Scrawl-canvas modularized code - London crime charts
Related files:
/*
Data format requirements - a Javascript object with structure:
{
area: 'area-label',
yearLabels: ['year-1-label', 'year-2-label', ...],
categoryLabels: ['category-1-label', 'category-2-label', ...],
yearData: {
'year-1-label': ["category-1-data", "category-2-data", ...],
'year-2-label': ["category-1-data", "category-2-data", ...],
...
}
}
*/import {
api as frame,
dims as frameDims,
} from './simple-chart-frame.js';const extractHighestAnnualMaximum = (yearLabels, yearData) => {
let max = 0;
for (let i = 0; i < yearLabels.length; i++) {
const total = yearData[yearLabels[i]].reduce((a, v) => a + v, 0);
if (total > max) max = total;
}
return ((Math.floor(max / 1000)) * 1000) + 1000;
};
const colorArray = ['#257394', '#947a25', '#fc0004', '#00fcbd', '#de9bc8', '#9bdeaf', '#970b99', '#0b9910', '#5f11f0', '#66f011', '#a09de0', '#d1e09d'];export const api = {};The exported build function
api.build = function (items) {
const { namespace, canvas, data, scrawl } = items;Module state
let selectedColumn = 0,
selectedRow = 0;
const currentData = data;
if (namespace && canvas && data && scrawl) {Namespace boilerplate
const name = (item) => `${namespace}-${item}`;Local variables defined at the top of the build function
const yearLabels = data.yearLabels,
categoryLabels = data.categoryLabels,
yearData = data.yearData,
gap = 1,Magic numbers
graphWidth = frameDims.graphWidth,
graphHeight = frameDims.graphHeight,
graphBottom = frameDims.graphBottom,
graphLeft = frameDims.graphLeft + (gap / 2),Graph baseline calculations
maximumBarTotal = extractHighestAnnualMaximum(yearLabels, yearData),
numberOfYears = yearLabels.length,
barDistance = graphWidth / numberOfYears,
barWidth = `${barDistance - gap}%`,
singleCrimeHeight = graphHeight / maximumBarTotal;Create group
const group = scrawl.makeGroup({
name: name('bargroup'),
host: canvas.get('baseName'),
order: 2,
});Build bars
yearLabels.forEach((year, yearIndex) => {
const xPosition = (barDistance * yearIndex) + graphLeft,
categoryLen = categoryLabels.length;
let localHeight = 0;
categoryLabels.forEach((category, categoryIndex) => {
const categoryItem = yearData[year][categoryIndex],
crimeHeight = categoryItem * singleCrimeHeight;
localHeight += crimeHeight;
scrawl.makeBlock({
name: name(`${year}-${category}`),
group,
width: barWidth,
height: `${crimeHeight}%`,
startX: `${xPosition}%`,
startY: `${graphBottom - localHeight}%`,
fillStyle: colorArray[categoryIndex % categoryLen],
onEnter: function () {
selectedColumn = yearIndex;
selectedRow = categoryIndex;
updateSelected();
},
});
});
});Build highlight cursor
const currentDatapoint = scrawl.makeBlock({
name: name('dataframe'),
group,
mimic: name(`${selectedColumn}-${selectedRow}`),
useMimicDimensions: true,
useMimicStart: true,
useMimicHandle: true,
lockTo: 'mimic',
lineWidth: 6,
strokeStyle: 'yellow',
method: 'draw',
});
const redSpan = 'style="color: red; --SC-fill-style: red"';
const updateSelected = () => {
const {yearLabels, categoryLabels, yearData} = currentData;
const category = categoryLabels[selectedRow],
year = yearLabels[selectedColumn],
data = yearData[year][selectedRow];
currentDatapoint.set({
mimic: name(`${year}-${category}`),
});
frame.updateSubtitle(`${category} in ${year}: <span ${redSpan}>${data.toLocaleString()}</span>`);
};
updateSelected();Personalize the chart frame to meet this graph’s requirements
frame.updateSubtitle('No data selected');
frame.updateXLeft(yearLabels[0]);
frame.updateXRight(yearLabels[numberOfYears - 1]);
frame.updateYTop(maximumBarTotal.toLocaleString());Accessibility
const doNavigation = (direction) => {
const {yearLabels, categoryLabels} = currentData;
const columnLen = yearLabels.length,
rowLen = categoryLabels.length;
switch (direction) {
case 'up' :
selectedRow++;
break;
case 'down' :
selectedRow--;
break;
case 'left' :
selectedColumn--;
break;
case 'right' :
selectedColumn++;
break;
}
if (selectedColumn < 0) selectedColumn = columnLen - 1;
else if (selectedColumn >= columnLen) selectedColumn = 0;
if (selectedRow < 0) selectedRow = rowLen - 1;
else if (selectedRow >= rowLen) selectedRow = 0;
updateSelected();
};
frame.keyboard = scrawl.makeKeyboardZone({
zone: canvas,
none: {
ArrowLeft: () => doNavigation('left'),
ArrowUp: () => doNavigation('up'),
ArrowRight: () => doNavigation('right'),
ArrowDown: () => doNavigation('down'),
},
});
}
};