kicad/pcbnew/editrack.cpp

/*******************************/
/* Edition des pistes			*/
/* Routines de trace de pistes */
/*******************************/

#include "fctsys.h"
#include "gr_basic.h"
#include "common.h"
#include "class_drawpanel.h"

#include "pcbnew.h"
#include "autorout.h"

#include "protos.h"
#include "drc_stuff.h"
#include "trigo.h"



/* Routines Locales */
static void     Exit_Editrack( WinEDA_DrawPanel* panel, wxDC* DC );
void            ShowNewTrackWhenMovingCursor( WinEDA_DrawPanel* panel,
                                              wxDC* DC, bool erase );
static void     ComputeBreakPoint( TRACK* track, int n, wxPoint end );
static void     DeleteNullTrackSegments( BOARD* pcb, DLIST<TRACK>& aTrackList );

static void     EnsureEndTrackOnPad( D_PAD* Pad );

/* variables locales */
static int OldNetCodeSurbrillance;
static int OldEtatSurbrillance;


/************************************************************/
static void Exit_Editrack( WinEDA_DrawPanel* Panel, wxDC* DC )
/************************************************************/

/* routine d'annulation de la Commande Begin_Route si une piste est en cours
 *  de tracage, ou de sortie de l'application EDITRACK.
 */
{
    WinEDA_PcbFrame* frame = (WinEDA_PcbFrame*) Panel->m_Parent;
    TRACK*           track = (TRACK*) frame->GetCurItem();

    if( track && ( track->Type()==TYPE_VIA || track->Type()==TYPE_TRACK ) )
    {
        /* Erase the current drawing */
        ShowNewTrackWhenMovingCursor( Panel, DC, FALSE );
        if( g_HightLigt_Status )
            frame->Hight_Light( DC );

        g_HightLigth_NetCode = OldNetCodeSurbrillance;
        if( OldEtatSurbrillance )
            frame->Hight_Light( DC );

        frame->MsgPanel->EraseMsgBox();

        // Delete current (new) track
        g_CurrentTrackList.DeleteAll();
    }

    Panel->ManageCurseur = NULL;
    Panel->ForceCloseManageCurseur = NULL;
    frame->SetCurItem( NULL );
}


/*************************************************************/
TRACK* WinEDA_PcbFrame::Begin_Route( TRACK* aTrack, wxDC* DC )
/*************************************************************/

/*
 *  Routine d'initialisation d'un trace de piste et/ou de mise en place d'un
 *  nouveau point piste
 *
 *  Si pas de piste en cours de trace:
 *      - Recherche de netname de la nouvelle piste ( pad de depart out netname
 *       de la piste si depart sur une ancienne piste
 *      - Met en surbrillance tout le net
 *      - Initilise les divers pointeurs de trace
 *  Si piste en cours:
 *      - controle DRC
 *      - si DRC OK : addition d'un nouveau point piste
 */
{
    D_PAD*          pt_pad = NULL;
    TRACK*          TrackOnStartPoint = NULL;
    int             masquelayer = g_TabOneLayerMask[((PCB_SCREEN*)GetScreen())->m_Active_Layer];
    BOARD_ITEM*     LockPoint;
    wxPoint         pos = GetScreen()->m_Curseur;

    static int      InitialTrackWidthValue; /* first track segment width.
                                            * used when we are in the auto tack width mode */

    DrawPanel->ManageCurseur = ShowNewTrackWhenMovingCursor;
    DrawPanel->ForceCloseManageCurseur = Exit_Editrack;

    if( aTrack == NULL )  /* Starting a new track  */
    {
        /* erase old highlight */
        OldNetCodeSurbrillance = g_HightLigth_NetCode;
        OldEtatSurbrillance    = g_HightLigt_Status;

        if( g_HightLigt_Status )
            Hight_Light( DC );

        InitialTrackWidthValue = -1;        // Set to "no value"

        g_CurrentTrackList.PushBack( new TRACK( GetBoard() ) );
        g_CurrentTrackSegment->m_Flags = IS_NEW;

        g_HightLigth_NetCode = 0;

        // Search for a starting point of the new track, a track or pad
        LockPoint = LocateLockPoint( GetBoard(), pos, masquelayer );

        if( LockPoint ) // An item (pad or track) is found
        {
            if( LockPoint->Type() == TYPE_PAD )
            {
                pt_pad = (D_PAD*) LockPoint;

