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 /* -*- Mode: Java; c-basic-offset: 4; tab-width: 20; indent-tabs-mode: nil; -*-

  * This Source Code Form is subject to the terms of the Mozilla Public

  * License, v. 2.0. If a copy of the MPL was not distributed with this

  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

 package org.mozilla.gecko.gfx;

 import org.mozilla.gecko.GeckoAppShell;

 import org.mozilla.gecko.GeckoEvent;

 import org.mozilla.gecko.gfx.LayerView.DrawListener;

 import org.mozilla.gecko.Tab;

 import org.mozilla.gecko.Tabs;

 import org.mozilla.gecko.ZoomConstraints;

 import org.mozilla.gecko.mozglue.RobocopTarget;

 import org.mozilla.gecko.mozglue.generatorannotations.WrapElementForJNI;

 import org.mozilla.gecko.EventDispatcher;

 import org.mozilla.gecko.util.FloatUtils;

 import android.content.Context;

 import android.graphics.PointF;

 import android.graphics.RectF;

 import android.os.SystemClock;

 import android.util.DisplayMetrics;

 import android.util.Log;

 import java.util.ArrayList;

 import java.util.List;

 class GeckoLayerClient implements LayerView.Listener, PanZoomTarget

 {

     private static final String LOGTAG = "GeckoLayerClient";

     private LayerRenderer mLayerRenderer;

     private boolean mLayerRendererInitialized;

     private Context mContext;

     private IntSize mScreenSize;

     private IntSize mWindowSize;

     private DisplayPortMetrics mDisplayPort;

     private boolean mRecordDrawTimes;

     private final DrawTimingQueue mDrawTimingQueue;

     private VirtualLayer mRootLayer;

     /* The Gecko viewport as per the UI thread. Must be touched only on the UI thread.

      * If any events being sent to Gecko that are relative to the Gecko viewport position,

      * they must (a) be relative to this viewport, and (b) be sent on the UI thread to

      * avoid races. As long as these two conditions are satisfied, and the events being

      * sent to Gecko are processed in FIFO order, the events will properly be relative

      * to the Gecko viewport position. Note that if Gecko updates its viewport independently,

      * we get notified synchronously and also update this on the UI thread.

      */

     private ImmutableViewportMetrics mGeckoViewport;

     /*

      * The viewport metrics being used to draw the current frame. This is only

      * accessed by the compositor thread, and so needs no synchronisation.

      */

     private ImmutableViewportMetrics mFrameMetrics;

     private List<DrawListener> mDrawListeners;

     /* Used as temporaries by syncViewportInfo */

     private final ViewTransform mCurrentViewTransform;

     private final RectF mCurrentViewTransformMargins;

     /* Used as the return value of progressiveUpdateCallback */

     private final ProgressiveUpdateData mProgressiveUpdateData;

     private DisplayPortMetrics mProgressiveUpdateDisplayPort;

     private boolean mLastProgressiveUpdateWasLowPrecision;

     private boolean mProgressiveUpdateWasInDanger;

     private boolean mForceRedraw;

     /* The current viewport metrics.

      * This is volatile so that we can read and write to it from different threads.

      * We avoid synchronization to make getting the viewport metrics from

      * the compositor as cheap as possible. The viewport is immutable so

      * we don't need to worry about anyone mutating it while we're reading from it.

      * Specifically:

      * 1) reading mViewportMetrics from any thread is fine without synchronization

      * 2) writing to mViewportMetrics requires synchronizing on the layer controller object

      * 3) whenver reading multiple fields from mViewportMetrics without synchronization (i.e. in

      *    case 1 above) you should always frist grab a local copy of the reference, and then use

      *    that because mViewportMetrics might get reassigned in between reading the different

      *    fields. */

     private volatile ImmutableViewportMetrics mViewportMetrics;

     private LayerView.OnMetricsChangedListener mViewportChangeListener;

     private ZoomConstraints mZoomConstraints;

     private boolean mGeckoIsReady;

     private final PanZoomController mPanZoomController;

     private final LayerMarginsAnimator mMarginsAnimator;

     private LayerView mView;

     /* This flag is true from the time that browser.js detects a first-paint is about to start,

      * to the time that we receive the first-paint composite notification from the compositor.

      * Note that there is a small race condition with this; if there are two paints that both

      * have the first-paint flag set, and the second paint happens concurrently with the

      * composite for the first paint, then this flag may be set to true prematurely. Fixing this

      * is possible but risky; see https://bugzilla.mozilla.org/show_bug.cgi?id=797615#c751

      */

     private volatile boolean mContentDocumentIsDisplayed;

     public GeckoLayerClient(Context context, LayerView view, EventDispatcher eventDispatcher) {

         // we can fill these in with dummy values because they are always written

         // to before being read

         mContext = context;

         mScreenSize = new IntSize(0, 0);

         mWindowSize = new IntSize(0, 0);

         mDisplayPort = new DisplayPortMetrics();

         mRecordDrawTimes = true;

         mDrawTimingQueue = new DrawTimingQueue();

         mCurrentViewTransform = new ViewTransform(0, 0, 1);

         mCurrentViewTransformMargins = new RectF();

         mProgressiveUpdateData = new ProgressiveUpdateData();

         mProgressiveUpdateDisplayPort = new DisplayPortMetrics();

         mLastProgressiveUpdateWasLowPrecision = false;

         mProgressiveUpdateWasInDanger = false;

         mForceRedraw = true;

