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Move drawing of gridLines into separate plugin and add border functionality #4117

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7 changes: 4 additions & 3 deletions src/chart.js
Original file line number Diff line number Diff line change
Expand Up @@ -52,9 +52,10 @@ require('./charts/Chart.Scatter')(Chart);
var plugins = [];

plugins.push(
require('./plugins/plugin.filler')(Chart),
require('./plugins/plugin.legend')(Chart),
require('./plugins/plugin.title')(Chart)
require('./plugins/plugin.filler')(Chart),
require('./plugins/plugin.gridlines')(Chart),
require('./plugins/plugin.legend')(Chart),
require('./plugins/plugin.title')(Chart)
);

Chart.plugins.register(plugins);
Expand Down
97 changes: 56 additions & 41 deletions src/core/core.scale.js
Original file line number Diff line number Diff line change
Expand Up @@ -9,6 +9,10 @@ defaults._set('scale', {
display: true,
position: 'left',
offset: false,
borderColor: 'rgba(0, 0, 0, 0.4)',
borderWidth: 0,
borderDash: [],
borderDashOffset: 0.0,

// grid line settings
gridLines: {
Expand Down Expand Up @@ -672,7 +676,7 @@ module.exports = function(Chart) {
},

// Actually draw the scale on the canvas
// @param {rectangle} chartArea : the area of the chart to draw full grid lines on
// @param {rectangle} chartArea : the area of the chart to draw all ticks and labels on
draw: function(chartArea) {
var me = this;
var options = me.options;
Expand Down Expand Up @@ -732,7 +736,7 @@ module.exports = function(Chart) {
}

// Common properties
var tx1, ty1, tx2, ty2, x1, y1, x2, y2, labelX, labelY;
var tx1, ty1, tx2, ty2, labelX, labelY;
var textAlign = 'middle';
var textBaseline = 'middle';
var tickPadding = optionTicks.padding;
Expand Down Expand Up @@ -760,11 +764,9 @@ module.exports = function(Chart) {

labelX = me.getPixelForTick(index) + optionTicks.labelOffset; // x values for optionTicks (need to consider offsetLabel option)

tx1 = tx2 = x1 = x2 = xLineValue;
tx1 = tx2 = xLineValue;
ty1 = yTickStart;
ty2 = yTickEnd;
y1 = chartArea.top;
y2 = chartArea.bottom;
} else {
var isLeft = options.position === 'left';
var labelXOffset;
Expand All @@ -789,43 +791,53 @@ module.exports = function(Chart) {

tx1 = xTickStart;
tx2 = xTickEnd;
x1 = chartArea.left;
x2 = chartArea.right;
ty1 = ty2 = y1 = y2 = yLineValue;
ty1 = ty2 = yLineValue;
}

itemsToDraw.push({
tx1: tx1,
ty1: ty1,
tx2: tx2,
ty2: ty2,
x1: x1,
y1: y1,
x2: x2,
y2: y2,
labelX: labelX,
labelY: labelY,
glWidth: lineWidth,
glColor: lineColor,
glBorderDash: borderDash,
glBorderDashOffset: borderDashOffset,
tmWidth: lineWidth,
tmColor: lineColor,
tmBorderDash: borderDash,
tmBorderDashOffset: borderDashOffset,
rotation: -1 * labelRotationRadians,
label: label,
label: '' + label,
major: tick.major,
textBaseline: textBaseline,
textAlign: textAlign
});
});

// Draw all of the tick labels, tick marks, and grid lines at the correct places
// When offsetGridLines is enabled, there should be one more tick mark than there
// are ticks in scale.ticks array, therefore the missing gridLine has to be manually added
if (gridLines.offsetGridLines) {
var aliasPixel = helpers.aliasPixel(gridLines.lineWidth);
itemsToDraw.push({
tx1: !isHorizontal ? xTickStart : chartArea.right + aliasPixel,
ty1: !isHorizontal ? chartArea.bottom + aliasPixel : yTickStart,
tx2: !isHorizontal ? xTickEnd : chartArea.right + aliasPixel,
ty2: !isHorizontal ? chartArea.bottom + aliasPixel : yTickEnd,
tmWidth: helpers.valueAtIndexOrDefault(gridLines.lineWidth, ticks.length),
tmColor: helpers.valueAtIndexOrDefault(gridLines.color, ticks.length),
tmBorderDash: gridLines.borderDash,
tmBorderDashOffset: gridLines.borderDashOffset
});
}

