What did I miss?
There seems to be no shape suitable to represent a single point with a single coordinate pair as its position, which can be visibly inserted into any DrawPage, but has no (logical) extension > 0.
A line with empty end circles would be a candidate. (Better might be crosses.) You can create such a line, and give it length 0 (.Width=0; .Height=0). It will then exist as an object, but will not be visible.
(The “common” tag is added because most components have at least one DrawPage, and can create and insert shapes.)
What about a lonely, small, filled-in circle?
It has an extension. Even if the .Height and .Width are small they cause a probably significant error.
The current reason for asking this question (which is very old in my brain) now was an attempt to update and enhance old code for the creation of calculated shapes. In this context I considered ways to represent the center of a circle as a point in the precise position.
See also this thread.
@Lupp, clarify please.
Suppose we have to draw a circle of radius r centered on the point (a, b).
We have to call setPosition passing it the appropriate structure (x=a-r, y=b-r) and setSize with the parameter (height=2r, width=2r).
What’s wrong?
Choose the Ellipse tool, Hold Alt+Shift and start dragging at the point in question. This will draw a filled circle around the chosen point.
Shift+Drag draws a shape with equal height and weight (a circle in this case), Alt+Drag draws around the starting point.
Nothing insofar.
But you can neither draw the circle by GUI means based on center and radius, nor is the center graphically represented.
To give another example I recently worked with:
I had given 3 points by their coordinates in 6 cells of a spreadsheet. I wanted to draw the triangle and its circumcircle. This requires a bit more of calculation, but can be done. I also can (did not yet) represent the center of the circle as an endpoint of a specific radius line. I can not visualize the center exactly without choosing such a radius line.
Yes. However, the “chosen point” is chosen either “blind” or (probably) using a Snappoint (if this works at all). It’s not based on an ordinary visual element.
Well, I knew that Draw (or drawing in different components) can’t do like geometry software (I worked hundreds of hours with) and now I behave a bit as if it was otherwise. Anyway: Points are so fundamental elements of drawings that I really miss an appropriate precise, visual, and clear representation (with a few selectable variants like they are created for charts, e.g.).
To visualize the center of the circle, you can, for example, set shape’s string “+” with a suitable font size and align to the center.
Thanks for your ideas and for taking the time to present them here. However, I can’t accept one of the posts as a solution.
To explain my intention and my own considerations concerning a kind of (unsatisfactory) workaround, I made the attached drawing.
pointSurrogates.odg (23.7 KB)