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 * The Original Code is Mozilla Android code.
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 * Contributor(s):
 *   Patrick Walton <pcwalton@mozilla.com>
 *   Chris Lord <chrislord.net@gmail.com>
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package org.mozilla.gecko.gfx;

import org.mozilla.gecko.gfx.IntSize;
import org.mozilla.gecko.gfx.Layer;
import org.mozilla.gecko.gfx.LayerClient;
import org.mozilla.gecko.gfx.LayerView;
import org.mozilla.gecko.ui.PanZoomController;
import org.mozilla.gecko.ui.SimpleScaleGestureDetector;
import org.mozilla.gecko.GeckoApp;
import org.mozilla.gecko.GeckoEvent;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.graphics.Point;
import android.graphics.PointF;
import android.graphics.Rect;
import android.graphics.RectF;
import android.util.Log;
import android.view.MotionEvent;
import android.view.GestureDetector;
import android.view.ScaleGestureDetector;
import android.view.View.OnTouchListener;
import java.lang.Math;
import java.util.Timer;
import java.util.TimerTask;

/**
 * The layer controller manages a tile that represents the visible page. It does panning and
 * zooming natively by delegating to a panning/zooming controller. Touch events can be dispatched
 * to a higher-level view.
 *
 * Many methods require that the monitor be held, with a synchronized (controller) { ... } block.
 */
public class LayerController {
    private static final String LOGTAG = "GeckoLayerController";

    private Layer mRootLayer;                   /* The root layer. */
    private LayerView mView;                    /* The main rendering view. */
    private Context mContext;                   /* The current context. */
    private ViewportMetrics mViewportMetrics;   /* The current viewport metrics. */
    private boolean mWaitForTouchListeners;

    private PanZoomController mPanZoomController;
    /*
     * The panning and zooming controller, which interprets pan and zoom gestures for us and
     * updates our visible rect appropriately.
     */

    private OnTouchListener mOnTouchListener;       /* The touch listener. */
    private LayerClient mLayerClient;               /* The layer client. */

    /* The new color for the checkerboard. */
    private int mCheckerboardColor;

    private boolean mForceRedraw;

    /* The extra area on the sides of the page that we want to buffer to help with
     * smooth, asynchronous scrolling. Depending on a device's support for NPOT
     * textures, this may be rounded up to the nearest power of two.
     */
    public static final IntSize MIN_BUFFER = new IntSize(512, 1024);

    /* If the visible rect is within the danger zone (measured in pixels from each edge of a tile),
     * we start aggressively redrawing to minimize checkerboarding. */
    private static final int DANGER_ZONE_X = 75;
    private static final int DANGER_ZONE_Y = 150;

    /* The time limit for pages to respond with preventDefault on touchevents
     * before we begin panning the page */
    private static final int PREVENT_DEFAULT_TIMEOUT = 200;

    private boolean allowDefaultActions = true;
    private Timer allowDefaultTimer =  null;
    private boolean inTouchSession = false;
    private PointF initialTouchLocation = null;

    public LayerController(Context context) {
        mContext = context;

        mForceRedraw = true;
        mViewportMetrics = new ViewportMetrics();
        mPanZoomController = new PanZoomController(this);
        mView = new LayerView(context, this);
    }

    public void setRoot(Layer layer) { mRootLayer = layer; }

    public void setLayerClient(LayerClient layerClient) {
        mLayerClient = layerClient;
        layerClient.setLayerController(this);
    }

    public void setForceRedraw() {
        mForceRedraw = true;
    }

    public LayerClient getLayerClient()           { return mLayerClient; }
    public Layer getRoot()                        { return mRootLayer; }
    public LayerView getView()                    { return mView; }
    public Context getContext()                   { return mContext; }
    public ViewportMetrics getViewportMetrics()   { return mViewportMetrics; }

    public RectF getViewport() {
        return mViewportMetrics.getViewport();
    }

    public FloatSize getViewportSize() {
        return mViewportMetrics.getSize();
    }

    public FloatSize getPageSize() {
        return mViewportMetrics.getPageSize();
    }

    public PointF getOrigin() {
        return mViewportMetrics.getOrigin();
    }

    public float getZoomFactor() {
        return mViewportMetrics.getZoomFactor();
    }

    public Bitmap getBackgroundPattern()    { return getDrawable("background"); }
    public Bitmap getShadowPattern()        { return getDrawable("shadow"); }

    public PanZoomController getPanZoomController()                                 { return mPanZoomController; }
    public GestureDetector.OnGestureListener getGestureListener()                   { return mPanZoomController; }
    public SimpleScaleGestureDetector.SimpleScaleGestureListener getScaleGestureListener() {
        return mPanZoomController;
    }
    public GestureDetector.OnDoubleTapListener getDoubleTapListener()               { return mPanZoomController; }

    private Bitmap getDrawable(String name) {
        Resources resources = mContext.getResources();
        int resourceID = resources.getIdentifier(name, "drawable", mContext.getPackageName());
        BitmapFactory.Options options = new BitmapFactory.Options();
        options.inScaled = false;
        return BitmapFactory.decodeResource(mContext.getResources(), resourceID, options);
    }

