Groups.cpp

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/* Groups.cpp

   Copyright (C)  David C. J. Matthews 2004  dm at prolingua.co.uk

   This program is free software; you can redistribute it and/or
   modify it under the terms of the GNU General Public License
   as published by the Free Software Foundation; either version 2
   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 General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
   Or, point your browser to http://www.gnu.org/copyleft/gpl.html

*/

#include "Root.h"
#include "Groups.h"
#include "ASN1Codes.h"
#include "ParseNode.h"
#include "Ingredients.h"
#include "Programs.h"
#include "Variables.h"
#include "Presentable.h"
#include "Visible.h"
#include "Engine.h"
#include "Text.h"
#include "Bitmap.h"
#include "Stream.h"
#include "DynamicLineArt.h"
#include "Link.h"
#include "TokenGroup.h"
#include "Logging.h"

MHGroup::MHGroup()
{
    m_nOrigGCPriority = 127; // Default.
    m_Timers.setAutoDelete(true);
    m_nLastId = 0;
}

void MHGroup::Initialise(MHParseNode *p, MHEngine *engine)
{
    engine->GetGroupId().Copy(""); // Set to empty before we start (just in case).
    MHRoot::Initialise(p, engine);
    // Must be an external reference with an object number of zero.
    if (m_ObjectReference.m_nObjectNo != 0 || m_ObjectReference.m_GroupId.Size() == 0)
        MHERROR("Object reference for a group object must be zero and external");
    // Set the group id for the rest of the group to this.
    engine->GetGroupId().Copy(m_ObjectReference.m_GroupId);
    // Some of the information is irrelevant.
//  MHParseNode *pStdId = p->GetNamedArg(C_STANDARD_IDENTIFIER);
//  MHParseNode *pStdVersion = p->GetNamedArg(C_STANDARD_VERSION);
//  MHParseNode *pObjectInfo = p->GetNamedArg(C_OBJECT_INFORMATION);

    MHParseNode *pOnStartUp = p->GetNamedArg(C_ON_START_UP);
    if (pOnStartUp) m_StartUp.Initialise(pOnStartUp, engine);
    MHParseNode *pOnCloseDown = p->GetNamedArg(C_ON_CLOSE_DOWN);
    if (pOnCloseDown) m_CloseDown.Initialise(pOnCloseDown, engine);
    MHParseNode *pOriginalGCPrio = p->GetNamedArg(C_ORIGINAL_GC_PRIORITY);
    if (pOriginalGCPrio) m_nOrigGCPriority = pOriginalGCPrio->GetArgN(0)->GetIntValue();

