Rounded rectangle

Here's a roundedRectangle() function with the same syntax as rectangle(), but with an added corner radius argument.

// e.g. of function call
roundedRectangle(
    -25 /*top*/, 25 /*left*/, 50 /*w*/, 50 /*h*/, 10 /*cornerRadius*/);

/*
 * roundedRectangle by Femke Blanco
 * Beta 04/08/2022
 */
function roundedRectangle(top, left, w, h, r) {
    var paths = app.activeDocument.pathItems;
    var path1 = paths.add();
    var p;
    var c = r * ((4 / 3) * Math.tan(Math.PI / 8));  // handle length
    // p2
    point(left + r, top, left + r, top, left + r - c, top);
    // p3
    point(left + w - r, top, left + w - r + c, top, left + w - r, top);
    // p4
    point(left + w , top - r, left + w , top - r, left + w , top - r + c);
    // p5
    point(left + w, top - h + r, left + w, top - h + r - c, 
        left + w, top - h + r);
    // p6
    point(left + w - r, top - h, left + w - r, top - h, 
        left + w - r + c, top - h);
    // p7
    point(left + r, top - h, left + r - c, top - h, left + r, top - h);
    // p8
    point(left, top - h + r, left, top - h + r, left, top - h + r - c);
    // p1
    point(left, top - r, left, top - r + c, left, top - r);
    path1.closed = true;
    function point(x, y, Rx, Ry, Lx, Ly) {
        p = path1.pathPoints.add();
        p.anchor = [x, y];
        p.rightDirection = [Rx, Ry];
        p.leftDirection = [Lx, Ly];
    }
}

Ok... So just like any petulant, stubborn child.... I don't like being told what I can't do... And your post here was the last straw for me.. I've decided i'm no longer going to simply accept that we can't set our own custom corner radii... 

To that end... Here's a function i just threw together that lets you create a rectangle at whatever dimensions you want, and lets you pass in an array of "corner radii" listed clockwise from top left to bottom left. So, if you need a rectangle at [0,0] and 200pt wide and 400pt tall with rounded corners of the radii [20,10,25,50] for whatever reason, you could create one with this function call:

customRoundedRectangle(app.activeDocument, 0,0,200,400,[20,10,25,50]);

the first argument is the "parent" object. The container in which you want the rectangle to be created. This could be the document, a layer, a group, a compound path.. (though i th ink this will need some refinement to properly handle making something inside a clipping mask.. otherwise the pathfinder logic won't work properly, i suspect.. I'll get to it). The next 4 arguments are the standard rectangle arguments (top, left, width, height). Then the last argument is the array of corner radii, again sorted clockwise from top left.

Here's the code:

//Custom Rounded Rectangle Generator
//The built in roundedRectangle() method only allows for changing
//"verticalRadius" and "horizontalRadius".. But if you use different
//values for these, the corners are not truly rounded, and the values given
//will apply to both left and right sides or top and bottom.
//This customRoundedRectangle() function allows for each corner to have a separate
//corner radius that is truly rounded.

//author: William Dowling
//email: illustrator.dev.pro@gmail.com
//github: https://www.github.com/wdjsdev
    //this project on githuh: https://github.com/wdjsdev/public_illustrator_scripts/blob/master/custom_rounded_rectangle.js
//linkedin: https://www.linkedin.com/in/william-dowling-4537449a/
//Adobe Discussion Forum Post that initiated this: https://community.adobe.com/t5/illustrator-discussions/rounded-rectangle/td-p/13076613

//*******//

//Did you find this useful? Would you like to buy me a cup (or a pot) of coffee to say thanks?
//paypal.me/illustratordev
//<3

//Do you have some work to do, but you have more money than time/skill?
//Send me an email or a dm! I'll see what I can do to help you out.

//*******//

//arguments:
//parent: the parent container object inside which to create the rectangle 
//y: y coordinate of the point (Number)
//x: x coordinate of the point  (Number)
//w: width of the rectangle (Number)
//h: height of the rectangle (Number)
//r: array of radii clockwise from top left corner (array)
function customRoundedRectangle(parent, y, x, w, h, r) {

    ///////////////////////////////////////////////////////////////////////////
    ///////////////////////////////////////////////////////////////////////////
    //function calls//
    ///////////////////////////////////////////////////////////////////////////
    ///////////////////////////////////////////////////////////////////////////
    if (!app.documents.length) {
        alert("Please open a document and try again.");
        return;
    }


    var doc = app.activeDocument;
    var swatches = doc.swatches;
    var blackSwatch;
    try {
        blackSwatch = swatches["Black"];
    } catch (error) {
        blackSwatch = swatches.add();
        blackSwatch.name = "Black";
        blackSwatch.color = new CMYKColor();
        blackSwatch.color.black = 100;
    }

