pixel-editor/js/_history.js

var undoStates = [];
var redoStates = [];

const undoLogStyle = 'background: #87ff1c; color: black; padding: 5px;';

//prototype for undoing canvas changes
function HistoryStateEditCanvas () {
  this.canvas = context.getImageData(0, 0, canvasSize[0], canvasSize[1]);
  
  this.undo = function () {
    var currentCanvas = context.getImageData(0, 0, canvasSize[0], canvasSize[1]);
    context.putImageData(this.canvas, 0, 0);
    
    this.canvas = currentCanvas;
    redoStates.push(this);
  }
  
  this.redo = function () {
    var currentCanvas = context.getImageData(0, 0, canvasSize[0], canvasSize[1]);
    context.putImageData(this.canvas, 0, 0);
    
    this.canvas = currentCanvas;
    undoStates.push(this);
  }
  
  //add self to undo array
  saveHistoryState(this);
}

//prototype for undoing added colors
function HistoryStateAddColor (colorValue) {
  this.colorValue = colorValue;
  
  this.undo = function () {
    redoStates.push(this);
    deleteColor(this.colorValue);
  }
  
  this.redo = function () {
    addColor(this.colorValue);
    undoStates.push(this);
  }
  
  //add self to undo array
  saveHistoryState(this);
}

//prototype for undoing deleted colors
function HistoryStateDeleteColor (colorValue) {
  this.colorValue = colorValue;
  this.canvas = context.getImageData(0, 0, canvasSize[0], canvasSize[1]);
  
  this.undo = function () {
    var currentCanvas = context.getImageData(0, 0, canvasSize[0], canvasSize[1]);
    context.putImageData(this.canvas, 0, 0);
    
    addColor(this.colorValue);
    
    this.canvas = currentCanvas;
    redoStates.push(this);
  }
  
  this.redo = function () {
    var currentCanvas = context.getImageData(0, 0, canvasSize[0], canvasSize[1]);
    context.putImageData(this.canvas, 0, 0);
    
    deleteColor(this.colorValue);
  
    this.canvas = currentCanvas;
    undoStates.push(this);
  }
  
  //add self to undo array
  saveHistoryState(this);
}

//prototype for undoing colors edits
function HistoryStateEditColor (newColorValue, oldColorValue) {
  this.newColorValue = newColorValue;
  this.oldColorValue = oldColorValue;
  this.canvas = context.getImageData(0, 0, canvasSize[0], canvasSize[1]);
  
  this.undo = function () {
    var currentCanvas = context.getImageData(0, 0, canvasSize[0], canvasSize[1]);
    context.putImageData(this.canvas, 0, 0);
    
    //find new color in palette and change it back to old color
    var colors = document.getElementsByClassName('color-button');
    for (var i = 0; i < colors.length; i++) {
      console.log(newColorValue, '==', colors[i].jscolor.toString())
      if (newColorValue == colors[i].jscolor.toString()) {
        colors[i].jscolor.fromString(oldColorValue);
        break;
      }
    }
    
    this.canvas = currentCanvas;
    redoStates.push(this);
  }
  
  this.redo = function () {
    var currentCanvas = context.getImageData(0, 0, canvasSize[0], canvasSize[1]);
    context.putImageData(this.canvas, 0, 0);
    
    //find old color in palette and change it back to new color
    var colors = document.getElementsByClassName('color-button');
    for (var i = 0; i < colors.length; i++) {
      console.log(oldColorValue, '==', colors[i].jscolor.toString())
      if (oldColorValue == colors[i].jscolor.toString()) {
        colors[i].jscolor.fromString(newColorValue);
        break;
      }
    }
    
    this.canvas = currentCanvas;
    undoStates.push(this);
  }
  
  //add self to undo array
  saveHistoryState(this);
}


//rename to add undo state
function saveHistoryState (state) {
  console.log('%csaving history state', undoLogStyle)
  console.log(state)

  //get current canvas data and save to undoStates array
  undoStates.push(state);
  
  //limit the number of states to settings.numberOfHistoryStates
  if (undoStates.length > settings.numberOfHistoryStates) {
    undoStates = undoStates.splice(-settings.numberOfHistoryStates, settings.numberOfHistoryStates);
  }
  
  //there is now definitely at least 1 undo state, so the button shouldnt be disabled
  document.getElementById('undo-button').classList.remove('disabled');
  
  //there should be no redoStates after an undoState is saved
  redoStates = [];
  
  console.log(undoStates)
  console.log(redoStates)
}

function undo () {
  console.log('%cundo', undoLogStyle);
  
  //if there are any states saved to undo
  if (undoStates.length > 0) {

    document.getElementById('redo-button').classList.remove('disabled');
    
    //get state 
    var undoState = undoStates[undoStates.length-1];
    console.log(undoState);
    
    //restore the state
    undoState.undo();
    
    //remove from the undo list
    undoStates.splice(undoStates.length-1,1);
    
    //if theres none left to undo, disable the option
    if (undoStates.length == 0) 
      document.getElementById('undo-button').classList.add('disabled');
  }
  
  console.log(undoStates)
  console.log(redoStates)
}

function redo () {
  console.log('%credo', undoLogStyle);

  if (redoStates.length > 0) {

    //enable undo button
    document.getElementById('undo-button').classList.remove('disabled');
    
    //get state 
    var redoState = redoStates[redoStates.length-1];
    console.log(redoState);
    
    //restore the state
    redoState.redo();
    
    //remove from redo array
    redoStates.splice(redoStates.length-1,1);
    
    //if theres none left to redo, disable the option
    if (redoStates.length == 0) 
      document.getElementById('redo-button').classList.add('disabled');
  }
  console.log(undoStates)
  console.log(redoStates)
}