X-Git-Url: https://adrianiainlam.tk/git/?a=blobdiff_plain;f=auto_tests%2Ftests%2FPixelSampler.js;h=d45ab8a30e681fcb1a8d0a0626de8af2b29a08f4;hb=refs%2Fheads%2Fopt-size-check;hp=89c520fad0bc04e97cd1fbd8b1f406beb6ded06e;hpb=9f636500f08868182ecd88288636e7f8718e28de;p=dygraphs.git

diff --git a/auto_tests/tests/PixelSampler.js b/auto_tests/tests/PixelSampler.js
index 89c520f..d45ab8a 100644
--- a/auto_tests/tests/PixelSampler.js
+++ b/auto_tests/tests/PixelSampler.js
@@ -17,6 +17,7 @@ var PixelSampler = function(dygraph) {
   var canvas = dygraph.hidden_;
   var ctx = canvas.getContext("2d");
   this.imageData_ = ctx.getImageData(0, 0, canvas.width, canvas.height);
+  this.scale = canvas.width / dygraph.width_;
 };
 
 /**
@@ -26,12 +27,23 @@ var PixelSampler = function(dygraph) {
  * are in [0, 255]. A pixel which has never been touched will be [0,0,0,0].
  */
 PixelSampler.prototype.colorAtPixel = function(x, y) {
-  var i = 4 * (x + this.imageData_.width * y);
+  var i = 4 * (x * this.scale + this.imageData_.width * y * this.scale);
   var d = this.imageData_.data;
   return [d[i], d[i+1], d[i+2], d[i+3]];
 };
 
 /**
+ * Convenience wrapper around colorAtPixel if you only care about RGB (not A).
+ * @param {number} x The screen x-coordinate at which to sample.
+ * @param {number} y The screen y-coordinate at which to sample.
+ * @return {Array.<number>} a 3D array: [R, G, B]. All three values
+ *     are in [0, 255]. A pixel which has never been touched will be [0,0,0].
+ */
+PixelSampler.prototype.rgbAtPixel = function(x, y) {
+  return this.colorAtPixel(x, y).slice(0, 3);
+};
+
+/**
  * The method samples a color using data coordinates (not screen coordinates).
  * This will round your data coordinates to the nearest screen pixel before
  * sampling.
@@ -44,3 +56,5 @@ PixelSampler.prototype.colorAtCoordinate = function(x, y) {
   var dom_xy = this.dygraph_.toDomCoords(x, y);
   return this.colorAtPixel(Math.round(dom_xy[0]), Math.round(dom_xy[1]));
 };
+
+export default PixelSampler;