Writing spreadsheet with SVG and Vue.js

#svg #vue #javascript

I like handsontable, but I want to write my own from scratch.

DEMO

Try it from here:

https://anydown-example-vue-spreadsheet-lite.netlify.com/

Repo:

https://github.com/anydown/vue-spreadsheet-lite

How to implement

There are so many things to implement. I can't do them all.

Selection UI

Because SVG Spec doesn't have z-index for now, I decided to split UI and Contents layer into two svg elements.

The UI layer has visual elements such as bounding-boxes or selection rects. They have to be always on top.

In-place editing

There is a hidden text field on selected cell. At first its opacity is set to 0. When the cell is clicked, opacity changes to 1.

This hidden text field always capture key inputs to handle Input Method. This is important to users who uses Chinese characters.

SVG

SVG is very useful to implement complex GUI. It's just DOM and bindable with Vue's ViewModel. Especially, I like to handle SVG with computed.

<template>
  <div class="grid" @mouseup="onMouseUpSvg()" @mousemove="headerResizeMove">
    <svg :width="positionLeft(data.length + 1) + 1" height=24>
      <g v-for="(col, ci) in headerObj" :key="ci" :transform="translateCol(ci)" @mousedown="startColumnSelect(ci)" @mousemove="changeColumnSelect(ci)" @mouseup="endColumnSelect">
        <rect class="col-header" x=0 y=0 :width="widthAt(ci)" :height="rowHeight">
        </rect>
        <text class="col-header__text" text-anchor="middle" :x="widthAt(ci) / 2" y=12 :width="widthAt(ci)" :height="rowHeight">{{col.name}}</text>
        <rect class="col-header__resize" :class="{'active': ci === headerResizeAt}" :x="widthAt(ci) - 5" :y=0 :width="5" :height="rowHeight" @mousedown.stop="headerResizeStart(ci)"></rect>
      </g>
    </svg>

    <div ref="wrapper" style="height: 400px; overflow: scroll; position:relative;">
      <svg :width="positionLeft(data.length + 1) + 1" :height="data.length * 24" >
        <g v-for="(row, ri) in data" :key="ri" :transform="translateRow(ri)">
          <g v-for="(col, ci) in row" :key="ci" :transform="translateCol(ci)" @mousedown="onMouseDownCell(ci, ri)" @mousemove="onMouseMoveCell(ci, ri)">
            <rect x=0 y=0 :width="widthAt(ci)" :height="rowHeight">
            </rect>
            <text x=2 y=12 :width="widthAt(ci)" :height="rowHeight">{{col}}</text>
          </g>
        </g>
        <rect :transform="selectionTransform" class="selection" x=0 y=0 :width="selectionSize.w" :height="selectionCount.h * rowHeight"></rect>
      </svg>
      <div class="editor__frame" :style="editorStyleObj">
        <input ref="hiddenInput"  @mousedown="onMouseDownCell(selection.c, selection.r)" class="editor__textarea" v-model="editingText" @blur="onBlur" :class="{'editor--visible': editing}" autofocus />
      </div>
    </div>
  </div>
</template>