Fix float precision issue in sideTitles, #1473

CHANGELOG.md

@@ -1,5 +1,6 @@
 ## nextVersion
 * **FEATURE** (by @Dartek12): Added gradient to [FlLine](https://github.com/imaNNeo/fl_chart/blob/master/repo_files/documentations/base_chart.md#FlLine), #1197
+* **BUGFIX** (by @imaNNeo): Fix [float precision issue](https://stackoverflow.com/a/57491365/3543738) in sideTitles, #1473
 
 ## 0.64.0
 * **BUGFIX** (by @Anas35) Fix Tooltip not displaying when value from BackgroundBarChartRodData is less than zero. #1345.

example/ios/Podfile.lock

@@ -0,0 +1,29 @@
+PODS:
+  - Flutter (1.0.0)
+  - path_provider_foundation (0.0.1):
+    - Flutter
+    - FlutterMacOS
+  - url_launcher_ios (0.0.1):
+    - Flutter
+
+DEPENDENCIES:
+  - Flutter (from `Flutter`)
+  - path_provider_foundation (from `.symlinks/plugins/path_provider_foundation/darwin`)
+  - url_launcher_ios (from `.symlinks/plugins/url_launcher_ios/ios`)
+
+EXTERNAL SOURCES:
+  Flutter:
+    :path: Flutter
+  path_provider_foundation:
+    :path: ".symlinks/plugins/path_provider_foundation/darwin"
+  url_launcher_ios:
+    :path: ".symlinks/plugins/url_launcher_ios/ios"
+
+SPEC CHECKSUMS:
+  Flutter: f04841e97a9d0b0a8025694d0796dd46242b2854
+  path_provider_foundation: 29f094ae23ebbca9d3d0cec13889cd9060c0e943
+  url_launcher_ios: 08a3dfac5fb39e8759aeb0abbd5d9480f30fc8b4
+
+PODFILE CHECKSUM: ef19549a9bc3046e7bb7d2fab4d021637c0c58a3
+
+COCOAPODS: 1.13.0

example/ios/Runner.xcodeproj/project.pbxproj

@@ -3,12 +3,13 @@
 	archiveVersion = 1;
 	classes = {
 	};
-	objectVersion = 50;
+	objectVersion = 54;
 	objects = {
 
 /* Begin PBXBuildFile section */
 		1498D2341E8E89220040F4C2 /* GeneratedPluginRegistrant.m in Sources */ = {isa = PBXBuildFile; fileRef = 1498D2331E8E89220040F4C2 /* GeneratedPluginRegistrant.m */; };
 		3B3967161E833CAA004F5970 /* AppFrameworkInfo.plist in Resources */ = {isa = PBXBuildFile; fileRef = 3B3967151E833CAA004F5970 /* AppFrameworkInfo.plist */; };
+		5D3F081B63EC9B3A946844DA /* Pods_Runner.framework in Frameworks */ = {isa = PBXBuildFile; fileRef = 06A47E3243ABDE701C1B259D /* Pods_Runner.framework */; };
 		74858FAF1ED2DC5600515810 /* AppDelegate.swift in Sources */ = {isa = PBXBuildFile; fileRef = 74858FAE1ED2DC5600515810 /* AppDelegate.swift */; };
 		97C146FC1CF9000F007C117D /* Main.storyboard in Resources */ = {isa = PBXBuildFile; fileRef = 97C146FA1CF9000F007C117D /* Main.storyboard */; };
 		97C146FE1CF9000F007C117D /* Assets.xcassets in Resources */ = {isa = PBXBuildFile; fileRef = 97C146FD1CF9000F007C117D /* Assets.xcassets */; };
@@ -29,12 +30,16 @@
 /* End PBXCopyFilesBuildPhase section */
 
