X-Git-Url: https://adrianiainlam.tk/git/?a=blobdiff_plain;f=dygraph-canvas.js;h=fc7ab1d80bdd4be6b09b4b5a1a9fb6ba5739a47f;hb=e4416fb9d0c2894387c2c2eedaa953d10998700f;hp=c6c5b1e87b5bc6adee6fbc84f5e041d434dfd330;hpb=b304aaecb6728af27bc6f7e2b553570556e85e45;p=dygraphs.git

diff --git a/dygraph-canvas.js b/dygraph-canvas.js
index c6c5b1e..fc7ab1d 100644
--- a/dygraph-canvas.js
+++ b/dygraph-canvas.js
@@ -88,6 +88,9 @@ DygraphLayout.prototype._evaluateLimits = function() {
     axis.maxyval = axis.computedValueRange[1];
     axis.yrange = axis.maxyval - axis.minyval;
     axis.yscale = (axis.yrange != 0 ? 1.0 / axis.yrange : 1.0);
+
+    axis.ylogrange = Math.log(axis.maxyval) - Math.log(axis.minyval);
+    axis.ylogscale = (axis.ylogrange != 0 ? 1.0 / axis.ylogrange : 1.0);
   }
 };
 
@@ -102,10 +105,17 @@ DygraphLayout.prototype._evaluateLineCharts = function() {
 
     for (var j = 0; j < dataset.length; j++) {
       var item = dataset[j];
+      
+      var yval;
+      if (this.dygraph_.attr_("logscale")) {
+        yval = 1.0 - ((Math.log(parseFloat(item[1])) - Math.log(axis.minyval)) * axis.ylogscale); // really should just be yscale.
+      } else {
+        yval = 1.0 - ((parseFloat(item[1]) - axis.minyval) * axis.yscale);
+      }
       var point = {
         // TODO(danvk): here
         x: ((parseFloat(item[0]) - this.minxval) * this.xscale),
-        y: 1.0 - ((parseFloat(item[1]) - axis.minyval) * axis.yscale),
+        y: yval,
         xval: parseFloat(item[0]),
         yval: parseFloat(item[1]),
         name: setName
@@ -133,7 +143,7 @@ DygraphLayout.prototype._evaluateLineTicks = function() {
     for (var j = 0; j < axis.ticks.length; j++) {
       var tick = axis.ticks[j];
       var label = tick.label;
-      var pos = 1.0 - (axis.yscale * (tick.v - axis.minyval));
+      var pos = this.dygraph_.toPercentYCoord(tick.v, i);
       if ((pos >= 0.0) && (pos <= 1.0)) {
         this.yticks.push([i, pos, label]);
       }
@@ -386,11 +396,16 @@ DygraphCanvasRenderer.isSupported = function(canvasName) {
  * Draw an X/Y grid on top of the existing plot
  */
 DygraphCanvasRenderer.prototype.render = function() {
-  // Draw the new X/Y grid
+  // Draw the new X/Y grid. Lines appear crisper when pixels are rounded to
+  // half-integers. This prevents them from drawing in two rows/cols.
   var ctx = this.element.getContext("2d");
+  function halfUp(x){return Math.round(x)+0.5};
+  function halfDown(y){return Math.round(y)-0.5};
 
   if (this.options.underlayCallback) {
-    this.options.underlayCallback(ctx, this.area, this.layout, this.dygraph_);
+    // NOTE: we pass the dygraph object to this callback twice to avoid breaking
+    // users who expect a deprecated form of this callback.
+    this.options.underlayCallback(ctx, this.area, this.dygraph_, this.dygraph_);
   }
 
