Add fetch-data example (#558)

Author: kurkle

docs/.vuepress/config.js

@@ -23,7 +23,7 @@ module.exports = {
       {
         entryPoints: ['../../types/index.d.ts'],
         hideInPageTOC: true,
-        tsconfig: '../../tsconfig.json',
+        tsconfig: 'tsconfig.json',
         sidebar: {
           fullNames: true,
           parentCategory: 'API',
@@ -100,6 +100,7 @@ module.exports = {
           ]
         },
         'api',
+        'fetch-data',
         'pan-region',
       ],
     }

docs/samples/fetch-data.md

@@ -0,0 +1,148 @@
+# Fetch data
+
+```js chart-editor
+// <block:data:2>
+const start = new Date().valueOf();
+const end = start + 1000 * 60 * 60 * 24 * 2;
+const allData = [];
+let y = 100;
+for (let x = start; x <= end; x += 1000) {
+  y += 5 - Math.random() * 10;
+  allData.push({x, y});
+}
+
+function fetchData(x1, x2) {
+  const step = Math.max(1, Math.round((x2 - x1) / 100000));
+  const data = [];
+  let i = 0;
+  while (i < allData.length && allData[i].x < x1) {
+    i++;
+  }
+  while (i < allData.length && allData[i].x <= x2) {
+    data.push(allData[i]);
+    i += step;
+  }
+  return data;
+}
+// </block:data>
+
+// <block:fetch:1>
+let timer;
+function startFetch({chart}) {
+  const {min, max} = chart.scales.x;
+  clearTimeout(timer);
+  timer = setTimeout(() => {
+    console.log('Fetched data between ' + min + ' and ' + max);
+    chart.data.datasets[0].data = fetchData(min, max);
+    chart.stop(); // make sure animations are not running
+    chart.update('none');
+  }, 500);
+}
+// </block:fetch>
+
+// <block:scales:3>
+const scales = {
+  x: {
+    position: 'bottom',
+    min: start,
+    max: end,
+    type: 'time',
+    ticks: {
+      autoSkip: true,
+      autoSkipPadding: 50,
+      maxRotation: 0
+    },
+    time: {
+      displayFormats: {
+        hour: 'HH:mm',
+        minute: 'HH:mm',
+        second: 'HH:mm:ss'
+      }
+    }
+  },
+  y: {
+    type: 'linear',
+    position: 'left',
+  },
+};
+// </block:scales>
+
+// <block:zoom:0>
+const zoomOptions = {
+  limits: {
+    x: {min: 'original', max: 'original', minRange: 60 * 1000},
+  },
+  pan: {
+    enabled: true,
+    mode: 'x',
+    modifierKey: 'ctrl',
+    onPanComplete: startFetch
+  },
+  zoom: {
+    wheel: {
+      enabled: true,
+    },
+    drag: {
+      enabled: true,
+    },
+    pinch: {
+      enabled: true
+    },
+    mode: 'x',
+    onZoomComplete: startFetch
+  }
+};
+// </block:zoom>
+
+const zoomStatus = (chart) => 'zoom level: ' + chart.getZoomLevel() + '';
+
+// <block:config:1>
+const config = {
+  type: 'line',
+  data: {
+    datasets: [{
+      label: 'My First dataset',
+      borderColor: Utils.randomColor(0.4),
+      backgroundColor: Utils.randomColor(0.1),
+      pointBorderColor: Utils.randomColor(0.7),
+      pointBackgroundColor: Utils.randomColor(0.5),
+      pointBorderWidth: 1,
+      data: fetchData(start, end),
+    }]
+  },
+  options: {
+    scales: scales,
+    plugins: {
+      zoom: zoomOptions,
+      title: {
+        display: true,
+        position: 'bottom',
+        text: (ctx) => zoomStatus(ctx.chart)
+      }
+    },
+    transitions: {
+      zoom: {
+        animation: {
+          duration: 100
+        }
+      }
+    }
+  }
+};
+// </block:config>
+
+const actions = [
+  {
+    name: 'Reset zoom',
+    handler(chart) {
+      chart.resetZoom('zoom');
+    }
+  }
+];
+
+module.exports = {
+  actions,
+  config,
+  output: 'console.log output'
+};
+```