// Draw all of the tick labels and tick marks at the correct places
helpers.each(itemsToDraw, function(itemToDraw) {
if (gridLines.display) {
context.save();
context.lineWidth = itemToDraw.glWidth;
context.strokeStyle = itemToDraw.glColor;
context.lineWidth = itemToDraw.tmWidth;
context.strokeStyle = itemToDraw.tmColor;
if (context.setLineDash) {
context.setLineDash(itemToDraw.glBorderDash);
context.lineDashOffset = itemToDraw.glBorderDashOffset;
context.setLineDash(itemToDraw.tmBorderDash);
context.lineDashOffset = itemToDraw.tmBorderDashOffset;
}

context.beginPath();
Expand All @@ -835,16 +847,11 @@ module.exports = function(Chart) {
context.lineTo(itemToDraw.tx2, itemToDraw.ty2);
}

if (gridLines.drawOnChartArea) {
context.moveTo(itemToDraw.x1, itemToDraw.y1);
context.lineTo(itemToDraw.x2, itemToDraw.y2);
}

context.stroke();
context.restore();
}

if (optionTicks.display) {
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Might make sense to do this for any value of itemToDraw.label that isn't truthy. Blank labels don't need to be drawn and same with null labels. What do you think?

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items with null or undefined label aren't pushed into the array at all, thanks to this statement.
The blank labels don't need to be drawn tho. The question is if they should be skipped the same way as when it's null(its ticks and gridLines wont be drawn) or in the statement you linked so there will be a blank tick, but the label itself wont be drawn.

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Hmmm, for grid lines we have the following logic:
if label is a string, draw label, tick and grid line
if label is null or undefined hide the label, tick and gridline.

This allows users to filter out grid lines by return null from the tick callback. here is an example of filtering

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i understand, i'll add just add the statement to skip the drawing of label itself if it's empty string then

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Sounds good

if (optionTicks.display && itemToDraw.label) {
// Make sure we draw text in the correct color and font
context.save();
context.translate(itemToDraw.labelX, itemToDraw.labelY);
Expand Down Expand Up @@ -901,30 +908,38 @@ module.exports = function(Chart) {
context.restore();
}

if (gridLines.drawBorder) {
// Draw the line at the edge of the axis
context.lineWidth = helpers.valueAtIndexOrDefault(gridLines.lineWidth, 0);
context.strokeStyle = helpers.valueAtIndexOrDefault(gridLines.color, 0);
var x1 = me.left;
var x2 = me.right;
var y1 = me.top;
var y2 = me.bottom;
// gridLines.drawBorder is deprecated
if (gridLines.drawBorder && options.borderColor && options.borderWidth) {
// Draw the scale border
context.lineWidth = options.borderWidth;
context.strokeStyle = options.borderColor;
if (context.setLineDash) {
context.setLineDash(helpers.getValueOrDefault(options.borderDash, globalDefaults.borderDash));
context.lineDashOffset = helpers.getValueOrDefault(options.borderDashOffset, globalDefaults.borderDashOffset);
}

var x1 = Math.round(me.left);
var x2 = Math.round(me.right);
var y1 = Math.round(me.top);
var y2 = Math.round(me.bottom);

var aliasPixel = helpers.aliasPixel(context.lineWidth);
if (isHorizontal) {
y1 = y2 = options.position === 'top' ? me.bottom : me.top;
y1 += aliasPixel;
y2 += aliasPixel;
y1 += helpers.aliasPixel(context.lineWidth);
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I would put the var aliasPixel = helpers.aliasPixel(context.lineWidth) back in since it minifies better

y2 += helpers.aliasPixel(context.lineWidth);
} else {
x1 = x2 = options.position === 'left' ? me.right : me.left;
x1 += aliasPixel;
x2 += aliasPixel;
x1 += helpers.aliasPixel(context.lineWidth);
x2 += helpers.aliasPixel(context.lineWidth);
}

context.beginPath();

context.moveTo(x1, y1);
context.lineTo(x2, y2);

context.stroke();
context.restore();
}
}
});
Expand Down
182 changes: 182 additions & 0 deletions src/plugins/plugin.gridlines.js
Original file line number Diff line number Diff line change
@@ -0,0 +1,182 @@
'use strict';

var defaults = require('../core/core.defaults');
var helpers = require('../helpers/index');
var MODEL_KEY = '$gridlines';

// This is copied from core.scale.js, which is also required here and im not sure where it should be placed for both of them to access it
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This should not be here, but i dont know where to move it for both core.scale.js and this plugin to access it

function getLineValue(scale, index, offsetGridLines) {
var lineValue = scale.getPixelForTick(index);

if (offsetGridLines) {
if (index === 0) {
lineValue -= (scale.getPixelForTick(1) - lineValue) / 2;
} else {
lineValue -= (lineValue - scale.getPixelForTick(index - 1)) / 2;
}
}
return lineValue;
}

module.exports = function() {
function getGridLine(chart, scale, position, tickIndex) {
var chartArea = chart.chartArea;
var scaleOptions = scale.options;
var gridLines = scaleOptions.gridLines;

var lineWidth, lineColor, borderDash, borderDashOffset;