         DisplayMetrics displayMetrics = context.getResources().getDisplayMetrics();

         mViewportMetrics = new ImmutableViewportMetrics(displayMetrics)

                            .setViewportSize(view.getWidth(), view.getHeight());

         mZoomConstraints = new ZoomConstraints(false);

         Tab tab = Tabs.getInstance().getSelectedTab();

         if (tab != null) {

             mZoomConstraints = tab.getZoomConstraints();

             mViewportMetrics = mViewportMetrics.setIsRTL(tab.getIsRTL());

         }

         mFrameMetrics = mViewportMetrics;

         mDrawListeners = new ArrayList<DrawListener>();

         mPanZoomController = PanZoomController.Factory.create(this, view, eventDispatcher);

         mMarginsAnimator = new LayerMarginsAnimator(this, view);

         mView = view;

         mView.setListener(this);

         mContentDocumentIsDisplayed = true;

     }

     public void setOverscrollHandler(final Overscroll listener) {

         mPanZoomController.setOverscrollHandler(listener);

     }

     /** Attaches to root layer so that Gecko appears. */

     public void notifyGeckoReady() {

         mGeckoIsReady = true;

         mRootLayer = new VirtualLayer(new IntSize(mView.getWidth(), mView.getHeight()));

         mLayerRenderer = mView.getRenderer();

         sendResizeEventIfNecessary(true);

         DisplayPortCalculator.initPrefs();

         // Gecko being ready is one of the two conditions (along with having an available

         // surface) that cause us to create the compositor. So here, now that we know gecko

         // is ready, call updateCompositor() to see if we can actually do the creation.

         // This needs to run on the UI thread so that the surface validity can't change on

         // us while we're in the middle of creating the compositor.

         mView.post(new Runnable() {

             @Override

             public void run() {

                 mView.getGLController().updateCompositor();

             }

         });

     }

     public void destroy() {

         mPanZoomController.destroy();

         mMarginsAnimator.destroy();

         mDrawListeners.clear();

     }

     /**

      * Returns true if this client is fine with performing a redraw operation or false if it

      * would prefer that the action didn't take place.

      */

     private boolean getRedrawHint() {

         if (mForceRedraw) {

             mForceRedraw = false;

             return true;

         }

         if (!mPanZoomController.getRedrawHint()) {

             return false;

         }

         return DisplayPortCalculator.aboutToCheckerboard(mViewportMetrics,

                 mPanZoomController.getVelocityVector(), mDisplayPort);

     }

     Layer getRoot() {

         return mGeckoIsReady ? mRootLayer : null;

     }

     public LayerView getView() {

         return mView;

     }

     public FloatSize getViewportSize() {

         return mViewportMetrics.getSize();

     }

     /**

      * The view calls this function to indicate that the viewport changed size. It must hold the

      * monitor while calling it.

      *

      * TODO: Refactor this to use an interface. Expose that interface only to the view and not

      * to the layer client. That way, the layer client won't be tempted to call this, which might

      * result in an infinite loop.

      */

     void setViewportSize(int width, int height) {

         mViewportMetrics = mViewportMetrics.setViewportSize(width, height);

         if (mGeckoIsReady) {

             // here we send gecko a resize message. The code in browser.js is responsible for

             // picking up on that resize event, modifying the viewport as necessary, and informing

             // us of the new viewport.

             sendResizeEventIfNecessary(true);

             // the following call also sends gecko a message, which will be processed after the resize

             // message above has updated the viewport. this message ensures that if we have just put

             // focus in a text field, we scroll the content so that the text field is in view.

             GeckoAppShell.viewSizeChanged();

         }

     }

     PanZoomController getPanZoomController() {

         return mPanZoomController;

     }

     LayerMarginsAnimator getLayerMarginsAnimator() {

         return mMarginsAnimator;

     }

     /* Informs Gecko that the screen size has changed. */

     private void sendResizeEventIfNecessary(boolean force) {

         DisplayMetrics metrics = mContext.getResources().getDisplayMetrics();

         IntSize newScreenSize = new IntSize(metrics.widthPixels, metrics.heightPixels);

         IntSize newWindowSize = new IntSize(mView.getWidth(), mView.getHeight());

         boolean screenSizeChanged = !mScreenSize.equals(newScreenSize);

         boolean windowSizeChanged = !mWindowSize.equals(newWindowSize);

         if (!force && !screenSizeChanged && !windowSizeChanged) {

             return;

         }

         mScreenSize = newScreenSize;

         mWindowSize = newWindowSize;

         if (screenSizeChanged) {

             Log.d(LOGTAG, "Screen-size changed to " + mScreenSize);

         }

         if (windowSizeChanged) {

             Log.d(LOGTAG, "Window-size changed to " + mWindowSize);