 /* Begin PBXFileReference section */
+		06A47E3243ABDE701C1B259D /* Pods_Runner.framework */ = {isa = PBXFileReference; explicitFileType = wrapper.framework; includeInIndex = 0; path = Pods_Runner.framework; sourceTree = BUILT_PRODUCTS_DIR; };
 		1498D2321E8E86230040F4C2 /* GeneratedPluginRegistrant.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = GeneratedPluginRegistrant.h; sourceTree = "<group>"; };
 		1498D2331E8E89220040F4C2 /* GeneratedPluginRegistrant.m */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.objc; path = GeneratedPluginRegistrant.m; sourceTree = "<group>"; };
 		3B3967151E833CAA004F5970 /* AppFrameworkInfo.plist */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.plist.xml; name = AppFrameworkInfo.plist; path = Flutter/AppFrameworkInfo.plist; sourceTree = "<group>"; };
+		4F5DA8BD3BF791E081EEB28A /* Pods-Runner.debug.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-Runner.debug.xcconfig"; path = "Target Support Files/Pods-Runner/Pods-Runner.debug.xcconfig"; sourceTree = "<group>"; };
 		74858FAD1ED2DC5600515810 /* Runner-Bridging-Header.h */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.c.h; path = "Runner-Bridging-Header.h"; sourceTree = "<group>"; };
 		74858FAE1ED2DC5600515810 /* AppDelegate.swift */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.swift; path = AppDelegate.swift; sourceTree = "<group>"; };
 		7AFA3C8E1D35360C0083082E /* Release.xcconfig */ = {isa = PBXFileReference; lastKnownFileType = text.xcconfig; name = Release.xcconfig; path = Flutter/Release.xcconfig; sourceTree = "<group>"; };
+		905CD23AF7EB07828B45A749 /* Pods-Runner.release.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-Runner.release.xcconfig"; path = "Target Support Files/Pods-Runner/Pods-Runner.release.xcconfig"; sourceTree = "<group>"; };
+		95C47DA37FAFE0A8C6F9659F /* Pods-Runner.profile.xcconfig */ = {isa = PBXFileReference; includeInIndex = 1; lastKnownFileType = text.xcconfig; name = "Pods-Runner.profile.xcconfig"; path = "Target Support Files/Pods-Runner/Pods-Runner.profile.xcconfig"; sourceTree = "<group>"; };
 		9740EEB21CF90195004384FC /* Debug.xcconfig */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.xcconfig; name = Debug.xcconfig; path = Flutter/Debug.xcconfig; sourceTree = "<group>"; };
 		9740EEB31CF90195004384FC /* Generated.xcconfig */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = text.xcconfig; name = Generated.xcconfig; path = Flutter/Generated.xcconfig; sourceTree = "<group>"; };
 		97C146EE1CF9000F007C117D /* Runner.app */ = {isa = PBXFileReference; explicitFileType = wrapper.application; includeInIndex = 0; path = Runner.app; sourceTree = BUILT_PRODUCTS_DIR; };
@@ -49,12 +54,32 @@
 			isa = PBXFrameworksBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				5D3F081B63EC9B3A946844DA /* Pods_Runner.framework in Frameworks */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};
 /* End PBXFrameworksBuildPhase section */
 
 /* Begin PBXGroup section */
+		3E426055A90FF197987466F2 /* Pods */ = {
+			isa = PBXGroup;
+			children = (
+				4F5DA8BD3BF791E081EEB28A /* Pods-Runner.debug.xcconfig */,
+				905CD23AF7EB07828B45A749 /* Pods-Runner.release.xcconfig */,
+				95C47DA37FAFE0A8C6F9659F /* Pods-Runner.profile.xcconfig */,
+			);
+			name = Pods;
+			path = Pods;
+			sourceTree = "<group>";
+		};
+		7D81FA6B330011F05D782E95 /* Frameworks */ = {
+			isa = PBXGroup;
+			children = (
+				06A47E3243ABDE701C1B259D /* Pods_Runner.framework */,
+			);
+			name = Frameworks;
+			sourceTree = "<group>";
+		};
 		9740EEB11CF90186004384FC /* Flutter */ = {
 			isa = PBXGroup;
 			children = (
@@ -72,6 +97,8 @@
 				9740EEB11CF90186004384FC /* Flutter */,
 				97C146F01CF9000F007C117D /* Runner */,
 				97C146EF1CF9000F007C117D /* Products */,
+				3E426055A90FF197987466F2 /* Pods */,
+				7D81FA6B330011F05D782E95 /* Frameworks */,
 			);
 			sourceTree = "<group>";
 		};
@@ -105,12 +132,14 @@
 			isa = PBXNativeTarget;
 			buildConfigurationList = 97C147051CF9000F007C117D /* Build configuration list for PBXNativeTarget "Runner" */;
 			buildPhases = (
+				181828416FC74716E515F1DE /* [CP] Check Pods Manifest.lock */,
 				9740EEB61CF901F6004384FC /* Run Script */,
 				97C146EA1CF9000F007C117D /* Sources */,
 				97C146EB1CF9000F007C117D /* Frameworks */,
 				97C146EC1CF9000F007C117D /* Resources */,
 				9705A1C41CF9048500538489 /* Embed Frameworks */,
 				3B06AD1E1E4923F5004D2608 /* Thin Binary */,
+				27C90C58091E21A7ACF1CA26 /* [CP] Embed Pods Frameworks */,
 			);
 			buildRules = (
 			);
@@ -127,7 +156,7 @@
 		97C146E61CF9000F007C117D /* Project object */ = {
 			isa = PBXProject;
 			attributes = {
-				LastUpgradeCheck = 1300;
+				LastUpgradeCheck = 1430;
 				ORGANIZATIONNAME = "";
 				TargetAttributes = {
 					97C146ED1CF9000F007C117D = {
@@ -169,12 +198,53 @@
 /* End PBXResourcesBuildPhase section */
 