    // Ignore the other stuff at the moment.
    MHParseNode *pItems = p->GetNamedArg(C_ITEMS);
    if (pItems == NULL) p->Failure("Missing :Items block");
    for (int i = 0; i < pItems->GetArgCount(); i++) {
        MHParseNode *pItem = pItems->GetArgN(i);
        MHIngredient *pIngredient = NULL;
        try {
            // Generate the particular kind of ingredient.
            switch (pItem->GetTagNo()) {
            case C_RESIDENT_PROGRAM: pIngredient = new MHResidentProgram; break;
            case C_REMOTE_PROGRAM: pIngredient = new MHRemoteProgram; break;
            case C_INTERCHANGED_PROGRAM: pIngredient = new MHInterChgProgram; break;
            case C_PALETTE: pIngredient = new MHPalette; break;
            case C_FONT: pIngredient = new MHFont; break;
            case C_CURSOR_SHAPE: pIngredient = new MHCursorShape; break;
            case C_BOOLEAN_VARIABLE: pIngredient = new MHBooleanVar; break;
            case C_INTEGER_VARIABLE: pIngredient = new MHIntegerVar; break;
            case C_OCTET_STRING_VARIABLE: pIngredient = new MHOctetStrVar; break;
            case C_OBJECT_REF_VARIABLE: pIngredient = new MHObjectRefVar; break;
            case C_CONTENT_REF_VARIABLE: pIngredient = new MHContentRefVar; break;
            case C_LINK: pIngredient = new MHLink; break;
            case C_STREAM: pIngredient = new MHStream; break;
            case C_BITMAP: pIngredient = new MHBitmap; break;
            case C_LINE_ART: pIngredient = new MHLineArt; break;
            case C_DYNAMIC_LINE_ART: pIngredient = new MHDynamicLineArt; break;
            case C_RECTANGLE: pIngredient = new MHRectangle; break;
            case C_HOTSPOT: pIngredient = new MHHotSpot; break;
            case C_SWITCH_BUTTON: pIngredient = new MHSwitchButton; break;
            case C_PUSH_BUTTON: pIngredient = new MHPushButton; break;
            case C_TEXT: pIngredient = new MHText; break;
            case C_ENTRY_FIELD: pIngredient = new MHEntryField; break;
            case C_HYPER_TEXT: pIngredient = new MHHyperText; break;
            case C_SLIDER: pIngredient = new MHSlider; break;
            case C_TOKEN_GROUP: pIngredient = new MHTokenGroup; break;
            case C_LIST_GROUP: pIngredient = new MHListGroup; break;
            default:
                MHLOG(MHLogWarning, QString("Unknown ingredient %1").arg(pItem->GetTagNo()));
                // Future proofing: ignore any ingredients that we don't know about.
                // Obviously these can only arise in the binary coding.
            }
            if (pIngredient) {
                // Initialise it from its argments.
                pIngredient->Initialise(pItem, engine);
                // Remember the highest numbered ingredient
                if (pIngredient->m_ObjectReference.m_nObjectNo > m_nLastId)
                    m_nLastId = pIngredient->m_ObjectReference.m_nObjectNo;
                // Add it to the ingedients of this group.
                m_Items.Append(pIngredient);
            }
        }
        catch (...) {
            delete(pIngredient);
            throw;
        }
    }
}

void MHGroup::PrintMe(FILE *fd, int nTabs) const
{
    MHRoot::PrintMe(fd, nTabs);
    if (m_StartUp.Size() != 0) {
        PrintTabs(fd, nTabs+1); fprintf(fd, ":OnStartUp (\n");
        m_StartUp.PrintMe(fd, nTabs+2);
        PrintTabs(fd, nTabs+2); fprintf(fd, ")\n");
    }
    if (m_CloseDown.Size() != 0) {
        PrintTabs(fd, nTabs+1); fprintf(fd, ":OnCloseDown (\n");
        m_CloseDown.PrintMe(fd, nTabs+2);
        PrintTabs(fd, nTabs+2); fprintf(fd, ")\n");
    }
    if (m_nOrigGCPriority != 127) { PrintTabs(fd, nTabs+1); fprintf(fd, ":OrigGCPriority %d\n", m_nOrigGCPriority); }
    PrintTabs(fd, nTabs+1); fprintf(fd, ":Items ( \n");
    for (int i = 0; i < m_Items.Size(); i++) m_Items.GetAt(i)->PrintMe(fd, nTabs+2);
    PrintTabs(fd, nTabs+1); fprintf(fd, ")\n");
}

// Preparation - sets up the run-time representation.  Sets m_fAvailable and generates IsAvailable event.
void MHGroup::Preparation(MHEngine *engine)
{
    // Prepare the ingredients first if they are initially active or are initially available programs. 
    for (int i = 0; i < m_Items.Size(); i++) {
        MHIngredient *pIngredient = m_Items.GetAt(i);
        if (pIngredient->InitiallyActive() || pIngredient->InitiallyAvailable()) {
            pIngredient->Preparation(engine);
        }
    }
    MHRoot::Preparation(engine); // Prepare the root object and send the IsAvailable event.
}