         }

         GeckoEvent event = GeckoEvent.createSizeChangedEvent(mWindowSize.width, mWindowSize.height,

                                                              mScreenSize.width, mScreenSize.height);

         GeckoAppShell.sendEventToGecko(event);

         GeckoAppShell.sendEventToGecko(GeckoEvent.createBroadcastEvent("Window:Resize", ""));

     }

     /** Sets the current page rect. You must hold the monitor while calling this. */

     private void setPageRect(RectF rect, RectF cssRect) {

         // Since the "rect" is always just a multiple of "cssRect" we don't need to

         // check both; this function assumes that both "rect" and "cssRect" are relative

         // the zoom factor in mViewportMetrics.

         if (mViewportMetrics.getCssPageRect().equals(cssRect))

             return;

         mViewportMetrics = mViewportMetrics.setPageRect(rect, cssRect);

         // Page size is owned by the layer client, so no need to notify it of

         // this change.

         post(new Runnable() {

             @Override

             public void run() {

                 mPanZoomController.pageRectUpdated();

                 mView.requestRender();

             }

         });

     }

     /**

      * Derives content document fixed position margins/fixed layer margins from

      * the view margins in the given metrics object.

      */

     private void getFixedMargins(ImmutableViewportMetrics metrics, RectF fixedMargins) {

         fixedMargins.left = 0;

         fixedMargins.top = 0;

         fixedMargins.right = 0;

         fixedMargins.bottom = 0;

         // The maximum margins are determined by the scrollable area of the page.

         float maxMarginWidth = Math.max(0, metrics.getPageWidth() - metrics.getWidthWithoutMargins());

         float maxMarginHeight = Math.max(0, metrics.getPageHeight() - metrics.getHeightWithoutMargins());

         // If the margins can't fully hide, they're pinned on - in which case,

         // fixed margins should always be zero.

         if (maxMarginWidth < metrics.marginLeft + metrics.marginRight) {

           maxMarginWidth = 0;

         }

         if (maxMarginHeight < metrics.marginTop + metrics.marginBottom) {

           maxMarginHeight = 0;

         }

         PointF offset = metrics.getMarginOffset();

         RectF overscroll = metrics.getOverscroll();

         if (offset.x >= 0) {

             fixedMargins.right = Math.max(0, Math.min(offset.x - overscroll.right, maxMarginWidth));

         } else {

             fixedMargins.left = Math.max(0, Math.min(-offset.x - overscroll.left, maxMarginWidth));

         }

         if (offset.y >= 0) {

             fixedMargins.bottom = Math.max(0, Math.min(offset.y - overscroll.bottom, maxMarginHeight));

         } else {

             fixedMargins.top = Math.max(0, Math.min(-offset.y - overscroll.top, maxMarginHeight));

         }

         // Adjust for overscroll. If we're overscrolled on one side, add that

         // distance to the margins of the other side (limiting to the maximum

         // margin size calculated above).

         if (overscroll.left > 0) {

             fixedMargins.right = Math.min(maxMarginWidth - fixedMargins.left,

                                           fixedMargins.right + overscroll.left);

         } else if (overscroll.right > 0) {

             fixedMargins.left = Math.min(maxMarginWidth - fixedMargins.right,

                                          fixedMargins.left + overscroll.right);

         }

         if (overscroll.top > 0) {

             fixedMargins.bottom = Math.min(maxMarginHeight - fixedMargins.top,

                                            fixedMargins.bottom + overscroll.top);

         } else if (overscroll.bottom > 0) {

             fixedMargins.top = Math.min(maxMarginHeight - fixedMargins.bottom,

                                         fixedMargins.top + overscroll.bottom);

         }

     }

     private void adjustViewport(DisplayPortMetrics displayPort) {

         ImmutableViewportMetrics metrics = getViewportMetrics();

         ImmutableViewportMetrics clampedMetrics = metrics.clamp();

         RectF margins = new RectF();

         getFixedMargins(metrics, margins);

         clampedMetrics = clampedMetrics.setMargins(

             margins.left, margins.top, margins.right, margins.bottom);

         if (displayPort == null) {

             displayPort = DisplayPortCalculator.calculate(metrics, mPanZoomController.getVelocityVector());

         }

         mDisplayPort = displayPort;

         mGeckoViewport = clampedMetrics;

         if (mRecordDrawTimes) {

             mDrawTimingQueue.add(displayPort);

         }

         GeckoAppShell.sendEventToGecko(GeckoEvent.createViewportEvent(clampedMetrics, displayPort));

     }

     /** Aborts any pan/zoom animation that is currently in progress. */

     private void abortPanZoomAnimation() {

         if (mPanZoomController != null) {

             post(new Runnable() {

                 @Override

                 public void run() {

                     mPanZoomController.abortAnimation();

                 }

             });

         }

     }

     /**

      * The different types of Viewport messages handled. All viewport events

      * expect a display-port to be returned, but can handle one not being

      * returned.

