# LocationCacheAspect.java

    /*
    ** Module   : LocationCacheAspect.java
    ** Abstract : An aspect which intercepts APIs related to screen location cache.
    **
    ** Copyright (c) 2018-2024, Golden Code Development Corporation.
    **
    ** -#- -I- --Date-- ---------------------------------Description----------------------------------
    ** 001 CA  20180208 Created initial version.
    ** 002 CA  20180209 A fix - iajc compiler requires absolute names in the aspect definition.
    ** 003 HC  20240806 Added support for displaying frame widget in an overlay window.
    */
    /*
    ** This program is free software: you can redistribute it and/or modify
    ** it under the terms of the GNU Affero General Public License as
    ** published by the Free Software Foundation, either version 3 of the
    ** License, or (at your option) any later version.
    **
    ** This program is distributed in the hope that it will be useful,
    ** but WITHOUT ANY WARRANTY; without even the implied warranty of
    ** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    ** GNU Affero General Public License for more details.
    **
    ** You may find a copy of the GNU Affero GPL version 3 at the following
    ** location: https://www.gnu.org/licenses/agpl-3.0.en.html
    **
    ** Additional terms under GNU Affero GPL version 3 section 7:
    **
    **   Under Section 7 of the GNU Affero GPL version 3, the following additional
    **   terms apply to the works covered under the License.  These additional terms
    **   are non-permissive additional terms allowed under Section 7 of the GNU
    **   Affero GPL version 3 and may not be removed by you.
    **
    **   0. Attribution Requirement.
    **
    **     You must preserve all legal notices or author attributions in the covered
    **     work or Appropriate Legal Notices displayed by works containing the covered
    **     work.  You may not remove from the covered work any author or developer
    **     credit already included within the covered work.
    **
    **   1. No License To Use Trademarks.
    **
    **     This license does not grant any license or rights to use the trademarks
    **     Golden Code, FWD, any Golden Code or FWD logo, or any other trademarks
    **     of Golden Code Development Corporation. You are not authorized to use the
    **     name Golden Code, FWD, or the names of any author or contributor, for
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    **     Golden Code Development Corporation, FWD, or any author or contributor to
    **     the covered work, without written authorization.
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    **
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    **     versions of the covered work must be marked in a reasonable way to make it
    **     clear that the modified work is not originating from Golden Code Development
    **     Corporation or FWD.  All modified versions must contain the notices of
    **     attribution required in this license.
    */

    package com.goldencode.p2j.aspects.ui;

    import org.aspectj.lang.*;
    import org.aspectj.lang.annotation.*;

    import com.goldencode.p2j.ui.client.*;
    import com.goldencode.p2j.ui.client.widget.*;

    /**
     * This aspects takes care of intercepting the APIs which require to either cache the screen
     * location values or disable the caching for them.  This includes:
     * <ul>
     *    <li>disabling and/or reseting the cached values when layout is performed.</li>
     *    <li>caching these values (as appropriate) when the {@link Widget#screenLocation()} and
     *    {@link Widget#screenPhysicalLocation()} APIs are executed.</li>
     * </ul>
     */
    @Aspect()
    public class LocationCacheAspect
    {
       /**
        * Tracks the depth of layout-related nested API calls.  When is zero, it will force the
        * {@link AbstractWidget#reflectLocationChanged() cached values to be reset.}
        */
       private static int layoutDepth = 0;

       /**
        * Executed around the {@link com.goldencode.p2j.ui.client.layout.LayoutManager} APIs, keeping
        * track of the nested depth via {@link #layoutDepth}.
        * <p>
        * Before executing the API, it will reset any cached location values.
        *
        * @param    thisJoinPoint
        *           A join point reference.
        * @param    container
        *           The container parameter instance.
        *
        * @return   The value of the join point method.
        *
        * @throws  Throwable
        *          Any exceptions are untouched propagated out.
        */
       @Around("args(container) " +
               " && execution(public void com.goldencode.p2j.ui.client.layout.LayoutManager+.*(..))")
       public Object disableLocationCacheForLayout(ProceedingJoinPoint thisJoinPoint,
                                                   Container<?> container)
       throws Throwable
       {
          AbstractWidget<?> widget = (AbstractWidget<?>) container;

          if (layoutDepth == 0)
          {
             // ensure nothing is cached
             widget.reflectLocationChanged();
          }

          layoutDepth += 1;

          try
          {
             return thisJoinPoint.proceed();
          }
          finally
          {
             // no need to reflectLocationChange, as nothing gets cached while the depth is non-zero
             layoutDepth -= 1;
          }
       }