                /* A pad is found: put the starting point on pad centre */
                pos = pt_pad->m_Pos;
                g_HightLigth_NetCode = pt_pad->GetNet();
            }
            else /* A track segment is found */
            {
                TrackOnStartPoint    = (TRACK*) LockPoint;
                g_HightLigth_NetCode = TrackOnStartPoint->GetNet();
                CreateLockPoint( &pos.x, &pos.y, TrackOnStartPoint, NULL );
            }
        }

        else    // no starting point, but a filled zone area can exist. This is also a good starting point.
        {
            ZONE_CONTAINER* zone = GetBoard()->HitTestForAnyFilledArea( pos, GetScreen()->m_Active_Layer );
            if( zone )
                g_HightLigth_NetCode = zone->GetNet();
        }

        D( g_CurrentTrackList.VerifyListIntegrity(); );

        build_ratsnest_pad( LockPoint, wxPoint( 0, 0 ), TRUE );

        D( g_CurrentTrackList.VerifyListIntegrity(); );

        Hight_Light( DC );

        g_CurrentTrackSegment->SetLayer( ((PCB_SCREEN*)GetScreen())->m_Active_Layer );
        g_CurrentTrackSegment->m_Width = g_DesignSettings.m_CurrentTrackWidth;

        if( g_DesignSettings.m_UseConnectedTrackWidth )
        {
            if( TrackOnStartPoint && TrackOnStartPoint->Type() == TYPE_TRACK )
            {
                InitialTrackWidthValue = TrackOnStartPoint->m_Width;
                g_CurrentTrackSegment->m_Width = InitialTrackWidthValue;
            }
        }

        g_CurrentTrackSegment->m_Start = pos;
        g_CurrentTrackSegment->m_End   = pos;
        g_CurrentTrackSegment->SetNet( g_HightLigth_NetCode );

        if( pt_pad )
        {
            g_CurrentTrackSegment->start = pt_pad;
            g_CurrentTrackSegment->SetState( BEGIN_ONPAD, ON );
        }
        else
            g_CurrentTrackSegment->start = TrackOnStartPoint;

        if( g_TwoSegmentTrackBuild )
        {
            // Create 2nd segment
            g_CurrentTrackList.PushBack( g_CurrentTrackSegment->Copy() );

            D( g_CurrentTrackList.VerifyListIntegrity(); );

            g_CurrentTrackSegment->start = g_FirstTrackSegment;
            g_FirstTrackSegment->end     = g_CurrentTrackSegment;

            g_FirstTrackSegment->SetState( BEGIN_ONPAD | END_ONPAD, OFF );
        }

        D( g_CurrentTrackList.VerifyListIntegrity(); );

        g_CurrentTrackSegment->DisplayInfo( this );
        SetCurItem( g_CurrentTrackSegment );
        DrawPanel->ManageCurseur( DrawPanel, DC, FALSE );

        if( Drc_On )
        {
            if( BAD_DRC == m_drc->Drc( g_CurrentTrackSegment, GetBoard()->m_Track ) )
            {
                return g_CurrentTrackSegment;
            }
        }
    }
    else    /* Track in progress : segment coordinates are updated by ShowNewTrackWhenMovingCursor*/
    {
        /* Tst for a D.R.C. error: */
        if( Drc_On )
        {
            if( BAD_DRC == m_drc->Drc( g_CurrentTrackSegment, GetBoard()->m_Track ) )
                return NULL;

            // We must handle 2 segments
            if( g_TwoSegmentTrackBuild && g_CurrentTrackSegment->Back() )
            {
                if( BAD_DRC == m_drc->Drc( g_CurrentTrackSegment->Back(), GetBoard()->m_Track ) )
                    return NULL;
            }
        }

        /* Current track is Ok: current segment is kept, and a new one is created
         * unless the current segment is null, or 2 last are null if a 2 segments track build
         */
        bool CanCreateNewSegment = TRUE;
        if( !g_TwoSegmentTrackBuild && g_CurrentTrackSegment->IsNull() )
            CanCreateNewSegment = FALSE;

        if( g_TwoSegmentTrackBuild && g_CurrentTrackSegment->IsNull()
           && g_CurrentTrackSegment->Back() && g_CurrentTrackSegment->Back()->IsNull() )
            CanCreateNewSegment = FALSE;

        if( CanCreateNewSegment )
        {
            /* Erase old track on screen */
            D( g_CurrentTrackList.VerifyListIntegrity(); );