if (tickIndex !== undefined && tickIndex === scale.zeroLineIndex) {
lineWidth = gridLines.zeroLineWidth;
lineColor = gridLines.zeroLineColor;
borderDash = gridLines.zeroLineBorderDash;
borderDashOffset = gridLines.zeroLineBorderDashOffset;
} else {
lineWidth = helpers.getValueAtIndexOrDefault(gridLines.lineWidth, tickIndex);
lineColor = helpers.getValueAtIndexOrDefault(gridLines.color, tickIndex);
borderDash = helpers.getValueOrDefault(gridLines.borderDash, defaults.global.borderDash);
borderDashOffset = helpers.getValueOrDefault(gridLines.borderDashOffset, defaults.global.borderDashOffset);
}

var x1, x2, y1, y2;

if (scale.isHorizontal()) {
x1 = x2 = position;
y1 = chartArea.top;
y2 = chartArea.bottom;
} else {
x1 = chartArea.left;
x2 = chartArea.right;
y1 = y2 = position;
}

return {
x1: x1,
x2: x2,
y1: y1,
y2: y2,
width: lineWidth,
color: lineColor,
borderDash: borderDash,
borderDashOffset: borderDashOffset
};
}

function collectVisibleGridLines(chart) {
var lines = [];

// Temporary object that stores already collected gridLine positions to prevent gridLines from overlapping
var gridLinesHash = {
horizontal: {},
vertical: {}
};

// Marks scale border positions to prevent overlapping of gridLines and scale borders
helpers.each(chart.scales, function(scale) {
var scaleOptions = scale.options;
var glHashByOrientantion = gridLinesHash[!scale.isHorizontal() ? 'horizontal' : 'vertical'];
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[nit] orientation has a typo in it

var borderPosition;

// gridLines.drawBorder is deprecated
if (scaleOptions.gridLines.drawBorder && scaleOptions.borderColor !== null && scaleOptions.borderWidth !== 0 && scaleOptions.borderWidth !== null) {
if (scale.isHorizontal()) {
borderPosition = scale.position === 'top' ? scale.bottom : scale.top;
} else {
borderPosition = scale.position === 'left' ? scale.right : scale.left;
}

glHashByOrientantion[Math.round(borderPosition)] = true;
}
});

// Collects gridLines
helpers.each(chart.scales, function(scale) {
var scaleOptions = scale.options;
var glHashByOrientantion = gridLinesHash[scale.isHorizontal() ? 'horizontal' : 'vertical'];
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[nit] same here

var position;

if (scaleOptions.display && scaleOptions.gridLines.display && scaleOptions.gridLines.drawOnChartArea) {
for (var tickIndex = 0, ticksCount = scale.ticks.length; tickIndex < ticksCount; tickIndex++) {
if (helpers.isNullOrUndef(scale.ticks[tickIndex])) {
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@simonbrunel @benmccann does this check make sense in the context of how ticks changed in 2.7.0?

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I think so

continue;
}

position = getLineValue(scale, tickIndex, scaleOptions.gridLines.offsetGridLines && ticksCount > 1);

if (glHashByOrientantion[position] === undefined) {
glHashByOrientantion[position] = true;
lines.push(getGridLine(chart, scale, position, tickIndex));
}
}

// When offsetGridLines is enabled, there should be one more gridLine than there
// are ticks in scale.ticks array, therefore the missing gridLine has to be manually added
if (scaleOptions.gridLines.offsetGridLines) {
position = Math.round(!scale.isHorizontal() ? scale.bottom : scale.right);

if (glHashByOrientantion[position] === undefined) {
glHashByOrientantion[position] = true;
lines.push(getGridLine(chart, scale, position, undefined));
}
}
}
});

return lines;
}

function drawGridLines(ctx, lines) {
var aliasPixel;
var x1, x2, y1, y2;

for (var i = 0, ilen = lines.length; i < ilen; i++) {
var line = lines[i];

ctx.lineWidth = line.width;
ctx.strokeStyle = line.color;
if (ctx.setLineDash) {
ctx.setLineDash(line.borderDash);
ctx.lineDashOffset = line.borderDashOffset;
}

aliasPixel = helpers.aliasPixel(ctx.lineWidth);
x1 = line.x1;
x2 = line.x2;
y1 = line.y1;
y2 = line.y2;

if (y1 === y2) {
y1 += aliasPixel;
y2 += aliasPixel;
} else {
x1 += aliasPixel;
x2 += aliasPixel;
}

ctx.beginPath();

ctx.moveTo(x1, y1);
ctx.lineTo(x2, y2);

ctx.stroke();
ctx.restore();
}
}

return {
id: 'gridlines',

afterUpdate: function(chart) {
chart[MODEL_KEY] = {
lines: collectVisibleGridLines(chart)
};
},

beforeDraw: function(chart) {
var model = chart[MODEL_KEY];
if (model) {
drawGridLines(chart.ctx, model.lines);
}
}
};
};