131 lines
3.5 KiB
JavaScript
131 lines
3.5 KiB
JavaScript
//
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// Chart extension for making the bars rounded
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// Code from: https://codepen.io/jedtrow/full/ygRYgo
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//
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Chart.elements.Rectangle.prototype.draw = function() {
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var ctx = this._chart.ctx;
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var vm = this._view;
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var left, right, top, bottom, signX, signY, borderSkipped, radius;
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var borderWidth = vm.borderWidth;
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// Set Radius Here
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// If radius is large enough to cause drawing errors a max radius is imposed
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var cornerRadius = 6;
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if (!vm.horizontal) {
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// bar
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left = vm.x - vm.width / 2;
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right = vm.x + vm.width / 2;
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top = vm.y;
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bottom = vm.base;
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signX = 1;
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signY = bottom > top ? 1 : -1;
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borderSkipped = vm.borderSkipped || 'bottom';
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} else {
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// horizontal bar
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left = vm.base;
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right = vm.x;
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top = vm.y - vm.height / 2;
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bottom = vm.y + vm.height / 2;
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signX = right > left ? 1 : -1;
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signY = 1;
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borderSkipped = vm.borderSkipped || 'left';
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}
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// Canvas doesn't allow us to stroke inside the width so we can
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// adjust the sizes to fit if we're setting a stroke on the line
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if (borderWidth) {
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// borderWidth shold be less than bar width and bar height.
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var barSize = Math.min(Math.abs(left - right), Math.abs(top - bottom));
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borderWidth = borderWidth > barSize ? barSize : borderWidth;
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var halfStroke = borderWidth / 2;
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// Adjust borderWidth when bar top position is near vm.base(zero).
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var borderLeft = left + (borderSkipped !== 'left' ? halfStroke * signX : 0);
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var borderRight = right + (borderSkipped !== 'right' ? -halfStroke * signX : 0);
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var borderTop = top + (borderSkipped !== 'top' ? halfStroke * signY : 0);
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var borderBottom = bottom + (borderSkipped !== 'bottom' ? -halfStroke * signY : 0);
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// not become a vertical line?
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if (borderLeft !== borderRight) {
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top = borderTop;
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bottom = borderBottom;
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}
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// not become a horizontal line?
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if (borderTop !== borderBottom) {
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left = borderLeft;
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right = borderRight;
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}
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}
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ctx.beginPath();
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ctx.fillStyle = vm.backgroundColor;
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ctx.strokeStyle = vm.borderColor;
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ctx.lineWidth = borderWidth;
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// Corner points, from bottom-left to bottom-right clockwise
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// | 1 2 |
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// | 0 3 |
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var corners = [
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[left, bottom],
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[left, top],
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[right, top],
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[right, bottom]
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];
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// Find first (starting) corner with fallback to 'bottom'
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var borders = ['bottom', 'left', 'top', 'right'];
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var startCorner = borders.indexOf(borderSkipped, 0);
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if (startCorner === -1) {
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startCorner = 0;
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}
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function cornerAt(index) {
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return corners[(startCorner + index) % 4];
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}
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// Draw rectangle from 'startCorner'
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var corner = cornerAt(0);
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ctx.moveTo(corner[0], corner[1]);
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for (var i = 1; i < 4; i++) {
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corner = cornerAt(i);
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nextCornerId = i + 1;
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if (nextCornerId == 4) {
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nextCornerId = 0
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}
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nextCorner = cornerAt(nextCornerId);
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width = corners[2][0] - corners[1][0];
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height = corners[0][1] - corners[1][1];
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x = corners[1][0];
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y = corners[1][1];
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var radius = cornerRadius;
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// Fix radius being too large
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if (radius > height / 2) {
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radius = height / 2;
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}
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if (radius > width / 2) {
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radius = width / 2;
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}
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ctx.moveTo(x + radius, y);
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ctx.lineTo(x + width - radius, y);
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ctx.quadraticCurveTo(x + width, y, x + width, y + radius);
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ctx.lineTo(x + width, y + height - radius);
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ctx.quadraticCurveTo(x + width, y + height, x + width - radius, y + height);
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ctx.lineTo(x + radius, y + height);
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ctx.quadraticCurveTo(x, y + height, x, y + height - radius);
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ctx.lineTo(x, y + radius);
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ctx.quadraticCurveTo(x, y, x + radius, y);
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}
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ctx.fill();
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if (borderWidth) {
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ctx.stroke();
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}
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};
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