Merge pull request plotly#3293 from plotly/contour-labels-on-reversed-axes

Fix contour label px bounds for reversed axes

Author: etpinard

src/traces/contour/plot.js

@@ -255,17 +255,37 @@ function makeLinesAndLabels(plotgroup, pathinfo, gd, cd0, contours, perimeter) {
             .attr('data-notex', 1)
             .call(Drawing.font, contours.labelfont);
 
-        var xLen = pathinfo[0].xaxis._length;
-        var yLen = pathinfo[0].yaxis._length;
+        var xa = pathinfo[0].xaxis;
+        var ya = pathinfo[0].yaxis;
+        var xLen = xa._length;
+        var yLen = ya._length;
+        var xRng = xa.range;
+        var yRng = ya.range;
+        var x0 = Math.max(perimeter[0][0], 0);
+        var x1 = Math.min(perimeter[2][0], xLen);
+        var y0 = Math.max(perimeter[0][1], 0);
+        var y1 = Math.min(perimeter[2][1], yLen);
 
         // visible bounds of the contour trace (and the midpoints, to
         // help with cost calculations)
-        var bounds = {
-            left: Math.max(perimeter[0][0], 0),
-            right: Math.min(perimeter[2][0], xLen),
-            top: Math.max(perimeter[0][1], 0),
-            bottom: Math.min(perimeter[2][1], yLen)
-        };
+        var bounds = {};
+
+        if(xRng[0] < xRng[1]) {
+            bounds.left = x0;
+            bounds.right = x1;
+        } else {
+            bounds.left = x1;
+            bounds.right = x0;
+        }
+
+        if(yRng[0] < yRng[1]) {
+            bounds.top = y0;
+            bounds.bottom = y1;
+        } else {
+            bounds.top = y1;
+            bounds.bottom = y0;
+        }
+
         bounds.middle = (bounds.top + bounds.bottom) / 2;
         bounds.center = (bounds.left + bounds.right) / 2;
 

test/image/baselines/contour_label-reversed-axes.png

@@ -0,0 +1,23 @@
+{
+  "data": [
+    {
+      "type": "contour",
+      "z": [
+        [1, 2, 1],
+        [2, 1, 2],
+        [2, 1, 2]
+      ],
+      "contours": {
+        "showlabels": true
+      }
+    }
+  ],
+  "layout": {
+    "yaxis": {
+      "autorange": "reversed"
+    },
+    "xaxis": {
+      "autorange": "reversed"
+    }
+  }
+}