    //draw the base rectangle
    var rect = parent.pathItems.rectangle(y, x, w, h);
    rect.filled = true;
    rect.fillColor = blackSwatch.color;
    rect.stroked = false;
    var rectData = { w: rect.width, h: rect.height, l: rect.left, t: rect.top, r: rect.left + rect.width, b: rect.top - rect.height };
    var cp = parent.compoundPathItems.add();
    //create an ellipse for each radius
    r.forEach(function (radius, i) {
        var rad = radius * 2;
        var ellipse = cp.pathItems.ellipse(y, x, rad, rad);
        ellipse.filled = true;
        ellipse.fillColor = blackSwatch.color;
        ellipse.stroked = false;
        switch (i) {
            case 1:
                ellipse.left += rectData.w - rad;
                break;
            case 2:
                ellipse.left += rectData.w - rad;
                ellipse.top -= rectData.h - rad;
                break;
            case 3:
                ellipse.top -= rectData.h - rad;
        }
    });

    //load pathfinder actions into actions panel
    createAction("pathfinder", getActionString());

    doc.selection = null;
    cp.selected = rect.selected = true;
    app.doScript("divide", "pathfinder");

    //look for the "corner"s of the rectangle...
    //the part that's outside our desired radius
    afc(doc.selection[0], "pageItems").forEach(function (item) {
        var area = Math.abs(item.area);
        var calcArea = item.width * item.height;
        if (area < (calcArea * .6)) {
            item.remove();
        }
    });

    //all that's left should be the base rectangle and
    //the ellipses for the corner radii. unite them all
    //together into a single pathItem.
    app.doScript("unite", "pathfinder");

    //remove pathfinder actions from actions panel
    removeAction("pathfinder");

    //end of script








    


    ///////////////////////////////////////////////////////////////////////////
    //dependencies:
    ///////////////////////////////////////////////////////////////////////////



    //array from container
    //get all elements of the type "crit" inside the container
    //and return as a standard javascript array
    function afc(container, crit) {
        var result = [];
        var items;
        if (!crit || crit === "any") {
            items = container.pageItems;
        } else {
            items = container[crit];
        }
        for (var x = 0; x < items.length; x++) {
            result.push(items[x])
        }
        return result;
    }

    //Array.forEach() prototype for easily looping arrays
    //this helps eliminate scope issues because variables
    //remain contained inside the function block. almost
    //kind of imitating "let" in modern javascript.
    //Plus, you don't need to worry about pre-declaring
    //variables outside the loop to prevent mrap/parm errors.
    //args:
    //callback: the function to call for each element
    //startPos: the index to start at (defaults to 0)
    //inc: the increment to move by (defaults to 1)
    Array.prototype.forEach = function (callback, startPos, inc) {
        if (!inc) inc = 1;
        if (!startPos) startPos = 0;
        for (var i = startPos; i < this.length; i += inc)
            callback(this[i], i, this);
    };


    //create and load a new action
    function createAction(name, actionString) {
        var documentsPath = "~/Documents/Adobe_Script_Helpers/";
        var dest = Folder(documentsPath);
        if (!dest.exists) {
            dest.create();
        }

        var actionFile = new File(decodeURI(dest + "/" + name + ".aia"));

        actionFile.open("w");
        actionFile.write(actionString);
        actionFile.close();

        //load the action
        app.loadAction(actionFile);
    }


    //remove all instances of an action with a given name
    function removeAction(actionName) {
        var localValid = true;

        while (localValid) {
            try {
                app.unloadAction(actionName, "");
            }
            catch (e) {
                localValid = false;
            }
        }
    }


