LiteRoomJS

LiteRoomJS is a lightweight canvas photo editor for web-based editing
of photographs.

Users can upload an image, edit it, and then export an edited version.

Technology

• HTML5 canvas to handle image state, filters, and display

  1. ctx.filter handles filtering logic
  2. ctx.rotate and ctx.translate to re-arrange canvas when rotating

• Vanilla JS classes

  1. main.js - initializes program with image (default or uploaded)
  2. canvas.js - holds state of canvas, stores filter values, draws image
  3. filter.js - callback functions to update image with new filter

Features

Upload image from computer

Modify image with filters (grayscale, saturation, contrast, etc.)

Download edited image locally

Image rotation

Code Examples

Sliders

applySlider(filter) {
  const self = this;
  const filterSlider = document.getElementById(filter);
    filterSlider.onchange = function(e) {
    self.canvas.drawCanvas(`${filter}(${e.target.value}%)`);
  };
}
grayscaleSlider() {
  this.applySlider('grayscale');
}
sepiaSlider() {
  this.applySlider('sepia');
}

Rotation

rotate() {
  const rotateButton = document.getElementById("rotate-image");
  let newImage;
  rotateButton.onclick = () => {
    newImage = new Image();
    newImage.src = this.canvas.toDataURL();
    newImage.onload = () => {
      const oldWidth = this.canvas.width;
      this.canvas.width = this.canvas.height;
      this.canvas.height = oldWidth;
      this.ctx.translate(this.canvas.width, this.canvas.height / this.canvas.width);
      this.ctx.rotate(Math.PI / 2);
      this.ctx.drawImage(newImage, 0, 0);
    };
  };
}

Filters

Stored as hashmap — updated with each draw method

updateFilters(filter) {
  const filterName = filter.match(/\w+/)[0];
  const filterValue = filter.match(/\d+/)[0];
  this.filters[filterName] = filterValue;
  let filterString = "";
  for (var key in this.filters) {
    filterString += ` ${key}(${this.filters[key]}%)`;
  }
  this.ctx.filter = filterString;
}