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Add 'onXOffsetChanged' event #25

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Add 'onXOffsetChanged' event #25

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17 changes: 16 additions & 1 deletion lib/src/interactive_chart.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@ import 'dart:math';

import 'package:flutter/gestures.dart';
import 'package:flutter/widgets.dart';
import 'package:interactive_chart/src/x_axis_offset_details.dart';
import 'package:intl/intl.dart' as intl;

import 'candle_data.dart';
Expand Down Expand Up @@ -60,6 +61,11 @@ class InteractiveChart extends StatefulWidget {
/// This provides the width of a candlestick at the current zoom level.
final ValueChanged<double>? onCandleResize;

/// Optional event fired when the user moves the chart along the X axis.
///
/// Provides X-axis offset details.
final ValueChanged<XAxisOffsetDetails>? onXOffsetChanged;

const InteractiveChart({
Key? key,
required this.candles,
Expand All @@ -70,6 +76,7 @@ class InteractiveChart extends StatefulWidget {
this.overlayInfo,
this.onTap,
this.onCandleResize,
this.onXOffsetChanged,
}) : this.style = style ?? const ChartStyle(),
assert(candles.length >= 3,
"InteractiveChart requires 3 or more CandleData"),
Expand Down Expand Up @@ -252,7 +259,8 @@ class _InteractiveChartState extends State<InteractiveChart> {
final zoomAdjustment = (currCount - prevCount) * candleWidth;
final focalPointFactor = focalPoint.dx / w;
startOffset -= zoomAdjustment * focalPointFactor;
startOffset = startOffset.clamp(0, _getMaxStartOffset(w, candleWidth));
final maxStartOffset = _getMaxStartOffset(w, candleWidth);
startOffset = startOffset.clamp(0, maxStartOffset);
// Fire candle width resize event
if (candleWidth != _candleWidth) {
widget.onCandleResize?.call(candleWidth);
Expand All @@ -262,6 +270,13 @@ class _InteractiveChartState extends State<InteractiveChart> {
_candleWidth = candleWidth;
_startOffset = startOffset;
});

if (_prevStartOffset != startOffset) {
widget.onXOffsetChanged?.call(XAxisOffsetDetails(
offset: startOffset,
maxOffset: maxStartOffset,
));
}
}

_handleResize(double w) {
Expand Down
25 changes: 25 additions & 0 deletions lib/src/x_axis_offset_details.dart
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Original file line number Diff line number Diff line change
@@ -0,0 +1,25 @@
class XAxisOffsetDetails {
XAxisOffsetDetails({
required this.offset,
required this.maxOffset,
});

final double offset;
final double maxOffset;

@override
bool operator ==(Object other) =>
identical(this, other) ||
other is XAxisOffsetDetails &&
runtimeType == other.runtimeType &&
offset == other.offset &&
maxOffset == other.maxOffset;

@override
int get hashCode => offset.hashCode ^ maxOffset.hashCode;

@override
String toString() {
return 'XAxisOffsetDetails{offset: $offset, maxOffset: $maxOffset}';
}
}