svelte-pan-zoom

svelte-pan-zoom

Canvas Pan and Zoom action for Svelte, 1Kb minified + gzipped

See Demo

Usage

Install using you package manager of choice:

pnpm i svelte-pan-zoom

Import action into page, create options and pass to action.

Options include:

• width & height in CSS pixels of item to render (will be centered and sized to fit canvas)
• render function to render to canvas (you don't have to draw an image)
• padding (optional, default 0)
• maxZoom (optional, default 16)
• friction how much momentum will be continues (optional, default to 0.97)

NOTE: if you set friction to 1, any movement will never stop, so you'll have re-invented the DVD screen saver!

Your render funcion will be passed the canvas 2d render context and the animation timer. It can return true if you want to reschedule another animation frame to be rendered. This is useful if what you are rendering is also itself being animated.

Example

<script lang="ts">
  import { panzoom, type Options } from '$lib'

  const promise = new Promise<Options>(resolve => {
    const image = new Image()

    image.onload = () =>
      resolve({
        width: image.width,
        height: image.height,
        render,
      })
    image.src = './svelte-kit-machine.png'

    function render(ctx: CanvasRenderingContext2D, t: number) {
      ctx.drawImage(image, 0, 0)
    }
  })
</script>

{#await promise then options}
  <canvas use:panzoom={options} />
{/await}

<style>
  canvas {
    box-sizing: border-box;
    width: 100%;
    height: 100%;
    user-select: none;
    touch-action: none;
    background-color: #ccc;
    overscroll-behavior: none;
    -webkit-user-select: none; /* disable selection/Copy of UIWebView */
    -webkit-touch-callout: none; /* disable the IOS popup when long-press on a link */
  }
</style>