зеркало из https://github.com/mozilla/gecko-dev.git
Bug 1668029 - When resetting background color for high contrast, preserve alpha channel appropriately. r=morgan
But discard it when backplating behind text, so that text is readable. This should be uncontroversial... Dealing with widgets is a bit harder so TBD. Differential Revision: https://phabricator.services.mozilla.com/D91779
This commit is contained in:
Emilio Cobos Álvarez
Родитель
47694b3690
Коммит
0967845f95
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@ -229,7 +229,11 @@ static Maybe<nscolor> GetBackplateColor(nsIFrame* aFrame) {
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}
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nscolor backgroundColor = bg->BackgroundColor(frame);
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if (NS_GET_A(backgroundColor) != 0) {
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return Some(backgroundColor);
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// NOTE: We intentionally disregard the alpha channel here for the purpose
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// of the backplate, in order to guarantee contrast.
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return Some(NS_RGB(NS_GET_R(backgroundColor),
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NS_GET_G(backgroundColor),
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NS_GET_B(backgroundColor)));
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}
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break;
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}
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@ -33,6 +33,8 @@ pref(browser.display.document_color_use,0) needs-focus != selection-001.html sel
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== color-transparent-001.html about:blank
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!= color-transparent-002.html about:blank
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!= semi-transparent-overlay.html about:blank
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!= semi-transparent-overlay.html semi-transparent-background.html
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== links.html links-ref.html
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== links-2.html links-ref.html
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@ -0,0 +1,11 @@
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<!doctype html>
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<style>
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.container {
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position: relative;
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background-color: rgba(0, 0, 0, .2);
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}
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</style>
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<div class="container">
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<a href="#"></a>
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Some text that you should be able to read.
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</div>
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@ -0,0 +1,15 @@
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<!doctype html>
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<style>
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.container {
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position: relative;
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}
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a {
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position: absolute;
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inset: 0;
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background-color: rgba(0, 0, 0, .2);
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}
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</style>
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<div class="container">
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<a href="#"></a>
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Some text that you should be able to read.
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</div>
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@ -385,6 +385,8 @@ fn tweak_when_ignoring_colors(
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declaration: &mut Cow<PropertyDeclaration>,
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declarations_to_apply_unless_overriden: &mut DeclarationsToApplyUnlessOverriden,
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) {
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use crate::values::specified::Color;
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if !longhand_id.ignored_when_document_colors_disabled() {
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return;
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}
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@ -401,21 +403,53 @@ fn tweak_when_ignoring_colors(
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return;
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}
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fn alpha_channel(color: &Color) -> u8 {
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match *color {
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// Seems safe enough to assume that the default color and system
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// colors are opaque in HCM, though maybe we shouldn't asume the
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// later?
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#[cfg(feature = "gecko")]
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Color::InheritFromBodyQuirk | Color::System(..) => 255,
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// We don't have the actual color here, but since except for color:
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// transparent we force opaque text colors, it seems sane to do
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// this. You can technically fool this bit of code with:
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//
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// color: transparent; background-color: currentcolor;
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//
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// but this is best-effort, and that seems unlikely to happen in
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// practice.
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Color::CurrentColor => 255,
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// Complex colors are results of interpolation only and probably
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// shouldn't show up around here in HCM, but we've always treated
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// them as opaque effectively so keep doing it.
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Color::Complex { .. } => 255,
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Color::Numeric { ref parsed, .. } => parsed.alpha,
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}
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}
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// A few special-cases ahead.
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match **declaration {
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// We honor color and background-color: transparent, and
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// "revert-or-initial" otherwise.
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PropertyDeclaration::BackgroundColor(ref color) => {
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if !color.is_transparent() {
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let color = builder.device.default_background_color();
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// For background-color, we revert or initial-with-preserved-alpha
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// otherwise, this is needed to preserve semi-transparent
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// backgrounds.
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//
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// FIXME(emilio, bug 1666059): We revert for alpha == 0, but maybe
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// should consider not doing that even if it causes some issues like
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// bug 1625036, or finding a performant way to preserve the original
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// widget background color's rgb channels but not alpha...
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let alpha = alpha_channel(color);
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if alpha != 0 {
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let mut color = builder.device.default_background_color();
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color.alpha = alpha;
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declarations_to_apply_unless_overriden.push(
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PropertyDeclaration::BackgroundColor(color.into())
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)
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}
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}
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PropertyDeclaration::Color(ref color) => {
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// otherwise.
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if color.0.is_transparent() {
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// We honor color: transparent, and "revert-or-initial" otherwise.
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if alpha_channel(&color.0) == 0 {
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return;
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}
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// If the inherited color would be transparent, but we would
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@ -529,15 +529,6 @@ impl Color {
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parse_hash_color(&serialization)
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.map_err(|()| location.new_custom_error(StyleParseErrorKind::UnspecifiedError))
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}
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/// Returns true if the color is completely transparent, and false
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/// otherwise.
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pub fn is_transparent(&self) -> bool {
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match *self {
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Color::Numeric { ref parsed, .. } => parsed.alpha == 0,
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_ => false,
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}
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}
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}
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#[cfg(feature = "gecko")]
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