1 files changed, 70 insertions, 1 deletions

diff --git a/core/java/android/view/WindowManager.java b/core/java/android/view/WindowManager.java
index 2889e11e6f1f..2053826d91a9 100644
--- a/core/java/android/view/WindowManager.java
+++ b/core/java/android/view/WindowManager.java
@@ -121,6 +121,7 @@ import java.lang.annotation.RetentionPolicy;
 import java.util.Arrays;
 import java.util.List;
 import java.util.Objects;
+import java.util.function.Consumer;
 
 /**
  * The interface that apps use to talk to the window manager.
@@ -809,6 +810,64 @@ public interface WindowManager extends ViewManager {
         return DISPLAY_IME_POLICY_FALLBACK_DISPLAY;
     }
 
+    /**
+     * Returns whether cross-window blur is currently enabled. This affects both window blur behind
+     * (see {@link LayoutParams#setBlurBehindRadius}) and window background blur (see
+     * {@link Window#setBackgroundBlurRadius}).
+     *
+     * Cross-window blur might not be supported by some devices due to GPU limitations. It can also
+     * be disabled at runtime, e.g. during battery saving mode, when multimedia tunneling is used or
+     * when minimal post processing is requested. In such situations, no blur will be computed or
+     * drawn, so the blur target area will not be blurred. To handle this, the app might want to
+     * change its theme to one that does not use blurs. To listen for cross-window blur
+     * enabled/disabled events, use {@link #addCrossWindowBlurEnabledListener}.
+     *
+     * @see #addCrossWindowBlurEnabledListener
+     * @see LayoutParams#setBlurBehindRadius
+     * @see Window#setBackgroundBlurRadius
+     */
+    default boolean isCrossWindowBlurEnabled() {
+        return false;
+    }
+
+    /**
+     * Adds a listener, which will be called when cross-window blurs are enabled/disabled at
+     * runtime. This affects both window blur behind (see {@link LayoutParams#setBlurBehindRadius})
+     * and window background blur (see {@link Window#setBackgroundBlurRadius}).
+     *
+     * Cross-window blur might not be supported by some devices due to GPU limitations. It can also
+     * be disabled at runtime, e.g. during battery saving mode, when multimedia tunneling is used or
+     * when minimal post processing is requested. In such situations, no blur will be computed or
+     * drawn, so the blur target area will not be blurred. To handle this, the app might want to
+     * change its theme to one that does not use blurs.
+     *
+     * The listener will be called on the main thread.
+     *
+     * If the listener is added successfully, it will be called immediately with the current
+     * cross-window blur enabled state.
+     *
+     *
+     * @param listener the listener to be added. It will be called back with a boolean parameter,
+     *                 which is true if cross-window blur is enabled and false if it is disabled
+     *
+     * @see #removeCrossWindowBlurEnabledListener
+     * @see #isCrossWindowBlurEnabled
+     * @see LayoutParams#setBlurBehindRadius
+     * @see Window#setBackgroundBlurRadius
+     */
+    default void addCrossWindowBlurEnabledListener(@NonNull Consumer<Boolean> listener) {
+    }
+
+    /**
+     * Removes a listener, previously added with {@link #addCrossWindowBlurEnabledListener}
+     *
+     * @param listener the listener to be removed
+     *
+     * @see #addCrossWindowBlurEnabledListener
+     */
+    default void removeCrossWindowBlurEnabledListener(@NonNull Consumer<Boolean> listener) {
+    }
+
     public static class LayoutParams extends ViewGroup.LayoutParams implements Parcelable {
         /**
          * X position for this window.  With the default gravity it is ignored.
@@ -3537,7 +3596,8 @@ public interface WindowManager extends ViewManager {
 
         /**
          * Blurs the screen behind the window. The effect is similar to that of {@link #dimAmount},
-         * but instead of dimmed, the content behind the window will be blurred.
+         * but instead of dimmed, the content behind the window will be blurred (or combined with
+         * the dim amount, if such is specified).
          *
          * The density of the blur is set by the blur radius. The radius defines the size
          * of the neighbouring area, from which pixels will be averaged to form the final
@@ -3550,10 +3610,19 @@ public interface WindowManager extends ViewManager {
          *
          * Requires {@link #FLAG_BLUR_BEHIND} to be set.
          *
+         * Cross-window blur might not be supported by some devices due to GPU limitations. It can
+         * also be disabled at runtime, e.g. during battery saving mode, when multimedia tunneling
+         * is used or when minimal post processing is requested. In such situations, no blur will
+         * be computed or drawn, resulting in there being no depth separation between the window
+         * and the content behind it. To avoid this, the app might want to use more
+         * {@link #dimAmount} on its window. To listen for cross-window blur enabled/disabled
+         * events, use {@link #addCrossWindowBlurEnabledListener}.
+         *
          * @param blurBehindRadius The blur radius to use for blur behind in pixels
          *
          * @see #FLAG_BLUR_BEHIND
          * @see #getBlurBehindRadius
+         * @see WindowManager#addCrossWindowBlurEnabledListener
          * @see Window#setBackgroundBlurRadius
          */
         public void setBlurBehindRadius(@IntRange(from = 0) int blurBehindRadius) {