2020-10-27 02:30:35 +01:00
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<!DOCTYPE html>
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<html>
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<head>
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<title>Tax forms: Bar chart with lines</title>
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<meta charset="UTF-8">
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<script src="taxForms.js"></script>
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</head>
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<body>
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<canvas id="chart" width="700" height="550"></canvas>
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<script>
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const canvas = document.getElementById('chart');
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const context = canvas.getContext('2d');
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/* Draw a line from (fromX, fromY) to (toX, toY) */
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function drawLine(fromX, fromY, toX, toY) {
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context.beginPath();
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context.moveTo(toX, toY);
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context.lineTo(fromX, fromY);
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context.stroke();
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}
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/* Draw a text (string) on (x, y) */
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function drawText(text, x, y) {
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context.fillStyle = 'black';
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context.fillText(text, x, y);
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}
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/* Draw a text and with a line to its right */
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function drawLineWithText(text, fromX, fromY, toX, toY) {
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drawText(text, fromX - 50, fromY + 10);
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drawLine(fromX, fromY, toX, toY);
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}
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/* Insert your code here. */
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/**
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* Draw lines on the y axis of the canvas
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*
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* @param {number} n - Number of lines to draw
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* @param {number} step - Number to add to y axis
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*/
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const drawNLines = (n, step) => {
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for (let i = 1; i <= n; i++) {
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const y = canvas.height * (n - i + 1 ) / (n+1);
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const text = step * i;
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drawLineWithText(text, 50, y, canvas.width - 100, y);
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}
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}
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/**
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* Draws a rectangle onto the canvas
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*
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* @param {number} x - x value of the upper left corner of the rectangle
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* @param {number} y - y value of the upper left corner of the rectangle
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* @param {number} width - Width of the rectangle
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* @param {number} height - Height of the rectangle (DOWNWARDS)
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* @param {string} color - Color of the rectangle
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*/
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const drawRectangle = (x, y, width, height, color='red') => {
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context.fillStyle = color;
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context.fillRect(x, y, width, height);
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}
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/**
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* Cycle a list of colors
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*
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* @generator
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*
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* @param {string[]} colors - List of colors to cycle
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* @yields {string} A color
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*/
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function* colorCycler(colors) {
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let i = 0;
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while (true) {
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yield colors[i];
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i = (i + 1) % colors.length;
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}
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}
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/**
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2020-10-27 15:19:15 +01:00
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* Draw a legend on the canvas
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2020-10-27 02:30:35 +01:00
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*
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* @param {string[]} properties - An array of labels
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* @param {[string[]} colorList - An array of colors to cycle when making labels
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*/
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const drawLabels = (properties, colorList) => {
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const colors = colorCycler(colorList);
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const drawLabel = (text, color, y) => {
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drawText(text, canvas.width-45, y + 15)
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drawRectangle(canvas.width - 90, y, 40, 20, color);
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}
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const yOffset = canvas.height / 12
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for (i in properties) {
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drawLabel(properties[i], colors.next().value, yOffset+30*i);
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}
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}
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drawNLines(10, 100000);
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const taxData = taxForms;
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taxData.forEach(form => delete form.realName);
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drawLabels(Object.getOwnPropertyNames(taxData[0]), ['red', 'blue']);
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</script>
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</body>
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</html>
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