feat: enhanced line chart curve function

CHANGELOG.md

@@ -1,5 +1,51 @@
-## newVersion
+## 1.2.0
 * **BUGFIX** (by @imaNNeo) Consider the `enabled` property in [LineTouchData](https://github.com/imaNNeo/fl_chart/blob/main/repo_files/documentations/line_chart.md#linetouchdata-read-about-touch-handling), [BarTouchData](https://github.com/imaNNeo/fl_chart/blob/main/repo_files/documentations/bar_chart.md#bartouchdata-read-about-touch-handling), [PieTouchData](https://github.com/imaNNeo/fl_chart/blob/main/repo_files/documentations/pie_chart.md#pietouchdata-read-about-touch-handling), [ScatterTouchData](https://github.com/imaNNeo/fl_chart/blob/main/repo_files/documentations/scatter_chart.md#scattertouchdata-read-about-touch-handling), [RadarTouchData](https://github.com/imaNNeo/fl_chart/blob/main/repo_files/documentations/radar_chart.md#radartouchdata-read-about-touch-handling) and [CandlestickTouchData](https://github.com/imaNNeo/fl_chart/blob/main/repo_files/documentations/candlestick_chart.md#candlesticktouchdata-read-about-touch-handling), #1676
+* **BREAKING** ⚠️ (by @huanghui1998hhh) Enhanced line chart curve function with a new extensible curve system. Introduced `LineChartCurve` abstract class. You can implement your own curve or use built-in curve: `LineChartCubicTensionCurve`(old curve implementation), and `LineChartCubicMonotoneCurve`.
+**Migration Guide:**
+
+Old API (deprecated):
+```dart
+LineChartBarData(
+  spots: spots,
+  isCurved: true,
+  curveSmoothness: 0.35,
+  preventCurveOverShooting: true,
+  preventCurveOvershootingThreshold: 10.0,
+)
+```
+
+New API:
+```dart
+LineChartBarData(
+  spots: spots,
+  curve: LineChartCurve.cubicTension( // or use LineChartCubicTensionCurve()
+    smoothness: 0.35,
+    preventCurveOverShooting: true,
+    preventCurveOvershootingThreshold: 10.0,
+  ),
+)
+```
+
+Or use the new monotone curve:
+```dart
+LineChartBarData(
+  spots: spots,
+  curve: LineChartCurve.cubicMonotone( // or use LineChartCubicMonotoneCurve()
+    smooth: 0.5,
+    monotone: SmoothMonotone.x,  // Prevents overshooting along X-axis
+  ),
+)
+```
+
+For straight lines (isCurved: false):
+```dart
+LineChartBarData(
+  spots: spots,
+  curve: LineChartCurve.noCurve,  // or omit the curve parameter (default)
+)
+```
+
+Check the updated [LineChart documentation](https://github.com/imaNNeo/fl_chart/blob/main/repo_files/documentations/line_chart.md#linechartcurve) for more details.
 
 ## 1.1.1
 * **IMPROVEMENT** (by @imaNNeo) Upgrade `vector_math` dependency to `2.2.0`, #1985

example/lib/presentation/samples/bar/bar_chart_sample7.dart

@@ -230,7 +230,8 @@ class _IconWidgetState extends AnimatedWidgetBaseState<_IconWidget> {
     final rotation = math.pi * 4 * _rotationTween!.evaluate(animation);
     final scale = 1 + _rotationTween!.evaluate(animation) * 0.5;
     return Transform(
-      transform: Matrix4.rotationZ(rotation).scaledByDouble(scale, scale, scale, 1.0),
+      transform:
+          Matrix4.rotationZ(rotation).scaledByDouble(scale, scale, scale, 1.0),
       origin: const Offset(14, 14),
       child: Icon(
         widget.isSelected ? Icons.face_retouching_natural : Icons.face,

example/lib/presentation/samples/line/line_chart_sample1.dart

@@ -163,7 +163,7 @@ class _LineChart extends StatelessWidget {
       );
 