 /* Begin PBXShellScriptBuildPhase section */
+		181828416FC74716E515F1DE /* [CP] Check Pods Manifest.lock */ = {
+			isa = PBXShellScriptBuildPhase;
+			buildActionMask = 2147483647;
+			files = (
+			);
+			inputFileListPaths = (
+			);
+			inputPaths = (
+				"${PODS_PODFILE_DIR_PATH}/Podfile.lock",
+				"${PODS_ROOT}/Manifest.lock",
+			);
+			name = "[CP] Check Pods Manifest.lock";
+			outputFileListPaths = (
+			);
+			outputPaths = (
+				"$(DERIVED_FILE_DIR)/Pods-Runner-checkManifestLockResult.txt",
+			);
+			runOnlyForDeploymentPostprocessing = 0;
+			shellPath = /bin/sh;
+			shellScript = "diff \"${PODS_PODFILE_DIR_PATH}/Podfile.lock\" \"${PODS_ROOT}/Manifest.lock\" > /dev/null\nif [ $? != 0 ] ; then\n    # print error to STDERR\n    echo \"error: The sandbox is not in sync with the Podfile.lock. Run 'pod install' or update your CocoaPods installation.\" >&2\n    exit 1\nfi\n# This output is used by Xcode 'outputs' to avoid re-running this script phase.\necho \"SUCCESS\" > \"${SCRIPT_OUTPUT_FILE_0}\"\n";
+			showEnvVarsInLog = 0;
+		};
+		27C90C58091E21A7ACF1CA26 /* [CP] Embed Pods Frameworks */ = {
+			isa = PBXShellScriptBuildPhase;
+			buildActionMask = 2147483647;
+			files = (
+			);
+			inputFileListPaths = (
+				"${PODS_ROOT}/Target Support Files/Pods-Runner/Pods-Runner-frameworks-${CONFIGURATION}-input-files.xcfilelist",
+			);
+			name = "[CP] Embed Pods Frameworks";
+			outputFileListPaths = (
+				"${PODS_ROOT}/Target Support Files/Pods-Runner/Pods-Runner-frameworks-${CONFIGURATION}-output-files.xcfilelist",
+			);
+			runOnlyForDeploymentPostprocessing = 0;
+			shellPath = /bin/sh;
+			shellScript = "\"${PODS_ROOT}/Target Support Files/Pods-Runner/Pods-Runner-frameworks.sh\"\n";
+			showEnvVarsInLog = 0;
+		};
 		3B06AD1E1E4923F5004D2608 /* Thin Binary */ = {
 			isa = PBXShellScriptBuildPhase;
+			alwaysOutOfDate = 1;
 			buildActionMask = 2147483647;
 			files = (
 			);
 			inputPaths = (
+				"${TARGET_BUILD_DIR}/${INFOPLIST_PATH}",
 			);
 			name = "Thin Binary";
 			outputPaths = (
@@ -185,6 +255,7 @@
 		};
 		9740EEB61CF901F6004384FC /* Run Script */ = {
 			isa = PBXShellScriptBuildPhase;
+			alwaysOutOfDate = 1;
 			buildActionMask = 2147483647;
 			files = (
 			);

example/ios/Runner.xcodeproj/xcshareddata/xcschemes/Runner.xcscheme

@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <Scheme
-   LastUpgradeVersion = "1300"
+   LastUpgradeVersion = "1430"
    version = "1.3">
    <BuildAction
       parallelizeBuildables = "YES"

lib/src/chart/base/axis_chart/axis_chart_helper.dart

@@ -1,4 +1,7 @@
+import 'dart:math';
+
 import 'package:fl_chart/fl_chart.dart';
+import 'package:fl_chart/src/extensions/double_extension.dart';
 import 'package:fl_chart/src/utils/utils.dart';
 import 'package:flutter/material.dart';
 
