Scale: draw border on separate layer after grid (#8936)

src/core/core.scale.js

@@ -1009,7 +1009,7 @@ export default class Scale extends Element {
     const tl = getTickMarkLength(grid);
     const items = [];
 
-    const borderOpts = grid.setContext(me.getContext(0));
+    const borderOpts = grid.setContext(me.getContext());
     const axisWidth = borderOpts.drawBorder ? borderOpts.borderWidth : 0;
     const axisHalfWidth = axisWidth / 2;
     const alignBorderValue = function(pixel) {
@@ -1414,9 +1414,6 @@ export default class Scale extends Element {
     const me = this;
     const grid = me.options.grid;
     const ctx = me.ctx;
-    const chart = me.chart;
-    const borderOpts = grid.setContext(me.getContext());
-    const axisWidth = grid.drawBorder ? borderOpts.borderWidth : 0;
     const items = me._gridLineItems || (me._gridLineItems = me._computeGridLineItems(chartArea));
     let i, ilen;
 
@@ -1463,27 +1460,42 @@ export default class Scale extends Element {
         }
       }
     }
+  }
 
-    if (axisWidth) {
-      // Draw the line at the edge of the axis
-      const lastLineWidth = borderOpts.lineWidth;
-      const borderValue = me._borderValue;
-      let x1, x2, y1, y2;
+  /**
+	 * @protected
+	 */
+  drawBorder() {
+    const me = this;
+    const {chart, ctx, options: {grid}} = me;
+    const borderOpts = grid.setContext(me.getContext());
+    const axisWidth = grid.drawBorder ? borderOpts.borderWidth : 0;
+    if (!axisWidth) {
+      return;
+    }
+    const lastLineWidth = grid.setContext(me.getContext(0)).lineWidth;
+    const borderValue = me._borderValue;
+    let x1, x2, y1, y2;
 
-      if (me.isHorizontal()) {
-        x1 = _alignPixel(chart, me.left, axisWidth) - axisWidth / 2;
-        x2 = _alignPixel(chart, me.right, lastLineWidth) + lastLineWidth / 2;
-        y1 = y2 = borderValue;
-      } else {
-        y1 = _alignPixel(chart, me.top, axisWidth) - axisWidth / 2;
-        y2 = _alignPixel(chart, me.bottom, lastLineWidth) + lastLineWidth / 2;
-        x1 = x2 = borderValue;
-      }
-      drawLine(
-        {x: x1, y: y1},
-        {x: x2, y: y2},
-        {width: axisWidth, color: borderOpts.borderColor});
+    if (me.isHorizontal()) {
+      x1 = _alignPixel(chart, me.left, axisWidth) - axisWidth / 2;
+      x2 = _alignPixel(chart, me.right, lastLineWidth) + lastLineWidth / 2;
+      y1 = y2 = borderValue;
+    } else {
+      y1 = _alignPixel(chart, me.top, axisWidth) - axisWidth / 2;
+      y2 = _alignPixel(chart, me.bottom, lastLineWidth) + lastLineWidth / 2;
+      x1 = x2 = borderValue;
     }
+    ctx.save();
+    ctx.lineWidth = borderOpts.borderWidth;
+    ctx.strokeStyle = borderOpts.borderColor;
+
+    ctx.beginPath();
+    ctx.moveTo(x1, y1);
+    ctx.lineTo(x2, y2);
+    ctx.stroke();
+
+    ctx.restore();
   }
 
   /**
@@ -1571,6 +1583,7 @@ export default class Scale extends Element {
 
     me.drawBackground();
     me.drawGrid(chartArea);
+    me.drawBorder();
     me.drawTitle();
     me.drawLabels(chartArea);
   }
@@ -1585,7 +1598,7 @@ export default class Scale extends Element {
     const tz = opts.ticks && opts.ticks.z || 0;
     const gz = opts.grid && opts.grid.z || 0;
 
-    if (!me._isVisible() || tz === gz || me.draw !== Scale.prototype.draw) {
+    if (!me._isVisible() || me.draw !== Scale.prototype.draw) {
       // backward compatibility: draw has been overridden by custom scale
       return [{
         z: tz,
@@ -1602,6 +1615,11 @@ export default class Scale extends Element {
         me.drawGrid(chartArea);
         me.drawTitle();
       }
+    }, {
+      z: gz + 1, // TODO, v4 move border options to its own object and add z
+      draw() {
+        me.drawBorder();
+      }
     }, {
       z: tz,
       draw(chartArea) {

src/scales/scale.radialLinear.js

@@ -506,6 +506,11 @@ export default class RadialLinearScale extends LinearScaleBase {
     }
   }
 