   if (this.options.drawYGrid) {
@@ -401,8 +416,8 @@ DygraphCanvasRenderer.prototype.render = function() {
     for (var i = 0; i < ticks.length; i++) {
       // TODO(danvk): allow secondary axes to draw a grid, too.
       if (ticks[i][0] != 0) continue;
-      var x = this.area.x;
-      var y = this.area.y + ticks[i][1] * this.area.h;
+      var x = halfUp(this.area.x);
+      var y = halfDown(this.area.y + ticks[i][1] * this.area.h);
       ctx.beginPath();
       ctx.moveTo(x, y);
       ctx.lineTo(x + this.area.w, y);
@@ -417,8 +432,8 @@ DygraphCanvasRenderer.prototype.render = function() {
     ctx.strokeStyle = this.options.gridLineColor;
     ctx.lineWidth = this.options.axisLineWidth;
     for (var i=0; i<ticks.length; i++) {
-      var x = this.area.x + ticks[i][0] * this.area.w;
-      var y = this.area.y + this.area.h;
+      var x = halfUp(this.area.x + ticks[i][0] * this.area.w);
+      var y = halfDown(this.area.y + this.area.h);
       ctx.beginPath();
       ctx.moveTo(x, y);
       ctx.lineTo(x, this.area.y);
@@ -438,6 +453,10 @@ DygraphCanvasRenderer.prototype._renderAxis = function() {
   if (!this.options.drawXAxis && !this.options.drawYAxis)
     return;
 
+  // Round pixels to half-integer boundaries for crisper drawing.
+  function halfUp(x){return Math.round(x)+0.5};
+  function halfDown(y){return Math.round(y)-0.5};
+
   var context = this.element.getContext("2d");
 
   var labelStyle = {
@@ -477,8 +496,8 @@ DygraphCanvasRenderer.prototype._renderAxis = function() {
         }
         var y = this.area.y + tick[1] * this.area.h;
         context.beginPath();
-        context.moveTo(x, y);
-        context.lineTo(x - sgn * this.options.axisTickSize, y);
+        context.moveTo(halfUp(x), halfDown(y));
+        context.lineTo(halfUp(x - sgn * this.options.axisTickSize), halfDown(y));
         context.closePath();
         context.stroke();
 
@@ -516,16 +535,18 @@ DygraphCanvasRenderer.prototype._renderAxis = function() {
       }
     }
 
+    // draw a vertical line on the left to separate the chart from the labels.
     context.beginPath();
-    context.moveTo(this.area.x, this.area.y);
-    context.lineTo(this.area.x, this.area.y + this.area.h);
+    context.moveTo(halfUp(this.area.x), halfDown(this.area.y));
+    context.lineTo(halfUp(this.area.x), halfDown(this.area.y + this.area.h));
     context.closePath();
     context.stroke();
 
+    // if there's a secondary y-axis, draw a vertical line for that, too.
     if (this.dygraph_.numAxes() == 2) {
       context.beginPath();
-      context.moveTo(this.area.x + this.area.w, this.area.y);
-      context.lineTo(this.area.x + this.area.w, this.area.y + this.area.h);
+      context.moveTo(halfDown(this.area.x + this.area.w), halfDown(this.area.y));
+      context.lineTo(halfDown(this.area.x + this.area.w), halfDown(this.area.y + this.area.h));
       context.closePath();
       context.stroke();
     }
@@ -540,8 +561,8 @@ DygraphCanvasRenderer.prototype._renderAxis = function() {
         var x = this.area.x + tick[0] * this.area.w;
         var y = this.area.y + this.area.h;
         context.beginPath();
-        context.moveTo(x, y);
-        context.lineTo(x, y + this.options.axisTickSize);
+        context.moveTo(halfUp(x), halfDown(y));
+        context.lineTo(halfUp(x), halfDown(y + this.options.axisTickSize));
         context.closePath();
         context.stroke();
 
@@ -567,8 +588,8 @@ DygraphCanvasRenderer.prototype._renderAxis = function() {
     }
 
     context.beginPath();
-    context.moveTo(this.area.x, this.area.y + this.area.h);
-    context.lineTo(this.area.x + this.area.w, this.area.y + this.area.h);
+    context.moveTo(halfUp(this.area.x), halfDown(this.area.y + this.area.h));
+    context.lineTo(halfUp(this.area.x + this.area.w), halfDown(this.area.y + this.area.h));
     context.closePath();
     context.stroke();
   }