Toggling multiple tools on Paper.js

Question

Can someone show me a working example (JSFiddle or otherwise) of how to have two tools on Paper.js that a user can click on to draw different shapes, say one for circles and one for squares? Thanks!

Answer 1

You've got at least a couple of options here,

1. Activate Tool from paper.tools

Paper.js allows you to activate a Tool by calling tool.activate(), which causes only that particular Tool to receive Tool events, such as mousedown, mousedrag etc ...

When you create a new Tool via new paper.Tool(), that Tool is added in paper.tools so you can lookup for the Tool within that Array and call tool.activate() on it.

An example:

window.onload = () => {
  // Setup Paper

  paper.setup(document.querySelector('canvas'))
    
  // Find a Tool in `paper.tools` and activate it

  const activateTool = name => {
    const tool = paper.tools.find(tool => tool.name === name)
    tool.activate()
  }

  // Tool Path, draws paths on mouse-drag.
  // Note: Wrap each Tool in an IIFE to avoid polluting the 
  //       global scope with variables related with that Tool.

  ;(() => {
    const tool = new paper.Tool()
    tool.name = 'toolPath'

    let path

    tool.onMouseDown = function(event) {
      path = new paper.Path()
      path.strokeColor = '#424242'
      path.strokeWidth = 4
      path.add(event.point)
    }

    tool.onMouseDrag = function(event) {
      path.add(event.point)
    }
  })()

  // Tool Circle, draws a 30px circle on mousedown

  ;(() => {
    const tool = new paper.Tool()
    tool.name = 'toolCircle'

    let path

    tool.onMouseDown = function(event) {
      path = new paper.Path.Circle({
        center: event.point,
        radius: 30,
        fillColor: '#9C27B0'
      })
    }
  })()

  // Attach click handlers for Tool activation on all
  // DOM buttons with class '.tool-button'

  document.querySelectorAll('.tool-button').forEach(toolBtn => {
    toolBtn.addEventListener('click', e => {
      activateTool(e.target.getAttribute('data-tool-name'))
    })
  })
}

html,
body,
canvas {
  width: 100%;
  height: 100%;
  margin: 0;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/paper.js/0.11.5/paper-core.js"></script>

<button 
 class="tool-button"
 data-tool-name="toolPath">
 Draw Paths
</button>

<button 
 class="tool-button"
 data-tool-name="toolCircle">
 Stamp Circles
</button>

<canvas resize></canvas>

2. Create a ToolStack Class

However, I find it far more practical to create a ToolStack Class since it allows me to add additional methods later on, i.e isToolActive(), onToolSelect() (for adding is-active classes to DOM tool buttons) etc..

The ToolStack should then implement various methods for handling your Tools, the first and foremost being an activateTool method, that will lookup for a Tool by name and call it's tool.activate() method.

An example:

window.onload = () => {
  // Setup Paper

  paper.setup(document.querySelector('canvas'))

  // Toolstack

  class ToolStack {
    constructor(tools) {
      this.tools = tools.map(tool => tool())
    }

    activateTool(name) {
      const tool = this.tools.find(tool => tool.name === name)
      tool.activate()
    }

    // add more methods here as you see fit ...
  }

  // Tool Path, draws paths on mouse-drag

  const toolPath = () => {
    const tool = new paper.Tool()
    tool.name = 'toolPath'

    let path

    tool.onMouseDown = function(event) {
      path = new paper.Path()
      path.strokeColor = '#424242'
      path.strokeWidth = 4
      path.add(event.point)
    }

    tool.onMouseDrag = function(event) {
      path.add(event.point)
    }

    return tool
  }

  // Tool Circle, draws a 30px circle on mousedown

  const toolCircle = () => {
    const tool = new paper.Tool()
    tool.name = 'toolCircle'

    let path

    tool.onMouseDown = function(event) {
      path = new paper.Path.Circle({
        center: event.point,
        radius: 30,
        fillColor: '#9C27B0'
      })
    }

    return tool
  }

  // Construct a Toolstack, passing your Tools

  const toolStack = new ToolStack([toolPath, toolCircle])

  // Activate a certain Tool

  toolStack.activateTool('toolPath')

  // Attach click handlers for Tool activation on all
  // DOM buttons with class '.tool-button'

  document.querySelectorAll('.tool-button').forEach(toolBtn => {
    toolBtn.addEventListener('click', e => {
      toolStack.activateTool(e.target.getAttribute('data-tool-name'))
    })
  })
}

html,
body,
canvas {
  width: 100%;
  height: 100%;
  margin: 0;
}

<script src="https://cdnjs.cloudflare.com/ajax/libs/paper.js/0.11.5/paper-core.js"></script>

<button 
 class="tool-button"
 data-tool-name="toolPath">
 Draw Paths
</button>

<button 
 class="tool-button"
 data-tool-name="toolCircle">
 Stamp Circles
</button>

<canvas resize></canvas>