force alpha to 1 when using background color as inverted foreground color.

src/browser/Color.test.ts

@@ -4,7 +4,7 @@
  */
 
 import { assert } from 'chai';
-import { blend, fromCss, toPaddedHex, toCss, toRgba } from 'browser/Color';
+import { blend, fromCss, toPaddedHex, toCss, toRgba, fromRgba } from 'browser/Color';
 
 describe('Color', () => {
   describe('blend', () => {
@@ -135,4 +135,26 @@ describe('Color', () => {
       assert.equal(toRgba(0xff, 0xff, 0xff, 0xff), 0xffffffff);
     });
   });
+
+  describe('fromRgba', () => {
+    it('should convert an rgba number to an rgba array', () => {
+      assert.deepEqual(fromRgba(0x00000000), [0x00, 0x00, 0x00, 0x00]);
+      assert.deepEqual(fromRgba(0x10101010), [0x10, 0x10, 0x10, 0x10]);
+      assert.deepEqual(fromRgba(0x20202020), [0x20, 0x20, 0x20, 0x20]);
+      assert.deepEqual(fromRgba(0x30303030), [0x30, 0x30, 0x30, 0x30]);
+      assert.deepEqual(fromRgba(0x40404040), [0x40, 0x40, 0x40, 0x40]);
+      assert.deepEqual(fromRgba(0x50505050), [0x50, 0x50, 0x50, 0x50]);
+      assert.deepEqual(fromRgba(0x60606060), [0x60, 0x60, 0x60, 0x60]);
+      assert.deepEqual(fromRgba(0x70707070), [0x70, 0x70, 0x70, 0x70]);
+      assert.deepEqual(fromRgba(0x80808080), [0x80, 0x80, 0x80, 0x80]);
+      assert.deepEqual(fromRgba(0x90909090), [0x90, 0x90, 0x90, 0x90]);
+      assert.deepEqual(fromRgba(0xa0a0a0a0), [0xa0, 0xa0, 0xa0, 0xa0]);
+      assert.deepEqual(fromRgba(0xb0b0b0b0), [0xb0, 0xb0, 0xb0, 0xb0]);
+      assert.deepEqual(fromRgba(0xc0c0c0c0), [0xc0, 0xc0, 0xc0, 0xc0]);
+      assert.deepEqual(fromRgba(0xd0d0d0d0), [0xd0, 0xd0, 0xd0, 0xd0]);
+      assert.deepEqual(fromRgba(0xe0e0e0e0), [0xe0, 0xe0, 0xe0, 0xe0]);
+      assert.deepEqual(fromRgba(0xf0f0f0f0), [0xf0, 0xf0, 0xf0, 0xf0]);
+      assert.deepEqual(fromRgba(0xffffffff), [0xff, 0xff, 0xff, 0xff]);
+    });
+  });
 });