            ShowNewTrackWhenMovingCursor( DrawPanel, DC, FALSE );

            D( g_CurrentTrackList.VerifyListIntegrity(); );

            if( g_Raccord_45_Auto )
            {
                Add_45_degrees_Segment( DC );
            }

            TRACK* oneBeforeLatest = g_CurrentTrackSegment;

            TRACK* newTrack = g_CurrentTrackSegment->Copy();
            g_CurrentTrackList.PushBack( newTrack );
            newTrack->m_Flags = IS_NEW;

            newTrack->SetState( BEGIN_ONPAD | END_ONPAD, OFF );

            oneBeforeLatest->end = Locate_Pad_Connecte( GetBoard(), oneBeforeLatest, END );
            if( oneBeforeLatest->end )
            {
                oneBeforeLatest->SetState( END_ONPAD, ON );
                newTrack->SetState( BEGIN_ONPAD, ON );
            }
            newTrack->start = oneBeforeLatest->end;

            D( g_CurrentTrackList.VerifyListIntegrity(); );

            newTrack->m_Start = newTrack->m_End;

            newTrack->SetLayer( ((PCB_SCREEN*)GetScreen())->m_Active_Layer );

            if( !g_DesignSettings.m_UseConnectedTrackWidth )
            {
                newTrack->m_Width = g_DesignSettings.m_CurrentTrackWidth;
            }

            D( g_CurrentTrackList.VerifyListIntegrity(); );

            /* Show the new position */
            ShowNewTrackWhenMovingCursor( DrawPanel, DC, FALSE );
        }
        g_CurrentTrackSegment->DisplayInfo( this );
    }

    SetCurItem( g_CurrentTrackSegment );
    return g_CurrentTrackSegment;
}


/**************************************************************************/
bool WinEDA_PcbFrame::Add_45_degrees_Segment( wxDC* DC )
/***************************************************************************/

/* rectifie un virage a 90 et le modifie par 2 coudes a 45
 *  n'opere que sur des segments horizontaux ou verticaux.
 *
 *  entree : pointeur sur le segment qui vient d'etre trace
 *          On suppose que le segment precedent est celui qui a ete
 *          precedement trace
 *  retourne:
 *      1 si ok
 *      0 si impossible
 */
{
    int    pas_45;
    int    dx0, dy0, dx1, dy1;

    if( g_CurrentTrackList.GetCount() < 2 )
        return false;                               /* il faut au moins 2 segments */

    TRACK* curTrack  = g_CurrentTrackSegment;
    TRACK* prevTrack = curTrack->Back();

    // Test s'il y a 2 segments consecutifs a raccorder
    if( curTrack->Type() != TYPE_TRACK || prevTrack->Type() != TYPE_TRACK )
    {
        return false;
    }

    pas_45 = (int)GetScreen()->GetGrid().x / 2;
    if( pas_45 < curTrack->m_Width )
        pas_45 = (int)GetScreen()->GetGrid().x;

    while( pas_45 < curTrack->m_Width )
        pas_45 *= 2;

    // OK : tst si les segments sont a 90 degre et vertic ou horiz
    dx0 = prevTrack->m_End.x - prevTrack->m_Start.x;
    dy0 = prevTrack->m_End.y - prevTrack->m_Start.y;

    dx1 = curTrack->m_End.x - curTrack->m_Start.x;
    dy1 = curTrack->m_End.y - curTrack->m_Start.y;

    // les segments doivent etre de longueur suffisante:
    if( MAX( abs( dx0 ), abs( dy0 ) ) < (pas_45 * 2) )
        return false;

    if( MAX( abs( dx1 ), abs( dy1 ) ) < (pas_45 * 2) )
        return false;

