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// Copyright 2015 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
import 'dart:math' as math;
import 'package:flutter/foundation.dart';
import 'package:flutter/rendering.dart';
import 'package:flutter/widgets.dart';
import 'button_theme.dart';
import 'constants.dart';
import 'ink_well.dart';
import 'material.dart';
import 'theme.dart';
import 'theme_data.dart';
/// Creates a button based on [Semantics], [Material], and [InkWell]
/// widgets.
///
/// This class does not use the current [Theme] or [ButtonTheme] to
/// compute default values for unspecified parameters. It's intended to
/// be used for custom Material buttons that optionally incorporate defaults
/// from the themes or from app-specific sources.
///
/// [RaisedButton] and [FlatButton] configure a [RawMaterialButton] based
/// on the current [Theme] and [ButtonTheme].
class RawMaterialButton extends StatefulWidget {
/// Create a button based on [Semantics], [Material], and [InkWell] widgets.
///
/// The [shape], [elevation], [highlightElevation], [disabledElevation],
/// [padding], [constraints], and [clipBehavior] arguments must not be null.
/// Additionally, [elevation], [highlightElevation], and [disabledElevation]
/// must be non-negative.
const RawMaterialButton({
Key key,
@required this.onPressed,
this.onHighlightChanged,
this.textStyle,
this.fillColor,
this.highlightColor,
this.splashColor,
this.elevation = 2.0,
this.highlightElevation = 8.0,
this.disabledElevation = 0.0,
this.padding = EdgeInsets.zero,
this.constraints = const BoxConstraints(minWidth: 88.0, minHeight: 36.0),
this.shape = const RoundedRectangleBorder(),
this.animationDuration = kThemeChangeDuration,
this.clipBehavior = Clip.none,
MaterialTapTargetSize materialTapTargetSize,
this.child,
}) : materialTapTargetSize = materialTapTargetSize ?? MaterialTapTargetSize.padded,
assert(shape != null),
assert(elevation != null && elevation >= 0.0),
assert(highlightElevation != null && highlightElevation >= 0.0),
assert(disabledElevation != null && disabledElevation >= 0.0),
assert(padding != null),
assert(constraints != null),
assert(animationDuration != null),
assert(clipBehavior != null),
super(key: key);
/// Called when the button is tapped or otherwise activated.
///
/// If this is set to null, the button will be disabled, see [enabled].
final VoidCallback onPressed;
/// Called by the underlying [InkWell] widget's [InkWell.onHighlightChanged]
/// callback.
///
/// If [onPressed] changes from null to non-null while a gesture is ongoing,
/// this can fire during the build phase (in which case calling
/// [State.setState] is not allowed).
final ValueChanged<bool> onHighlightChanged;
/// Defines the default text style, with [Material.textStyle], for the
/// button's [child].
final TextStyle textStyle;
/// The color of the button's [Material].
final Color fillColor;
/// The highlight color for the button's [InkWell].
final Color highlightColor;
/// The splash color for the button's [InkWell].
final Color splashColor;
/// The elevation for the button's [Material] when the button
/// is [enabled] but not pressed.
///
/// Defaults to 2.0. The value is always non-negative.
///
/// See also:
///
/// * [highlightElevation], the default elevation.
/// * [disabledElevation], the elevation when the button is disabled.
final double elevation;
/// The elevation for the button's [Material] when the button
/// is [enabled] and pressed.
///
/// Defaults to 8.0. The value is always non-negative.
///
/// See also:
///
/// * [elevation], the default elevation.
/// * [disabledElevation], the elevation when the button is disabled.
final double highlightElevation;
/// The elevation for the button's [Material] when the button
/// is not [enabled].
///
/// Defaults to 0.0. The value is always non-negative.
///
/// See also:
///
/// * [elevation], the default elevation.
/// * [highlightElevation], the elevation when the button is pressed.
final double disabledElevation;
/// The internal padding for the button's [child].
final EdgeInsetsGeometry padding;
/// Defines the button's size.
///
/// Typically used to constrain the button's minimum size.
final BoxConstraints constraints;
/// The shape of the button's [Material].
///
/// The button's highlight and splash are clipped to this shape. If the
/// button has an elevation, then its drop shadow is defined by this shape.
final ShapeBorder shape;
/// Defines the duration of animated changes for [shape] and [elevation].
///
/// The default value is [kThemeChangeDuration].
final Duration animationDuration;
/// Typically the button's label.
final Widget child;
/// Whether the button is enabled or disabled.
///
/// Buttons are disabled by default. To enable a button, set its [onPressed]
/// property to a non-null value.
bool get enabled => onPressed != null;
/// Configures the minimum size of the tap target.