    /**
     * 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.
     */
    public void setViewportSize(FloatSize size) {
        // Resize the viewport, and modify its zoom factor so that the page retains proportionally
        // zoomed relative to the screen.
        float oldHeight = mViewportMetrics.getSize().height;
        float oldWidth = mViewportMetrics.getSize().width;
        float oldZoomFactor = mViewportMetrics.getZoomFactor();
        mViewportMetrics.setSize(size);

        // if the viewport got larger (presumably because the vkb went away), and the page
        // is smaller than the new viewport size, increase the page size so that the panzoomcontroller
        // doesn't zoom in to make it fit (bug 718270). this page size change is in anticipation of
        // gecko increasing the page size to match the new viewport size, which will happen the next
        // time we get a draw update.
        if (size.width >= oldWidth && size.height >= oldHeight) {
            FloatSize pageSize = mViewportMetrics.getPageSize();
            if (pageSize.width < size.width || pageSize.height < size.height) {
                mViewportMetrics.setPageSize(new FloatSize(Math.max(pageSize.width, size.width),
                                                           Math.max(pageSize.height, size.height)));
            }
        }

        PointF newFocus = new PointF(size.width / 2.0f, size.height / 2.0f);
        float newZoomFactor = size.width * oldZoomFactor / oldWidth;
        mViewportMetrics.scaleTo(newZoomFactor, newFocus);

        Log.d(LOGTAG, "setViewportSize: " + mViewportMetrics);
        setForceRedraw();

        if (mLayerClient != null)
            mLayerClient.viewportSizeChanged();

        notifyLayerClientOfGeometryChange();
        mPanZoomController.abortAnimation();
        mView.requestRender();
    }

    /** Scrolls the viewport by the given offset. You must hold the monitor while calling this. */
    public void scrollBy(PointF point) {
        PointF origin = mViewportMetrics.getOrigin();
        origin.offset(point.x, point.y);
        mViewportMetrics.setOrigin(origin);
        Log.d(LOGTAG, "scrollBy: " + mViewportMetrics);

        notifyLayerClientOfGeometryChange();
        GeckoApp.mAppContext.repositionPluginViews(false);
        mView.requestRender();
    }

    /** Sets the current page size. You must hold the monitor while calling this. */
    public void setPageSize(FloatSize size) {
        if (mViewportMetrics.getPageSize().fuzzyEquals(size))
            return;

        mViewportMetrics.setPageSize(size);
        Log.d(LOGTAG, "setPageSize: " + mViewportMetrics);

        // Page size is owned by the LayerClient, so no need to notify it of
        // this change.
        mView.requestRender();
    }

    /**
     * Sets the entire viewport metrics at once. This function does not notify the layer client or
     * the pan/zoom controller, so you will need to call notifyLayerClientOfGeometryChange() or
     * notifyPanZoomControllerOfGeometryChange() after calling this. You must hold the monitor
     * while calling this.
     */
    public void setViewportMetrics(ViewportMetrics viewport) {
        mViewportMetrics = new ViewportMetrics(viewport);
        Log.d(LOGTAG, "setViewportMetrics: " + mViewportMetrics);
        // this function may or may not be called on the UI thread,
        // but repositionPluginViews must only be called on the UI thread.
        GeckoApp.mAppContext.runOnUiThread(new Runnable() {
            public void run() {
                GeckoApp.mAppContext.repositionPluginViews(false);
            }
        });
        mView.requestRender();
    }

    /**
     * Scales the viewport, keeping the given focus point in the same place before and after the
     * scale operation. You must hold the monitor while calling this.
     */
    public void scaleWithFocus(float zoomFactor, PointF focus) {
        mViewportMetrics.scaleTo(zoomFactor, focus);
        Log.d(LOGTAG, "scaleWithFocus: " + mViewportMetrics + "; zf=" + zoomFactor);

        // We assume the zoom level will only be modified by the
        // PanZoomController, so no need to notify it of this change.
        notifyLayerClientOfGeometryChange();
        GeckoApp.mAppContext.repositionPluginViews(false);
        mView.requestRender();
    }

    public boolean post(Runnable action) { return mView.post(action); }

    public void setOnTouchListener(OnTouchListener onTouchListener) {
        mOnTouchListener = onTouchListener;
    }

    /**
     * The view as well as the controller itself use this method to notify the layer client that
     * the geometry changed.
     */
    public void notifyLayerClientOfGeometryChange() {
        if (mLayerClient != null)
            mLayerClient.geometryChanged();
    }

    /** Aborts any pan/zoom animation that is currently in progress. */
    public void abortPanZoomAnimation() {
        if (mPanZoomController != null) {
            mView.post(new Runnable() {
                public void run() {
                    mPanZoomController.abortAnimation();
                }
            });
        }
    }

