Constraining drag/mousemove to circular path �� <a href="http://bl.ocks.org/3669333" title="view this gist via bl.ocks.org">?</a> <a href="http://bl.ocks.org/GerHobbelt" title="view a list of all my gists at bl.ocks.org">8</a>

Circle Dragging I

This example shows a set of colored circles scattered across an SVG canvas, which users can drag with the mouse. Each circle’s position is stored as x and y properties in its data object, and those values update live during the drag. The code uses d3.select and d3.drag from the d3-drag module to handle the interaction, attaching event handlers for start, drag, and end. At drag start, the circle is raised to the foreground with `.raise()` and gets a black stroke via the `.active` class; the stroke is removed on release. The circles are rendered as SVG `<circle>` elements, colored with a categorical scheme from `d3.scaleOrdinal` and `d3.schemeCategory20`, with random initial positions computed from the SVG’s dimensions.

78% match

Circle Dragging IV

This example demonstrates an improved method for dragging SVG circles, where the circle nearest to the pointer is selected for interaction rather than the topmost one. A Voronoi overlay, computed with `d3.voronoi`, is used for hit-testing, with its cells rendered as light-gray paths. Each circle is clipped to its corresponding Voronoi cell using a `clipPath`. During a drag, the `dragged` function updates the circle’s position and recalculates the Voronoi polygons. The code uses `d3.drag` for the interaction and `d3.scaleOrdinal` with `d3.schemeCategory20` for automatic circle colors.

Drag circles

Five colored circles are positioned in a row on an 800×480 SVG canvas, each with a radius of 60 pixels. The example demonstrates a basic drag-and-drop interaction using D3.js v4, where users can move any circle freely by clicking and dragging it. The circles change cursor to a move icon on hover and gain a black outline while being dragged. The code uses `d3.drag()` with `dragstarted`, `dragged`, and `dragended` handlers, along with `d3.scaleOrdinal` and `d3.schemeCategory20` for coloring, and `d3.select(this).raise()` to bring the active circle to the front.

EEfratVil

Circle Dragging II

This example shows a canvas-based visualization where users can drag any of twenty randomly positioned circles. It uses the d3.drag module with a custom subject function for hit-testing, checking if the pointer falls within a circle’s radius. During a drag, the circle is reordered to the foreground, marked with a temporary stroke, and its position updates, triggering a redraw via render listeners. The implementation relies on D3 v4’s event handling, Canvas’s 2D context, and d3.scaleOrdinal with the schemeCategory20 palette for circle fill colors, producing smooth, interactive feedback.

circle-arc-drag

This example demonstrates how a draggable arc can be reconstructed from three movable points, showing the relationship between a circle's geometry and its SVG path. The code uses D3 v3’s `d3.behavior.drag` to update point positions, then calculates the circumcircle and radius via trigonometric formulas, applying the large-arc and sweep flags to render the correct arc. The visualization starts with a pre-defined path parsed into three points using `getTotalLength` and `getPointAtLength`, and the SVG `path` element updates on each drag event. Circles and paths are styled with strokes and fills, with the background set to black.

11wheel

Fork of Mouse Follower edited

A circle, rectangle, and text label all follow the mouse cursor across the screen, while a separate set of draggable circles is rendered using D3's data join and drag behavior. Clicking anywhere on the SVG appends a new circle with a random radius from the `d3.range` array, colored via `d3.schemePastel1`. The code uses D3 v7 selections and event handlers (`svg.on("mousemove")`) to update SVG attributes (`cx`, `cy`, `x`, `y`) in real time, with `d3.drag()` enabling interactive circle repositioning.

KKhatera Alizada

75% match

Circle Dragging III

This example demonstrates an improved technique for dragging circles rendered on a Canvas, using a custom drag subject that selects the circle closest to the pointer rather than simply the topmost overlapping circle. The code defines a linear scan in `dragsubject` to find the nearest circle within double the radius, increasing the effective hit area for easier interaction. Twenty randomly positioned circles are drawn and updated via d3-drag’s event handlers, with active circles highlighted by a stroke. The implementation relies on d3.drag, d3.scaleOrdinal with d3.schemeCategory20, and the Canvas 2D API.

75% match