usePanZoom is a low-level react hook for enabling interactive charts that use d3 scales.
Provides primitives for transforming user interactions (mouse, touch, wheel) into mutations of a given set of d3 scales (for the X and Y axes).
Free and unconstrained pan/zoom manipulation.
free-manipulation.mp4
Preserving aspect ratio.
preserveAspectRatio.mp4
Locked axes.
lock-y-axis.mp4
Smart detection of predominant gestures.
predominant.gestures.mp4
Transforming grouped elements.
transform-group.mp4
Out-of-bounds manipulation.
out-of-bounds-gestures.mp4
- Supports multi-touch interactions (e.g. 2+ fingers).
- Unbounded interactions (a panning gesture can continue beyond the edge of the chart and even the window).
- Full d3 scale support. Properly handles both linear and non-linear scales (e.g.
scalePow). - Optionally preserve zoom aspect ratio, or allow independent scale manipulation.
- Optionally lock the X or Y axis.
- Full UI customizability.
- No support yet for the mobile "double tap to zoom" interaction or "long press to zoom out" (PRs welcome).
- No support yet for inertia (PRs welcome).
- Rotation gestures are not supported. This library is meant for 2D xy charts where rotation is not used.
- Not very good support for minExtent/maxExtent constraints, or customizing the constraint method (contain vs cover), or elasticity.
In d3, each axis is represented by a scale, where the range represents the chart size in pixels, and the domain represents the data being shown. Each are represented by two numbers:
- The domain is the start and the end of the currently visible extent of the data.
- The range is
[0, chartWidth]for the x scale, or[chartHeight, 0]for the y scale.
Note: usePanZoom does not support scales that have non-numeric domains, i.e. scales without invert methods.
usePanZoom accepts the x and y scales either as actual d3 scales or a compatible callable object with domain, range, invert, and copy methods (See IScale).
usePanZoom will modify the scales' domains in-place, and will call onUpdate on each animation frame that the domain changed.
In a Y scale, the convention is to invert the range, making it [chartHeight, 0] instead of [0, chartHeight].
The reason is that in the DOM, Y=0 is at the top, and Y gets larger as it goes downward.
However, the domain is not inverted; i.e. [lowValue, highValue].
This is a d3 convention that paints the low values at the bottom of a chart, and high values at the top of the chart.
To summarize:
| DOM | Chart | Scale domain |
|---|---|---|
| Y=0 | top of chart | high values |
| Y=chartHeight | bottom of chart | low values |
One or more pointers define a bbox in pixel space. When a new pointer is added (such as a second or third finger touching the screen), it ends the previous gesture and defines a new origin bbox.
- When pointers move, the bbox resizes. The origin bbox is compared to the current bbox, and the difference is applied to the domain.
- Along with the origin bbox, the origin domain is saved as well. When the gesture is in progress, the calculations are done using the origin domain, not the current domain. This avoids error, because otherwise, JS floating-point math inaccuracies would accumulate on each move, making the interaction feel sloppy.
This is a "headless component" — a hook that gives you the tools to build your own UI component.
Here is a standard example:
import { scalePow } from 'd3-scale';
import { useEffect, useMemo, useRef, useState } from 'react';
import { usePanZoom, normalizeWheelDelta } from 'use-d3-pan-zoom';
export function MyChart () {
const chartWidth = 1000;
const chartHeight = 600;
const [chartElement, setChartElement] = useState<Element | null>();
// When the chartElement is resolved, prevent the default action of certain events:
// - touchstart — or else touch events on the chart will sometimes get intercepted by the browser for scrolling, page navigation ("swipe"), or full-page pixelated zooming.
// - wheel — so that zooming the chart doesn't cause page scrolling.
//
// Note: this can't be done inline because JSX syntax doesn't support passing `{passive: false}` when registering event listener callbacks.
// See https://github.com/facebook/react/issues/6436
useEffect(() => {
if (!chartElement) return;
const preventDefault = (e: Event) => {e.preventDefault();};
chartElement.addEventListener('touchstart', preventDefault, {passive: false});
chartElement.addEventListener('wheel', preventDefault, {passive: false});
return () => {
chartElement.removeEventListener('touchstart', preventDefault);
chartElement.removeEventListener('wheel', preventDefault);
}
}, [chartElement]);
// Track the chart's offset, to be used when we calculate a pointer's position relative to the chart.
const chartOffset = useRef({x: 0, y: 0});
const updateChartOffset = () => {
if (!chartElement) return;
const rect = chartElement.getBoundingClientRect();
chartOffset.current = {
x: rect.x,
y: rect.y,
};
}
// Create scales
const sampleXDomainStart = 0;
const sampleXDomainEnd = 100;
const sampleYDomainStart = 0;
const sampleYDomainEnd = 100;
// the scale objects should be memoized and never change
const xScale = useMemo(() => {
return scalePow().exponent(2);
}, []);
const yScale = useMemo(() => {
return scalePow().exponent(2);
}, []);
// update the scale domains if you want to programmatically set the chart extent.