+  /**
+	 * @protected
+	 */
+  drawBorder() {}
+
   /**
 	 * @protected
 	 */

test/fixtures/core.scale/grid/border-over-grid.js

@@ -0,0 +1,37 @@
+module.exports = {
+  config: {
+    type: 'scatter',
+    options: {
+      scales: {
+        x: {
+          position: {y: 0},
+          min: -10,
+          max: 10,
+          grid: {
+            borderColor: 'black',
+            borderWidth: 5,
+            color: 'lightGray',
+            lineWidth: 3,
+          },
+          ticks: {
+            display: false
+          },
+        },
+        y: {
+          position: {x: 0},
+          min: -10,
+          max: 10,
+          grid: {
+            borderColor: 'black',
+            borderWidth: 5,
+            color: 'lightGray',
+            lineWidth: 3,
+          },
+          ticks: {
+            display: false
+          },
+        }
+      }
+    }
+  }
+};

test/fixtures/core.scale/grid/colors.js

@@ -0,0 +1,38 @@
+module.exports = {
+  config: {
+    type: 'line',
+    data: {
+      labels: ['1', '2', '3', '4', '5', '6'],
+      datasets: [{
+        label: '# of Votes',
+        data: [12, 19, 3, 5, 2, 3]
+      }],
+    },
+    options: {
+      scales: {
+        x: {
+          ticks: {
+            display: false
+          },
+          grid: {
+            borderColor: 'blue',
+            borderWidth: 2,
+            color: 'green',
+            drawTicks: false,
+          }
+        },
+        y: {
+          ticks: {
+            display: false
+          },
+          grid: {
+            borderColor: 'black',
+            borderWidth: 2,
+            color: 'red',
+            drawTicks: false,
+          }
+        }
+      }
+    }
+  }
+};

test/specs/core.scale.tests.js

@@ -433,7 +433,7 @@ describe('Core.scale', function() {
   });
 
   describe('_layers', function() {
-    it('should default to one layer', function() {
+    it('should default to three layers', function() {
       var chart = window.acquireChart({
         type: 'line',
         options: {
@@ -446,7 +446,7 @@ describe('Core.scale', function() {
       });
 
       var scale = chart.scales.x;
-      expect(scale._layers().length).toEqual(1);
+      expect(scale._layers().length).toEqual(3);
     });
 
     it('should default to one layer for custom scales', function() {
@@ -482,30 +482,7 @@ describe('Core.scale', function() {
       expect(scale._layers()[0].z).toEqual(20);
     });
 
-    it('should default to one layer when z is equal between ticks and grid', function() {
-      var chart = window.acquireChart({
-        type: 'line',
-        options: {
-          scales: {
-            x: {
-              type: 'linear',
-              ticks: {
-                z: 10
-              },
-              grid: {
-                z: 10
-              }
-            }
-          }
-        }
-      });
-
-      var scale = chart.scales.x;
-      expect(scale._layers().length).toEqual(1);
-    });
-
-
-    it('should return 2 layers when z is not equal between ticks and grid', function() {
+    it('should return 3 layers when z is not equal between ticks and grid', function() {
       var chart = window.acquireChart({
         type: 'line',
         options: {
@@ -520,7 +497,7 @@ describe('Core.scale', function() {
         }
       });
 
-      expect(chart.scales.x._layers().length).toEqual(2);
+      expect(chart.scales.x._layers().length).toEqual(3);
 
       chart = window.acquireChart({
         type: 'line',
@@ -536,7 +513,7 @@ describe('Core.scale', function() {
         }
       });
 
-      expect(chart.scales.x._layers().length).toEqual(2);
+      expect(chart.scales.x._layers().length).toEqual(3);
 
       chart = window.acquireChart({
         type: 'line',
@@ -555,7 +532,7 @@ describe('Core.scale', function() {
         }
       });
 
-      expect(chart.scales.x._layers().length).toEqual(2);
+      expect(chart.scales.x._layers().length).toEqual(3);
 
     });