prefers-reduced-motion per https://www.w3.org/TR/2020/WD-mediaqueries-5-20200731/#descdef-media-prefers-reduced-motion

Author: ylafon

org/w3c/css/atrules/css3/media/MediaPrefersReducedMotion.java

@@ -0,0 +1,128 @@
+// $Id$
+//
+// (c) COPYRIGHT MIT, ECRIM and Keio University, 2011
+// Please first read the full copyright statement in file COPYRIGHT.html
+
+package org.w3c.css.atrules.css3.media;
+
+import org.w3c.css.atrules.css.media.MediaFeature;
+import org.w3c.css.util.ApplContext;
+import org.w3c.css.util.InvalidParamException;
+import org.w3c.css.values.CssExpression;
+import org.w3c.css.values.CssIdent;
+import org.w3c.css.values.CssTypes;
+import org.w3c.css.values.CssValue;
+
+/**
+ * @spec https://www.w3.org/TR/2020/WD-mediaqueries-5-20200731/#descdef-media-prefers-reduced-motion
+ */
+public class MediaPrefersReducedMotion extends MediaFeature {
+
+    public static final CssIdent[] allowed_values;
+
+    static {
+        String[] _allowed_values = {"no-preference", "reduce"};
+        allowed_values = new CssIdent[_allowed_values.length];
+        int i = 0;
+        for (String s : _allowed_values) {
+            allowed_values[i++] = CssIdent.getIdent(s);
+        }
+    }
+
+    public static CssIdent getAllowedIdent(CssIdent ident) {
+        for (CssIdent id : allowed_values) {
+            if (id.equals(ident)) {
+                return id;
+            }
+        }
+        return null;
+    }
+
+    /**
+     * Create a new MediaPrefersReducedMotion
+     */
+    public MediaPrefersReducedMotion() {
+    }
+
+    /**
+     * Create a new MediaPrefersReducedMotion.
+     *
+     * @param expression The expression for this media feature
+     * @throws InvalidParamException Values are incorrect
+     */
+    public MediaPrefersReducedMotion(ApplContext ac, String modifier,
+                                     CssExpression expression, boolean check)
+            throws InvalidParamException {
+
+        if (modifier != null) {
+            throw new InvalidParamException("nomodifiermedia",
+                    getFeatureName(), ac);
+        }
+
+        if (expression != null) {
+            if (expression.getCount() > 1) {
+                throw new InvalidParamException("unrecognize", ac);
+            }
+            if (expression.getCount() == 0) {
+                throw new InvalidParamException("few-value", getFeatureName(), ac);
+            }
+            CssValue val = expression.getValue();
+
+            switch (val.getType()) {
+                case CssTypes.CSS_IDENT:
+                    if (getAllowedIdent(val.getIdent()) != null) {
+                        value = val;
+                        break;
+                    }
+                    // let it flow through the exception
+                default:
+                    throw new InvalidParamException("value", expression.getValue(),
+                            getFeatureName(), ac);
+            }
+        } else {
+            // TODO add a warning for value less mediafeature that makes no sense
+        }
+    }
+
+    public MediaPrefersReducedMotion(ApplContext ac, String modifier, CssExpression expression)
+            throws InvalidParamException {
+        this(ac, modifier, expression, false);
+    }
+
+    // just in case someone wants to call it externally...
+    public void setModifier(ApplContext ac, String modifier)
+            throws InvalidParamException {
+        throw new InvalidParamException("nomodifiermedia",
+                getFeatureName(), ac);
+    }
+
+    /**
+     * Returns the value of this media feature.
+     */
+
+    public Object get() {
+        return value;
+    }
+
+    /**
+     * Returns the name of this media feature.
+     */
+    public final String getFeatureName() {
+        return "prefers-reduced-motion";
+    }
+
+    /**
+     * Compares two media features for equality.
+     *
+     * @param other The other media features.
+     */
+    public boolean equals(MediaFeature other) {
+        try {
+            MediaPrefersReducedMotion mo = (MediaPrefersReducedMotion) other;
+            return (((value == null) && (mo.value == null)) || ((value != null) && value.equals(mo.value)));
+        } catch (ClassCastException cce) {
+            return false;
+        }
+
+    }
+}

org/w3c/css/properties/CSS3Properties.properties

@@ -544,6 +544,7 @@ mediafeature.orientation:               org.w3c.css.atrules.css3.media.MediaOrie
 mediafeature.overflow-block:            org.w3c.css.atrules.css3.media.MediaOverflowBlock
 mediafeature.overflow-inline:           org.w3c.css.atrules.css3.media.MediaOverflowInline
 mediafeature.pointer:                   org.w3c.css.atrules.css3.media.MediaPointer
+mediafeature.prefers-reduced-motion:    org.w3c.css.atrules.css3.media.MediaPrefersReducedMotion
 mediafeature.resolution:                org.w3c.css.atrules.css3.media.MediaResolution
 mediafeature.scan:                      org.w3c.css.atrules.css3.media.MediaScan
 mediafeature.scripting:                 org.w3c.css.atrules.css3.media.MediaScripting