useEffect(() => {
xScale.domain([sampleXDomainStart, sampleXDomainEnd]);
}, [sampleXDomainStart, sampleXDomainEnd, xScale]);
useEffect(() => {
yScale.domain([sampleYDomainStart, sampleYDomainEnd]);
}, [sampleYDomainStart, sampleYDomainEnd, yScale]);
// update the scale ranges when the view size changes.
useEffect(() => {
xScale.range([0, chartWidth]);
}, [chartWidth, xScale]);
useEffect(() => {
yScale.range([chartHeight, 0]);
}, [chartHeight, yScale]);
// Create a point to draw
const pointDomainX = 30;
const pointDomainY = 30;
const {
onPointerDown,
onPointerUp,
onWheelZoom,
} = usePanZoom({
xScale,
yScale,
registerMoveListener: (onPointerMove) => {
// Only listen to move events while an interaction is happening.
// Listen on `document` so that a panning gesture can continue beyond the edge of the chart.
const handlePointermove = (e: PointerEvent) => {
onPointerMove(e.pointerId, {
x: e.clientX - chartOffset.current.x,
y: e.clientY - chartOffset.current.y,
});
};
document.addEventListener('pointermove', handlePointermove, {passive: false});
return () => {
document.removeEventListener('pointermove', handlePointermove);
};
},
});
return (
<div style={{
width: chartWidth,
height: chartHeight,
border: '1px solid #ddd',
}}>
<svg
ref={setChartElement}
width={chartWidth}
height={chartHeight}
viewBox={`0 0 ${chartWidth} ${chartHeight}`}
style={{
overflow: 'hidden',
userSelect: 'none',
}}
onPointerDown={(e) => {
// Only listen to primary button events (no right-clicks, etc).
if (e.button !== 0) return;
// Take note of the chart's on-screen position when the gesture starts.
updateChartOffset();
// Capturing the pointer lets panning gestures avoid being interrupted when they stray outside the window bounds.
e.currentTarget.setPointerCapture(e.pointerId);
// Report a pointer down, passing coordinates relative to the chart.
onPointerDown(e.pointerId, {
x: e.clientX - chartOffset.current.x,
y: e.clientY - chartOffset.current.y,
});
}}
onPointerUp={(e) => {
e.currentTarget.releasePointerCapture(e.pointerId);
onPointerUp(e.pointerId);
}}
onPointerLeave={(e) => {
onPointerUp(e.pointerId);
}}
onPointerCancel={(e) => {
onPointerUp(e.pointerId);
}}
onWheel={(e) => {
// Take note of the chart's on-screen position.
updateChartOffset();
// Report a wheel zoom event, passing coordinates relative to the chart.
onWheelZoom({
center: {
x: e.clientX - chartOffset.current.x,
y: e.clientY - chartOffset.current.y,
},
zoomRatio: Math.pow(2, normalizeWheelDelta({
delta: e.deltaY,
deltaMode: e.deltaMode,
multiplier: e.ctrlKey ? 10 : 1,
})),
});
}}
>
<circle fill='orange' r={20}
cx={xScale(pointDomainX)}
cy={yScale(pointDomainY)}
/>
</svg>
</div>
);
}The useTransform hook allows you to transform a g group element with transform() and scale().
This is useful when you have a complex drawing with many points and you don't want to scale each point individually.
It also may be more performant.
However, be aware that this type of transformation scales the whole drawing, instead of just repositioning the points.
This can result in undesired stretching, so preserveAspectRatio is typically used with this.
See this useTransform story to see an example of scaling and skewing without preserveAspectRatio.
useTransform requires an "initial scale" in order to calculate the transform relative to the initial position.
import { useTransform, ... } from 'use-d3-pan-zoom';
import { useRev } from 'use-rev';
...
export function MyChart () {
...
const [scaleRev, bumpRev] = useRev();
const { ... } = usePanZoom({
...
onUpdate: () => {
bumpRev();
},
});
const {tx, ty, kx, ky} = useTransform({
initialXScale,
initialYScale,
xScale,
yScale,
scaleRev,
});
return (
<svg ... >
<g transform={`translate(${tx}, ${ty}) scale(${kx}, ${ky})`}>
<circle fill='orange' r={20}
cx={150}
cy={100}
/>
</g>
</svg>
);
}scaleRev is a value that changes when the scales change (since the scales themselves are not immutable).
Inside the group, coordinates are view pixel values indicating initial view positions.