    /* creation du nouveau segment, raccordant des 2 segm: */
    TRACK* newTrack = curTrack->Copy();

    newTrack->m_Start = prevTrack->m_End;
    newTrack->m_End   = curTrack->m_Start;

    if( dx0 == 0 )          // Segment precedent Vertical
    {
        if( dy1 != 0 )      // les 2 segments ne sont pas a 90 ;
        {
            delete newTrack;
            return false;
        }

        /* Calcul des coordonnees du point de raccord :
         *  le nouveau segment raccorde le 1er segment Vertical
         *  au 2eme segment Horizontal */

        if( dy0 > 0 )
            newTrack->m_Start.y -= pas_45;
        else
            newTrack->m_Start.y += pas_45;

        if( dx1 > 0 )
            newTrack->m_End.x += pas_45;
        else
            newTrack->m_End.x -= pas_45;

        if( Drc_On && BAD_DRC==m_drc->Drc( curTrack, GetBoard()->m_Track ) )
        {
            delete newTrack;
            return false;
        }

        prevTrack->m_End  = newTrack->m_Start;
        curTrack->m_Start = newTrack->m_End;

        g_CurrentTrackList.Insert( newTrack, curTrack );
        return true;
    }

    if( dy0 == 0 )      // Segment precedent Horizontal : dy0 = 0
    {
        if( dx1 != 0 )  // les 2 segments ne sont pas a 90 ;
        {
            delete newTrack;
            return false;
        }

        // Segments a 90

        /* Modif des coordonnees du point de raccord :
         *  un nouveau segment a ete cree, raccordant le 1er segment Horizontal
         *  au 2eme segment Vertical */

        if( dx0 > 0 )
            newTrack->m_Start.x -= pas_45;
        else
            newTrack->m_Start.x += pas_45;

        if( dy1 > 0 )
            newTrack->m_End.y += pas_45;
        else
            newTrack->m_End.y -= pas_45;

        if( Drc_On && BAD_DRC==m_drc->Drc( newTrack, GetBoard()->m_Track ) )
        {
            delete newTrack;
            return false;
        }

        prevTrack->m_End  = newTrack->m_Start;
        curTrack->m_Start = newTrack->m_End;

        g_CurrentTrackList.Insert( newTrack, curTrack );
        return true;
    }

    return false;
}


/**************************************************************/
void WinEDA_PcbFrame::End_Route( TRACK* aTrack, wxDC* DC )
/*************************************************************/

/*
 *  Routine de fin de trace d'une piste (succession de segments)
 */
{
    int masquelayer = g_TabOneLayerMask[((PCB_SCREEN*)GetScreen())->m_Active_Layer];

    if( aTrack == NULL )
        return;

    if( Drc_On && BAD_DRC==m_drc->Drc( g_CurrentTrackSegment, GetBoard()->m_Track ) )
        return;

    /* Sauvegarde des coord du point terminal de la piste */
    wxPoint pos = g_CurrentTrackSegment->m_End;

    D( g_CurrentTrackList.VerifyListIntegrity(); );

    if( Begin_Route( aTrack, DC ) == NULL )
        return;

    ShowNewTrackWhenMovingCursor( DrawPanel, DC, TRUE );    /* mise a jour trace reel */
    ShowNewTrackWhenMovingCursor( DrawPanel, DC, FALSE );   /* efface trace piste*/
    trace_ratsnest_pad( DC );                               /* efface trace chevelu*/

    /* cleanup
    if( g_CurrentTrackSegment->Next() != NULL )
    {
        delete g_CurrentTrackSegment->Next();
        g_CurrentTrackSegment->SetNext( NULL );
    }
    */

    D( g_CurrentTrackList.VerifyListIntegrity(); );


    /* La piste est ici non chainee a la liste des segments de piste.
     *  Il faut la replacer dans la zone de net,
     *  le plus pres possible du segment d'attache ( ou de fin ), car
     *  ceci contribue a la reduction du temps de calcul */

    /* Accrochage de la fin de la piste */
    BOARD_ITEM* LockPoint = LocateLockPoint( GetBoard(), pos, masquelayer );

    if( LockPoint ) /* La fin de la piste est sur un PAD */
    {
        if( LockPoint->Type() ==  TYPE_PAD )
        {
            EnsureEndTrackOnPad( (D_PAD*) LockPoint );
        }
        else    /* la fin de la piste est sur une autre piste: il faudra
                 *  peut-etre creer un point d'ancrage */
        {
            TRACK* adr_buf = (TRACK*) LockPoint;
            g_HightLigth_NetCode = adr_buf->GetNet();