// Activation - starts running the object.  Sets m_fRunning and generates IsRunning event.
void MHGroup::Activation(MHEngine *engine)
{
    if (m_fRunning) return;
    MHRoot::Activation(engine);
    // Run any start-up actions.
    engine->AddActions(m_StartUp);
    engine->RunActions();
    // Activate the ingredients in order.
    for (int i = 0; i < m_Items.Size(); i++) {
        MHIngredient *pIngredient = m_Items.GetAt(i);
        if (pIngredient->InitiallyActive()) pIngredient->Activation(engine);
    }
    m_fRunning = true;
    // Record the time here.  This is the basis for absolute times.
    m_StartTime.start();
    // Don't generate IsRunning here - that's done by the sub-classes.
}

// Deactivation - stops running the object.  Clears m_fRunning
void MHGroup::Deactivation(MHEngine *engine)
{
    if (! m_fRunning) return;
    // Run any close-down actions.
    engine->AddActions(m_CloseDown);
    engine->RunActions();
    MHRoot::Deactivation(engine);
}

// Destruction - deletes the run-time representation.  Clears m_fAvailable.
void MHGroup::Destruction(MHEngine *engine)
{
    for (int i = m_Items.Size(); i > 0; i--) m_Items.GetAt(i-1)->Destruction(engine);
    MHRoot::Destruction(engine);
}

// Return an object if its object ID matches (or if it's a stream, if it has a matching component).
MHRoot *MHGroup::FindByObjectNo(int n)
{
    if (n == m_ObjectReference.m_nObjectNo) return this;
    for (int i = m_Items.Size(); i > 0; i--) {
        MHRoot *pResult = m_Items.GetAt(i-1)->FindByObjectNo(n);
        if (pResult) return pResult;
    }
    return NULL;
}

// Set up a timer or cancel a timer.
void MHGroup::SetTimer(int nTimerId, bool fAbsolute, int nMilliSecs, MHEngine *)
{
    // First remove any existing timer with the same Id.
    for (int i = 0; i < (int)m_Timers.count(); i++) {
        MHTimer *pTimer = m_Timers.at(i);
        if (pTimer->m_nTimerId == nTimerId) {
            m_Timers.remove(i);
            break;
        }
    }
    // If the time has passed we don't set up a timer.
    QTime currentTime;
    currentTime.start(); // Set current time
    if (nMilliSecs < 0 || (fAbsolute && m_StartTime.addMSecs(nMilliSecs) < currentTime)) return;
    MHTimer *pTimer = new MHTimer;
    m_Timers.append(pTimer);
    pTimer->m_nTimerId = nTimerId;
    if (fAbsolute) pTimer->m_Time = m_StartTime.addMSecs(nMilliSecs);
    else pTimer->m_Time = currentTime.addMSecs(nMilliSecs);
}

// Fire any timers that have passed.
int MHGroup::CheckTimers(MHEngine *engine)
{
    QTime currentTime = QTime::currentTime(); // Get current time
    MHTimer *pTimer = m_Timers.first();
    int nMSecs = 0;
    while (pTimer != 0) {
        if (pTimer->m_Time <= currentTime) { // Use <= rather than < here so we fire timers with zero time immediately.
            // If the time has passed trigger the event and remove the timer from the queue.
            engine->EventTriggered(this, EventTimerFired, pTimer->m_nTimerId);
            m_Timers.remove(); // Remove the item.  This advances the "current" item.
            pTimer = m_Timers.current();
        }
        else {
            // This has not yet expired.  Set "nMSecs" to the earliest time we have.
            int nMSecsToGo = currentTime.msecsTo(pTimer->m_Time);
            if (nMSecs == 0 || nMSecsToGo < nMSecs) nMSecs = nMSecsToGo;
            pTimer = m_Timers.next();
        }
    }
    return nMSecs;
}

