topics intermediate

2024-08-21 13:36:58 +02:00
parent e75052aa99
commit 7fedbe260c
35 changed files with 2511 additions and 198 deletions
@@ -0,0 +1,91 @@
+import 'dart:math';
+
+import 'package:flutter/material.dart';
+
+final _rnd = Random();
+
+/// Check if is good condition to use white foreground color by passing
+/// the background color, and optional bias.
+///
+/// Reference:
+///
+/// Old: https://www.w3.org/TR/WCAG20-TECHS/G18.html
+///
+/// New: https://github.com/mchome/flutter_statusbarcolor/issues/40
+bool useWhiteForeground(Color backgroundColor, {double bias = 0.0}) {
+  // Old:
+  // return 1.05 / (color.computeLuminance() + 0.05) > 4.5;
+
+  // New:
+  final v = sqrt(
+    pow(backgroundColor.red, 2) * 0.299 +
+        pow(backgroundColor.green, 2) * 0.587 +
+        pow(backgroundColor.blue, 2) * 0.114,
+  ).round();
+  return v < (130 + bias);
+}
+
+const List<List<Color>> colorTypes = [
+  [Colors.red, Colors.redAccent],
+  [Colors.pink, Colors.pinkAccent],
+  [Colors.purple, Colors.purpleAccent],
+  [Colors.deepPurple, Colors.deepPurpleAccent],
+  [Colors.indigo, Colors.indigoAccent],
+  [Colors.blue, Colors.blueAccent],
+  [Colors.lightBlue, Colors.lightBlueAccent],
+  [Colors.cyan, Colors.cyanAccent],
+  [Colors.teal, Colors.tealAccent],
+  [Colors.green, Colors.greenAccent],
+  [Colors.lightGreen, Colors.lightGreenAccent],
+  [Colors.lime, Colors.limeAccent],
+  [Colors.yellow, Colors.yellowAccent],
+  [Colors.amber, Colors.amberAccent],
+  [Colors.orange, Colors.orangeAccent],
+  [Colors.deepOrange, Colors.deepOrangeAccent],
+  [Colors.brown],
+  [Colors.grey],
+  [Colors.blueGrey],
+  [Colors.black],
+];
+
+List<Map<Color, String>> shadingTypes(List<Color> colors) {
+  final List<Map<Color, String>> result = [];
+
+  for (final Color colorType in colors) {
+    if (colorType == Colors.grey) {
+      result.addAll(
+        [50, 100, 200, 300, 350, 400, 500, 600, 700, 800, 850, 900]
+            .map((int shade) => {Colors.grey[shade]!: shade.toString()})
+            .toList(),
+      );
+    } else if (colorType == Colors.black || colorType == Colors.white) {
+      result.addAll([
+        {Colors.black: ''},
+        {Colors.white: ''},
+      ]);
+    } else if (colorType is MaterialAccentColor) {
+      result.addAll(
+        [100, 200, 400, 700]
+            .map((int shade) => {colorType[shade]!: 'A$shade'})
+            .toList(),
+      );
+    } else if (colorType is MaterialColor) {
+      result.addAll(
+        [50, 100, 200, 300, 400, 500, 600, 700, 800, 900]
+            .map((int shade) => {colorType[shade]!: shade.toString()})
+            .toList(),
+      );
+    } else {
+      result.add({const Color(0x00000000): ''});
+    }
+  }
+
+  return result;
+}
+
+Color randomColorShade(List<Color> colors) {
+  final color = colors[_rnd.nextInt(colors.length)];
+  final shades = shadingTypes([color]);
+
+  return shades[_rnd.nextInt(shades.length)].keys.first;
+}