       /**
        * Executed around the {@link Container#doLayout()} and related APIs, keeping track of the
        * nested depth via {@link #layoutDepth}.
        * <p>
        * Before executing the API, it will reset any cached location values.
        *
        * @param    thisJoinPoint
        *           A join point reference.
        *
        * @return   The value of the join point method.
        *
        * @throws  Throwable
        *          Any exceptions are untouched propagated out.
        */
       @Around("execution(public void com.goldencode.p2j.ui.client.widget.Container+.doLayout()) " +
               " || execution(protected void com.goldencode.p2j.ui.client.Frame+.doLayoutWorker(boolean))")
       public Object disableLocationCacheInContainer(ProceedingJoinPoint thisJoinPoint)
       throws Throwable
       {
          AbstractWidget<?> widget = (AbstractWidget<?>) thisJoinPoint.getThis();

          if (layoutDepth == 0)
          {
             // ensure nothing is cached
             widget.reflectLocationChanged();
          }

          layoutDepth += 1;

          try
          {
             return thisJoinPoint.proceed();
          }
          finally
          {
             // no need to reflectLocationChange, as nothing gets cached while the depth is non-zero
             layoutDepth -= 1;
          }
       }

       /**
        * Executed around the {@link Widget#screenLocation()} API.  If the widget has an already
        * cached value and the {@link #layoutDepth} is zero, it will use it.  Otherwise, it will
        * compute it and cache it (if {@link #layoutDepth} is zero).
        *
        * @param    thisJoinPoint
        *           A join point reference.
        *
        * @return   The value of the join point method.
        *
        * @throws  Throwable
        *          Any exceptions are untouched propagated out.
        */
       @Around("execution(public com.goldencode.p2j.ui.client.Point " +
               "com.goldencode.p2j.ui.client.widget.Widget+.screenLocation())")
       public Object cacheScreenLocation(ProceedingJoinPoint thisJoinPoint)
       throws Throwable
       {
          AbstractWidget<?> widget = (AbstractWidget<?>) thisJoinPoint.getThis();

          if (layoutDepth == 0)
          {
             Point cached = widget.getCachedScreenLocation();
             if (cached != null)
             {
                return cached;
             }
          }

          Point location = (Point) thisJoinPoint.proceed();

          if (layoutDepth == 0)
          {
             widget.setCachedScreenLocation(location);
          }

          return location;
       }

       /**
        * Executed around the {@link Widget#screenPhysicalLocation()} API.  If the widget has an already
        * cached value and the {@link #layoutDepth} is zero, it will use it.  Otherwise, it will
        * compute it and cache it (if {@link #layoutDepth} is zero).
        *
        * @param    thisJoinPoint
        *           A join point reference.
        *
        * @return   The value of the join point method.
        *
        * @throws  Throwable
        *          Any exceptions are untouched propagated out.
        */
       @Around("execution(public com.goldencode.p2j.ui.client.NativePoint " +
               "com.goldencode.p2j.ui.client.widget.Widget+.screenPhysicalLocation())")
       public Object cacheScreenPhysicalLocation(ProceedingJoinPoint thisJoinPoint)
       throws Throwable
       {
          AbstractWidget<?> widget = (AbstractWidget<?>) thisJoinPoint.getThis();

          if (layoutDepth == 0)
          {
             NativePoint cached = widget.getCachedScreenPhysicalLocation();
             if (cached != null)
             {
                return cached;
             }
          }

          NativePoint location = (NativePoint) thisJoinPoint.proceed();

          if (layoutDepth == 0)
          {
             widget.setCachedScreenPhysicalLocation(location);
          }

          return location;
       }
    }