# all files / ol/ render.js

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     goog.provide('ol.render');

    goog.require('goog.vec.Mat4');
    goog.require('ol.render.canvas.Immediate');
    goog.require('ol.vec.Mat4');

    /**
     * Binds a Canvas Immediate API to a canvas context, to allow drawing geometries
     * to the context's canvas.
     *
     * The units for geometry coordinates are css pixels relative to the top left
     * corner of the canvas element.
     * ```js
     * var canvas = document.createElement('canvas');
     * var render = ol.render.toContext(canvas.getContext('2d'),
     *     { size: [100, 100] });
     * render.setFillStrokeStyle(new ol.style.Fill({ color: blue }));
     * render.drawPolygon(
     *     new ol.geom.Polygon([[[0, 0], [100, 100], [100, 0], [0, 0]]]));
     * ```
     *
     * @param {CanvasRenderingContext2D} context Canvas context.
     * @param {olx.render.ToContextOptions=} opt_options Options.
     * @return {ol.render.canvas.Immediate} Canvas Immediate.
     * @api
     */
    ol.render.toContext = function(context, opt_options) {
      var canvas = context.canvas;
      var options = opt_options ? opt_options : {};
      var pixelRatio = options.pixelRatio || ol.has.DEVICE_PIXEL_RATIO;
      var size = options.size;
      if (size) {
        canvas.width = size[0] * pixelRatio;
        canvas.height = size[1] * pixelRatio;
        canvas.style.width = size[0] + 'px';
        canvas.style.height = size[1] + 'px';
      }
      var extent = [0, 0, canvas.width, canvas.height];
      var transform = ol.vec.Mat4.makeTransform2D(goog.vec.Mat4.createNumber(),
          0, 0, pixelRatio, pixelRatio, 0, 0, 0);
      return new ol.render.canvas.Immediate(context, pixelRatio, extent, transform,
          0);
    };