Update example project documentation

Author: h65wang

example/lib/main.dart

@@ -51,25 +51,32 @@ class _MyAppState extends State<MyApp> {
           minimum: const EdgeInsets.all(24.0),
           child: InteractiveChart(
             candles: _data,
-            style: ChartStyle(
-              priceGainColor: Colors.teal[200]!,
-              priceLossColor: Colors.blueGrey,
-              volumeColor: Colors.teal.withOpacity(0.8),
-              trendLineColor: Colors.blueGrey[200]!,
-              priceGridLineColor: Colors.blue[200]!,
-              priceLabelStyle: TextStyle(color: Colors.blue[200]),
-              timeLabelStyle: TextStyle(color: Colors.blue[200]),
-              selectionHighlightColor: Colors.red.withOpacity(0.2),
-              overlayBackgroundColor: Colors.red[900]!.withOpacity(0.6),
-              overlayTextStyle: TextStyle(color: Colors.red[100]),
-              timeLabelHeight: 32,
-            ),
-            overlayInfo: (candle) => {
-              "💎": "🤚    ",
-              "高": "${candle.high?.toStringAsFixed(2)}",
-              "低": "${candle.low?.toStringAsFixed(2)}",
-            },
-            priceLabel: (price) => "${price.round()} 💎",
+            /** Uncomment the following to see more examples */
+            /** Example styling */
+            // style: ChartStyle(
+            //   priceGainColor: Colors.teal[200]!,
+            //   priceLossColor: Colors.blueGrey,
+            //   volumeColor: Colors.teal.withOpacity(0.8),
+            //   trendLineColor: Colors.blueGrey[200]!,
+            //   priceGridLineColor: Colors.blue[200]!,
+            //   priceLabelStyle: TextStyle(color: Colors.blue[200]),
+            //   timeLabelStyle: TextStyle(color: Colors.blue[200]),
+            //   selectionHighlightColor: Colors.red.withOpacity(0.2),
+            //   overlayBackgroundColor: Colors.red[900]!.withOpacity(0.6),
+            //   overlayTextStyle: TextStyle(color: Colors.red[100]),
+            //   timeLabelHeight: 32,
+            // ),
+            /** Customize axis labels */
+            // timeLabel: (timestamp, visibleDataCount) => "📅",
+            // priceLabel: (price) => "${price.round()} 💎",
+            /** Customize overlay (tap and hold to see it)
+             ** Or return a blank object to disable it. */
+            // overlayInfo: (candle) => {
+            //   "💎": "🤚    ",
+            //   "Hi": "${candle.high?.toStringAsFixed(2)}",
+            //   "Lo": "${candle.low?.toStringAsFixed(2)}",
+            // },
+
           ),
         ),
       ),

example/pubspec.lock

@@ -73,7 +73,7 @@ packages:
       path: ".."
       relative: true
     source: path
-    version: "0.0.1"
+    version: "0.2.0"
   intl:
     dependency: transitive
     description:

lib/src/chart_painter.dart

@@ -219,6 +219,7 @@ class ChartPainter extends CustomPainter {
           ..layout();
 
     final info = getOverlayInfo(candle);
+    if (info.isEmpty) return;
     final labels = info.keys.map((text) => makeTP(text)).toList();
     final values = info.values.map((text) => makeTP(text)).toList();