// Create a clone of the target and add it to the ingredients.
void MHGroup::MakeClone(MHRoot *pTarget, MHRoot *pRef, MHEngine *engine)
{
    MHIngredient *pClone = pTarget->Clone(engine); // Clone it.
    pClone->m_ObjectReference.m_GroupId.Copy(m_ObjectReference.m_GroupId); // Group id is the same as this.
    pClone->m_ObjectReference.m_nObjectNo = ++m_nLastId; // Create a new object id.
    m_Items.Append(pClone);
    // Set the object reference result to the newly constructed ref.
    pRef->SetVariableValue(pClone->m_ObjectReference);
    pClone->Preparation(engine); // Prepare the clone.
}

MHApplication::MHApplication()
{
    m_fIsApp = true;
    m_nCharSet = 0;
    m_nTextCHook = 0;
    m_nIPCHook = 0;
    m_nStrCHook = 0;
    m_nBitmapCHook = 0; 
    m_nLineArtCHook = 0;

    m_pCurrentScene = NULL;
    m_nLockCount = 0;
    m_fRestarting = false;
}

MHApplication::~MHApplication()
{
    delete(m_pCurrentScene); 
}

void MHApplication::Initialise(MHParseNode *p, MHEngine *engine)
{
    MHGroup::Initialise(p, engine);
    // OnSpawnCloseDown
    MHParseNode *pOnSpawn = p->GetNamedArg(C_ON_SPAWN_CLOSE_DOWN);
    if (pOnSpawn) m_OnSpawnCloseDown.Initialise(pOnSpawn, engine);
    // OnRestart
    MHParseNode *pOnRestart = p->GetNamedArg(C_ON_RESTART);
    if (pOnRestart) m_OnRestart.Initialise(pOnRestart, engine);
    // Default attributes.  These are encoded in a group in binary.
    MHParseNode *pDefattrs = p->GetNamedArg(C_DEFAULT_ATTRIBUTES);
    // but in the text form they're encoded in the Application block.
    if (pDefattrs == NULL) pDefattrs = p;
    MHParseNode *pCharSet = pDefattrs->GetNamedArg(C_CHARACTER_SET);
    if (pCharSet) m_nCharSet = pCharSet->GetArgN(0)->GetIntValue();
    // Colours
    MHParseNode *pBGColour = pDefattrs->GetNamedArg(C_BACKGROUND_COLOUR);
    if (pBGColour) m_BGColour.Initialise(pBGColour->GetArgN(0), engine);
    MHParseNode *pTextColour = pDefattrs->GetNamedArg(C_TEXT_COLOUR);
    if (pTextColour) m_TextColour.Initialise(pTextColour->GetArgN(0), engine);
    MHParseNode *pButtonRefColour = pDefattrs->GetNamedArg(C_BUTTON_REF_COLOUR);
    if (pButtonRefColour) m_ButtonRefColour.Initialise(pButtonRefColour->GetArgN(0), engine);
    MHParseNode *pHighlightRefColour = pDefattrs->GetNamedArg(C_HIGHLIGHT_REF_COLOUR);
    if (pHighlightRefColour) m_HighlightRefColour.Initialise(pHighlightRefColour->GetArgN(0), engine);
    MHParseNode *pSliderRefColour = pDefattrs->GetNamedArg(C_SLIDER_REF_COLOUR);
    if (pSliderRefColour) m_SliderRefColour.Initialise(pSliderRefColour->GetArgN(0), engine);
    // Content hooks
    MHParseNode *pTextCHook = pDefattrs->GetNamedArg(C_TEXT_CONTENT_HOOK);
    if (pTextCHook) m_nTextCHook = pTextCHook->GetArgN(0)->GetIntValue();
    MHParseNode *pIPCHook = pDefattrs->GetNamedArg(C_IP_CONTENT_HOOK);
    if (pIPCHook) m_nIPCHook = pIPCHook->GetArgN(0)->GetIntValue();
    MHParseNode *pStrCHook = pDefattrs->GetNamedArg(C_STREAM_CONTENT_HOOK);
    if (pStrCHook) m_nStrCHook = pStrCHook->GetArgN(0)->GetIntValue();
    MHParseNode *pBitmapCHook = pDefattrs->GetNamedArg(C_BITMAP_CONTENT_HOOK);
    if (pBitmapCHook) m_nBitmapCHook = pBitmapCHook->GetArgN(0)->GetIntValue();
    MHParseNode *pLineArtCHook = pDefattrs->GetNamedArg(C_LINE_ART_CONTENT_HOOK);
    if (pLineArtCHook) m_nLineArtCHook = pLineArtCHook->GetArgN(0)->GetIntValue();
    // Font.  This is a little tricky.  There are two attributes both called Font.
    // In the binary notation the font here is encoded as 42 whereas the text form
    // finds the first occurrence of :Font in the table and returns 13.
    MHParseNode *pFont = pDefattrs->GetNamedArg(C_FONT2);
    if (pFont == NULL) pFont = pDefattrs->GetNamedArg(C_FONT);
    if (pFont) m_Font.Initialise(pFont->GetArgN(0), engine);
    // Font attributes.
    MHParseNode *pFontAttrs = pDefattrs->GetNamedArg(C_FONT_ATTRIBUTES);
    if (pFontAttrs) pFontAttrs->GetArgN(0)->GetStringValue(m_FontAttrs);
}