            /* creation eventuelle d'un point d'accrochage */
            LockPoint = CreateLockPoint( &g_CurrentTrackSegment->m_End.x,
                                         &g_CurrentTrackSegment->m_End.y,
                                         adr_buf,
                                         g_CurrentTrackSegment );
        }
    }

    // Delete Null segments:
    DeleteNullTrackSegments( GetBoard(), g_CurrentTrackList );

    // Insert new segments if they exist.  This can be NULL on a double click on the start point
    if( g_FirstTrackSegment != NULL )
    {
        int     netcode    = g_FirstTrackSegment->GetNet();
        TRACK*  firstTrack = g_FirstTrackSegment;
        int     newCount   = g_CurrentTrackList.GetCount();

        // Put entire new current segment list in BOARD
        TRACK* track;
        TRACK* insertBeforeMe = g_CurrentTrackSegment->GetBestInsertPoint( GetBoard() );
        while( (track = g_CurrentTrackList.PopFront()) != NULL )
        {
            GetBoard()->m_Track.Insert( track, insertBeforeMe );
        }

        trace_ratsnest_pad( DC );

        Trace_Une_Piste( DrawPanel, DC, firstTrack, newCount, GR_OR );

        int i = 0;
        for( track=firstTrack; track && i<newCount;  ++i, track = track->Next() )
        {
            track->m_Flags = 0;
            track->SetState( BUSY, OFF );
        }

        // erase the old track, if exists
        if( g_AutoDeleteOldTrack )
        {
            EraseOldTrack( this, GetBoard(), DC, firstTrack, newCount );
        }

        /* compute the new rastnest : */
        test_1_net_connexion( DC, netcode );

        GetScreen()->SetModify();
        GetBoard()->DisplayInfo( this );
    }

    wxASSERT( g_FirstTrackSegment==NULL );
    wxASSERT( g_CurrentTrackSegment==NULL );
    wxASSERT( g_CurrentTrackList.GetCount()==0 );

    if( g_HightLigt_Status )
        Hight_Light( DC );

    g_HightLigth_NetCode = OldNetCodeSurbrillance;
    if( OldEtatSurbrillance )
        Hight_Light( DC );

    DrawPanel->ManageCurseur = NULL;
    DrawPanel->ForceCloseManageCurseur = NULL;
    SetCurItem( NULL );
}


TRACK* LocateIntrusion( TRACK* start, int net, int width )
{
    int     layer = ( (PCB_SCREEN*) ActiveScreen )->m_Active_Layer;

    wxPoint ref = ActiveScreen->RefPos( true );

    TRACK*  found = NULL;

    for( TRACK* track = start;  track;  track = track->Next() )
    {
        if( track->Type() == TYPE_TRACK )    // skip vias
        {
            if( track->GetState( BUSY | DELETED ) )
                continue;

            if( layer != track->GetLayer() )
                continue;

            if( track->GetNet() == net )
                continue;

            /* TRACK::HitTest */
            int dist = width / 2 + track->m_Width / 2 + g_DesignSettings.m_TrackClearence;

            wxPoint pos  = ref - track->m_Start;
            wxPoint vec  = track->m_End - track->m_Start;

            if( !DistanceTest( dist, vec.x, vec.y, pos.x, pos.y ) )
                continue;

            found = track;

            /* prefer intrusions from the side, not the end */
            double tmp = (double) pos.x * vec.x + (double) pos.y * vec.y;
            if( tmp >= 0 && tmp <= (double) vec.x * vec.x + (double) vec.y * vec.y )
                break;
        }
    }