      */

     private enum ViewportMessageType {

         UPDATE,       // The viewport has changed and should be entirely updated

         PAGE_SIZE     // The viewport's page-size has changed

     }

     /** Viewport message handler. */

     private DisplayPortMetrics handleViewportMessage(ImmutableViewportMetrics messageMetrics, ViewportMessageType type) {

         synchronized (getLock()) {

             ImmutableViewportMetrics newMetrics;

             ImmutableViewportMetrics oldMetrics = getViewportMetrics();

             switch (type) {

             default:

             case UPDATE:

                 // Keep the old viewport size

                 newMetrics = messageMetrics.setViewportSize(oldMetrics.getWidth(), oldMetrics.getHeight());

                 if (!oldMetrics.fuzzyEquals(newMetrics)) {

                     abortPanZoomAnimation();

                 }

                 break;

             case PAGE_SIZE:

                 // adjust the page dimensions to account for differences in zoom

                 // between the rendered content (which is what Gecko tells us)

                 // and our zoom level (which may have diverged).

                 float scaleFactor = oldMetrics.zoomFactor / messageMetrics.zoomFactor;

                 newMetrics = oldMetrics.setPageRect(RectUtils.scale(messageMetrics.getPageRect(), scaleFactor), messageMetrics.getCssPageRect());

                 break;

             }

             // Update the Gecko-side viewport metrics. Make sure to do this

             // before modifying the metrics below.

             final ImmutableViewportMetrics geckoMetrics = newMetrics.clamp();

             post(new Runnable() {

                 @Override

                 public void run() {

                     mGeckoViewport = geckoMetrics;

                 }

             });

             setViewportMetrics(newMetrics, type == ViewportMessageType.UPDATE);

             mDisplayPort = DisplayPortCalculator.calculate(getViewportMetrics(), null);

         }

         return mDisplayPort;

     }

     @WrapElementForJNI

     DisplayPortMetrics getDisplayPort(boolean pageSizeUpdate, boolean isBrowserContentDisplayed, int tabId, ImmutableViewportMetrics metrics) {

         Tabs tabs = Tabs.getInstance();

         if (isBrowserContentDisplayed && tabs.isSelectedTabId(tabId)) {

             // for foreground tabs, send the viewport update unless the document

             // displayed is different from the content document. In that case, just

             // calculate the display port.

             return handleViewportMessage(metrics, pageSizeUpdate ? ViewportMessageType.PAGE_SIZE : ViewportMessageType.UPDATE);

         } else {

             // for background tabs, request a new display port calculation, so that

             // when we do switch to that tab, we have the correct display port and

             // don't need to draw twice (once to allow the first-paint viewport to

             // get to java, and again once java figures out the display port).

             return DisplayPortCalculator.calculate(metrics, null);

         }

     }

     @WrapElementForJNI

     void contentDocumentChanged() {

         mContentDocumentIsDisplayed = false;

     }

     @WrapElementForJNI

     boolean isContentDocumentDisplayed() {

         return mContentDocumentIsDisplayed;

     }

     // This is called on the Gecko thread to determine if we're still interested

     // in the update of this display-port to continue. We can return true here

     // to abort the current update and continue with any subsequent ones. This

     // is useful for slow-to-render pages when the display-port starts lagging

     // behind enough that continuing to draw it is wasted effort.

     @WrapElementForJNI(allowMultithread = true)

     public ProgressiveUpdateData progressiveUpdateCallback(boolean aHasPendingNewThebesContent,

                                                            float x, float y, float width, float height,

                                                            float resolution, boolean lowPrecision) {

         // Reset the checkerboard risk flag when switching to low precision

         // rendering.

         if (lowPrecision && !mLastProgressiveUpdateWasLowPrecision) {

             // Skip low precision rendering until we're at risk of checkerboarding.

             if (!mProgressiveUpdateWasInDanger) {

                 mProgressiveUpdateData.abort = true;

                 return mProgressiveUpdateData;

             }

             mProgressiveUpdateWasInDanger = false;

         }

         mLastProgressiveUpdateWasLowPrecision = lowPrecision;

         // Grab a local copy of the last display-port sent to Gecko and the

         // current viewport metrics to avoid races when accessing them.

         DisplayPortMetrics displayPort = mDisplayPort;

         ImmutableViewportMetrics viewportMetrics = mViewportMetrics;

         mProgressiveUpdateData.setViewport(viewportMetrics);

         mProgressiveUpdateData.abort = false;

         // Always abort updates if the resolution has changed. There's no use

         // in drawing at the incorrect resolution.

         if (!FloatUtils.fuzzyEquals(resolution, viewportMetrics.zoomFactor)) {

             Log.d(LOGTAG, "Aborting draw due to resolution change: " + resolution + " != " + viewportMetrics.zoomFactor);

             mProgressiveUpdateData.abort = true;

             return mProgressiveUpdateData;

         }

         // Store the high precision displayport for comparison when doing low

         // precision updates.

         if (!lowPrecision) {

             if (!FloatUtils.fuzzyEquals(resolution, mProgressiveUpdateDisplayPort.resolution) ||