    function getActionString() {
        //pathfinder action string. this will create an
        //action set containing all of the pathfinder options.
        //this is much more reliable than app.executeMenuCommand()
        //which uses "live pathfinder" effects which don't always work
        //and need to be expanded.
        var pathfinderActionString = [
            "/version 3",
            "/name [ 10",
            "	7061746866696e646572",
            "]",
            "/isOpen 1",
            "/actionCount 10",
            "/action-1 {",
            "	/name [ 5",
            "		756e697465",
            "	]",
            "	/keyIndex 0",
            "	/colorIndex 0",
            "	/isOpen 0",
            "	/eventCount 1",
            "	/event-1 {",
            "		/useRulersIn1stQuadrant 0",
            "		/internalName (ai_plugin_pathfinder)",
            "		/localizedName [ 10",
            "			5061746866696e646572",
            "		]",
            "		/isOpen 0",
            "		/isOn 1",
            "		/hasDialog 0",
            "		/parameterCount 1",
            "		/parameter-1 {",
            "			/key 1851878757",
            "			/showInPalette 4294967295",
            "			/type (enumerated)",
            "			/name [ 3",
            "				416464",
            "			]",
            "			/value 0",
            "		}",
            "	}",
            "}",
            "/action-2 {",
            "	/name [ 11",
            "		6d696e75735f66726f6e74",
            "	]",
            "	/keyIndex 0",
            "	/colorIndex 0",
            "	/isOpen 0",
            "	/eventCount 1",
            "	/event-1 {",
            "		/useRulersIn1stQuadrant 0",
            "		/internalName (ai_plugin_pathfinder)",
            "		/localizedName [ 10",
            "			5061746866696e646572",
            "		]",
            "		/isOpen 0",
            "		/isOn 1",
            "		/hasDialog 0",
            "		/parameterCount 1",
            "		/parameter-1 {",
            "			/key 1851878757",
            "			/showInPalette 4294967295",
            "			/type (enumerated)",
            "			/name [ 8",
            "				5375627472616374",
            "			]",
            "			/value 3",
            "		}",
            "	}",
            "}",
            "/action-3 {",
            "	/name [ 9",
            "		696e74657273656374",
            "	]",
            "	/keyIndex 0",
            "	/colorIndex 0",
            "	/isOpen 0",
            "	/eventCount 1",
            "	/event-1 {",
            "		/useRulersIn1stQuadrant 0",
            "		/internalName (ai_plugin_pathfinder)",
            "		/localizedName [ 10",
            "			5061746866696e646572",
            "		]",
            "		/isOpen 0",
            "		/isOn 1",
            "		/hasDialog 0",
            "		/parameterCount 1",
            "		/parameter-1 {",
            "			/key 1851878757",
            "			/showInPalette 4294967295",
            "			/type (enumerated)",
            "			/name [ 9",
            "				496e74657273656374",
            "			]",
            "			/value 1",
            "		}",
            "	}",
            "}",
            "/action-4 {",
            "	/name [ 7",
            "		6578636c756465",
            "	]",
            "	/keyIndex 0",
            "	/colorIndex 0",
            "	/isOpen 1",
            "	/eventCount 1",
            "	/event-1 {",
            "		/useRulersIn1stQuadrant 0",
            "		/internalName (ai_plugin_pathfinder)",
            "		/localizedName [ 10",
            "			5061746866696e646572",
            "		]",
            "		/isOpen 0",
            "		/isOn 1",
            "		/hasDialog 0",
            "		/parameterCount 1",
            "		/parameter-1 {",
            "			/key 1851878757",
            "			/showInPalette 4294967295",
            "			/type (enumerated)",
            "			/name [ 7",
            "				4578636c756465",
            "			]",
            "			/value 2",
            "		}",
            "	}",
            "}",
            "/action-5 {",
            "	/name [ 6",
            "		646976696465",
            "	]",
            "	/keyIndex 0",
            "	/colorIndex 0",
            "	/isOpen 1",
            "	/eventCount 1",
            "	/event-1 {",
            "		/useRulersIn1stQuadrant 0",
            "		/internalName (ai_plugin_pathfinder)",
            "		/localizedName [ 10",
            "			5061746866696e646572",
            "		]",
            "		/isOpen 0",
            "		/isOn 1",
            "		/hasDialog 0",
            "		/parameterCount 1",
            "		/parameter-1 {",
            "			/key 1851878757",
            "			/showInPalette 4294967295",
            "			/type (enumerated)",
            "			/name [ 6",
            "				446976696465",
            "			]",
            "			/value 5",
            "		}",
            "	}",
            "}",
            "/action-6 {",
            "	/name [ 4",
            "		7472696d",
            "	]",
            "	/keyIndex 0",
            "	/colorIndex 0",
