From 0eff18732c7d3c3c7c998737f92da86d479486e9 Mon Sep 17 00:00:00 2001
From: Robert Carr <racarr@google.com>
Date: Fri, 1 Dec 2017 14:27:04 -0800
Subject: [PATCH] Fix support for negatively Z-ordered SubWindows.

It turns out the live wallpaper picker is a copy-pasted
implementation of the old version of SurfaceView which relies
on TYPE_APPLICATION_MEDIA to be placed beneath the main window.
This is the last user and we should aim to eliminate it by replacing
the wallpaper picker with a SurfaceView or simply a Child Surface.

Bug: 69928336
Bug: 70040778
Test: Manual. ZOrderingTests.
Change-Id: I462b8f11954ad2e892d23164f41359a73078c21f
---
 .../java/com/android/server/wm/WindowState.java    | 34 ++++++++++++++++------
 .../src/com/android/server/wm/ZOrderingTests.java  | 19 ++++++++++++
 2 files changed, 44 insertions(+), 9 deletions(-)

diff --git a/services/core/java/com/android/server/wm/WindowState.java b/services/core/java/com/android/server/wm/WindowState.java
index c2ac905219ea..9eab61c40323 100644
--- a/services/core/java/com/android/server/wm/WindowState.java
+++ b/services/core/java/com/android/server/wm/WindowState.java
@@ -50,6 +50,7 @@ import static android.view.WindowManager.LayoutParams.SOFT_INPUT_ADJUST_RESIZE;
 import static android.view.WindowManager.LayoutParams.SOFT_INPUT_MASK_ADJUST;
 import static android.view.WindowManager.LayoutParams.TYPE_APPLICATION;
 import static android.view.WindowManager.LayoutParams.TYPE_APPLICATION_MEDIA_OVERLAY;
+import static android.view.WindowManager.LayoutParams.TYPE_APPLICATION_MEDIA;
 import static android.view.WindowManager.LayoutParams.TYPE_APPLICATION_STARTING;
 import static android.view.WindowManager.LayoutParams.TYPE_BASE_APPLICATION;
 import static android.view.WindowManager.LayoutParams.TYPE_DOCK_DIVIDER;
@@ -4331,15 +4332,6 @@ class WindowState extends WindowContainer<WindowState> implements WindowManagerP
         }
     }
 
-    boolean usesRelativeZOrdering() {
-        if (!isChildWindow()) {
-            return false;
-        } else if (mAttrs.type == TYPE_APPLICATION_MEDIA_OVERLAY) {
-            return true;
-        } else {
-            return false;
-        }
-    }
 
     @Override
     boolean shouldMagnify() {
@@ -4414,4 +4406,28 @@ class WindowState extends WindowContainer<WindowState> implements WindowManagerP
     public boolean isDimming() {
         return mIsDimming;
     }
+
+    // TODO(b/70040778): We should aim to eliminate the last user of TYPE_APPLICATION_MEDIA
+    // then we can drop all negative layering on the windowing side and simply inherit
+    // the default implementation here.
+    public void assignChildLayers(Transaction t) {
+        int layer = 1;
+        for (int i = 0; i < mChildren.size(); i++) {
+            final WindowState w = mChildren.get(i);
+
+            // APPLICATION_MEDIA_OVERLAY needs to go above APPLICATION_MEDIA
+            // while they both need to go below the main window. However the
+            // relative layering of multiple APPLICATION_MEDIA/OVERLAY has never
+            // been defined and so we can use static layers and leave it that way.
+            if (w.mAttrs.type == TYPE_APPLICATION_MEDIA) {
+                w.assignLayer(t, -2);
+            } else if (w.mAttrs.type == TYPE_APPLICATION_MEDIA_OVERLAY) {
+                w.assignLayer(t, -1);
+            } else {
+                w.assignLayer(t, layer);
+            }
+            w.assignChildLayers(t);
+            layer++;
+        }
+    }
 }
diff --git a/services/tests/servicestests/src/com/android/server/wm/ZOrderingTests.java b/services/tests/servicestests/src/com/android/server/wm/ZOrderingTests.java
index 04f5e5e919aa..e5cbdba7b507 100644
--- a/services/tests/servicestests/src/com/android/server/wm/ZOrderingTests.java
+++ b/services/tests/servicestests/src/com/android/server/wm/ZOrderingTests.java
@@ -39,6 +39,7 @@ import static android.app.WindowConfiguration.WINDOWING_MODE_FULLSCREEN;
 import static android.app.WindowConfiguration.WINDOWING_MODE_PINNED;
 import static android.app.WindowConfiguration.WINDOWING_MODE_SPLIT_SCREEN_PRIMARY;
 import static android.view.WindowManager.LayoutParams.TYPE_APPLICATION_ATTACHED_DIALOG;
+import static android.view.WindowManager.LayoutParams.TYPE_APPLICATION_MEDIA;
 import static android.view.WindowManager.LayoutParams.TYPE_APPLICATION_MEDIA_OVERLAY;
 import static android.view.WindowManager.LayoutParams.TYPE_BASE_APPLICATION;
 import static android.view.WindowManager.LayoutParams.TYPE_SYSTEM_OVERLAY;
@@ -343,4 +344,22 @@ public class ZOrderingTests extends WindowTestsBase {
         assertWindowLayerGreaterThan(mTransaction, statusBarPanel, mStatusBarWindow);
         assertWindowLayerGreaterThan(mTransaction, statusBarSubPanel, statusBarPanel);
     }
+
+    @Test
+    public void testAssignWindowLayers_ForNegativelyZOrderedSubtype() throws Exception {
+        // TODO(b/70040778): We should aim to eliminate the last user of TYPE_APPLICATION_MEDIA
+        // then we can drop all negative layering on the windowing side.
+
+        final WindowState anyWindow =
+                createWindow(null, TYPE_BASE_APPLICATION, mDisplayContent, "anyWindow");
+        final WindowState child = createWindow(anyWindow, TYPE_APPLICATION_MEDIA, mDisplayContent,
+                "TypeApplicationMediaChild");
+        final WindowState mediaOverlayChild = createWindow(anyWindow, TYPE_APPLICATION_MEDIA_OVERLAY,
+                mDisplayContent, "TypeApplicationMediaOverlayChild");
+
+        mDisplayContent.assignChildLayers(mTransaction);
+
+        assertWindowLayerGreaterThan(mTransaction, anyWindow, mediaOverlayChild);
+        assertWindowLayerGreaterThan(mTransaction, mediaOverlayChild, child);
+    }
 }
-- 
2.11.0