                 !FloatUtils.fuzzyEquals(x, mProgressiveUpdateDisplayPort.getLeft()) ||

                 !FloatUtils.fuzzyEquals(y, mProgressiveUpdateDisplayPort.getTop()) ||

                 !FloatUtils.fuzzyEquals(x + width, mProgressiveUpdateDisplayPort.getRight()) ||

                 !FloatUtils.fuzzyEquals(y + height, mProgressiveUpdateDisplayPort.getBottom())) {

                 mProgressiveUpdateDisplayPort =

                     new DisplayPortMetrics(x, y, x+width, y+height, resolution);

             }

         }

         // If we're not doing low precision draws and we're about to

         // checkerboard, enable low precision drawing.

         if (!lowPrecision && !mProgressiveUpdateWasInDanger) {

             if (DisplayPortCalculator.aboutToCheckerboard(viewportMetrics,

                   mPanZoomController.getVelocityVector(), mProgressiveUpdateDisplayPort)) {

                 mProgressiveUpdateWasInDanger = true;

             }

         }

         // XXX All sorts of rounding happens inside Gecko that becomes hard to

         //     account exactly for. Given we align the display-port to tile

         //     boundaries (and so they rarely vary by sub-pixel amounts), just

         //     check that values are within a couple of pixels of the

         //     display-port bounds.

         // Never abort drawing if we can't be sure we've sent a more recent

         // display-port. If we abort updating when we shouldn't, we can end up

         // with blank regions on the screen and we open up the risk of entering

         // an endless updating cycle.

         if (Math.abs(displayPort.getLeft() - mProgressiveUpdateDisplayPort.getLeft()) <= 2 &&

             Math.abs(displayPort.getTop() - mProgressiveUpdateDisplayPort.getTop()) <= 2 &&

             Math.abs(displayPort.getBottom() - mProgressiveUpdateDisplayPort.getBottom()) <= 2 &&

             Math.abs(displayPort.getRight() - mProgressiveUpdateDisplayPort.getRight()) <= 2) {

             return mProgressiveUpdateData;

         }

         // Abort updates when the display-port no longer contains the visible

         // area of the page (that is, the viewport cropped by the page

         // boundaries).

         // XXX This makes the assumption that we never let the visible area of

         //     the page fall outside of the display-port.

         if (Math.max(viewportMetrics.viewportRectLeft, viewportMetrics.pageRectLeft) + 1 < x ||

             Math.max(viewportMetrics.viewportRectTop, viewportMetrics.pageRectTop) + 1 < y ||

             Math.min(viewportMetrics.viewportRectRight, viewportMetrics.pageRectRight) - 1 > x + width ||

             Math.min(viewportMetrics.viewportRectBottom, viewportMetrics.pageRectBottom) - 1 > y + height) {

             Log.d(LOGTAG, "Aborting update due to viewport not in display-port");

             mProgressiveUpdateData.abort = true;

             // Enable low-precision drawing, as we're likely to be in danger if

             // this situation has been encountered.

             mProgressiveUpdateWasInDanger = true;

             return mProgressiveUpdateData;

         }

         // Abort drawing stale low-precision content if there's a more recent

         // display-port in the pipeline.

         if (lowPrecision && !aHasPendingNewThebesContent) {

           mProgressiveUpdateData.abort = true;

         }

         return mProgressiveUpdateData;

     }

     void setZoomConstraints(ZoomConstraints constraints) {

         mZoomConstraints = constraints;

     }

     void setIsRTL(boolean aIsRTL) {

         synchronized (getLock()) {

             ImmutableViewportMetrics newMetrics = getViewportMetrics().setIsRTL(aIsRTL);

             setViewportMetrics(newMetrics, false);

         }

     }

     /** The compositor invokes this function just before compositing a frame where the document

       * is different from the document composited on the last frame. In these cases, the viewport

       * information we have in Java is no longer valid and needs to be replaced with the new

       * viewport information provided. setPageRect will never be invoked on the same frame that

       * this function is invoked on; and this function will always be called prior to syncViewportInfo.

       */

     @WrapElementForJNI(allowMultithread = true)

     public void setFirstPaintViewport(float offsetX, float offsetY, float zoom,

             float cssPageLeft, float cssPageTop, float cssPageRight, float cssPageBottom) {

         synchronized (getLock()) {

             ImmutableViewportMetrics currentMetrics = getViewportMetrics();

             Tab tab = Tabs.getInstance().getSelectedTab();

             RectF cssPageRect = new RectF(cssPageLeft, cssPageTop, cssPageRight, cssPageBottom);

             RectF pageRect = RectUtils.scaleAndRound(cssPageRect, zoom);

             final ImmutableViewportMetrics newMetrics = currentMetrics

                 .setViewportOrigin(offsetX, offsetY)

                 .setZoomFactor(zoom)

                 .setPageRect(pageRect, cssPageRect)

                 .setIsRTL(tab.getIsRTL());

             // Since we have switched to displaying a different document, we need to update any

             // viewport-related state we have lying around. This includes mGeckoViewport and

             // mViewportMetrics. Usually this information is updated via handleViewportMessage

             // while we remain on the same document.

             post(new Runnable() {

                 @Override

                 public void run() {

                     mGeckoViewport = newMetrics;

