Upstream transition-transform mixin from MobileFrontend

This specialised usage of transition allows hardware accelerated
transitions on mobile devices and is commonly used in MobileFrontend.

Change-Id: Iaa622043fdbb5be965716c88b48f30f61d259c8b

diff --git a/resources/src/mediawiki.less/mediawiki.mixins.less b/resources/src/mediawiki.less/mediawiki.mixins.less
index 1e952b0..e495b63 100644 (file)
--- a/resources/src/mediawiki.less/mediawiki.mixins.less
+++ b/resources/src/mediawiki.less/mediawiki.mixins.less
@@ -58,6 +58,20 @@
        transition: @value; // Chrome 26+, Firefox 16+, IE 10+, Safari 6.1+, Opera 12.1+, iOS 7+, Android 4.4+
 }
 
+// Provide a hardware accelerated transform transition
+// We can't use `.transition()` because WebKit requires `-webkit-` prefix before `transform`
+// Example usage: `.transition-transform( 1s, opacity 2s );`
+// First parameter is additional options for `transform` transition commencing with
+// duration property @see https://www.w3.org/TR/css3-transitions/#transition-duration-property
+// and remaining parameters are additional transitions."
+.transition-transform( ... ) {
+       -webkit-backface-visibility: hidden; // Older Webkit browsers: Promote element to a composite layer & involve the GPU
+
+       -webkit-transition: -webkit-transform @arguments; // Safari 3.1-8, iOS 3.2-8.4, Android 2.1-4.4.4
+       -moz-transition: -moz-transform @arguments; // Firefox 4-15 for `-moz-transition`
+       transition: transform @arguments; // Chrome 36+, Firefox 16+, IE 10+, Safari 9+, Opera 12.1+, iOS 9.2+, Android 36+
+}
+
 .box-sizing( @value ) {
        -webkit-box-sizing: @value; // Safari 3.1-5.0, iOS 3.2-4.3, Android 2.1-3.0
        -moz-box-sizing: @value; // Firefox 4-28,