    return found;
}


/**
 * Function PushTrack
 * detects if the mouse is pointing into a conflicting track.
 * In this case, it tries to push the new track out of the conflicting track's
 * clearance zone. This gives us a cheap mechanism for drawing tracks that
 * tightly follow others, independent of grid settings.
 *
 * KNOWN BUGS:
 * - we do the same sort of search and calculation up to three times:
 *   1) we search for magnetic hits (in controle.cpp)
 *   2) we check if there's a DRC violation in the making (also controle.cpp)
 *   3) we try to fix the DRC violation (here)
 * - if we have a magnetic hit and a DRC violation at the same time, we choose
 *   the magnetic hit instead of solving the violation
 * - should locate conflicting tracks also when we're crossing over them
 */
static void PushTrack( WinEDA_DrawPanel* panel )
{
    BOARD*  pcb    = ( (WinEDA_BasePcbFrame*) (panel->m_Parent) )->GetBoard();
    wxPoint cursor = ActiveScreen->m_Curseur;
    wxPoint cv, vec, n;
    TRACK*  track = g_CurrentTrackSegment;
    TRACK*  other;
    double  det;
    int     dist;
    double  f;

    other = LocateIntrusion( pcb->m_Track, track->GetNet(), track->m_Width );

    /* are we currently pointing into a conflicting trace ? */
    if( !other )
        return;

    if( other->GetNet() == track->GetNet() )
        return;

    cv  = cursor - other->m_Start;
    vec = other->m_End - other->m_Start;

    det = (double) cv.x * vec.y - (double) cv.y * vec.x;

    /* cursor is right at the center of the old track */
    if( !det )
        return;

    dist = (track->m_Width + 1) / 2 + (other->m_Width + 1) / 2 +
           g_DesignSettings.m_TrackClearence + 2;

    /*
     * DRC wants >, so +1.
     * We may have a quantization error of 1/sqrt(2), so +1 again.
     */

    /* Vector "n" is perpendicular to "other", pointing towards the cursor. */
    if( det > 0 )
    {
        n.x = vec.y;
        n.y = -vec.x;
    }
    else
    {
        n.x = -vec.y;
        n.y = vec.x;
    }
    f   = dist / hypot( double(n.x), double(n.y) );
    n.x = wxRound( f * n.x );
    n.y = wxRound( f * n.y );

    Project( &track->m_End, cursor, other );
    track->m_End += n;
}


/****************************************************************************/
void ShowNewTrackWhenMovingCursor( WinEDA_DrawPanel* panel, wxDC* DC, bool erase )
/****************************************************************************/

/* redessin du contour de la piste  lors des deplacements de la souris
 *  Cette routine est utilisee comme .ManageCurseur()
 *  si ShowIsolDuringCreateTrack_Item.State == RUN la marge d'isolation
 *  est aussi affichee
 */
{
    D( g_CurrentTrackList.VerifyListIntegrity(); );

    int         IsolTmp;
    bool        Track_fill_copy;
    PCB_SCREEN* screen = (PCB_SCREEN*) panel->GetScreen();

    Track_fill_copy = DisplayOpt.DisplayPcbTrackFill;
    DisplayOpt.DisplayPcbTrackFill = true;
    IsolTmp = DisplayOpt.DisplayTrackIsol;

    if( g_ShowIsolDuringCreateTrack )
        DisplayOpt.DisplayTrackIsol = TRUE;

    /* efface ancienne position si elle a ete deja dessinee */
    if( erase )
    {
        Trace_Une_Piste( panel, DC, g_FirstTrackSegment, g_CurrentTrackList.GetCount(), GR_XOR );
        ( (WinEDA_BasePcbFrame*) (panel->m_Parent) )->trace_ratsnest_pad( DC );
    }

    // MacOSX seems to need this.
    if( g_CurrentTrackList.GetCount() == 0 )
        return;

    /* dessin de la nouvelle piste : mise a jour du point d'arrivee */
    g_CurrentTrackSegment->SetLayer( screen->m_Active_Layer );
    if( ! g_DesignSettings.m_UseConnectedTrackWidth )
        g_CurrentTrackSegment->m_Width = g_DesignSettings.m_CurrentTrackWidth;

    if( g_TwoSegmentTrackBuild )
    {
        TRACK* previous_track = g_CurrentTrackSegment->Back();
        if( previous_track  &&  previous_track->Type()==TYPE_TRACK )
        {
            previous_track->SetLayer( screen->m_Active_Layer );
            if( ! g_DesignSettings.m_UseConnectedTrackWidth )
                previous_track->m_Width = g_DesignSettings.m_CurrentTrackWidth;
        }
    }

    if( Track_45_Only )
    {
        if( g_TwoSegmentTrackBuild )
        {
            g_CurrentTrackSegment->m_End = ActiveScreen->m_Curseur;

            if( Drc_On )
                PushTrack(panel);