   LineChartBarData get lineChartBarData1_1 => LineChartBarData(
-        isCurved: true,
+        curve: const LineChartCubicTensionCurve(),
         color: AppColors.contentColorGreen,
         barWidth: 8,
         isStrokeCapRound: true,
@@ -181,7 +181,7 @@ class _LineChart extends StatelessWidget {
       );
 
   LineChartBarData get lineChartBarData1_2 => LineChartBarData(
-        isCurved: true,
+        curve: const LineChartCubicTensionCurve(),
         color: AppColors.contentColorPink,
         barWidth: 8,
         isStrokeCapRound: true,
@@ -201,7 +201,7 @@ class _LineChart extends StatelessWidget {
       );
 
   LineChartBarData get lineChartBarData1_3 => LineChartBarData(
-        isCurved: true,
+        curve: const LineChartCubicMonotoneCurve(),
         color: AppColors.contentColorCyan,
         barWidth: 8,
         isStrokeCapRound: true,
@@ -217,8 +217,7 @@ class _LineChart extends StatelessWidget {
       );
 
   LineChartBarData get lineChartBarData2_1 => LineChartBarData(
-        isCurved: true,
-        curveSmoothness: 0,
+        curve: LineChartCurve.noCurve,
         color: AppColors.contentColorGreen.withValues(alpha: 0.5),
         barWidth: 4,
         isStrokeCapRound: true,
@@ -236,7 +235,7 @@ class _LineChart extends StatelessWidget {
       );
 
   LineChartBarData get lineChartBarData2_2 => LineChartBarData(
-        isCurved: true,
+        curve: const LineChartCubicTensionCurve(),
         color: AppColors.contentColorPink.withValues(alpha: 0.5),
         barWidth: 4,
         isStrokeCapRound: true,
@@ -256,8 +255,7 @@ class _LineChart extends StatelessWidget {
       );
 
   LineChartBarData get lineChartBarData2_3 => LineChartBarData(
-        isCurved: true,
-        curveSmoothness: 0,
+        curve: LineChartCurve.noCurve,
         color: AppColors.contentColorCyan.withValues(alpha: 0.5),
         barWidth: 2,
         isStrokeCapRound: true,

example/lib/presentation/samples/line/line_chart_sample10.dart

@@ -119,7 +119,7 @@ class _LineChartSample10State extends State<LineChartSample10> {
         stops: const [0.1, 1.0],
       ),
       barWidth: 4,
-      isCurved: false,
+      curve: LineChartCurve.noCurve,
     );
   }
 
@@ -134,7 +134,7 @@ class _LineChartSample10State extends State<LineChartSample10> {
         stops: const [0.1, 1.0],
       ),
       barWidth: 4,
-      isCurved: false,
+      curve: LineChartCurve.noCurve,
     );
   }
 

example/lib/presentation/samples/line/line_chart_sample13.dart

@@ -172,7 +172,7 @@ class _LineChartSample13State extends State<LineChartSample13> {
                               ),
                             );
                           }).toList(),
-                          isCurved: false,
+                          curve: LineChartCurve.noCurve,
                           dotData: const FlDotData(show: false),
                           color: AppColors.contentColorBlue,
                           barWidth: 1,

example/lib/presentation/samples/line/line_chart_sample2.dart

@@ -155,7 +155,7 @@ class _LineChartSample2State extends State<LineChartSample2> {
             FlSpot(9.5, 3),
             FlSpot(11, 4),
           ],
-          isCurved: true,
+          curve: const LineChartCubicTensionCurve(),
           gradient: LinearGradient(
             colors: gradientColors,
           ),
@@ -242,7 +242,7 @@ class _LineChartSample2State extends State<LineChartSample2> {
             FlSpot(9.5, 3.44),
             FlSpot(11, 3.44),
           ],
-          isCurved: true,
+          curve: const LineChartCubicTensionCurve(),
           gradient: LinearGradient(
             colors: [
               ColorTween(begin: gradientColors[0], end: gradientColors[1])

example/lib/presentation/samples/line/line_chart_sample3.dart

@@ -283,7 +283,7 @@ class _LineChartSample3State extends State<LineChartSample3> {
                     spots: widget.yValues.asMap().entries.map((e) {
                       return FlSpot(e.key.toDouble(), e.value);
                     }).toList(),
-                    isCurved: false,
+                    curve: LineChartCurve.noCurve,
                     barWidth: 4,
                     color: widget.lineColor,
                     belowBarData: BarAreaData(