///
/// Defaults to [MaterialTapTargetSize.padded].
///
/// See also:
///
/// * [MaterialTapTargetSize], for a description of how this affects tap targets.
final MaterialTapTargetSize materialTapTargetSize;
/// {@macro flutter.widgets.Clip}
final Clip clipBehavior;
@override
_RawMaterialButtonState createState() => _RawMaterialButtonState();
}
class _RawMaterialButtonState extends State<RawMaterialButton> {
bool _highlight = false;
void _handleHighlightChanged(bool value) {
if (_highlight != value) {
setState(() {
_highlight = value;
if (widget.onHighlightChanged != null)
widget.onHighlightChanged(value);
});
}
}
@override
void didUpdateWidget(RawMaterialButton oldWidget) {
super.didUpdateWidget(oldWidget);
if (_highlight && !widget.enabled) {
_highlight = false;
if (widget.onHighlightChanged != null)
widget.onHighlightChanged(false);
}
}
@override
Widget build(BuildContext context) {
final double elevation = widget.enabled
? (_highlight ? widget.highlightElevation : widget.elevation)
: widget.disabledElevation;
final Widget result = ConstrainedBox(
constraints: widget.constraints,
child: Material(
elevation: elevation,
textStyle: widget.textStyle,
shape: widget.shape,
color: widget.fillColor,
type: widget.fillColor == null ? MaterialType.transparency : MaterialType.button,
animationDuration: widget.animationDuration,
clipBehavior: widget.clipBehavior,
child: InkWell(
onHighlightChanged: _handleHighlightChanged,
splashColor: widget.splashColor,
highlightColor: widget.highlightColor,
onTap: widget.onPressed,
customBorder: widget.shape,
child: IconTheme.merge(
data: IconThemeData(color: widget.textStyle?.color),
child: Container(
padding: widget.padding,
child: Center(
widthFactor: 1.0,
heightFactor: 1.0,
child: widget.child,
),
),
),
),
),
);
Size minSize;
switch (widget.materialTapTargetSize) {
case MaterialTapTargetSize.padded:
minSize = const Size(48.0, 48.0);
break;
case MaterialTapTargetSize.shrinkWrap:
minSize = Size.zero;
break;
}
return Semantics(
container: true,
button: true,
enabled: widget.enabled,
child: _InputPadding(
minSize: minSize,
child: result,
),
);
}
}
/// A widget to pad the area around a [MaterialButton]'s inner [Material].
///
/// Redirect taps that occur in the padded area around the child to the center
/// of the child. This increases the size of the button and the button's
/// "tap target", but not its material or its ink splashes.
class _InputPadding extends SingleChildRenderObjectWidget {
const _InputPadding({
Key key,
Widget child,
this.minSize,
}) : super(key: key, child: child);
final Size minSize;
@override
RenderObject createRenderObject(BuildContext context) {
return _RenderInputPadding(minSize);
}
@override
void updateRenderObject(BuildContext context, covariant _RenderInputPadding renderObject) {
renderObject.minSize = minSize;
}
}
class _RenderInputPadding extends RenderShiftedBox {
_RenderInputPadding(this._minSize, [RenderBox child]) : super(child) ;
Size get minSize => _minSize;
Size _minSize;
set minSize(Size value) {
if (_minSize == value)
return;
_minSize = value;
markNeedsLayout();
}
@override
double computeMinIntrinsicWidth(double height) {
if (child != null)
return math.max(child.getMinIntrinsicWidth(height), minSize.width);
return 0.0;
}
@override
double computeMinIntrinsicHeight(double width) {
if (child != null)
return math.max(child.getMinIntrinsicHeight(width), minSize.height);
return 0.0;
}
@override
double computeMaxIntrinsicWidth(double height) {
if (child != null)
return math.max(child.getMaxIntrinsicWidth(height), minSize.width);
return 0.0;
}
@override
double computeMaxIntrinsicHeight(double width) {
if (child != null)
return math.max(child.getMaxIntrinsicHeight(width), minSize.height);
return 0.0;
}
@override
void performLayout() {
if (child != null) {
child.layout(constraints, parentUsesSize: true);
final double height = math.max(child.size.width, minSize.width);
final double width = math.max(child.size.height, minSize.height);
size = constraints.constrain(Size(height, width));
final BoxParentData childParentData = child.parentData;
childParentData.offset = Alignment.center.alongOffset(size - child.size);
} else {
size = Size.zero;
}
}
@override
bool hitTest(HitTestResult result, { Offset position }) {
return super.hitTest(result, position: position) ||
child.hitTest(result, position: child.size.center(Offset.zero));
}
}