            ComputeBreakPoint( g_CurrentTrackSegment, g_CurrentTrackList.GetCount(),
               g_CurrentTrackSegment->m_End );
        }
        else
        {
            /* Calcul de l'extremite de la piste pour orientations permises:
             * horiz,vertical ou 45 degre
             */
            Calcule_Coord_Extremite_45( g_CurrentTrackSegment->m_Start.x,
                                        g_CurrentTrackSegment->m_Start.y,
                                        &g_CurrentTrackSegment->m_End.x,
                                        &g_CurrentTrackSegment->m_End.y );
        }
    }
    else    /* ici l'angle d'inclinaison est quelconque */
    {
        g_CurrentTrackSegment->m_End = screen->m_Curseur;
    }

    D( g_CurrentTrackList.VerifyListIntegrity(); );
    Trace_Une_Piste( panel, DC, g_FirstTrackSegment, g_CurrentTrackList.GetCount(), GR_XOR );

    DisplayOpt.DisplayTrackIsol    = IsolTmp;
    DisplayOpt.DisplayPcbTrackFill = Track_fill_copy;

    ( (WinEDA_BasePcbFrame*) (panel->m_Parent) )->
    build_ratsnest_pad( NULL, g_CurrentTrackSegment->m_End, FALSE );

    ( (WinEDA_BasePcbFrame*) (panel->m_Parent) )->trace_ratsnest_pad( DC );
}


/*****************************************************************/
void Calcule_Coord_Extremite_45( int ox, int oy, int* fx, int* fy )
/*****************************************************************/

/* determine les parametres .fx et .fy du segment pointe par pt_segm
 *  pour avoir un segment oriente a 0, 90 ou 45 degres, selon position
 *  du oint d'origine et de la souris
 */
{
    int deltax, deltay, angle;

    deltax = ActiveScreen->m_Curseur.x - ox;
    deltay = ActiveScreen->m_Curseur.y - oy;

    /* calcul de l'angle preferentiel : 0, 45 , 90 degre */
    deltax = abs( deltax );
    deltay = abs( deltay );
    angle = 45;

    if( deltax >= deltay )
    {
        if( deltax == 0 )
            angle = 0;
        else if( ( (deltay << 6 ) / deltax ) < 26 )
            angle = 0;
    }
    else
    {
        angle = 45;

        if( deltay == 0 )
            angle = 90;
        else if( ( (deltax << 6 ) / deltay ) < 26 )
            angle = 90;
    }

    switch( angle )
    {
    case 0:
        *fx = ActiveScreen->m_Curseur.x;
        *fy = oy;
        break;

    case 45:
        deltax = MIN( deltax, deltay );
        deltay = deltax;

        /* recalcul des signes de deltax et deltay */
        if( (ActiveScreen->m_Curseur.x - ox) < 0 )
            deltax = -deltax;
        if( (ActiveScreen->m_Curseur.y - oy) < 0 )
            deltay = -deltay;

        *fx = ox + deltax;
        *fy = oy + deltay;
        break;

    case 90:
        *fx = ox;
        *fy = ActiveScreen->m_Curseur.y;
        break;
    }
}


/********************************************************/
void ComputeBreakPoint( TRACK* track, int SegmentCount, wxPoint end )
/********************************************************/

/**
 * Compute new track angle based on previous track.
 */
{
    int iDx    = 0;
    int iDy    = 0;
    int iAngle = 0;

    if( SegmentCount <= 0 )
        return;
    if( track == NULL )
        return;

    TRACK* newTrack = track;
    track = track->Back();
    SegmentCount--;
    if( track )
    {
        iDx = end.x - track->m_Start.x;
        iDy = end.y - track->m_Start.y;

        iDx = abs( iDx );
        iDy = abs( iDy );
    }

    TRACK* lastTrack = track ? track->Back() : NULL;
    if( lastTrack )
    {
        if( (lastTrack->m_End.x == lastTrack->m_Start.x)
         || (lastTrack->m_End.y == lastTrack->m_Start.y) )
        {
            iAngle = 45;
        }
    }

    if( iAngle == 0 )
    {
        if( iDx >= iDy )
            iAngle = 0;
        else
            iAngle = 90;
    }

    if( track == NULL )
        iAngle = -1;

    switch( iAngle )
    {
    case - 1:
        break;

    case 0:
        if( (end.x - track->m_Start.x) < 0 )
            track->m_End.x = end.x + iDy;
        else
            track->m_End.x = end.x - iDy;
        track->m_End.y = track->m_Start.y;
        break;

    case 45:
        iDx = MIN( iDx, iDy );
        iDy = iDx;