example/lib/presentation/samples/line/line_chart_sample4.dart

@@ -93,7 +93,7 @@ class LineChartSample4 extends StatelessWidget {
                   FlSpot(10, 6),
                   FlSpot(11, 7),
                 ],
-                isCurved: true,
+                curve: const LineChartCubicTensionCurve(),
                 barWidth: 8,
                 color: mainLineColor,
                 belowBarData: BarAreaData(

example/lib/presentation/samples/line/line_chart_sample5.dart

@@ -68,7 +68,7 @@ class _LineChartSample5State extends State<LineChartSample5> {
       LineChartBarData(
         showingIndicators: showingTooltipOnSpots,
         spots: allSpots,
-        isCurved: true,
+        curve: const LineChartCubicTensionCurve(),
         barWidth: 4,
         shadow: const Shadow(
           blurRadius: 8,

example/lib/presentation/samples/line/line_chart_sample6.dart

@@ -165,7 +165,7 @@ class LineChartSample6 extends StatelessWidget {
                   ],
                 ),
                 spots: reverseSpots(spots, minSpotY, maxSpotY),
-                isCurved: true,
+                curve: const LineChartCubicTensionCurve(),
                 isStrokeCapRound: true,
                 barWidth: 10,
                 belowBarData: BarAreaData(
@@ -195,7 +195,7 @@ class LineChartSample6 extends StatelessWidget {
                   ],
                 ),
                 spots: reverseSpots(spots2, minSpotY, maxSpotY),
-                isCurved: true,
+                curve: const LineChartCubicTensionCurve(),
                 isStrokeCapRound: true,
                 barWidth: 10,
                 belowBarData: BarAreaData(

example/lib/presentation/samples/line/line_chart_sample7.dart

@@ -87,7 +87,7 @@ class LineChartSample7 extends StatelessWidget {
                   FlSpot(10, 6),
                   FlSpot(11, 7),
                 ],
-                isCurved: true,
+                curve: const LineChartCubicTensionCurve(),
                 barWidth: 2,
                 color: line1Color,
                 dotData: const FlDotData(
@@ -109,7 +109,7 @@ class LineChartSample7 extends StatelessWidget {
                   FlSpot(10, 1),
                   FlSpot(11, 3),
                 ],
-                isCurved: false,
+                curve: LineChartCurve.noCurve,
                 barWidth: 2,
                 color: line2Color,
                 dotData: const FlDotData(

example/lib/presentation/samples/line/line_chart_sample8.dart

@@ -277,7 +277,7 @@ class _LineChartSample8State extends State<LineChartSample8> {
             FlSpot(11, 2.5),
           ],
           dashArray: [10, 6],
-          isCurved: true,
+          curve: const LineChartCubicTensionCurve(),
           color: AppColors.contentColorRed,
           barWidth: 4,
           isStrokeCapRound: true,

example/lib/presentation/samples/line/line_chart_sample9.dart

@@ -82,7 +82,7 @@ class LineChartSample9 extends StatelessWidget {
                   LineChartBarData(
                     color: AppColors.contentColorPink,
                     spots: spots,
-                    isCurved: true,
+                    curve: const LineChartCubicTensionCurve(),
                     isStrokeCapRound: true,
                     barWidth: 3,
                     belowBarData: BarAreaData(

lib/fl_chart.dart

@@ -9,6 +9,7 @@ export 'src/chart/base/base_chart/fl_touch_event.dart';
 export 'src/chart/candlestick_chart/candlestick_chart.dart';
 export 'src/chart/candlestick_chart/candlestick_chart_data.dart';
 export 'src/chart/line_chart/line_chart.dart';
+export 'src/chart/line_chart/line_chart_curve.dart';
 export 'src/chart/line_chart/line_chart_data.dart';
 export 'src/chart/pie_chart/pie_chart.dart';
 export 'src/chart/pie_chart/pie_chart_data.dart';