Implement Virtual Display class for Android.

ui/android/java/src/org/chromium/ui/display/DisplayAndroidManager.java

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package org.chromium.ui.display;
 
 import android.annotation.SuppressLint;
 import android.content.ComponentCallbacks;
 import android.content.Context;
 import android.content.res.Configuration;
@@ skipping 94 matching lines @@
         public void stopAccurateListening() {
             --mAccurateCount;
             assert mAccurateCount >= 0;
         }
 
         // ComponentCallbacks implementation:
 
         @Override
         public void onConfigurationChanged(Configuration newConfig) {
             updateDeviceDisplayInfo();
-            mIdMap.get(mMainSdkDisplayId).updateFromDisplay(
+            ((DisplayAndroidImpl) mIdMap.get(mMainSdkDisplayId)).updateFromDisplay(
                     getDefaultDisplayForContext(getContext()));
         }
 
         @Override
         public void onLowMemory() {
         }
     }
 
     /**
      * DisplayListenerBackendImpl implements DisplayListenerBackend
@@ skipping 38 matching lines @@
             DisplayAndroid displayAndroid = mIdMap.get(sdkDisplayId);
             if (displayAndroid == null) return;
 
             if (mNativePointer != 0) nativeRemoveDisplay(mNativePointer, sdkDisplayId);
             mIdMap.remove(sdkDisplayId);
         }
 
         @Override
         public void onDisplayChanged(int sdkDisplayId) {
             updateDeviceDisplayInfo();
-            DisplayAndroid displayAndroid = mIdMap.get(sdkDisplayId);
+            DisplayAndroidImpl displayAndroid = (DisplayAndroidImpl) mIdMap.get(sdkDisplayId);
             if (displayAndroid != null) {
                 displayAndroid.updateFromDisplay(getDisplayManager().getDisplay(sdkDisplayId));
             }
         }
     }
 
     private static DisplayAndroidManager sDisplayAndroidManager;
 
+    // Real displays on Android start at ID 0, so to avoid any overlap, start virtual displays at
+    // a much higher number.
+    private static final int VIRTUAL_DISPLAY_ID_BEGIN = 1000;

[boliu, 2016/11/28 15:53:31]

I need we need to double check how android generates its display IDs.

If it's internally also keeping a counter like this, then 1000 isn't an
impossibly high number to reach. But if it's immediately re-using empty slots
starting from 0 or something, then it's fine.

Can you double check and report back? "Settings->Developer options->Simulate
secondary display" should be good enough

[mthiesse, 2016/11/28 19:16:42]

Android effectively does what I'm doing here, but starts at 1. They never re-use
slots, and both virtual and physical displays are assigned IDs in the same way -
search for "assignDisplayIdLocked" in android source to verify. This is true for
at least as far back as jellybean.

I'll up it to something more impossibly high.

+
     private long mNativePointer;
     private int mMainSdkDisplayId;
     private SparseArray<DisplayAndroid> mIdMap;
     private DisplayListenerBackend mBackend;
+    private int mNextVirtualDisplayId = VIRTUAL_DISPLAY_ID_BEGIN;
 
     @SuppressFBWarnings("LI_LAZY_INIT_UPDATE_STATIC")
     /* package */ static DisplayAndroidManager getInstance() {
         if (sDisplayAndroidManager == null) {
             // Split between creation and initialization to allow for calls
             // from DisplayAndroid to DisplayAndroidManager during initialize().
             sDisplayAndroidManager = new DisplayAndroidManager();
             sDisplayAndroidManager.initialize();
         }
         return sDisplayAndroidManager;
@@ skipping 74 matching lines @@
     /* package */ void startAccurateListening() {
         mBackend.startAccurateListening();
     }
 
     /* package */ void stopAccurateListening() {
         mBackend.stopAccurateListening();
     }
 
     private DisplayAndroid addDisplay(Display display) {
         int sdkDisplayId = display.getDisplayId();
-        DisplayAndroid displayAndroid = new DisplayAndroid(display);
+        DisplayAndroidImpl displayAndroid = new DisplayAndroidImpl(display);
         mIdMap.put(sdkDisplayId, displayAndroid);
 
         displayAndroid.updateFromDisplay(display);
         return displayAndroid;
     }
 
+    /* package */ int getNextVirtualDisplayId() {

[boliu, 2016/11/28 15:53:31]

nit: maybe generating this ID can happen in addVirtualDisplay, then one less
back and forth call, and can also assert the generated id isn't already in the
map

also can we crash hard if the IDs ever collide, in both ways? if this is buggy,
we want to know immediately

[mthiesse, 2016/11/28 19:16:42]

Done.

+        return mNextVirtualDisplayId++;
+    }
+
+    /* package */ void addVirtualDisplay(VirtualDisplayAndroid display) {
+        mIdMap.put(display.getDisplayId(), display);

[boliu, 2016/11/28 15:53:31]

should this immediately create the native side display? or maybe
createVirtualDisplay should take all the params, so it's impossible for client
to leave things in an inconsistent state

[mthiesse, 2016/11/28 19:16:42]

Done.

+    }
+
+    /* package */ void removeVirtualDisplay(VirtualDisplayAndroid display) {
+        DisplayAndroid displayAndroid = mIdMap.get(display.getDisplayId());
+        assert displayAndroid == display;
+
+        if (mNativePointer != 0) nativeRemoveDisplay(mNativePointer, display.getDisplayId());
+        mIdMap.remove(display.getDisplayId());
+    }
+
     /* package */ void updateDisplayOnNativeSide(DisplayAndroid displayAndroid) {
         if (mNativePointer == 0) return;
-        nativeUpdateDisplay(mNativePointer, displayAndroid.getSdkDisplayId(),
+        nativeUpdateDisplay(mNativePointer, displayAndroid.getDisplayId(),
                 displayAndroid.getPhysicalDisplayWidth(), displayAndroid.getPhysicalDisplayHeight(),
                 displayAndroid.getDisplayWidth(), displayAndroid.getDisplayHeight(),
                 displayAndroid.getDipScale(), displayAndroid.getRotationDegrees(),
                 displayAndroid.getBitsPerPixel(), displayAndroid.getBitsPerComponent());
     }
 
     private native void nativeUpdateDisplay(long nativeDisplayAndroidManager, int sdkDisplayId,
             int physicalWidth, int physicalHeight, int width, int height, float dipScale,
             int rotationDegrees, int bitsPerPixel, int bitsPerComponent);
     private native void nativeRemoveDisplay(long nativeDisplayAndroidManager, int sdkDisplayId);
     private native void nativeSetPrimaryDisplayId(
             long nativeDisplayAndroidManager, int sdkDisplayId);
 }