Fix #1913 by pushing overflowed legend items to a new line

src/components/legend/draw.js

@@ -553,6 +553,8 @@ function computeLegendDimensions(gd, groups, traces) {
 
     var extraWidth = 0;
 
+    var traceGap = 5;
+
     opts._width = 0;
     opts._height = 0;
 
@@ -586,23 +588,53 @@ function computeLegendDimensions(gd, groups, traces) {
         extraWidth = 40;
     }
     else if(isGrouped) {
-        var groupXOffsets = [opts._width];
+        var maxHeight = 0;
+        var maxWidth = 0;
         var groupData = groups.data();
 
-        for(var i = 0, n = groupData.length; i < n; i++) {
-            var textWidths = groupData[i].map(function(legendItemArray) {
+        var maxItems = 0;
+
+        var i;
+        for(i = 0; i < groupData.length; i++) {
+            var group = groupData[i];
+            var groupWidths = group.map(function(legendItemArray) {
                 return legendItemArray[0].width;
             });
 
-            var groupWidth = 40 + Math.max.apply(null, textWidths);
+            var groupWidth = Lib.aggNums(Math.max, null, groupWidths);
+            var groupHeight = group.reduce(function(a, b) {
+                return a + b[0].height;
+            }, 0);
 
-            opts._width += opts.tracegroupgap + groupWidth;
+            maxWidth = Math.max(maxWidth, groupWidth);
+            maxHeight = Math.max(maxHeight, groupHeight);
+            maxItems = Math.max(maxItems, group.length);
+        }
 
+        maxWidth += traceGap;
+        maxWidth += 40;
+
+        var groupXOffsets = [opts._width];
+        var groupYOffsets = [];
+        var rowNum = 0;
+        for(i = 0; i < groupData.length; i++) {
+            if(fullLayout._size.w < (borderwidth + opts._width + traceGap + maxWidth)) {
+                groupXOffsets[groupXOffsets.length - 1] = groupXOffsets[0];
+                opts._width = maxWidth;
+                rowNum++;
+            } else {
+                opts._width += maxWidth + borderwidth;
+            }
+
+            var rowYOffset = (rowNum * maxHeight);
+            rowYOffset += rowNum > 0 ? opts.tracegroupgap : 0;
+
+            groupYOffsets.push(rowYOffset);
             groupXOffsets.push(opts._width);
         }
 
         groups.each(function(d, i) {
-            Drawing.setTranslate(this, groupXOffsets[i], 0);
+            Drawing.setTranslate(this, groupXOffsets[i], groupYOffsets[i]);
         });
 
         groups.each(function() {
@@ -620,11 +652,13 @@ function computeLegendDimensions(gd, groups, traces) {
 
                 groupHeight += textHeight;
             });
-
-            opts._height = Math.max(opts._height, groupHeight);
         });
 
-        opts._height += 10 + borderwidth * 2;
+        var maxYLegend = groupYOffsets[groupYOffsets.length - 1] + maxHeight;
+        opts._height = 10 + (borderwidth * 2) + maxYLegend;
+
+        var maxOffset = Math.max.apply(null, groupXOffsets);
+        opts._width = maxOffset + maxWidth + 40;
         opts._width += borderwidth * 2;
     }
     else {
@@ -633,7 +667,6 @@ function computeLegendDimensions(gd, groups, traces) {
         var maxTraceWidth = 0;
         var offsetX = 0;
         var fullTracesWidth = 0;
-        var traceGap = opts.tracegroupgap || 5;
 
         // calculate largest width for traces and use for width of all legend items
         traces.each(function(d) {

test/image/mocks/legendgroup_horizontal_wrapping.json

@@ -0,0 +1,57 @@
+{
+  "data": [{
+    "x": [1, 2, 3, 4],
+    "y": [63.69, 62.55, 61.64, 61.39],
+    "legendgroup": 1,
+    "name": "Trace A-1"
+  }, {
+    "x": [1, 2, 3, 4],
+    "y": [58.24, 54.93, 42.11, 50.75],
+    "legendgroup": 1,
+    "name":"Trace A-2"
+  }, {
+    "x": [1, 2, 3, 4],
+    "y": [51.49, 49.59, 37.12, 31.45],
+    "legendgroup":2,
+    "name":"Trace B-1"
+  }, {
+    "x": [1, 2, 3, 4],
+    "y": [49.09, 58.54, 53.91, 43.12],
+    "legendgroup":2,
+    "name":"Trace B-2"
+  }, {
+    "x": [1, 2, 3, 4],
+    "y": [70.53, 72.51, 72.28, 78.65],
+    "name":"Trace C-1"
+  }, {
+    "x": [1, 2, 3, 4],
+    "y": [62.69, 59.09, 63.82, 62],
+    "legendgroup":3,
+    "name":"Trace D-1"
+  }, {
+    "x": [1, 2, 3, 4],
+    "y": [76.27, 71.43, 59.83, 64.34],
+    "legendgroup":3,
+    "name":"Trace D-2"
+  }, {
+    "x": [1, 2, 3, 4],
+    "y": [71.15, 81.82, 88.46, 74.29],
+    "name":"Trace E-1"
+  }],
+  "layout": {
+    "width": 600,
+    "legend": {
+      "orientation": "h"
+    },
+    "xaxis": {
+      "type": "linear",
+      "range": [0.7840236686390533, 4.215976331360947],
+      "autorange": true
+    },
+    "yaxis": {
+      "type": "linear",
+      "range": [27.274108280254776, 92.63589171974522],
+      "autorange": true
+    }
+  }
+}

test/jasmine/tests/legend_test.js

@@ -703,6 +703,34 @@ describe('legend relayout update', function() {
             .then(done);
         });
     });
+
+    describe('with legendgroup', function() {
+        var mock = require('@mocks/legendgroup_horizontal_wrapping.json');
+        var gd;
+
+        beforeEach(function() {
+            gd = createGraphDiv();
+        });
+        afterEach(destroyGraphDiv);
+
+        it('changes the margin size to fit tracegroupgap', function(done) {
+            var mockCopy = Lib.extendDeep({}, mock);
+            Plotly.newPlot(gd, mockCopy)
+            .then(function() {
+                expect(gd._fullLayout._size.b).toBe(130);
+                return Plotly.relayout(gd, 'legend.tracegroupgap', 70);
+            })
+            .then(function() {
+                expect(gd._fullLayout._size.b).toBe(185);
+                return Plotly.relayout(gd, 'legend.tracegroupgap', 10);
+            })
+            .then(function() {
+                expect(gd._fullLayout._size.b).toBe(130);
+            })
+            .catch(failTest)
+            .then(done);
+        });
+    });
 });
 
 describe('legend orientation change:', function() {