void MHApplication::PrintMe(FILE *fd, int nTabs) const
{
    PrintTabs(fd, nTabs);
    fprintf(fd, "{:Application ");
    MHGroup::PrintMe(fd, nTabs);
    if (m_OnSpawnCloseDown.Size() != 0) {
        PrintTabs(fd, nTabs+1); fprintf(fd, ":OnSpawnCloseDown");
        m_OnSpawnCloseDown.PrintMe(fd, nTabs+1); fprintf(fd, "\n");
    }
    if (m_OnRestart.Size() != 0)  {
        PrintTabs(fd, nTabs+1); fprintf(fd, ":OnRestart");
        m_OnRestart.PrintMe(fd, nTabs+1); fprintf(fd, "\n");
    }
    if (m_nCharSet > 0) { PrintTabs(fd, nTabs+1); fprintf(fd, ":CharacterSet %d\n", m_nCharSet); }
    if (m_BGColour.IsSet()) { PrintTabs(fd, nTabs+1); fprintf(fd, ":BackgroundColour "); m_BGColour.PrintMe(fd, nTabs+1); fprintf(fd, "\n"); }
    if (m_nTextCHook > 0) { PrintTabs(fd, nTabs+1); fprintf(fd, ":TextCHook %d\n", m_nTextCHook); }
    if (m_TextColour.IsSet()) { PrintTabs(fd, nTabs+1); fprintf(fd, ":TextColour"); m_TextColour.PrintMe(fd, nTabs+1); fprintf(fd, "\n"); }
    if (m_Font.IsSet()) { PrintTabs(fd, nTabs+1); fprintf(fd, ":Font "); m_Font.PrintMe(fd, nTabs+1); fprintf(fd, "\n"); }
    if (m_FontAttrs.Size() > 0) { PrintTabs(fd, nTabs+1); fprintf(fd, ":FontAttributes "); m_FontAttrs.PrintMe(fd, nTabs+1); fprintf(fd, "\n"); }
    if (m_nIPCHook > 0) { PrintTabs(fd, nTabs+1); fprintf(fd, ":InterchgPrgCHook %d\n", m_nIPCHook); }
    if (m_nStrCHook > 0) { PrintTabs(fd, nTabs+1); fprintf(fd, ":StreamCHook %d\n", m_nStrCHook); }
    if (m_nBitmapCHook > 0) { PrintTabs(fd, nTabs+1); fprintf(fd, ":BitmapCHook %d\n", m_nBitmapCHook); }
    if (m_nLineArtCHook > 0) { PrintTabs(fd, nTabs+1); fprintf(fd, ":LineArtCHook %d\n", m_nLineArtCHook); }
    if (m_ButtonRefColour.IsSet()) { PrintTabs(fd, nTabs+1); fprintf(fd, ":ButtonRefColour "); m_ButtonRefColour.PrintMe(fd, nTabs+1); fprintf(fd, "\n"); }
    if (m_HighlightRefColour.IsSet()) { PrintTabs(fd, nTabs+1); fprintf(fd, ":HighlightRefColour "); m_HighlightRefColour.PrintMe(fd, nTabs+1); fprintf(fd, "\n"); }
    if (m_SliderRefColour.IsSet()) { PrintTabs(fd, nTabs+1); fprintf(fd, ":SliderRefColour "); m_SliderRefColour.PrintMe(fd, nTabs+1); fprintf(fd, "\n"); }
    fprintf(fd, "}\n");
}