                 }

             });

             setViewportMetrics(newMetrics);

             mView.setBackgroundColor(tab.getBackgroundColor());

             setZoomConstraints(tab.getZoomConstraints());

             // At this point, we have just switched to displaying a different document than we

             // we previously displaying. This means we need to abort any panning/zooming animations

             // that are in progress and send an updated display port request to browser.js as soon

             // as possible. The call to PanZoomController.abortAnimation accomplishes this by calling the

             // forceRedraw function, which sends the viewport to gecko. The display port request is

             // actually a full viewport update, which is fine because if browser.js has somehow moved to

             // be out of sync with this first-paint viewport, then we force them back in sync.

             abortPanZoomAnimation();

             // Indicate that the document is about to be composited so the

             // LayerView background can be removed.

             if (mView.getPaintState() == LayerView.PAINT_START) {

                 mView.setPaintState(LayerView.PAINT_BEFORE_FIRST);

             }

         }

         DisplayPortCalculator.resetPageState();

         mDrawTimingQueue.reset();

         mContentDocumentIsDisplayed = true;

     }

     /** The compositor invokes this function whenever it determines that the page rect

       * has changed (based on the information it gets from layout). If setFirstPaintViewport

       * is invoked on a frame, then this function will not be. For any given frame, this

       * function will be invoked before syncViewportInfo.

       */

     @WrapElementForJNI(allowMultithread = true)

     public void setPageRect(float cssPageLeft, float cssPageTop, float cssPageRight, float cssPageBottom) {

         synchronized (getLock()) {

             RectF cssPageRect = new RectF(cssPageLeft, cssPageTop, cssPageRight, cssPageBottom);

             float ourZoom = getViewportMetrics().zoomFactor;

             setPageRect(RectUtils.scale(cssPageRect, ourZoom), cssPageRect);

             // Here the page size of the document has changed, but the document being displayed

             // is still the same. Therefore, we don't need to send anything to browser.js; any

             // changes we need to make to the display port will get sent the next time we call

             // adjustViewport().

         }

     }

     /** The compositor invokes this function on every frame to figure out what part of the

       * page to display, and to inform Java of the current display port. Since it is called

       * on every frame, it needs to be ultra-fast.

       * It avoids taking any locks or allocating any objects. We keep around a

       * mCurrentViewTransform so we don't need to allocate a new ViewTransform

       * everytime we're called. NOTE: we might be able to return a ImmutableViewportMetrics

       * which would avoid the copy into mCurrentViewTransform.

       */

     @WrapElementForJNI(allowMultithread = true)

     public ViewTransform syncViewportInfo(int x, int y, int width, int height, float resolution, boolean layersUpdated) {

         // getViewportMetrics is thread safe so we don't need to synchronize.

         // We save the viewport metrics here, so we later use it later in

         // createFrame (which will be called by nsWindow::DrawWindowUnderlay on

         // the native side, by the compositor). The viewport

         // metrics can change between here and there, as it's accessed outside

         // of the compositor thread.

         mFrameMetrics = getViewportMetrics();

         mCurrentViewTransform.x = mFrameMetrics.viewportRectLeft;

         mCurrentViewTransform.y = mFrameMetrics.viewportRectTop;

         mCurrentViewTransform.scale = mFrameMetrics.zoomFactor;

         // Adjust the fixed layer margins so that overscroll subtracts from them.

         getFixedMargins(mFrameMetrics, mCurrentViewTransformMargins);

         mCurrentViewTransform.fixedLayerMarginLeft = mCurrentViewTransformMargins.left;

         mCurrentViewTransform.fixedLayerMarginTop = mCurrentViewTransformMargins.top;

         mCurrentViewTransform.fixedLayerMarginRight = mCurrentViewTransformMargins.right;

         mCurrentViewTransform.fixedLayerMarginBottom = mCurrentViewTransformMargins.bottom;

         // Offset the view transform so that it renders in the correct place.

         PointF offset = mFrameMetrics.getMarginOffset();

         mCurrentViewTransform.offsetX = offset.x;

         mCurrentViewTransform.offsetY = offset.y;

         mRootLayer.setPositionAndResolution(

             Math.round(x + mCurrentViewTransform.offsetX),

             Math.round(y + mCurrentViewTransform.offsetY),

             Math.round(x + width + mCurrentViewTransform.offsetX),

             Math.round(y + height + mCurrentViewTransform.offsetY),

             resolution);

         if (layersUpdated && mRecordDrawTimes) {

             // If we got a layers update, that means a draw finished. Check to see if the area drawn matches

             // one of our requested displayports; if it does calculate the draw time and notify the

             // DisplayPortCalculator

             DisplayPortMetrics drawn = new DisplayPortMetrics(x, y, x + width, y + height, resolution);

             long time = mDrawTimingQueue.findTimeFor(drawn);

             if (time >= 0) {

                 long now = SystemClock.uptimeMillis();

                 time = now - time;

                 mRecordDrawTimes = DisplayPortCalculator.drawTimeUpdate(time, width * height);

