X-Git-Url: https://adrianiainlam.tk/git/?a=blobdiff_plain;f=dygraph.js;h=eff3052e20ae26f19df9e82423aa668bb566372d;hb=d4b89d5690719c1d6e77b61b2afb132dd0cad92d;hp=9f843567ab164e2452d022019c2d45e9fcae143b;hpb=0cfa06d15634d173ebe7fd208b603642f2c8e847;p=dygraphs.git

diff --git a/dygraph.js b/dygraph.js
index 9f84356..eff3052 100644
--- a/dygraph.js
+++ b/dygraph.js
@@ -911,6 +911,8 @@ Dygraph.startPan = function(event, g, context) {
   context.isPanning = true;
   var xRange = g.xAxisRange();
   context.dateRange = xRange[1] - xRange[0];
+  context.initialLeftmostDate = xRange[0];
+  context.xUnitsPerPixel = context.dateRange / (g.plotter_.area.w - 1);
 
   // Record the range of each y-axis at the start of the drag.
   // If any axis has a valueRange or valueWindow, then we want a 2D pan.
@@ -918,14 +920,12 @@ Dygraph.startPan = function(event, g, context) {
   for (var i = 0; i < g.axes_.length; i++) {
     var axis = g.axes_[i];
     var yRange = g.yAxisRange(i);
+    // TODO(konigsberg): These values should be in |context|.
     axis.dragValueRange = yRange[1] - yRange[0];
-    axis.draggingValue = g.toDataYCoord(context.dragStartY, i);
+    axis.initialTopValue = yRange[1];
+    axis.unitsPerPixel = axis.dragValueRange / (g.plotter_.area.h - 1);
     if (axis.valueWindow || axis.valueRange) context.is2DPan = true;
   }
-
-  // TODO(konigsberg): Switch from all this math to toDataCoords?
-  // Seems to work for the dragging value.
-  context.draggingDate = (context.dragStartX / g.width_) * context.dateRange + xRange[0];
 };
 
 // Called in response to an interaction model operation that
@@ -939,30 +939,18 @@ Dygraph.movePan = function(event, g, context) {
   context.dragEndX = g.dragGetX_(event, context);
   context.dragEndY = g.dragGetY_(event, context);
 
-  // TODO(danvk): update this comment
-  // Want to have it so that:
-  // 1. draggingDate appears at dragEndX, draggingValue appears at dragEndY.
-  // 2. daterange = (dateWindow_[1] - dateWindow_[0]) is unaltered.
-  // 3. draggingValue appears at dragEndY.
-  // 4. valueRange is unaltered.
-
-  var minDate = context.draggingDate - (context.dragEndX / g.width_) * context.dateRange;
+  var minDate = context.initialLeftmostDate -
+    (context.dragEndX - context.dragStartX) * context.xUnitsPerPixel;
   var maxDate = minDate + context.dateRange;
   g.dateWindow_ = [minDate, maxDate];
 
   // y-axis scaling is automatic unless this is a full 2D pan.
   if (context.is2DPan) {
     // Adjust each axis appropriately.
-    // NOTE(konigsberg): I don't think this computation for y_frac is correct.
-    // I think it doesn't take into account the display of the x axis.
-    // See, when I tested this with console.log(y_frac), and move the mouse
-    // cursor to the botom, the largest y_frac was 0.94, and not 1.0. That
-    // could also explain why panning tends to start with a small jumpy shift.
-    var y_frac = context.dragEndY / g.height_;
-
     for (var i = 0; i < g.axes_.length; i++) {
       var axis = g.axes_[i];
-      var maxValue = axis.draggingValue + y_frac * axis.dragValueRange;
+      var maxValue = axis.initialTopValue +
+        (context.dragEndY - context.dragStartY) * axis.unitsPerPixel;
       var minValue = maxValue - axis.dragValueRange;
       axis.valueWindow = [ minValue, maxValue ];
     }
@@ -979,9 +967,12 @@ Dygraph.movePan = function(event, g, context) {
 // panning behavior.
 //
 Dygraph.endPan = function(event, g, context) {
+  // TODO(konigsberg): Clear the context data from the axis.
+  // TODO(konigsberg): mouseup should just delete the
+  // context object, and mousedown should create a new one.
   context.isPanning = false;
   context.is2DPan = false;
-  context.draggingDate = null;
+  context.initialLeftmostDate = null;
   context.dateRange = null;
   context.valueRange = null;
 }
@@ -1157,12 +1148,12 @@ Dygraph.prototype.createDragInterface_ = function() {
     prevEndY: null,
     prevDragDirection: null,
 
-    // TODO(danvk): update this comment
-    // draggingDate and draggingValue represent the [date,value] point on the
-    // graph at which the mouse was pressed. As the mouse moves while panning,
-    // the viewport must pan so that the mouse position points to
-    // [draggingDate, draggingValue]
-    draggingDate: null,
+    // The value on the left side of the graph when a pan operation starts.
+    initialLeftmostDate: null,
+
+    // The number of units each pixel spans. (This won't be valid for log
+    // scales)
+    xUnitsPerPixel: null,
 
     // TODO(danvk): update this comment
     // The range in second/value units that the viewport encompasses during a