http://imagej.273.s1.nabble.com/Feature-request-make-line-selection-tool-show-dx-dy-tp5022813p5022817.html
> Thank you Jan and Herbie for your macros, using them will make the
> measurements a breeze, especially once I figure out how to get scaled
> lengths in addition to pixel dimensions.
>
> The nice icon is much appreciated too @imagejan :-)
>
> Adrian
>
>
> On 06/01/2020 14.31, Jan Eglinger wrote:
>> Hi Adrian,
>>
>> you might want to create a custom line selection tool for this. Here's
>> an example (mind the possible line breaks introduced by the mail
>> client - that's one of the reasons I prefer the image.sc forum over
>> the mailing list):
>>
>>
>> // Author: Jan Eglinger
>> macro "Kymograph Line Selection Tool -
>> L1af1Ca00V0933Ve033C00fL1afaLfaf1" {
>> var leftButton = 16;
>> getCursorLoc(x, y, z, flags);
>> x0 = x;
>> y0 = y;
>> while (true) {
>> getCursorLoc(x, y, z, flags);
>> makeLine(x0, y0, x, y);
>> showStatus("dx: " + (x-x0) + "; dy: " + (y-y0));
>> if (flags&leftButton==0) {
>> return;
>> }
>> }
>> }
>>
>>
>>
>>
>>
>>
>> On 2020-01-06 12:43 PM, Adrian Daerr wrote:
>>> Hello,
>>>
>>> I frequently use the line selection tool to measure the speed on
>>> kymographs[1] (also known as spatio-temporal diagrams), which are
>>> images where one dimension (say the horizontal) is a spatial
>>> dimension, and the other (say the vertical) is a temporal dimension.
>>> A moving object or interface produces an oblique trace, whose speed
>>> is just the slope dx/dy (assuming, as above, that the y axis
>>> represents time).
>>>
>>> [1]
https://en.wikipedia.org/wiki/Kymograph>>>
>>> To get the speed or slope of a trace, I use the line selection tool
>>> to visually fit a tangent to this trace. This tool shows the angle of
>>> the line in the status bar of the main application window, and
>>> computing its tangent yields the slope in the chosen units.
>>>
>>> I wonder if it were possible for the line selection tool to show the
>>> two increments dx and dy of the line selection - that is the x and y
>>> offsets of the current point to the starting point - 'live' in the
>>> statusbar along with the other information ? The increments are more
>>> meaningful as measurements than the angle in my use case, and the
>>> calculations become less error-prone (e.g. when using the angle,
>>> depending on which dimension is the time, one must take either the
>>> tangent or the cotangent, and the wrong choice may go unnoticed for a
>>> while). Moreover the spatial and temporal measurement intervals -
>>> that is the length of the fitted line segment - are lost in this
>>> process, and thus estimating the uncertainty from the angle alone is
>>> impossible.
>>>
>>> If that makes the infoline too long, one could add to the line
>>> selection tool options (currently only line width) the possiblity to
>>> choose what data is shown (I am very rarely interested in the x/y
>>> coordinates of the cursor location when I use this tool for example,
>>> and would happily trade them for the dx/dy of the segment).
>>>
>>> I am aware of at least two work-arounds:
>>>
>>> 1) finishing the line selection (second mouse click) and doing a
>>> measurement with 'bounding box' selected will give me the desired
>>> increments as 'Width' and 'Height' in the measurement results table.
>>>
>>> 2) using the rectangle selection tool provides the increments between
>>> current and starting points as Width and Height in the statusbar, but
>>> fitting the invisible diagonal of the rectangle to the trace via just
>>> the two corners is much less reliable and reproducible than visually
>>> fitting a line to the entire trace.
>>>
>>> If there is an easy way of replacing/customising the status bar
>>> information via a macro or plugin, that could be an interesting and
>>> flexible solution.
>>>
>>> So this is merely a feature request to ease the workflow.
>>>
>>> Thanks for reading up to here,
>>> cheers,
>>> Adrian
>>>
>>> --
>>> ImageJ mailing list:
http://imagej.nih.gov/ij/list.html