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Revert "Fix off-by-one fromRGBO alpha value calculation (#13777)" (flutter/engine#14548)

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This reverts commit dc0401f8e483fd698529d9376dc806b85038093f.
This commit is contained in:
Lau Ching Jun 2019-12-18 00:22:50 -08:00 committed by GitHub
parent 1649fd41c8
commit 288a793a46
2 changed files with 5 additions and 11 deletions
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10
engine/src/flutter/lib/ui/painting.dart
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@ -129,17 +129,17 @@ class Color {
/// * `r` is [red], from 0 to 255.
/// * `g` is [green], from 0 to 255.
/// * `b` is [blue], from 0 to 255.
/// * `opacity` is the alpha channel of this color as a double, with 0.0 being
/// * `opacity` is alpha channel of this color as a double, with 0.0 being
/// transparent and 1.0 being fully opaque.
///
/// Out of range values are brought into range using modulo 255.
///
/// See also [fromARGB], which takes the opacity as an integer value.
const Color.fromRGBO(int r, int g, int b, double opacity) :
value = (((((opacity * 0xff + 0.5) ~/ 1) & 0xff) << 24) | // Since colors are canonicalized we need to round the alpha value manually
((r & 0xff) << 16) |
((g & 0xff) << 8) |
((b & 0xff) << 0)) & 0xFFFFFFFF;
value = ((((opacity * 0xff ~/ 1) & 0xff) << 24) |
((r & 0xff) << 16) |
((g & 0xff) << 8) |
((b & 0xff) << 0)) & 0xFFFFFFFF;
/// A 32 bit value representing this color.
///

6
engine/src/flutter/testing/dart/color_test.dart
View File

@ -55,12 +55,6 @@ void main() {
expect(const NotAColor(123), equals(const NotAColor(123)));
});
test('Color.fromRGBO', () {
expect(const Color.fromRGBO(0, 0, 0, 1.0), const Color(0xFF000000));
expect(const Color.fromRGBO(0, 0, 0, 0.5), const Color(0x80000000));
expect(const Color.fromRGBO(0, 0, 0, 0.0), const Color(0x00000000));
});
test('Color.lerp', () {
expect(
Color.lerp(const Color(0x00000000), const Color(0xFFFFFFFF), 0.0),