Web前端笔记-画布拖动及放缩（two.js）

程序运行截图如下：

结构图如下：

关键代码如下：

界面调用

HelloWorld.vue

js关键代码如下：

zui.js

(function(Two){

  let _ = Two.Utils;

  let Surface = function(object) {

    this.object = object;

  };

  _.extend(Surface.prototype, {

    limits: function(min, max) {

      let min_exists = !_.isUndefined(min);
      let max_exists = !_.isUndefined(max);

      if (!max_exists && !min_exists) {
        return { min: this.min, max: this.max };
      }

      this.min = min_exists ? min : this.min;
      this.max = max_exists ? max : this.max;

      return this;

    },

    apply: function(px, py, s) {
      this.object.translation.set(px, py);
      this.object.scale = s;
      return this;
    }

  });

  let ZUI = Two.ZUI = function(group, domElement) {

    this.limits = {

      scale: ZUI.Limit.clone(),
      x: ZUI.Limit.clone(),
      y: ZUI.Limit.clone()
    };

    this.viewport = domElement || document.body;
    this.viewportOffset = {
      matrix: new Two.Matrix()
    };

    this.surfaceMatrix = new Two.Matrix();

    this.surfaces = [];
    this.reset();
    this.updateSurface();

    this.add(new Surface(group));

  };

  _.extend(ZUI, {

    Surface: Surface,

    Clamp: function(v, min, max) {
      return Math.min(Math.max(v, min), max);
    },

    Limit: {

      min: -Infinity,
      max: Infinity,
      clone: function() {

        let result = {};
        for (let k in this) {

          result[k] = this[k];
        }
        return result;
      }
    },

    TranslateMatrix: function(m, x, y) {

      m.elements[2] += x;
      m.elements[5] += y;
      return m;
    },

    PositionToScale: function(pos){

      return Math.exp(pos);
    },

    ScaleToPosition: function(scale){

      return Math.log(scale);
    }

  });

  _.extend(ZUI.prototype, {

    constructor: ZUI,

    add: function(surface){

      this.surfaces.push(surface);
      let limits = surface.limits();
      this.addLimits(limits.min, limits.max);
      return this;
    },

    addLimits: function(min, max, type) {

      type = type || 'scale';

      if (!_.isUndefined(min)){

        if(this.limits[type].min){

          this.limits[type].min = Math.max(min, this.limits[type].min);
        }
        else{

          this.limits[type].min = min;
        }
      }

      if(_.isUndefined(max)){

        return this;
      }

      if(this.limits[type].max){

        this.limits[type].max = Math.min(max, this.limits[type].max);
      }
      else{

        this.limits[type].max = max;
      }

      return this;

    },

    clientToSurface: function(x, y) {

      this.updateOffset();
      let m = this.surfaceMatrix.inverse();
      let n = this.viewportOffset.matrix.inverse().multiply(x, y, 1);
      return m.multiply.apply(m, _.toArray(n));
    },

    surfaceToClient: function(v) {

      this.updateOffset();
      let vo = this.viewportOffset.matrix.clone();
      let sm = this.surfaceMatrix.multiply.apply(this.surfaceMatrix, _.toArray(v));
      return vo.multiply.apply(vo, _.toArray(sm));
    },

    graphicMove: function(clientX, clientY){

      let dx = clientX;
      let dy = clientY;
      this.translateSurface(dx, dy);
      return this;
    },

    zoomBy: function(byF, clientX, clientY){

      let s = ZUI.PositionToScale(this.zoom + byF);
      this.zoomSet(s, clientX, clientY);
      return this;
    },

    zoomSet: function(zoom, clientX, clientY) {

      let newScale = this.fitToLimits(zoom);
      this.zoom = ZUI.ScaleToPosition(newScale);

      if (newScale === this.scale) {

        return this;
      }

      let sf = this.clientToSurface(clientX, clientY);
      let scaleBy = newScale / this.scale;

      this.surfaceMatrix.scale(scaleBy);
      this.scale = newScale;

      let c = this.surfaceToClient(sf);
      let dx = clientX - c.x;
      let dy = clientY - c.y;
      this.translateSurface(dx, dy);

      return this;
    },

    translateSurface: function(x, y) {

      ZUI.TranslateMatrix(this.surfaceMatrix, x, y);
      this.updateSurface();
      return this;
    },

    updateOffset: function() {

      let rect = this.viewport.getBoundingClientRect();
      _.extend(this.viewportOffset, rect);

      this.viewportOffset.left -= document.body.scrollLeft;
      this.viewportOffset.top -= document.body.scrollTop;

      this.viewportOffset.matrix
        .identity()
        .translate(this.viewportOffset.left, this.viewportOffset.top);

      return this;

    },

    updateSurface: function() {

      let e = this.surfaceMatrix.elements;
      for(let i = 0; i < this.surfaces.length; i++){

        this.surfaces[i].apply(e[2], e[5], e[0]);
      }
      return this;
    },

    reset: function() {
      this.zoom = 0;
      this.scale = 1.0;
      this.surfaceMatrix.identity();
      return this;
    },

    fitToLimits: function(s) {
      return ZUI.Clamp(s, this.limits.scale.min, this.limits.scale.max);
    }

  });

})
((typeof global !== 'undefined' ? global : (this || window)).Two);

test1.js

;

import * as Two from "JS/two";
import * as $ from "JS/jquery"


export function demo1(){

  let elem = document.getElementById('draw-shapes');
  let params = {
    type: Two.Types['webgl'],
    fullscreen: true,
    autostart: true
  }

  let two = new Two(params).appendTo(elem);

  let circle = two.makeCircle(0, 0, 50);
  let rect = two.makeRectangle(2000, 2000, 100, 100);

  circle.fill = '#FF8000';
  circle.stroke = 'orangered';
  circle.linewidth = 5;

  rect.fill = 'rgb(0, 200, 255)';
  rect.opacity = 5;
  rect.noStroke();

  two.update();

  let zui = new Two.ZUI(two.scene);
  zui.addLimits(0.06, 8);

  let $stage = $(two.renderer.domElement);
  $stage.bind('mousewheel wheel' , function (event){

    let e = event.originalEvent;
    e.stopPropagation();
    e.preventDefault();

    let dy = (e.wheelDeltaY || -e.deltaY) / 1000;
    zui.zoomBy(dy, e.clientX, e.clientY);
  });

  let isPressed = false;
  let originalPositionX = 0;
  let originalPositionY = 0;
  $stage.bind('mouseup', function(event){

    isPressed = false;
  });

  $stage.bind('mousemove', function(event){

    if(isPressed){

      let boolX = event.clientX - originalPositionX;
      let boolY = event.clientY - originalPositionY;
      zui.graphicMove(boolX, boolY);
      originalPositionX = event.clientX;
      originalPositionY = event.clientY;
    }
  });

  $stage.bind('mousedown', function(event){

    isPressed = true;
    originalPositionX = event.clientX;
    originalPositionY = event.clientY;
  });
}