ZoomCanvas

Overview

ZoomCanvas is a built-in behavior in G6 used to implement the canvas zooming feature, supporting zooming in and out of the canvas using the mouse wheel or keyboard shortcuts. This is one of the most commonly used interactions in graph visualization, helping users view both the overall structure and local details of the graph.

Use Cases

This behavior is mainly used for:

Browsing large-scale graph data, freely switching between the whole and details
Focusing on specific areas for detailed analysis

Online Experience

createGraph(
  {
    data: { nodes: [{ id: 'node-1' }] },
    layout: { type: 'force' },
    behaviors: [
      {
        type: 'zoom-canvas',
        key: 'zoom-canvas',
      },
    ],
    node: { style: { fill: '#873bf4' } },
    edge: { style: { stroke: '#8b9baf' } },
    plugins: [{ type: 'grid-line', size: 30 }],
  },
  { width: 600, height: 300 },
  (gui, graph) => {
    const options = {
      key: 'zoom-canvas',
      type: 'zoom-canvas',
      animation: true,
      enable: true,
      sensitivity: 1,
      trigger: 'Use wheel by default',
    };
    const optionFolder = gui.addFolder('ZoomCanvas Options');
    optionFolder.add(options, 'type').disable(true);
    optionFolder.add(options, 'animation');
    optionFolder.add(options, 'enable');
    optionFolder.add(options, 'sensitivity', 0, 10, 1);
    optionFolder.add(options, 'trigger', {
      'Use wheel by default': [],
      'Control+Wheel': ['Control'],
      'zoomIn:Ctrl+1 zoomOut:Ctrl+2 reset:Ctrl+0': {
        zoomIn: ['Control', '1'],
        zoomOut: ['Control', '2'],
        reset: ['Control', '0'],
      },
    });
    optionFolder.onChange(({ property, value }) => {
      graph.updateBehavior({
        key: 'zoom-canvas',
        [property]: value,
      });
      graph.render();
    });
  },
);

Basic Usage

Add this behavior in the graph configuration:

1. Quick Configuration (Static)

Declare directly using a string form. This method is simple but only supports default configuration and cannot be dynamically modified after configuration:

const graph = new Graph({
  // Other configurations...
  behaviors: ['zoom-canvas'],
});

2. Object Configuration (Recommended)

Configure using an object form, supporting custom parameters, and can dynamically update the configuration at runtime:

const graph = new Graph({
  // Other configurations...
  behaviors: [
    {
      type: 'zoom-canvas',
      key: 'zoom-canvas-1', // Specify an identifier for the behavior for dynamic updates
      sensitivity: 1.5, // Set sensitivity
    },
  ],
});

Configuration Options

Option	Description	Type	Default	Required
type	Behavior type name	string	`zoom-canvas`	✓
animation	Zoom animation effect settings	ViewportAnimationEffectTiming	`{ duration: 200 }`
enable	Whether to enable this behavior	boolean \| ((event: Event) => boolean)	true
origin	Zoom center point (viewport coordinates)	Point	-
onFinish	Callback function when zooming is finished	() => void	-
preventDefault	Whether to prevent the browser's default event	boolean	true
sensitivity	Zoom sensitivity, the larger the value, the faster the zoom	number	1
trigger	How to trigger zooming, supports mouse wheel and keyboard shortcuts, configuration options	string[] \| object	-

Trigger

trigger has two usage methods, suitable for different scenarios:

Method 1: Modifier keys combined with the mouse wheel

If you want to trigger zooming only when certain keys are pressed while scrolling the mouse wheel, you can configure it like this:

{
  trigger: ['Control']; // Hold down the Control key and scroll the mouse wheel to zoom
}

Common modifier keys include:

Control
Shift
Alt

Not sure what value corresponds to a keyboard key? Refer to MDN Key Values.

Method 2: Pure keyboard shortcuts

If you want to control zooming entirely using the keyboard, you can set up key combinations:

{
  trigger: {
    zoomIn: ['Control', '+'],  // Zoom in shortcut
    zoomOut: ['Control', '-'], // Zoom out shortcut
    reset: ['Control', '0']    // Reset zoom ratio shortcut
  }
}

Code Examples

Basic Zoom Functionality

const graph = new Graph({
  container: 'container',
  width: 800,
  height: 600,
  behaviors: ['zoom-canvas'],
});

Custom Zoom Center

const graph = new Graph({
  // Other configurations...
  behaviors: [
    function () {
      return {
        type: 'zoom-canvas',
        origin: this.getCanvasCenter(), // Zoom with the viewport center as the origin
      };
    },
  ],
});

Custom Zoom Sensitivity

const graph = new Graph({
  // Other configurations...
  behaviors: [
    {
      type: 'zoom-canvas',
      sensitivity: 0.8, // Lower sensitivity for smoother zoom changes
    },
  ],
});

Zoom with Shift + Mouse Wheel

const graph = new Graph({
  // Other configurations...
  behaviors: [
    {
      type: 'zoom-canvas',
      trigger: ['Shift'], // Hold down the Shift key and scroll to zoom
    },
  ],
});

Control Zoom with Keyboard Shortcuts

const graph = new Graph({
  // Other configurations...
  behaviors: [
    {
      type: 'zoom-canvas',
      trigger: {
        zoomIn: ['Control', '='], // Ctrl + = to zoom in
        zoomOut: ['Control', '-'], // Ctrl + - to zoom out
        reset: ['Control', '0'], // Ctrl + 0 to reset
      },
    },
  ],
});

Supports pinch-to-zoom on mobile devices

const graph = new Graph({
  // 其他配置...
  behaviors: [
    {
      type: 'zoom-canvas',
      // Other configurations for the PC side...
    },
    function () {
      return {
        type: 'zoom-canvas',
        trigger: ['pinch'],
        sensitivity: 0.8, // Lower sensitivity for smoother zoom changes
        origin: this.getCanvasCenter(), // Zoom with the viewport center as the origin
      };
    },
  ],
});

FAQ

1. What if the canvas zoom exceeds the expected range?

To avoid excessive zooming in or out, you can set zoom limits:

const graph = new Graph({
  // Other configurations...
  zoomRange: [0.5, 3], // Allow zooming out to 50% and zooming in to 300%
  behaviors: ['zoom-canvas'],
});

2. How to use it with other interactions?

Zooming and dragging are common combinations for a complete navigation experience:

const graph = new Graph({
  // Other configurations...
  behaviors: ['drag-canvas', 'zoom-canvas'],
});

Practical Example