            "	/isOpen 1",
            "	/eventCount 1",
            "	/event-1 {",
            "		/useRulersIn1stQuadrant 0",
            "		/internalName (ai_plugin_pathfinder)",
            "		/localizedName [ 10",
            "			5061746866696e646572",
            "		]",
            "		/isOpen 0",
            "		/isOn 1",
            "		/hasDialog 0",
            "		/parameterCount 1",
            "		/parameter-1 {",
            "			/key 1851878757",
            "			/showInPalette 4294967295",
            "			/type (enumerated)",
            "			/name [ 4",
            "				5472696d",
            "			]",
            "			/value 7",
            "		}",
            "	}",
            "}",
            "/action-7 {",
            "	/name [ 5",
            "		6d65726765",
            "	]",
            "	/keyIndex 0",
            "	/colorIndex 0",
            "	/isOpen 1",
            "	/eventCount 1",
            "	/event-1 {",
            "		/useRulersIn1stQuadrant 0",
            "		/internalName (ai_plugin_pathfinder)",
            "		/localizedName [ 10",
            "			5061746866696e646572",
            "		]",
            "		/isOpen 0",
            "		/isOn 1",
            "		/hasDialog 0",
            "		/parameterCount 1",
            "		/parameter-1 {",
            "			/key 1851878757",
            "			/showInPalette 4294967295",
            "			/type (enumerated)",
            "			/name [ 5",
            "				4d65726765",
            "			]",
            "			/value 8",
            "		}",
            "	}",
            "}",
            "/action-8 {",
            "	/name [ 4",
            "		63726f70",
            "	]",
            "	/keyIndex 0",
            "	/colorIndex 0",
            "	/isOpen 1",
            "	/eventCount 1",
            "	/event-1 {",
            "		/useRulersIn1stQuadrant 0",
            "		/internalName (ai_plugin_pathfinder)",
            "		/localizedName [ 10",
            "			5061746866696e646572",
            "		]",
            "		/isOpen 0",
            "		/isOn 1",
            "		/hasDialog 0",
            "		/parameterCount 1",
            "		/parameter-1 {",
            "			/key 1851878757",
            "			/showInPalette 4294967295",
            "			/type (enumerated)",
            "			/name [ 4",
            "				43726f70",
            "			]",
            "			/value 9",
            "		}",
            "	}",
            "}",
            "/action-9 {",
            "	/name [ 7",
            "		6f75746c696e65",
            "	]",
            "	/keyIndex 0",
            "	/colorIndex 0",
            "	/isOpen 1",
            "	/eventCount 1",
            "	/event-1 {",
            "		/useRulersIn1stQuadrant 0",
            "		/internalName (ai_plugin_pathfinder)",
            "		/localizedName [ 10",
            "			5061746866696e646572",
            "		]",
            "		/isOpen 0",
            "		/isOn 1",
            "		/hasDialog 0",
            "		/parameterCount 1",
            "		/parameter-1 {",
            "			/key 1851878757",
            "			/showInPalette 4294967295",
            "			/type (enumerated)",
            "			/name [ 7",
            "				4f75746c696e65",
            "			]",
            "			/value 6",
            "		}",
            "	}",
            "}",
            "/action-10 {",
            "	/name [ 10",
            "		6d696e75735f6261636b",
            "	]",
            "	/keyIndex 0",
            "	/colorIndex 0",
            "	/isOpen 1",
            "	/eventCount 1",
            "	/event-1 {",
            "		/useRulersIn1stQuadrant 0",
            "		/internalName (ai_plugin_pathfinder)",
            "		/localizedName [ 10",
            "			5061746866696e646572",
            "		]",
            "		/isOpen 0",
            "		/isOn 1",
            "		/hasDialog 0",
            "		/parameterCount 1",
            "		/parameter-1 {",
            "			/key 1851878757",
            "			/showInPalette 4294967295",
            "			/type (enumerated)",
            "			/name [ 10",
            "				4d696e7573204261636b",
            "			]",
            "			/value 4",
            "		}",
            "	}",
            "}"
        ].join("\n");

        return pathfinderActionString;
    }
}

//sample function call:
// customRoundedRectangle(app.activeDocument, 0, 0, 200, 400, [20, 10, 25, 50]);

https://community.adobe.com/t5/illustrator-discussions/javascript-illustrator-change-rounded-rectangle-corner-radius/m-p/13006185 

app.activeDocument.pathItems.roundedRectangle(0,0,100,100,10,10);

parameters are as follows, in order:

top, left, width, height, horizontalRadius, verticalRadius

So it looks like you could KIND OF input different radii... but i don't believe you can set the radii of each corner individually without doing the math to set up pathPoints with specific controlBounds.

Another possible option is to create a regular rectangle, then circles in each corner at a certain radius, then "divide" and then "unite" them with a dynamic action.