From 1efe370101ca1d3e9597ce7a328b08b59fffb29c Mon Sep 17 00:00:00 2001
From: Nico-DF <difalco.nicola@gmail.com>
Date: Mon, 12 Apr 2021 08:50:44 +0200
Subject: [PATCH 1/4] Setting correct decimated values when below threshold

---
 src/plugins/plugin.decimation.js | 13 +++++++------
 1 file changed, 7 insertions(+), 6 deletions(-)

diff --git a/src/plugins/plugin.decimation.js b/src/plugins/plugin.decimation.js
index f9bada37d24..2a31ebd7021 100644
--- a/src/plugins/plugin.decimation.js
+++ b/src/plugins/plugin.decimation.js
@@ -229,12 +229,6 @@ export default {
         return;
       }
 
-      let {start, count} = getStartAndCountOfVisiblePointsSimplified(meta, data);
-      if (count <= 4 * availableWidth) {
-        // No decimation is required until we are above this threshold
-        return;
-      }
-
       if (isNullOrUndef(_data)) {
         // First time we are seeing this dataset
         // We override the 'data' property with a setter that stores the
@@ -253,6 +247,13 @@ export default {
         });
       }
 
+      let {start, count} = getStartAndCountOfVisiblePointsSimplified(meta, data);
+      if (count <= 4 * availableWidth) {
+        // No decimation is required until we are above this threshold
+        dataset._decimated = data.slice(start, start + count);
+        return;
+      }
+
       // Point the chart to the decimated data
       let decimated;
       switch (options.algorithm) {

From 0f94e815153334e9e17803b93c64e71516810f1e Mon Sep 17 00:00:00 2001
From: Nico-DF <difalco.nicola@gmail.com>
Date: Mon, 12 Apr 2021 09:52:52 +0200
Subject: [PATCH 2/4] Using existing function for cleaning decimated data

---
 src/plugins/plugin.decimation.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/plugins/plugin.decimation.js b/src/plugins/plugin.decimation.js
index 2a31ebd7021..c359b2aac79 100644
--- a/src/plugins/plugin.decimation.js
+++ b/src/plugins/plugin.decimation.js
@@ -250,7 +250,7 @@ export default {
       let {start, count} = getStartAndCountOfVisiblePointsSimplified(meta, data);
       if (count <= 4 * availableWidth) {
         // No decimation is required until we are above this threshold
-        dataset._decimated = data.slice(start, start + count);
+        cleanDecimatedData(chart);
         return;
       }
 

From 5b3f260d02b01ff4fc103809006cb33568989472 Mon Sep 17 00:00:00 2001
From: Nico-DF <difalco.nicola@gmail.com>
Date: Mon, 12 Apr 2021 10:15:15 +0200
Subject: [PATCH 3/4] Cleaning decimated only on current dataset

---
 src/plugins/plugin.decimation.js | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/src/plugins/plugin.decimation.js b/src/plugins/plugin.decimation.js
index c359b2aac79..d5dce1a739d 100644
--- a/src/plugins/plugin.decimation.js
+++ b/src/plugins/plugin.decimation.js
@@ -153,14 +153,18 @@ function minMaxDecimation(data, start, count, availableWidth) {
   return decimated;
 }
 
+function cleanDecimatedDataset(dataset) {
+  if (dataset._decimated) {
+    const data = dataset._data;
+    delete dataset._decimated;
+    delete dataset._data;
+    Object.defineProperty(dataset, 'data', {value: data});
+  }
+}
+
 function cleanDecimatedData(chart) {
   chart.data.datasets.forEach((dataset) => {
-    if (dataset._decimated) {
-      const data = dataset._data;
-      delete dataset._decimated;
-      delete dataset._data;
-      Object.defineProperty(dataset, 'data', {value: data});
-    }
+    cleanDecimatedDataset(dataset);
   });
 }
 
@@ -250,7 +254,7 @@ export default {
       let {start, count} = getStartAndCountOfVisiblePointsSimplified(meta, data);
       if (count <= 4 * availableWidth) {
         // No decimation is required until we are above this threshold
-        cleanDecimatedData(chart);
+        cleanDecimatedDataset(dataset);
         return;
       }
 

From 4bd7e8776c5cfe31540678337637e3f8472cd8ce Mon Sep 17 00:00:00 2001
From: Nico-DF <difalco.nicola@gmail.com>
Date: Mon, 12 Apr 2021 10:44:18 +0200
Subject: [PATCH 4/4] Reordering decimation clean to avoid allocation

---
 src/plugins/plugin.decimation.js | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/plugins/plugin.decimation.js b/src/plugins/plugin.decimation.js
index d5dce1a739d..4f1db3661bd 100644
--- a/src/plugins/plugin.decimation.js
+++ b/src/plugins/plugin.decimation.js
@@ -233,6 +233,13 @@ export default {
         return;
       }
 
+      let {start, count} = getStartAndCountOfVisiblePointsSimplified(meta, data);
+      if (count <= 4 * availableWidth) {
+        // No decimation is required until we are above this threshold
+        cleanDecimatedDataset(dataset);
+        return;
+      }
+
       if (isNullOrUndef(_data)) {
         // First time we are seeing this dataset
         // We override the 'data' property with a setter that stores the
@@ -251,13 +258,6 @@ export default {
         });
       }
 
-      let {start, count} = getStartAndCountOfVisiblePointsSimplified(meta, data);
-      if (count <= 4 * availableWidth) {
-        // No decimation is required until we are above this threshold
-        cleanDecimatedDataset(dataset);
-        return;
-      }
-
       // Point the chart to the decimated data
       let decimated;
       switch (options.algorithm) {