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Fix arc border with circumference over 2*PI #6215

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merged 6 commits into from Apr 30, 2019
Merged

Fix arc border with circumference over 2*PI #6215

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52e174c
Fix arc border with circumference over 2*PI
kurkle Apr 18, 2019
954009d
Fill overlapping area, refactor
kurkle Apr 18, 2019
0d9a902
Remove legacy tests, please CC
kurkle Apr 18, 2019
7781054
fill support for circumference > 4PI
kurkle Apr 24, 2019
5a87436
fix borders
kurkle Apr 24, 2019
3fd37be
address even circle border glitch
kurkle Apr 24, 2019
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90 changes: 63 additions & 27 deletions src/elements/element.arc.js
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Expand Up @@ -15,6 +15,38 @@ defaults._set('global', {
}
});

function pathArc(ctx, x, y, args) {
var innerRadius = args.innerRadius;
var outerRadius = args.outerRadius;
var startAngle = args.startAngle;
var endAngle = args.endAngle;

ctx.beginPath();
ctx.arc(x, y, outerRadius, startAngle, endAngle);
ctx.arc(x, y, innerRadius, endAngle, startAngle, true);
ctx.closePath();
}

function clipArc(ctx, vm, args) {
var startAngle = args.startAngle;
var endAngle = args.endAngle;
var pixelMargin = args.pixelMargin;
var angleMargin = pixelMargin / vm.outerRadius;

// Draw an inner border by cliping the arc and drawing a double-width border
// Enlarge the clipping arc by 0.33 pixels to eliminate glitches between borders
ctx.beginPath();
ctx.arc(vm.x, vm.y, vm.outerRadius, startAngle - angleMargin, endAngle + angleMargin);
if (vm.innerRadius > pixelMargin) {
angleMargin = pixelMargin / vm.innerRadius;
ctx.arc(vm.x, vm.y, vm.innerRadius - pixelMargin, endAngle + angleMargin, startAngle - angleMargin, true);
} else {
ctx.arc(vm.x, vm.y, pixelMargin, endAngle + Math.PI / 2, startAngle - Math.PI / 2);
}
ctx.closePath();
ctx.clip();
}

module.exports = Element.extend({
inLabelRange: function(mouseX) {
var vm = this._view;
Expand All @@ -30,7 +62,7 @@ module.exports = Element.extend({

if (vm) {
var pointRelativePosition = helpers.getAngleFromPoint(vm, {x: chartX, y: chartY});
var angle = pointRelativePosition.angle;
var angle = pointRelativePosition.angle;
var distance = pointRelativePosition.distance;

// Sanitise angle range
Expand Down Expand Up @@ -84,41 +116,45 @@ module.exports = Element.extend({
draw: function() {
var ctx = this._chart.ctx;
var vm = this._view;
var sA = vm.startAngle;
var eA = vm.endAngle;
var startAngle = vm.startAngle;
var endAngle = vm.endAngle;
var pixelMargin = (vm.borderAlign === 'inner') ? 0.33 : 0;
var angleMargin;
var outerRadius = Math.max(vm.outerRadius - pixelMargin, 0);
var innerRadius = vm.innerRadius;
var x = vm.x;
var y = vm.y;
var tA;

ctx.save();

ctx.beginPath();
ctx.arc(vm.x, vm.y, Math.max(vm.outerRadius - pixelMargin, 0), sA, eA);
ctx.arc(vm.x, vm.y, vm.innerRadius, eA, sA, true);
ctx.closePath();

ctx.fillStyle = vm.backgroundColor;

if (vm.circumference > Math.PI * 2) {
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@nagix nagix Apr 24, 2019 •
edited

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Looks good in case 0 <= circumference <= 2*PI and 2*PI < circumference <= 4*PI, but appearance is not consistent when circumference > 4*PI. How about looping this part (endAngle - startAngle) / (Math.PI * 2) times?

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Loop implemented, did some more refactoring to keep CC (and me) happy 😄
Demo updated.

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Instead of a loop would doing % 2PI be more efficient?

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@etimberg that was my initial approach, but with transparency it is not consistent with circumference > 4*PI.
Not sure if anyone is going to use circumference that high anyway, but now its drawn consistently.

tA = startAngle;
startAngle += (endAngle - startAngle) % (Math.PI * 2);
pathArc(ctx, x, y, {
innerRadius: innerRadius, outerRadius: outerRadius,
startAngle: tA, endAngle: startAngle
});
ctx.fill();
}

pathArc(ctx, x, y, {
innerRadius: innerRadius, outerRadius: outerRadius,
startAngle: startAngle, endAngle: endAngle
});
ctx.fill();

if (vm.borderWidth) {
if (vm.borderAlign === 'inner') {
// Draw an inner border by cliping the arc and drawing a double-width border
// Enlarge the clipping arc by 0.33 pixels to eliminate glitches between borders
ctx.beginPath();
angleMargin = pixelMargin / vm.outerRadius;
ctx.arc(vm.x, vm.y, vm.outerRadius, sA - angleMargin, eA + angleMargin);
if (vm.innerRadius > pixelMargin) {
angleMargin = pixelMargin / vm.innerRadius;
ctx.arc(vm.x, vm.y, vm.innerRadius - pixelMargin, eA + angleMargin, sA - angleMargin, true);
} else {
ctx.arc(vm.x, vm.y, pixelMargin, eA + Math.PI / 2, sA - Math.PI / 2);
}
ctx.closePath();
ctx.clip();

