Creating multiple interactive handles in a graph box

rassart

Hi,

From a table with two columns defining X and Y coordinates, I'm trying to create a graph box with an interactive handle for each point defined in the table.  Adding handles one by one (see nw1 below) works perfectly, but when I try to automate the process by using ForEachRow or a For loop (see nw2 and nw3), I get a graph box with the points, but they can't be moved interactively.  What would be the correct way to automate the creation of the handles?

Thanks, Étienne

 

dt = NewTable("DataPoints", AddRows(3),

        NewColumn("xVar", Numeric, "Continuous", SetValues( [1, 2, 3])),

        NewColumn("yVar", Numeric, "Continuous", SetValues( [1, 2, 3]))

);

 

CurrentDataTable(dt);

 

nw1 = NewWindow("Example 1",

        gr1 = GraphBox(

                FrameSize(400, 400), XScale(0, 5), YScale(0, 5),

                Handle(:xVar[1], :yVar[1], :xVar[1] = x; :yVar[1] = y;);

                Handle(:xVar[2], :yVar[2], :xVar[2] = x; :yVar[2] = y;);

                Handle(:xVar[3], :yVar[3], :xVar[3] = x; :yVar[3] = y;);

        );

);

 

nw2 = NewWindow("Example 2",

        gr2 = GraphBox(

                FrameSize(400, 400), XScale(0, 5), YScale(0, 5),

                ForEachRow(

                        Handle(:xVar, :yVar, :xVar = x; :yVar = y;);

                );

        );

);

 

nw3 = NewWindow("Example 3",

        gr3 = GraphBox(

                FrameSize(400, 400), XScale(0, 5), YScale(0, 5),

                For(i=1, i<=NRows(dt), i++,

                        Handle(:xVar[i], :yVar[i], :xVar[i] = x; :yVar[i] = y;);

                );

        );

);

cwillden

Hi @rassart,

This one case where you need to hard-code in the row values from your table when adding the handles.  The reason becomes apparent when you get the graphics script you just created back out of graph box from your window.  For example, the graphics script from Example 3 looks like this afterward:

gr3 << Get Graphics Script;
/*:

{For( i = 1, i <= N Rows( dt ), i++,
	Handle(
		:xVar[i],
		:yVar[i],
		:xVar[i] = x;
		:yVar[i] = y;
	)
)}

The final value of the variable 'i' will be set to 4 with your example, so none of the handles will work properly since the value of 'i' was not hard-coded in.  Without hard-coding, the graphics script will always rely on the current value of 'i'.

Here's a way you can hard-code these values in using a for-loop:

nw4 = New Window( "Example 4", gr4 = Graph Box( FrameSize( 400, 400 ), X Scale( 0, 5 ), Y Scale( 0, 5 ), ) );

For( i = 1, i <= N Rows( dt ), i++,
	Eval( Parse( Eval Insert( "gr4[framebox(1)] << Add Graphics Script(Handle(:xVar[^i^], :yVar[^i^], :xVar[^i^] = x; :yVar[^i^] = y;));" ) ) )
);