Re: makeSelection() error with decimal numbers

Posted by Rasband, Wayne (NIH/NIMH) [E] on Jul 27, 2015; 6:49pm
URL: http://imagej.273.s1.nabble.com/makeSelection-error-with-decimal-numbers-tp5013768p5013769.html

On Jul 27, 2015, at 2:04 PM, Jochen Reichel <[hidden email]> wrote:

>
> Hallo everyone,
>
> I am writing an imageJ macro. I want to recreate a hand-drawn straight line selection, that can easily contain not integer coordinates, as can be seen from this code (if the selection was done at high magnification/zoomed in):
> ---------------------
> Roi.getCoordinates(x,y);
> Array.print(x);
> Array.print(y);
> ---------------------
>
>
> When trying to create a selection that contains only integers, everything is fine. But when I try to create a selection that also contains coordinates with decimal numbers with the following code, I get an error:

This bug is fixed in the latest ImageJ daily build (1.50b3).

-wayne

> ---------------------
> newImage("Untitled", "8-bit black", 512, 512, 1);
> xCoords1 = newArray(200, 400);
> yCoords1 = newArray(200, 400);
> xCoords2 = newArray(200.5, 400);             //<- this .5 causes the error lateron
> yCoords2 = newArray(200, 400);
> makeSelection(5, xCoords1, yCoords1);        //5 stands for "straight line"
> print("everthing fine");
> wait(2000);
> makeSelection(5, xCoords2, yCoords2);
> ---------------------
>
>
> The error message is the following:
> #####################
> ImageJ 1.50a; Java 1.6.0_20 [64-bit]; Windows 7 6.1; 55MB of 8192MB (<1%)
>
> java.lang.NullPointerException
>    at ij.macro.Functions.makeSelection(Functions.java:1972)
>    at ij.macro.Functions.doFunction(Functions.java:142)
>    at ij.macro.Interpreter.doStatement(Interpreter.java:227)
>    at ij.macro.Interpreter.doStatements(Interpreter.java:215)
>    at ij.macro.Interpreter.run(Interpreter.java:112)
>    at ij.macro.Interpreter.run(Interpreter.java:82)
>    at ij.macro.MacroRunner.run(MacroRunner.java:139)
>    at java.lang.Thread.run(Thread.java:619)
> ######################
>
> Is this a bug, that the coordinates of a selection can have decimal numbers when drawn by hand but not when done programmatically? Or am I missing something here?
>
> I have got a second question: Is there a tool/plugin/macro to easily measure the width of some long "worm-like" structure along its way?
>
> Thank you in advance for any help,
> Jochen (PhD student)

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