCFF"></Polygon>
                <Image Canvas.Left="-50" Canvas.Top="-70" Height="53" Name="image32" Source="img/outlet.png" Stretch="Fill" Width="30" Tag="relative" />
            </Canvas>

And I would like to shift the whole canvas and its elements to the left - no problem with Translate Transform. Furthermore I would like to scale down only the Line, no problem with Scale Transform.

But (!) at the same time, I want that the Polygons stick to the two line endings of the line. When scaling down only the line, the Polygons, at least one, floats away.

I don't know how to dock these elements or define them at a relative basis. It works fine with a scale down on the whole Canvas, bu开发者_开发问答t this changes the Polygon and Images as well.

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In order to me you have to define hanchors points, as attached properties. Even define a behavior that track these points accordingly to poligon placements. Then you can bind these property to the line start/end point. In this way line should stay gripped to the polygons. But I did'nt try, is just a design idea.