// This is a bit messy.  The MHEG corrigendum says that we need to process OnRestart actions
// BEFORE generating IsRunning.  That's important because TransitionTo etc are ignored during
// OnRestart but allowed in events triggered by IsRunning.
void MHApplication::Activation(MHEngine *engine)
{
    if (m_fRunning) return;
    MHGroup::Activation(engine);
    if (m_fRestarting) { // Set by Quit
        engine->AddActions(m_OnRestart);
        engine->RunActions();
    }
    engine->EventTriggered(this, EventIsRunning);
}

int MHApplication::FindOnStack(const MHRoot *pVis) // Returns the index on the stack or -1 if it's not there.
{
    for (int i = 0; i < m_DisplayStack.Size(); i++) {
        if (m_DisplayStack.GetAt(i) == pVis) return i;
    }
    return -1; // Not there
}

MHScene::MHScene()
{
    m_fIsApp = false;
    // TODO: In UK MHEG 1.06 the aspect ratio is optional and if not specified "the
    // scene has no aspect ratio".
    m_nAspectRatioW = 4; m_nAspectRatioH = 3;
    m_fMovingCursor = false;
}

void MHScene::Initialise(MHParseNode *p, MHEngine *engine)
{
    MHGroup::Initialise(p, engine);
    // Event register.
    MHParseNode *pInputEventReg = p->GetNamedArg(C_INPUT_EVENT_REGISTER);
    m_nEventReg = pInputEventReg->GetArgN(0)->GetIntValue();
    // Co-ordinate system
    MHParseNode *pSceneCoords = p->GetNamedArg(C_SCENE_COORDINATE_SYSTEM);
    m_nSceneCoordX = pSceneCoords->GetArgN(0)->GetIntValue();
    m_nSceneCoordY = pSceneCoords->GetArgN(1)->GetIntValue();
    // Aspect ratio
    MHParseNode *pAspectRatio = p->GetNamedArg(C_ASPECT_RATIO);
    if (pAspectRatio) {
        // Is the binary encoded as a sequence or a pair of arguments?
        m_nAspectRatioW = pAspectRatio->GetArgN(0)->GetIntValue();
        m_nAspectRatioH = pAspectRatio->GetArgN(1)->GetIntValue();
    }
    // Moving cursor
    MHParseNode *pMovingCursor = p->GetNamedArg(C_MOVING_CURSOR);
    if (pMovingCursor) pMovingCursor->GetArgN(0)->GetBoolValue();
    // Next scene sequence: this is just a hint and isn't implemented
}

void MHScene::PrintMe(FILE *fd, int nTabs) const
{
    PrintTabs(fd, nTabs);
    fprintf(fd, "{:Scene ");
    MHGroup::PrintMe(fd, nTabs);
    PrintTabs(fd, nTabs+1); fprintf(fd, ":InputEventReg %d\n", m_nEventReg);
    PrintTabs(fd, nTabs+1); fprintf(fd, ":SceneCS %d %d\n", m_nSceneCoordX, m_nSceneCoordY);
    if (m_nAspectRatioW != 4 || m_nAspectRatioH != 3) { PrintTabs(fd, nTabs+1); fprintf(fd, ":AspectRatio %d %d\n", m_nAspectRatioW, m_nAspectRatioH); }
    if (m_fMovingCursor) { PrintTabs(fd, nTabs+1); fprintf(fd, ":MovingCursor true\n"); }
    fprintf(fd, "}\n");
}

void MHScene::Activation(MHEngine *engine)
{
    if (m_fRunning) return;
    MHGroup::Activation(engine);
    engine->EventTriggered(this, EventIsRunning);
}