             }

         }

         if (layersUpdated) {

             for (DrawListener listener : mDrawListeners) {

                 listener.drawFinished();

             }

         }

         return mCurrentViewTransform;

     }

     @WrapElementForJNI(allowMultithread = true)

     public ViewTransform syncFrameMetrics(float offsetX, float offsetY, float zoom,

                 float cssPageLeft, float cssPageTop, float cssPageRight, float cssPageBottom,

                 boolean layersUpdated, int x, int y, int width, int height, float resolution,

                 boolean isFirstPaint)

     {

         if (isFirstPaint) {

             setFirstPaintViewport(offsetX, offsetY, zoom,

                                   cssPageLeft, cssPageTop, cssPageRight, cssPageBottom);

         }

         return syncViewportInfo(x, y, width, height, resolution, layersUpdated);

     }

     @WrapElementForJNI(allowMultithread = true)

     public LayerRenderer.Frame createFrame() {

         // Create the shaders and textures if necessary.

         if (!mLayerRendererInitialized) {

             mLayerRenderer.checkMonitoringEnabled();

             mLayerRenderer.createDefaultProgram();

             mLayerRendererInitialized = true;

         }

         try {

             return mLayerRenderer.createFrame(mFrameMetrics);

         } catch (Exception e) {

             Log.w(LOGTAG, e);

             return null;

         }

     }

     @WrapElementForJNI(allowMultithread = true)

     public void activateProgram() {

         mLayerRenderer.activateDefaultProgram();

     }

     @WrapElementForJNI(allowMultithread = true)

     public void deactivateProgram() {

         mLayerRenderer.deactivateDefaultProgram();

     }

     private void geometryChanged(DisplayPortMetrics displayPort) {

         /* Let Gecko know if the screensize has changed */

         sendResizeEventIfNecessary(false);

         if (getRedrawHint()) {

             adjustViewport(displayPort);

         }

     }

     /** Implementation of LayerView.Listener */

     @Override

     public void renderRequested() {

         try {

             GeckoAppShell.scheduleComposite();

         } catch (UnsupportedOperationException uoe) {

             // In some very rare cases this gets called before libxul is loaded,

             // so catch and ignore the exception that will throw. See bug 837821

             Log.d(LOGTAG, "Dropping renderRequested call before libxul load.");

         }

     }

     /** Implementation of LayerView.Listener */

     @Override

     public void sizeChanged(int width, int height) {

         // We need to make sure a draw happens synchronously at this point,

         // but resizing the surface before the SurfaceView has resized will

         // cause a visible jump.

         mView.getGLController().resumeCompositor(mWindowSize.width, mWindowSize.height);

     }

     /** Implementation of LayerView.Listener */

     @Override

     public void surfaceChanged(int width, int height) {

         setViewportSize(width, height);

     }

     /** Implementation of PanZoomTarget */

     @Override

     public ImmutableViewportMetrics getViewportMetrics() {

         return mViewportMetrics;

     }

     /** Implementation of PanZoomTarget */

     @Override

     public ZoomConstraints getZoomConstraints() {

         return mZoomConstraints;

     }

     /** Implementation of PanZoomTarget */

     @Override

     public boolean isFullScreen() {

         return mView.isFullScreen();

     }

     /** Implementation of PanZoomTarget */

     @Override

     public RectF getMaxMargins() {

         return mMarginsAnimator.getMaxMargins();

     }

     /** Implementation of PanZoomTarget */

     @Override

     public void setAnimationTarget(ImmutableViewportMetrics metrics) {

         if (mGeckoIsReady) {

             // We know what the final viewport of the animation is going to be, so

             // immediately request a draw of that area by setting the display port

             // accordingly. This way we should have the content pre-rendered by the

             // time the animation is done.

             DisplayPortMetrics displayPort = DisplayPortCalculator.calculate(metrics, null);

             adjustViewport(displayPort);

         }

     }

     /** Implementation of PanZoomTarget

      * You must hold the monitor while calling this.

      */

     @Override

     public void setViewportMetrics(ImmutableViewportMetrics metrics) {

         setViewportMetrics(metrics, true);

     }

     /*

      * You must hold the monitor while calling this.

      */

     private void setViewportMetrics(ImmutableViewportMetrics metrics, boolean notifyGecko) {

         // This class owns the viewport size and the fixed layer margins; don't let other pieces

         // of code clobber either of them. The only place the viewport size should ever be

         // updated is in GeckoLayerClient.setViewportSize, and the only place the margins should

         // ever be updated is in GeckoLayerClient.setFixedLayerMargins; both of these assign to

         // mViewportMetrics directly.

         metrics = metrics.setViewportSize(mViewportMetrics.getWidth(), mViewportMetrics.getHeight());

         metrics = metrics.setMarginsFrom(mViewportMetrics);

         mViewportMetrics = metrics;

         viewportMetricsChanged(notifyGecko);

     }

     /*

      * You must hold the monitor while calling this.

