title: D3 Canvas brush and zoom
body: <p>I am working on a heat map using canvas. I am not using SVG because I want to render data points more than 30,000 . I found this example of using brush for focus+context.
  <a href="https://bl.ocks.org/mbostock/34f08d5e11952a80609169b7917d4172" rel="nofollow noreferrer">https://bl.ocks.org/mbostock/34f08d5e11952a80609169b7917d4172</a></p>
  
  <p>But this works for SVG and I want to use this functionality of brush for Canvas.
  Is it even possible to do that with d3?
  If not what can be the workaround ideas to implement focus+context on canvas.</p>