piskel/js/drawingtools/BaseTool.js

/**
 * @provide pskl.drawingtools.BaseTool
 *
 * @require pskl.utils
 */
(function() {
  var ns = $.namespace("pskl.drawingtools");

  ns.BaseTool = function() {};

  ns.BaseTool.prototype.applyToolAt = function(col, row, color, frame, overlay, event) {};

  ns.BaseTool.prototype.moveToolAt = function(col, row, color, frame, overlay, event) {};

  ns.BaseTool.prototype.moveUnactiveToolAt = function(col, row, color, frame, overlay, event) {
    if (overlay.containsPixel(col, row)) {
      if (!isNaN(this.highlightedPixelCol) &&
        !isNaN(this.highlightedPixelRow) &&
        (this.highlightedPixelRow != row ||
          this.highlightedPixelCol != col)) {

        // Clean the previously highlighted pixel:
        overlay.clear();
      }

      // Show the current pixel targeted by the tool:
      overlay.setPixel(col, row, Constants.TOOL_TARGET_HIGHLIGHT_COLOR);

      this.highlightedPixelCol = col;
      this.highlightedPixelRow = row;
    }
  };

  ns.BaseTool.prototype.hideHighlightedPixel = function(overlay) {
    if (this.highlightedPixelRow !== null && this.highlightedPixelCol !== null) {
      try {
        overlay.setPixel(this.highlightedPixelCol, this.highlightedPixelRow, Constants.TRANSPARENT_COLOR);
      } catch (e) {
        console.warn('ns.BaseTool.prototype.hideHighlightedPixel failed');
      }
      this.highlightedPixelRow = null;
      this.highlightedPixelCol = null;
    }
  };


  ns.BaseTool.prototype.releaseToolAt = function(col, row, color, frame, overlay, event) {};

  /**
   * Bresenham line algorihtm: Get an array of pixels from
   * start and end coordinates.
   *
   * http://en.wikipedia.org/wiki/Bresenham's_line_algorithm
   * http://stackoverflow.com/questions/4672279/bresenham-algorithm-in-javascript
   *
   * @private
   */
  ns.BaseTool.prototype.getLinePixels_ = function(x0, x1, y0, y1) {

    var pixels = [];
    var dx = Math.abs(x1-x0);
    var dy = Math.abs(y1-y0);
    var sx = (x0 < x1) ? 1 : -1;
    var sy = (y0 < y1) ? 1 : -1;
    var err = dx-dy;

    while(true){

      // Do what you need to for this
      pixels.push({"col": x0, "row": y0});

      if ((x0==x1) && (y0==y1)) {
        break;
      }

      var e2 = 2*err;
      if (e2>-dy){
        err -= dy;
        x0  += sx;
      }
      if (e2 < dx) {
        err += dx;
        y0  += sy;
      }
    }
    return pixels;
  };
})();