This is a quick and fairly lightweight abstraction to get the mouse coordinates on click and drag motion. Three different modes determine the behavior for when the mouse leaves the click area. It works in Pure Data vanilla without any external.

Download: xy.zip

Usage:
Type [xy 500 300 1] to create a 500 x 300 pixel area in mode 1. See help file for details.

How it works:
A rectangle scalar of the size of the click area, a one pixel scalar and two graphical arrays are placed on top of each other. The second array has an inverted y-range. Both arrays are set to zero. On click both arrays jump to the respective y-value at x-position. When the rectangle scalar receives the click, it reads the x and y values from the first array. If y is zero, it takes the x value from the second array. Now we have x and y for the click.

The arrays are immediately reset to zero and the pixel scalar is placed to where the mouse is, so that it gets the grab. From there on x and y positions are read from the pixel scalar when its struct sends a change event. That's it.

Some more tricks where necessary to create everything dynamically and make it nice.

Have fun!

Update 2022-01-17: Finally fixed the bug that broke the patch when dragging near the bottom left corner. Everything should work now!

Just realized that it is even possible to get the click coordinates from a combination of a size one array and a hslider... Should be even lighter...
click-demo.pd

@ingox Really great, very responsive, It took me a while to work out how you used the 2 arrays, and I think you have discovered a way to hide the name of graph arrays (although I'm not quite sure how yet) that has been so elusive.

@ingox This is great! Thank you.

@Balwyn yes, hiding the array names was tricky. Only late in the process i realized that they wouldn't go away so easily and thought this would destroy the whole project. As they apparently cannot be turned off, i needed invisible names instead that would still contain $0 to be unique across different instances. So the idea was to take $0, combine it with a number for each array and convert it to binary, but with spaces instead of 0 and 1. i found this thread about putting spaces into symbols. Luckily there are two spaces in ASCII, that i needed to make unique symbols out of binary numbers.

The conversion takes place in the two subpatches [pd uniqueInvisible]. They take a number, add $0 multiplied by 1000 (10 would have been enough) and convert this into binary, using 32 and 160 (the ASCII spaces) instead of 0 and 1. The result is a list of 32s and 160s that is converted to a symbol by [list tosymbol]. So the symbol is made out of two different spaces, representing a number containing $0 in binary form.

This is based on [baseconverter] which i made a while ago.

@ingox very nice. i tried to combine the xy abstraction and the multislider. the additional stuff is highlighted in the abstraction. still some bugs and not resizeable yet, but perhaps its the right direction. the same way it should be possible to combine for example the s-controlsurface with the xy abstraction. xy_mslider.zip

here is a combination with the s-controlsurface: xy_point.zip

this one shows a cross instead of a point(small rectangle): xy_cross.zip

just for fun with 4 colors: xy_4colors.zip

painting with structs xy-paint.zip i think its (not yet) possible to sequence through the painted dots (in the order of creation).

hey, I loved this and stole many tricks I learned here to make my own two dimensional slider version, you can find it in this library release: https://forum.pdpatchrepo.info/topic/11287/else-library-version-1-0-beta-8-released - the object is called [slider2d] and has dependencies to other externals in the library. I never claim copyright or license for things I do, so feel free to steal from this and make a vanilla compatible variant if you don't care to use my library.

I still have a long way to go, as I want to still include many features, like independente x/y size, a non jump-on-click behaviour and the ability to edit many things from a properties window, such as a grid, no dot, no cross, colors, etc... I already have some progress on this list, so the next release might include many new stuff!

cheers

thanks