[PR fluttercandies#27 feature] Repaint when the last candle changed

Author: Zack-GL

lib/src/candle_data.dart

@@ -71,6 +71,29 @@ class CandleData {
     return result;
   }
 
+  @override
+  bool operator ==(Object other) =>
+      identical(this, other) ||
+      other is CandleData &&
+          runtimeType == other.runtimeType &&
+          timestamp == other.timestamp &&
+          open == other.open &&
+          high == other.high &&
+          low == other.low &&
+          close == other.close &&
+          volume == other.volume &&
+          trends == other.trends;
+
+  @override
+  int get hashCode =>
+      timestamp.hashCode ^
+      open.hashCode ^
+      high.hashCode ^
+      low.hashCode ^
+      close.hashCode ^
+      volume.hashCode ^
+      trends.hashCode;
+
   @override
   String toString() => "<CandleData ($timestamp: $close)>";
 }

lib/src/chart_painter.dart

@@ -27,6 +27,8 @@ class ChartPainter extends CustomPainter {
     // Draw time labels (dates) & price labels
     _drawTimeLabels(canvas, params);
     _drawPriceGridAndLabels(canvas, params);
+    _drawCurrentPriceLabel(canvas, params);
+    _drawCurrentPriceLine(canvas, params);
 
     // Draw prices, volumes & trend line
     canvas.save();
@@ -107,6 +109,65 @@ class ChartPainter extends CustomPainter {
     });
   }
 
+  void _drawCurrentPriceLabel(
+    Canvas canvas,
+    PainterParams params,
+  ) {
+    final currentPrice = params.currentPrice;
+    if (currentPrice == null) {
+      return;
+    }
+    final priceTp = TextPainter(
+      text: TextSpan(
+        text: getPriceLabel(currentPrice),
+        style: params.style.currentPriceStyle.labelStyle,
+      ),
+    )
+      ..textDirection = TextDirection.ltr
+      ..layout();
+
+    final dx = params.chartWidth + 4;
+    final dy =
+        params.fitPrice(currentPrice).clamp(0, params.chartHeight).toDouble() -
+            priceTp.height / 2;
+
+    final padding = params.style.currentPriceStyle.rectPadding;
+    final radius = params.style.currentPriceStyle.rectRadius;
+    final rectColor = params.style.currentPriceStyle.rectColor;
+
+    final rect = Rect.fromLTWH(
+        dx, dy, priceTp.width + 2 * padding, priceTp.height + 2 * padding);
+    final rrect = RRect.fromRectAndRadius(rect, Radius.circular(radius));
+    canvas.drawRRect(rrect, Paint()..color = rectColor);
+
+    priceTp.paint(canvas, Offset(dx + padding, dy + padding));
+  }
+
+  void _drawCurrentPriceLine(Canvas canvas, PainterParams params) {
+    final currentPrice = params.currentPrice;
+    if (currentPrice == null) {
+      return;
+    }
+    final paint = Paint()
+      ..color = Colors.red
+      ..strokeWidth = 1
+      ..style = PaintingStyle.stroke;
+
+    final dashWidth = 4.0;
+    final dashSpace = 2.0;
+    double startX = 0;
+    final clampedPrice =
+        params.fitPrice(currentPrice).clamp(0, params.chartHeight).toDouble();
+    while (startX < params.chartWidth) {
+      canvas.drawLine(
+        Offset(startX, clampedPrice),
+        Offset(startX + dashWidth, clampedPrice),
+        paint,
+      );
+      startX += dashWidth + dashSpace;
+    }
+  }
+
   void _drawSingleDay(canvas, PainterParams params, int i) {
     final candle = params.candles[i];
     final x = i * params.candleWidth;

lib/src/chart_style.dart

@@ -54,6 +54,9 @@ class ChartStyle {
   /// This appears when user clicks on the chart.
   final Color overlayBackgroundColor;
 
+  /// The style of current price labels (on the right of the chart).
+  final CurrentPriceStyle currentPriceStyle;
+
   const ChartStyle({
     this.volumeHeightFactor = 0.2,
     this.priceLabelWidth = 48.0,
@@ -77,5 +80,34 @@ class ChartStyle {
     this.priceGridLineColor = Colors.grey,
     this.selectionHighlightColor = const Color(0x33757575),
     this.overlayBackgroundColor = const Color(0xEE757575),
+    this.currentPriceStyle = const CurrentPriceStyle(
+        labelStyle: TextStyle(
+          fontSize: 12,
+          color: Colors.white,
+        ),
+        rectPadding: 4.0,
+        rectRadius: 2.0,
+        rectColor: Colors.red),
+  });
+}
+
+class CurrentPriceStyle {
+  const CurrentPriceStyle({
+    required this.labelStyle,
+    required this.rectPadding,
+    required this.rectRadius,
+    required this.rectColor,
   });
+
+  /// The style of current price labels (on the right of the chart).
+  final TextStyle labelStyle;
+
+  /// The padding around the current price rect.
+  final double rectPadding;
+
+  /// The radius of the current price rect.
+  final double rectRadius;
+
+  /// The color of the current price rect.
+  final Color rectColor;
 }

lib/src/interactive_chart.dart

@@ -66,6 +66,9 @@ class InteractiveChart extends StatefulWidget {
   /// Provides X-axis offset details.
   final ValueChanged<XAxisOffsetDetails>? onXOffsetChanged;
 
+  /// The current price to be displayed on the right side of the chart.
+  final double? currentPrice;
+
   const InteractiveChart({
     Key? key,
     required this.candles,
@@ -76,6 +79,7 @@ class InteractiveChart extends StatefulWidget {
     this.overlayInfo,
     this.onTap,
     this.onCandleResize,
+    this.currentPrice,
     this.onXOffsetChanged,
   })  : this.style = style ?? const ChartStyle(),
         assert(candles.length >= 3,
@@ -192,6 +196,7 @@ class _InteractiveChartState extends State<InteractiveChart> {
               tapPosition: _tapPosition,
               leadingTrends: leadingTrends,
               trailingTrends: trailingTrends,
+              currentPrice: widget.currentPrice,
             ),
           ),
           duration: Duration(milliseconds: 300),

lib/src/painter_params.dart

@@ -1,11 +1,13 @@
 import 'dart:ui';
+
 import 'package:flutter/widgets.dart';
 
-import 'chart_style.dart';
 import 'candle_data.dart';
+import 'chart_style.dart';
 
 class PainterParams {
   final List<CandleData> candles;
+  final double? currentPrice;
   final ChartStyle style;
   final Size size;
   final double candleWidth;
@@ -23,6 +25,7 @@ class PainterParams {
 
   PainterParams({
     required this.candles,
+    this.currentPrice,
     required this.style,
     required this.size,
     required this.candleWidth,
@@ -97,12 +100,16 @@ class PainterParams {
       tapPosition: b.tapPosition,
       leadingTrends: b.leadingTrends,
       trailingTrends: b.trailingTrends,
+      currentPrice:
+          b.currentPrice != null ? lerpField((p) => p.currentPrice!) : null,
     );
   }
 
   bool shouldRepaint(PainterParams other) {
     if (candles.length != other.candles.length) return true;
 
+    if (other.currentPrice != currentPrice) return true;
+
     if (size != other.size ||
         candleWidth != other.candleWidth ||
         startOffset != other.startOffset ||