@@ -45,15 +48,24 @@ class AxisChartHelper {
     if (minIncluded && !firstPositionOverlapsWithMin) {
       yield min;
     }
+    final intervalPrecision = pow(10, interval.precisionCount).toInt();
     while (axisSeek <= end + epsilon) {
       yield axisSeek;
-      axisSeek += interval;
+      axisSeek = _roundTo(
+        axisSeek + interval,
+        intervalPrecision,
+      );
     }
     if (maxIncluded && !lastPositionOverlapsWithMax) {
       yield max;
     }
   }
 
+  /// Fixes the float precisionIssue
+  /// https://stackoverflow.com/a/57491365/3543738
+  double _roundTo(double value, int precision) =>
+      (value * precision).round() / precision;
+
   /// Calculate translate offset to keep [SideTitle] child
   /// placed inside its corresponding axis.
   /// The offset will translate the child to the closest edge inside

lib/src/extensions/double_extension.dart

@@ -0,0 +1,16 @@
+extension DoubleExtension on double {
+  int get precisionCount {
+    if (this % 1.0 == 0) {
+      return 0;
+    }
+    final str = toString();
+    final eDashIndex = str.indexOf('e-');
+    if (eDashIndex > -1) {
+      final firstPart = str.substring(0, eDashIndex);
+      final firstPartPrecision = double.parse(firstPart).precisionCount;
+      final secondPart = str.substring(eDashIndex + 2);
+      return firstPartPrecision + int.parse(secondPart);
+    }
+    return toString().length - 2;
+  }
+}

lib/src/utils/utils.dart

@@ -1,6 +1,7 @@
 import 'dart:math' as math;
 import 'dart:math';
 
+import 'package:fl_chart/src/extensions/double_extension.dart';
 import 'package:flutter/material.dart';
 
 class Utils {
@@ -162,7 +163,7 @@ class Utils {
     }
 
     final inputString = input.toString();
-    var precisionCount = inputString.length - 2;
+    var precisionCount = input.precisionCount;
 
     var zeroCount = 0;
     for (var i = 2; i <= inputString.length; i++) {

test/chart/base/axis_chart/axis_chart_helper_test.dart

@@ -5,6 +5,20 @@ import 'package:flutter_test/flutter_test.dart';
 void main() {
   const tolerance = 0.0001;
   group('iterateThroughAxis()', () {
+    test('test 0', () {
+      final results = <double>[];
+      final axisValues = AxisChartHelper().iterateThroughAxis(
+        min: 0,
+        max: 0.001,
+        interval: 0.000000001,
+        baseLine: 0,
+      );
+      for (final axisValue in axisValues) {
+        results.add(axisValue);
+      }
+      expect(results.length, 1000001);
+    });
+
     test('test 1', () {
       final results = <double>[];
       final axisValues = AxisChartHelper().iterateThroughAxis(
@@ -76,7 +90,7 @@ void main() {
       expect(results[4], 10);
     });
 
-    test('test 4', () {
+    test('test 5', () {
       final results = <double>[];
       final axisValues = AxisChartHelper().iterateThroughAxis(
         min: 0,
@@ -95,7 +109,7 @@ void main() {
       expect(results[2], 9);
     });
 
-    test('test 4', () {
+    test('test 6', () {
       final results = <double>[];
       final axisValues = AxisChartHelper().iterateThroughAxis(
         min: 35,

test/extensions/double_extension_test.dart

@@ -0,0 +1,21 @@
+import 'package:fl_chart/src/extensions/double_extension.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  test('test double.precision', () {
+    expect(0.0.precisionCount, 0);
+    expect(0.1.precisionCount, 1);
+    expect(0.02.precisionCount, 2);
+    expect(3.000.precisionCount, 0);
+    expect(3.001.precisionCount, 3);
+    expect(0.23232323.precisionCount, 8);
+    expect(0.493234898.precisionCount, 9);
+    expect(0.4932348985.precisionCount, 10);
+    expect(0.0000000005.precisionCount, 10);
+    expect(0.0000000000005.precisionCount, 13);
+    expect(0.0000000000000005.precisionCount, 16);
+    expect(0.00000000000000000005.precisionCount, 20);
+    expect(0.4343828875389984.precisionCount, 16);
+    expect(0.0000000005389984.precisionCount, 16);
+  });
+}