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Zoom using zoomPercent #381

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85 changes: 85 additions & 0 deletions samples/zoom-large-dataset.html
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Original file line number Diff line number Diff line change
@@ -0,0 +1,85 @@
<!doctype html>
<html>

<head>
<title>Bar Chart Zoom - Large dataset</title>
<script src="https://cdn.jsdelivr.net/npm/chart.js@2.9.1"></script>
<script src="https://cdn.jsdelivr.net/npm/hammerjs@2.0.8"></script>
<script src="../dist/chartjs-plugin-zoom.min.js"></script>

<style>
canvas {
-moz-user-select: none;
-webkit-user-select: none;
-ms-user-select: none;
}
</style>
</head>

<body>
<div id="container" style="width: 75%;">
<canvas id="canvas"></canvas>
</div>

<script>
var randomScalingFactor = function() {
return (Math.random() > 0.5 ? 1.0 : -1.0) * Math.round(Math.random() * 100);
};

const labels = [];
const data = [];
const dataCount = 1000;
for (let i = 0; i < dataCount; i++) {
data.push(randomScalingFactor());
labels.push(i);
}

var barChartData = {
labels: labels,
datasets: [{
label: 'Dataset 1',
backgroundColor: 'rgba(220,220,220,0.5)',
data: data
}]
};

window.onload = function() {
var ctx = document.getElementById('canvas').getContext('2d');
window.myBar = new window.Chart(ctx, {
type: 'bar',
data: barChartData,
options: {
// Elements options apply to all of the options unless overridden in a dataset
// In this case, we are setting the border of each bar to be 2px wide and green
elements: {
rectangle: {
borderWidth: 2,
borderColor: 'rgb(0, 255, 0)',
borderSkipped: 'bottom'
}
},
responsive: true,
legend: {
position: 'top',
},
title: {
display: true,
text: 'Chart.js Bar Chart'
},
plugins: {
zoom: {
zoom: {
enabled: true,
mode: 'x',
sensitivity: 0,
speed: 0.1
}
}
}
}
});
};
</script>
</body>

</html>
19 changes: 13 additions & 6 deletions src/plugin.js
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Original file line number Diff line number Diff line change
Expand Up @@ -120,30 +120,36 @@ function zoomCategoryScale(scale, zoom, center, zoomOptions) {
var sensitivity = zoomOptions.sensitivity;
var chartCenter = scale.isHorizontal() ? scale.left + (scale.width / 2) : scale.top + (scale.height / 2);
var centerPointer = scale.isHorizontal() ? center.x : center.y;
var range = maxIndex - minIndex;
var absoluteZoom = Math.abs(1 - zoom);

zoomNS.zoomCumulativeDelta = zoom > 1 ? zoomNS.zoomCumulativeDelta + 1 : zoomNS.zoomCumulativeDelta - 1;

if (Math.abs(zoomNS.zoomCumulativeDelta) > sensitivity) {
if (zoomNS.zoomCumulativeDelta < 0) {
// Zoom out
if (centerPointer >= chartCenter) {
if (minIndex <= 0) {
maxIndex = Math.min(lastLabelIndex, maxIndex + 1);
// We've already zoomed all the way out to the right
maxIndex = Math.min(lastLabelIndex, Math.floor(maxIndex + range * absoluteZoom));
} else {
minIndex = Math.max(0, minIndex - 1);
minIndex = Math.max(0, Math.floor(minIndex - range * absoluteZoom));
}
} else if (centerPointer < chartCenter) {
if (maxIndex >= lastLabelIndex) {
minIndex = Math.max(0, minIndex - 1);
minIndex = Math.max(0, Math.floor(minIndex - range * absoluteZoom));
} else {
maxIndex = Math.min(lastLabelIndex, maxIndex + 1);
// We've already zoomed all the way out to the left
maxIndex = Math.min(lastLabelIndex, Math.floor(maxIndex + range * absoluteZoom));
}
}
zoomNS.zoomCumulativeDelta = 0;
} else if (zoomNS.zoomCumulativeDelta > 0) {
// Zoom in
if (centerPointer >= chartCenter) {
minIndex = minIndex < maxIndex ? minIndex = Math.min(maxIndex, minIndex + 1) : minIndex;
minIndex = minIndex < maxIndex ? Math.min(maxIndex, Math.floor(minIndex + range * absoluteZoom)) : minIndex;
} else if (centerPointer < chartCenter) {
maxIndex = maxIndex > minIndex ? maxIndex = Math.max(minIndex, maxIndex - 1) : maxIndex;
maxIndex = maxIndex > minIndex ? Math.max(minIndex, Math.floor(maxIndex - range * absoluteZoom)) : maxIndex;
}
zoomNS.zoomCumulativeDelta = 0;
}
Expand Down Expand Up @@ -537,6 +543,7 @@ var zoomPlugin = {
speedPercent = -speedPercent;
}
doZoom(chartInstance, 1 + speedPercent, 1 + speedPercent, center);
// doZoom(chartInstance, speedPercent, speedPercent, center);

clearTimeout(_scrollTimeout);
_scrollTimeout = setTimeout(function() {
Expand Down