// Action added in UK MHEG profile.  It doesn't define a new internal attribute for this. 
void MHScene::SetInputRegister(int nReg, MHEngine *engine)
{
    m_nEventReg = nReg;
    engine->SetInputRegister(nReg);
}


void MHSendEvent::Initialise(MHParseNode *p, MHEngine *engine)
{
    MHElemAction::Initialise(p, engine); // Target
    m_EventSource.Initialise(p->GetArgN(1), engine);
    m_EventType = (enum EventType)p->GetArgN(2)->GetEnumValue();
    if (p->GetArgCount() >= 4) {
        // TODO: We could check here that we only have bool, int or string and not object ref or content ref.
        m_EventData.Initialise(p->GetArgN(3), engine);
    }
}

void MHSendEvent::PrintArgs(FILE *fd, int) const
{
    m_EventSource.PrintMe(fd, 0);
    fprintf(fd, MHLink::EventTypeToString(m_EventType).ascii());
    fprintf(fd, " ");
    if (m_EventData.m_Type != MHParameter::P_Null) m_EventData.PrintMe(fd, 0);
}

void MHSendEvent::Perform(MHEngine *engine)
{
    // The target is always the current scene so we ignore it here.
    MHObjectRef target, source;
    m_Target.GetValue(target, engine); // TODO: Check this is the scene?
    m_EventSource.GetValue(source, engine);
    // Generate the event.
    if (m_EventData.m_Type == MHParameter::P_Null)
        engine->EventTriggered(engine->FindObject(source), m_EventType);
    else {
        MHUnion data;
        data.GetValueFrom(m_EventData, engine);
        engine->EventTriggered(engine->FindObject(source), m_EventType, data);
    }
}

void MHSetTimer::Initialise(MHParseNode *p, MHEngine *engine)
{
    MHElemAction::Initialise(p, engine);
    m_TimerId.Initialise(p->GetArgN(1), engine); // The timer id
    if (p->GetArgCount() > 2) {
        MHParseNode *pNewTimer = p->GetArgN(2);
        m_TimerValue.Initialise(pNewTimer->GetSeqN(0), engine);
        if (pNewTimer->GetSeqCount() > 1) {
            m_TimerType = ST_TimerAbsolute; // May be absolute - depends on the value.
            m_AbsFlag.Initialise(pNewTimer->GetSeqN(1), engine);
        }
        else m_TimerType = ST_TimerRelative;
    }
}

void MHSetTimer::PrintArgs(FILE *fd, int /*nTabs*/) const
{
    m_TimerId.PrintMe(fd, 0);
    if (m_TimerType != ST_NoNewTimer) {
        fprintf(fd, "( ");
        m_TimerValue.PrintMe(fd, 0);
        if (m_TimerType == ST_TimerAbsolute) m_AbsFlag.PrintMe(fd, 0);
        fprintf(fd, ") ");
    }
}

void MHSetTimer::Perform(MHEngine *engine)
{
    int nTimerId = m_TimerId.GetValue(engine);
    bool fAbsolute = false; // Defaults to relative time.
    int newTime = -1;
    switch (m_TimerType) {
    case ST_NoNewTimer: fAbsolute = true; newTime = -1; break; // We treat an absolute time of -1 as "cancel"
    case ST_TimerAbsolute: fAbsolute = m_AbsFlag.GetValue(engine); // And drop to the next
    case ST_TimerRelative: newTime = m_TimerValue.GetValue(engine);
    }
    Target(engine)->SetTimer(nTimerId, fAbsolute, newTime, engine);
}