        /* recalcul des signes de deltax et deltay */
        if( (end.x - track->m_Start.x) < 0 )
            iDx = -iDx;
        if( (end.y - track->m_Start.y) < 0 )
            iDy = -iDy;

        track->m_End.x = track->m_Start.x + iDx;
        track->m_End.y = track->m_Start.y + iDy;
        break;

    case 90:
        if( (end.y - track->m_Start.y) < 0 )
            track->m_End.y = end.y + iDx;
        else
            track->m_End.y = end.y - iDx;

        track->m_End.x = track->m_Start.x;
        break;
    }

    if( track )
    {
        if( track->IsNull() )
            track->m_End = end;

        newTrack->m_Start = track->m_End;
    }
    newTrack->m_End = end;
}


/****************************************************************************/
void DeleteNullTrackSegments( BOARD* pcb, DLIST<TRACK>& aTrackList )
/****************************************************************************/

/* Delete track segments which have len = 0; after creating a new track
 *  return a pointer on the first segment (start of track list)
 */
{
    if( aTrackList.GetCount() == 0 )
        return;

    TRACK*      track = aTrackList.GetFirst();
    TRACK*      firsttrack = track;
    TRACK*      oldtrack;

    BOARD_ITEM* LockPoint = track->start;
    while( track != NULL )
    {
        oldtrack = track;
        track    = track->Next();
        if( !oldtrack->IsNull() )
        {
            continue;
        }

        // NULL segment, delete it
        if( firsttrack == oldtrack )
            firsttrack = track;

        delete aTrackList.Remove( oldtrack );
    }

    if( aTrackList.GetCount() == 0 )
        return;         // all the new track segments have been deleted

    // we must set the pointers on connected items and the connection status
    oldtrack = track = firsttrack;
    firsttrack->start = NULL;
    while( track != NULL )
    {
        oldtrack      = track;
        track         = track->Next();
        oldtrack->end = track;

        if( track )
            track->start = oldtrack;

        oldtrack->SetStatus( 0 );
    }

    firsttrack->start = LockPoint;
    if( LockPoint &&  LockPoint->Type()==TYPE_PAD )
        firsttrack->SetState( BEGIN_ONPAD, ON );

    track = firsttrack;
    while( track != NULL )
    {
        TRACK* next_track = track->Next();
        LockPoint = Locate_Pad_Connecte( pcb, track, END );
        if( LockPoint )
        {
            track->end = LockPoint;
            track->SetState( END_ONPAD, ON );
            if( next_track )
            {
                next_track->start = LockPoint;
                next_track->SetState( BEGIN_ONPAD, ON );
            }
        }
        track = next_track;
    }
}


/************************************/
void EnsureEndTrackOnPad( D_PAD* Pad )
/************************************/

/* Ensure the end point of g_CurrentTrackSegment is on the pas "Pad"
 *  if no, create a new track segment if necessary
 *  and move current (or new) end segment on pad
 */
{
    if( g_CurrentTrackSegment->m_End == Pad->m_Pos ) // Ok !
    {
        g_CurrentTrackSegment->end = Pad;
        g_CurrentTrackSegment->SetState( END_ONPAD, ON );
        return;
    }

    TRACK* lasttrack = g_CurrentTrackSegment;
    if( !g_CurrentTrackSegment->IsNull() )
    {
        /* Must create a new segment, from track end to pad center */
        g_CurrentTrackList.PushBack( lasttrack->Copy() );

        lasttrack->end = g_CurrentTrackSegment;
    }

    g_CurrentTrackSegment->m_End = Pad->m_Pos;
    g_CurrentTrackSegment->SetState( END_ONPAD, OFF );

    g_CurrentTrackSegment->end = Pad;
    g_CurrentTrackSegment->SetState( END_ONPAD, ON );
}