    /**
     * Returns true if this controller is fine with performing a redraw operation or false if it
     * would prefer that the action didn't take place.
     */
    public boolean getRedrawHint() {
        if (mForceRedraw) {
            mForceRedraw = false;
            return true;
        }

        return aboutToCheckerboard() && mPanZoomController.getRedrawHint();
    }

    private RectF getTileRect() {
        if (mRootLayer == null)
            return new RectF();

        float x = mRootLayer.getOrigin().x, y = mRootLayer.getOrigin().y;
        IntSize layerSize = mRootLayer.getSize();
        return new RectF(x, y, x + layerSize.width, y + layerSize.height);
    }

    public RectF restrictToPageSize(RectF aRect) {
        FloatSize pageSize = getPageSize();
        return RectUtils.restrict(aRect, new RectF(0, 0, pageSize.width, pageSize.height));
    }

    // Returns true if a checkerboard is about to be visible.
    private boolean aboutToCheckerboard() {
        // Increase the size of the viewport (and clamp to page boundaries), and
        // intersect it with the tile's displayport to determine whether we're
        // close to checkerboarding.
        FloatSize pageSize = getPageSize();
        RectF adjustedViewport = RectUtils.expand(getViewport(), DANGER_ZONE_X, DANGER_ZONE_Y);
        if (adjustedViewport.top < 0) adjustedViewport.top = 0;
        if (adjustedViewport.left < 0) adjustedViewport.left = 0;
        if (adjustedViewport.right > pageSize.width) adjustedViewport.right = pageSize.width;
        if (adjustedViewport.bottom > pageSize.height) adjustedViewport.bottom = pageSize.height;

        return !getTileRect().contains(adjustedViewport);
    }

    /**
     * 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 top left corner of the root layer, in the coordinate system of the
     * layer itself. This method is used by the viewport controller as part of the process of
     * translating touch events to Gecko's coordinate system.
     */
    public PointF convertViewPointToLayerPoint(PointF viewPoint) {
        if (mRootLayer == null)
            return null;

        // Undo the transforms.
        PointF origin = mViewportMetrics.getOrigin();
        PointF newPoint = new PointF(origin.x, origin.y);
        newPoint.offset(viewPoint.x, viewPoint.y);

        Point rootOrigin = mRootLayer.getOrigin();
        newPoint.offset(-rootOrigin.x, -rootOrigin.y);

        return newPoint;
    }

    /*
     * Gesture detection. This is handled only at a high level in this class; we dispatch to the
     * pan/zoom controller to do the dirty work.
     */
    public boolean onTouchEvent(MotionEvent event) {
        int action = event.getAction();
        PointF point = new PointF(event.getX(), event.getY());
        if ((action & MotionEvent.ACTION_MASK) == MotionEvent.ACTION_DOWN) {
            initialTouchLocation = point;
            post(new Runnable() {
                public void run() {
                    mView.clearEventQueue();
                    preventPanning(mWaitForTouchListeners);
                }
            });
        }

        if (initialTouchLocation != null && (action & MotionEvent.ACTION_MASK) == MotionEvent.ACTION_MOVE) {
            if (PointUtils.subtract(point, initialTouchLocation).length() > PanZoomController.PAN_THRESHOLD * 240) {
                initialTouchLocation = null;
            } else {
                return !allowDefaultActions;
            }
        }

        if (mOnTouchListener != null)
            mOnTouchListener.onTouch(mView, event);

        if (!mWaitForTouchListeners)
            return !allowDefaultActions;

        switch (action & MotionEvent.ACTION_MASK) {
            case MotionEvent.ACTION_MOVE: {
                if (!inTouchSession && allowDefaultTimer == null) {
                    inTouchSession = true;
                    allowDefaultTimer = new Timer();
                    allowDefaultTimer.schedule(new TimerTask() {
                        public void run() {
                            post(new Runnable() {
                                public void run() {
                                    preventPanning(false);
                                }
                            });
                        }
                    }, PREVENT_DEFAULT_TIMEOUT);
                }
                break;
            }
            case MotionEvent.ACTION_CANCEL:
            case MotionEvent.ACTION_UP: {
                inTouchSession = false;
            }
        }
        return !allowDefaultActions;
    }

    public void preventPanning(boolean aValue) {
        if (allowDefaultTimer != null) {
            allowDefaultTimer.cancel();
            allowDefaultTimer.purge();
            allowDefaultTimer = null;
        }
        allowDefaultActions = !aValue;

        if (aValue) {
            mView.clearEventQueue();
            mPanZoomController.cancelTouch();
        } else {
            mView.processEventQueue();
        }
    }

    public void setWaitForTouchListeners(boolean aValue) {
        mWaitForTouchListeners = aValue;
    }

    /** Retrieves the color that the checkerboard should be. */
    public int getCheckerboardColor() {
        return mCheckerboardColor;
    }

    /** Sets a new color for the checkerboard. */
    public void setCheckerboardColor(int newColor) {
        mCheckerboardColor = newColor;
        mView.requestRender();
    }
}