Improve Gradient Model Identity Check

[victoreronmosele]

Improvements

The logic for determining an AbstractGradient's identity has some improvements that can be made:

1. Add Gradient Direction To AbstractGradient's Identity Check

The GradientDirection is not considered part of the AbstractGradient's identity check.

The only properties checked are:

1. the widget string,
2. the gradient style and
3. the flutter gradient object.

This leads to specifying the gradient direction separately from the gradient object when selecting rebuild triggers for the PreviewSection. See #80 (comment).

LinearStyleGradient

flutter_gradient_generator/lib/models/linear_style_gradient.dart

Lines 83 to 94 in f725587

	@override
	bool operator ==(Object other) =>
	identical(this, other) ||
	other is LinearStyleGradient &&
	runtimeType == other.runtimeType &&
	toWidgetString() == other.toWidgetString() &&
	getGradientStyle() == other.getGradientStyle() &&
	toFlutterGradient() == other.toFlutterGradient();
	@override
	int get hashCode => hash3(toWidgetString().hashCode,
	getGradientStyle().hashCode, toFlutterGradient().hashCode);

2. Reuse Identity Check Logic

The logic for the identity check is duplicated across LinearStyleGradient, RadialStyleGradient, and SweepStyleGradient.

The logic can be centralized in the AbstractGradient class.

This will improve maintainability, especially as other gradient styles will be introduced.

LinearStyleGradient:

flutter_gradient_generator/lib/models/linear_style_gradient.dart

Lines 83 to 94 in f725587

	@override
	bool operator ==(Object other) =>
	identical(this, other) ||
	other is LinearStyleGradient &&
	runtimeType == other.runtimeType &&
	toWidgetString() == other.toWidgetString() &&
	getGradientStyle() == other.getGradientStyle() &&
	toFlutterGradient() == other.toFlutterGradient();
	@override
	int get hashCode => hash3(toWidgetString().hashCode,
	getGradientStyle().hashCode, toFlutterGradient().hashCode);

RadialStyleGradient:

flutter_gradient_generator/lib/models/radial_style_gradient.dart

Lines 67 to 78 in f725587

	@override
	bool operator ==(Object other) =>
	identical(this, other) ||
	other is RadialStyleGradient &&
	runtimeType == other.runtimeType &&
	toWidgetString() == other.toWidgetString() &&
	getGradientStyle() == other.getGradientStyle() &&
	toFlutterGradient() == other.toFlutterGradient();
	@override
	int get hashCode => hash3(toWidgetString().hashCode,
	getGradientStyle().hashCode, toFlutterGradient().hashCode);

SweepStyleGradient:

flutter_gradient_generator/lib/models/sweep_style_gradient.dart

Lines 69 to 80 in f725587

	@override
	bool operator ==(Object other) =>
	identical(this, other) ||
	other is SweepStyleGradient &&
	runtimeType == other.runtimeType &&
	toWidgetString() == other.toWidgetString() &&
	getGradientStyle() == other.getGradientStyle() &&
	toFlutterGradient() == other.toFlutterGradient();
	@override
	int get hashCode => hash3(toWidgetString().hashCode,
	getGradientStyle().hashCode, toFlutterGradient().hashCode);