Finding viewPoint center coordinates relative to a Shape?

GoJS
1

Assume I have a digram 6x6.

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I insert a Shape 3x3 square into this document in the bottom right.

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| | | |o|o|o|
| | | |o|x|o|
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Problem: When I hover over this shape using mouseHover, how do I retrieve the center coordinate of the shape relative to the document (the x), ie. (5,5)?

Currently, if I perform getDocumentPoint(go.Spot.Center) on the Shape it returns me the coordinates of the center relative to the shape, (2,2). But I am looking for the coordinates relative to the entire diagram.

e.viewPoint only returns the center coordinates relative to the entire diagram.

2

Is your 6x6 diagram talking about the Diagram.documentBounds or the Diagram.viewportBounds?

Note that almost everything in GoJS is in document units, which are unaffected by scrolling/panning/zooming. The position and size of Parts are in document coordinates. The very few places where one encounters viewport coordinates are clearly documented. GoJS Coordinate Systems-- Northwoods Software

Certainly GraphObject.getDocumentPoint returns a point in document coordinates. That point is in the same coordinate system as Diagram.documentBounds.

3

I guess I shouldn’t have drawn a grid. :smiley:

It was a more a generic question… if I had a shape somewhere on the diagram, how do I get the exact center of that shape? Whenever I do node.getDocumentPoint(go.Spot.Center) it does indeed return me the center (x,y) of the shape, but not relative to the canvas, just relative to itself, if that makes sense.

Does that clarify?

4

Read GoJS Coordinate Systems-- Northwoods Software for an explanation and example showing the differences between viewport and document coordinates.