      */

     private void viewportMetricsChanged(boolean notifyGecko) {

         if (mViewportChangeListener != null) {

             mViewportChangeListener.onMetricsChanged(mViewportMetrics);

         }

         mView.requestRender();

         if (notifyGecko && mGeckoIsReady) {

             geometryChanged(null);

         }

     }

     /*

      * Updates the viewport metrics, overriding the viewport size and margins

      * which are normally retained when calling setViewportMetrics.

      * You must hold the monitor while calling this.

      */

     void forceViewportMetrics(ImmutableViewportMetrics metrics, boolean notifyGecko, boolean forceRedraw) {

         if (forceRedraw) {

             mForceRedraw = true;

         }

         mViewportMetrics = metrics;

         viewportMetricsChanged(notifyGecko);

     }

     /** Implementation of PanZoomTarget

      * Scroll the viewport by a certain amount. This will take viewport margins

      * and margin animation into account. If margins are currently animating,

      * this will just go ahead and modify the viewport origin, otherwise the

      * delta will be applied to the margins and the remainder will be applied to

      * the viewport origin.

      *

      * You must hold the monitor while calling this.

      */

     @Override

     public void scrollBy(float dx, float dy) {

         // Set mViewportMetrics manually so the margin changes take.

         mViewportMetrics = mMarginsAnimator.scrollBy(mViewportMetrics, dx, dy);

         viewportMetricsChanged(true);

     }

     /** Implementation of PanZoomTarget

      * Notification that a subdocument has been scrolled by a certain amount.

      * This is used here to make sure that the margins are still accessible

      * during subdocument scrolling.

      *

      * You must hold the monitor while calling this.

      */

     @Override

     public void scrollMarginsBy(float dx, float dy) {

         ImmutableViewportMetrics newMarginsMetrics =

             mMarginsAnimator.scrollBy(mViewportMetrics, dx, dy);

         mViewportMetrics = mViewportMetrics.setMarginsFrom(newMarginsMetrics);

         viewportMetricsChanged(true);

     }

     /** Implementation of PanZoomTarget */

     @Override

     public void panZoomStopped() {

         if (mViewportChangeListener != null) {

             mViewportChangeListener.onPanZoomStopped();

         }

     }

     /** Implementation of PanZoomTarget */

     @Override

     public void forceRedraw(DisplayPortMetrics displayPort) {

         mForceRedraw = true;

         if (mGeckoIsReady) {

             geometryChanged(displayPort);

         }

     }

     /** Implementation of PanZoomTarget */

     @Override

     public boolean post(Runnable action) {

         return mView.post(action);

     }

     /** Implementation of PanZoomTarget */

     @Override

     public void postRenderTask(RenderTask task) {

         mView.postRenderTask(task);

     }

     /** Implementation of PanZoomTarget */

     @Override

     public void removeRenderTask(RenderTask task) {

         mView.removeRenderTask(task);

     }

     /** Implementation of PanZoomTarget */

     @Override

     public boolean postDelayed(Runnable action, long delayMillis) {

         return mView.postDelayed(action, delayMillis);

     }

     /** Implementation of PanZoomTarget */

     @Override

     public Object getLock() {

         return this;

     }

     /** Implementation of PanZoomTarget

      * Converts a point from layer view coordinates to layer coordinates. In other words, given a

      * point measured in pixels from the top left corner of the layer view, returns the point in

      * pixels measured from the last scroll position we sent to Gecko, in CSS pixels. Assuming the

      * events being sent to Gecko are processed in FIFO order, this calculation should always be

      * correct.

      */

     @Override

     public PointF convertViewPointToLayerPoint(PointF viewPoint) {

         if (!mGeckoIsReady) {

             return null;

         }

         ImmutableViewportMetrics viewportMetrics = mViewportMetrics;

         PointF origin = viewportMetrics.getOrigin();

         PointF offset = viewportMetrics.getMarginOffset();

         origin.offset(-offset.x, -offset.y);

         float zoom = viewportMetrics.zoomFactor;

         ImmutableViewportMetrics geckoViewport = mGeckoViewport;

         PointF geckoOrigin = geckoViewport.getOrigin();

         float geckoZoom = geckoViewport.zoomFactor;

         // viewPoint + origin - offset gives the coordinate in device pixels from the top-left corner of the page.

         // Divided by zoom, this gives us the coordinate in CSS pixels from the top-left corner of the page.

         // geckoOrigin / geckoZoom is where Gecko thinks it is (scrollTo position) in CSS pixels from

         // the top-left corner of the page. Subtracting the two gives us the offset of the viewPoint from

         // the current Gecko coordinate in CSS pixels.

         PointF layerPoint = new PointF(

                 ((viewPoint.x + origin.x) / zoom) - (geckoOrigin.x / geckoZoom),

                 ((viewPoint.y + origin.y) / zoom) - (geckoOrigin.y / geckoZoom));

         return layerPoint;

     }

     void setOnMetricsChangedListener(LayerView.OnMetricsChangedListener listener) {

         mViewportChangeListener = listener;

     }

     public void addDrawListener(DrawListener listener) {

         mDrawListeners.add(listener);

     }

     public void removeDrawListener(DrawListener listener) {

         mDrawListeners.remove(listener);

     }

 }