ctx.beginPath();
ctx.arc(vm.x, vm.y, vm.outerRadius, sA, eA);
ctx.arc(vm.x, vm.y, vm.innerRadius, eA, sA, true);
ctx.closePath();
clipArc(ctx, vm, {
startAngle: startAngle, endAngle: endAngle,
pixelMargin: pixelMargin
});
pathArc(ctx, x, y, {
innerRadius: innerRadius, outerRadius: vm.outerRadius,
startAngle: startAngle, endAngle: endAngle
});

ctx.lineWidth = vm.borderWidth * 2;
ctx.lineJoin = 'round';
Expand Down
24 changes: 24 additions & 0 deletions test/fixtures/controller.doughnut/doughnut-circumference-over-2pi.json
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@@ -0,0 +1,24 @@
{
"config": {
"type": "doughnut",
"data": {
"labels": ["A"],
"datasets": [{
"data": [100],
"backgroundColor": [
"rgba(153, 102, 255, 0.8)"
],
"borderWidth": 20,
"borderColor": [
"rgb(153, 102, 255)"
]
}]
},
"options": {
"circumference": 7,
"responsive": false,
"legend": false,
"title": false
}
}
}
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210 changes: 0 additions & 210 deletions test/specs/element.arc.tests.js
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Expand Up @@ -99,214 +99,4 @@ describe('Arc element tests', function() {
expect(center.x).toBeCloseTo(0.5, 6);
expect(center.y).toBeCloseTo(0.5, 6);
});

it ('should draw correctly with no border', function() {
var mockContext = window.createMockContext();
var arc = new Chart.elements.Arc({
_datasetIndex: 2,
_index: 1,
_chart: {
ctx: mockContext,
}
});

// Mock out the view as if the controller put it there
arc._view = {
startAngle: 0,
endAngle: Math.PI / 2,
x: 10,
y: 5,
innerRadius: 1,
outerRadius: 3,

backgroundColor: 'rgb(0, 0, 255)',
borderColor: 'rgb(255, 0, 0)',
};

arc.draw();

expect(mockContext.getCalls()).toEqual([{
name: 'save',
args: []
}, {
name: 'beginPath',
args: []
}, {
name: 'arc',
args: [10, 5, 3, 0, Math.PI / 2]
}, {
name: 'arc',
args: [10, 5, 1, Math.PI / 2, 0, true]
}, {
name: 'closePath',
args: []
}, {
name: 'setFillStyle',
args: ['rgb(0, 0, 255)']
}, {
name: 'fill',
args: []
}, {
name: 'restore',
args: []
}]);
});

it ('should draw correctly with a border', function() {
var mockContext = window.createMockContext();
var arc = new Chart.elements.Arc({
_datasetIndex: 2,
_index: 1,
_chart: {
ctx: mockContext,
}
});

// Mock out the view as if the controller put it there
arc._view = {
startAngle: 0,
endAngle: Math.PI / 2,
x: 10,
y: 5,
innerRadius: 1,
outerRadius: 3,

backgroundColor: 'rgb(0, 0, 255)',
borderColor: 'rgb(255, 0, 0)',
borderWidth: 5
};

arc.draw();

expect(mockContext.getCalls()).toEqual([{
name: 'save',
args: []
}, {
name: 'beginPath',
args: []
}, {
name: 'arc',
args: [10, 5, 3, 0, Math.PI / 2]
}, {
name: 'arc',
args: [10, 5, 1, Math.PI / 2, 0, true]
}, {
name: 'closePath',
args: []
}, {
name: 'setFillStyle',
args: ['rgb(0, 0, 255)']
}, {
name: 'fill',
args: []
}, {
name: 'setLineWidth',
args: [5]
}, {
name: 'setLineJoin',
args: ['bevel']
}, {
name: 'setStrokeStyle',
args: ['rgb(255, 0, 0)']
}, {
name: 'stroke',
args: []
}, {
name: 'restore',
args: []
}]);
});

it ('should draw correctly with an inner border', function() {
var mockContext = window.createMockContext();
var arc = new Chart.elements.Arc({
_datasetIndex: 2,
_index: 1,
_chart: {
ctx: mockContext,
}
});

// Mock out the view as if the controller put it there
arc._view = {
startAngle: 0,
endAngle: Math.PI / 2,
x: 10,
y: 5,
innerRadius: 1,
outerRadius: 3,

backgroundColor: 'rgb(0, 0, 255)',
borderColor: 'rgb(255, 0, 0)',
borderWidth: 5,
borderAlign: 'inner'
};

arc.draw();

expect(mockContext.getCalls()).toEqual([{
name: 'save',
args: []
}, {
name: 'beginPath',
args: []
}, {
name: 'arc',
args: [10, 5, 2.67, 0, Math.PI / 2]
}, {
name: 'arc',
args: [10, 5, 1, Math.PI / 2, 0, true]
}, {
name: 'closePath',
args: []
}, {
name: 'setFillStyle',
args: ['rgb(0, 0, 255)']
}, {
name: 'fill',
args: []
}, {
name: 'beginPath',
args: []
}, {
name: 'arc',
args: [10, 5, 3, -0.11, Math.PI / 2 + 0.11]
}, {
name: 'arc',
args: [10, 5, 1 - 0.33, Math.PI / 2 + 0.33, -0.33, true]
}, {
name: 'closePath',
args: []
}, {
name: 'clip',
args: []
}, {
name: 'beginPath',
args: []
}, {
name: 'arc',
args: [10, 5, 3, 0, Math.PI / 2]
}, {
name: 'arc',
args: [10, 5, 1, Math.PI / 2, 0, true]
}, {
name: 'closePath',
args: []
}, {
name: 'setLineWidth',
args: [10]
}, {
name: 'setLineJoin',
args: ['round']
}, {
name: 'setStrokeStyle',
args: ['rgb(255, 0, 0)']
}, {
name: 'stroke',
args: []
}, {
name: 'restore',
args: []
}]);
});
});