minimum bar length setting keeps bar base in view (#10157)

src/controllers/controller.bar.js

@@ -543,6 +543,11 @@ export default class BarController extends DatasetController {
       if (value === actualBase) {
         base -= size / 2;
       }
+      const startPixel = vScale.getPixelForDecimal(0);
+      const endPixel = vScale.getPixelForDecimal(1);
+      const min = Math.min(startPixel, endPixel);
+      const max = Math.max(startPixel, endPixel);
+      base = Math.max(Math.min(base, max), min);
       head = base + size;
     }
 

test/fixtures/controller.bar/minBarLength/horizontal-stacked.js

@@ -0,0 +1,43 @@
+module.exports = {
+  config: {
+    type: 'bar',
+    data: {
+      labels: [0, 1, 2, 3, 4],
+      datasets: [{
+        data: [0, 0.01, 30],
+        backgroundColor: '#00ff00',
+        borderColor: '#000',
+        borderWidth: 4,
+        minBarLength: 20,
+        xAxisID: 'x2',
+      }]
+    },
+    options: {
+      indexAxis: 'y',
+      scales: {
+        x: {
+          stack: 'demo',
+          ticks: {
+            display: false
+          }
+        },
+        x2: {
+          type: 'linear',
+          position: 'bottom',
+          stack: 'demo',
+          stackWeight: 1,
+          ticks: {
+            display: false
+          }
+        },
+        y: {display: false},
+      }
+    }
+  },
+  options: {
+    canvas: {
+      height: 512,
+      width: 512
+    }
+  }
+};

test/fixtures/controller.bar/minBarLength/vertical-stacked.js

@@ -0,0 +1,42 @@
+module.exports = {
+  config: {
+    type: 'bar',
+    data: {
+      labels: [0, 1, 2, 3, 4],
+      datasets: [{
+        data: [0, 0.01, 30],
+        backgroundColor: '#00ff00',
+        borderColor: '#000',
+        borderWidth: 4,
+        minBarLength: 20,
+        yAxisID: 'y2',
+      }]
+    },
+    options: {
+      scales: {
+        x: {display: false},
+        y: {
+          stack: 'demo',
+          ticks: {
+            display: false
+          }
+        },
+        y2: {
+          type: 'linear',
+          position: 'left',
+          stack: 'demo',
+          stackWeight: 1,
+          ticks: {
+            display: false
+          }
+        }
+      }
+    }
+  },
+  options: {
+    canvas: {
+      height: 512,
+      width: 512
+    }
+  }
+};