void MHPersistent::Initialise(MHParseNode *p, MHEngine *engine)
{
    MHElemAction::Initialise(p, engine); // Target
    m_Succeeded.Initialise(p->GetArgN(1), engine);
    MHParseNode *pVarSeq = p->GetArgN(2);
    for (int i = 0; i < pVarSeq->GetSeqCount(); i++) {
        MHObjectRef *pVar = new MHObjectRef;
        m_Variables.Append(pVar);
        pVar->Initialise(pVarSeq->GetSeqN(i), engine);
    }
    m_FileName.Initialise(p->GetArgN(3), engine);
}

void MHPersistent::PrintArgs(FILE *fd, int nTabs) const
{
    m_Succeeded.PrintMe(fd, nTabs);
    fprintf(fd, " ( ");
    for (int i = 0; i < m_Variables.Size(); i++) m_Variables.GetAt(i)->PrintMe(fd, 0);
    fprintf(fd, " ) ");
    m_FileName.PrintMe(fd, nTabs);
}

void MHPersistent::Perform(MHEngine *engine)
{
    MHObjectRef target;
    m_Target.GetValue(target, engine); // Get the target - this should always be the application
    MHOctetString fileName;
    m_FileName.GetValue(fileName, engine);
    bool fResult = engine->LoadStorePersistent(m_fIsLoad, fileName, m_Variables);
    engine->FindObject(m_Succeeded)->SetVariableValue(fResult);
}

MHTransitionTo::MHTransitionTo(): MHElemAction(":TransitionTo")
{
    m_fIsTagged = false;
    m_nConnectionTag = 0;
    m_nTransitionEffect = -1;
}

void MHTransitionTo::Initialise(MHParseNode *p, MHEngine *engine)
{
    MHElemAction::Initialise(p, engine); // Target
    // The next one may be present but NULL in binary.
    if (p->GetArgCount() > 1) {
        MHParseNode *pCtag = p->GetArgN(1);
        if (pCtag->m_nNodeType == MHParseNode::PNInt) {
            m_fIsTagged = TRUE;
            m_nConnectionTag = pCtag->GetIntValue();
        }
    }
    if (p->GetArgCount() > 2) {
        MHParseNode *pTrEff = p->GetArgN(2);
        m_nTransitionEffect = pTrEff->GetIntValue();
    }
}

void MHTransitionTo::PrintArgs(FILE *fd, int /*nTabs*/) const
{
    if (m_fIsTagged) fprintf(fd, " %d ", m_nConnectionTag);
    else if (m_nTransitionEffect >= 0) fprintf(fd, " NULL ");
    if (m_nTransitionEffect >= 0) fprintf(fd, " %d", m_nTransitionEffect);
}

// Do the action - Transition to a new scene.
void MHTransitionTo::Perform(MHEngine *engine)
{
    MHObjectRef target;
    m_Target.GetValue(target, engine); // Get the target
    engine->TransitionToScene(target);
}

void MHLaunch::Perform(MHEngine *engine) { MHObjectRef target; m_Target.GetValue(target, engine); engine->Launch(target); }
void MHQuit::Perform(MHEngine *engine) { engine->Quit(); }
void MHSpawn::Perform(MHEngine *engine) { MHObjectRef target; m_Target.GetValue(target, engine); engine->Spawn(target); }
void MHLockScreen::Perform(MHEngine *engine) { engine->LockScreen(); }
void MHUnlockScreen::Perform(MHEngine *engine) { engine->UnlockScreen(); }

void MHGetEngineSupport::Initialise(MHParseNode *p, MHEngine *engine)
{
    MHElemAction::Initialise(p, engine);
    m_Feature.Initialise(p->GetArgN(1), engine);
    m_Answer.Initialise(p->GetArgN(2), engine);
}

void MHGetEngineSupport::Perform(MHEngine *engine)
{
    // Ignore the target which isn't used.
    MHOctetString feature;
    m_Feature.GetValue(feature, engine);
    engine->FindObject(m_Answer)->SetVariableValue(engine->GetEngineSupport(feature));
}

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