// Copyright 2014 The Flutter 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 'package:flutter/painting.dart'; // Based on https://material.io/design/environment/elevation.html // Currently, only the elevation values that are bound to one or more widgets are // defined here. /// Map of elevation offsets used by Material Design to [BoxShadow] definitions. /// /// The following elevations have defined shadows: 1, 2, 3, 4, 6, 8, 9, 12, 16, 24. /// /// Each entry has three shadows which must be combined to obtain the defined /// effect for that elevation. /// /// This is useful when simulating a shadow with a [BoxDecoration] or other /// class that uses a list of [BoxShadow] objects. /// /// See also: /// /// * [Material], which takes an arbitrary double for its elevation and generates /// a shadow dynamically. /// * <https://material.io/design/environment/elevation.html> const Map<int, List<BoxShadow>> kElevationToShadow = _elevationToShadow; // to hide the literal from the docs const Color _kKeyUmbraOpacity = Color(0x33000000); // alpha = 0.2 const Color _kKeyPenumbraOpacity = Color(0x24000000); // alpha = 0.14 const Color _kAmbientShadowOpacity = Color(0x1F000000); // alpha = 0.12 const Map<int, List<BoxShadow>> _elevationToShadow = <int, List<BoxShadow>>{ // The empty list depicts no elevation. 0: <BoxShadow>[], 1: <BoxShadow>[ BoxShadow(offset: Offset(0.0, 2.0), blurRadius: 1.0, spreadRadius: -1.0, color: _kKeyUmbraOpacity), BoxShadow(offset: Offset(0.0, 1.0), blurRadius: 1.0, color: _kKeyPenumbraOpacity), BoxShadow(offset: Offset(0.0, 1.0), blurRadius: 3.0, color: _kAmbientShadowOpacity), ], 2: <BoxShadow>[ BoxShadow(offset: Offset(0.0, 3.0), blurRadius: 1.0, spreadRadius: -2.0, color: _kKeyUmbraOpacity), BoxShadow(offset: Offset(0.0, 2.0), blurRadius: 2.0, color: _kKeyPenumbraOpacity), BoxShadow(offset: Offset(0.0, 1.0), blurRadius: 5.0, color: _kAmbientShadowOpacity), ], 3: <BoxShadow>[ BoxShadow(offset: Offset(0.0, 3.0), blurRadius: 3.0, spreadRadius: -2.0, color: _kKeyUmbraOpacity), BoxShadow(offset: Offset(0.0, 3.0), blurRadius: 4.0, color: _kKeyPenumbraOpacity), BoxShadow(offset: Offset(0.0, 1.0), blurRadius: 8.0, color: _kAmbientShadowOpacity), ], 4: <BoxShadow>[ BoxShadow(offset: Offset(0.0, 2.0), blurRadius: 4.0, spreadRadius: -1.0, color: _kKeyUmbraOpacity), BoxShadow(offset: Offset(0.0, 4.0), blurRadius: 5.0, color: _kKeyPenumbraOpacity), BoxShadow(offset: Offset(0.0, 1.0), blurRadius: 10.0, color: _kAmbientShadowOpacity), ], 6: <BoxShadow>[ BoxShadow(offset: Offset(0.0, 3.0), blurRadius: 5.0, spreadRadius: -1.0, color: _kKeyUmbraOpacity), BoxShadow(offset: Offset(0.0, 6.0), blurRadius: 10.0, color: _kKeyPenumbraOpacity), BoxShadow(offset: Offset(0.0, 1.0), blurRadius: 18.0, color: _kAmbientShadowOpacity), ], 8: <BoxShadow>[ BoxShadow(offset: Offset(0.0, 5.0), blurRadius: 5.0, spreadRadius: -3.0, color: _kKeyUmbraOpacity), BoxShadow(offset: Offset(0.0, 8.0), blurRadius: 10.0, spreadRadius: 1.0, color: _kKeyPenumbraOpacity), BoxShadow(offset: Offset(0.0, 3.0), blurRadius: 14.0, spreadRadius: 2.0, color: _kAmbientShadowOpacity), ], 9: <BoxShadow>[ BoxShadow(offset: Offset(0.0, 5.0), blurRadius: 6.0, spreadRadius: -3.0, color: _kKeyUmbraOpacity), BoxShadow(offset: Offset(0.0, 9.0), blurRadius: 12.0, spreadRadius: 1.0, color: _kKeyPenumbraOpacity), BoxShadow(offset: Offset(0.0, 3.0), blurRadius: 16.0, spreadRadius: 2.0, color: _kAmbientShadowOpacity), ], 12: <BoxShadow>[ BoxShadow(offset: Offset(0.0, 7.0), blurRadius: 8.0, spreadRadius: -4.0, color: _kKeyUmbraOpacity), BoxShadow(offset: Offset(0.0, 12.0), blurRadius: 17.0, spreadRadius: 2.0, color: _kKeyPenumbraOpacity), BoxShadow(offset: Offset(0.0, 5.0), blurRadius: 22.0, spreadRadius: 4.0, color: _kAmbientShadowOpacity), ], 16: <BoxShadow>[ BoxShadow(offset: Offset(0.0, 8.0), blurRadius: 10.0, spreadRadius: -5.0, color: _kKeyUmbraOpacity), BoxShadow(offset: Offset(0.0, 16.0), blurRadius: 24.0, spreadRadius: 2.0, color: _kKeyPenumbraOpacity), BoxShadow(offset: Offset(0.0, 6.0), blurRadius: 30.0, spreadRadius: 5.0, color: _kAmbientShadowOpacity), ], 24: <BoxShadow>[ BoxShadow(offset: Offset(0.0, 11.0), blurRadius: 15.0, spreadRadius: -7.0, color: _kKeyUmbraOpacity), BoxShadow(offset: Offset(0.0, 24.0), blurRadius: 38.0, spreadRadius: 3.0, color: _kKeyPenumbraOpacity), BoxShadow(offset: Offset(0.0, 9.0), blurRadius: 46.0, spreadRadius: 8.0, color: _kAmbientShadowOpacity), ], };