path: root/src/display/canvas-grid.cpp

#define INKSCAPE_CANVAS_GRID_C

/*
 *
 * Copyright (C) Johan Engelen 2006-2007 <johan@shouraizou.nl>
 * Copyright (C) Lauris Kaplinski 2000
 *
 */


#include "sp-canvas-util.h"
#include "display-forward.h"
#include <libnr/nr-pixops.h>
#include "desktop-handles.h"
#include "helper/units.h"
#include "svg/svg-color.h"
#include "xml/node-event-vector.h"
#include "sp-object.h"

#include "sp-namedview.h"
#include "inkscape.h"
#include "desktop.h"

#include "../document.h"

#include "canvas-grid.h"
#include "canvas-axonomgrid.h"

namespace Inkscape {

static void grid_canvasitem_class_init (GridCanvasItemClass *klass);
static void grid_canvasitem_init (GridCanvasItem *grid);
static void grid_canvasitem_destroy (GtkObject *object);

static void grid_canvasitem_update (SPCanvasItem *item, NR::Matrix const &affine, unsigned int flags);
static void grid_canvasitem_render (SPCanvasItem *item, SPCanvasBuf *buf);

static SPCanvasItemClass * parent_class;

GtkType
grid_canvasitem_get_type (void)
{
    static GtkType grid_canvasitem_type = 0;

    if (!grid_canvasitem_type) {
        GtkTypeInfo grid_canvasitem_info = {
            "GridCanvasItem",
            sizeof (GridCanvasItem),
            sizeof (GridCanvasItemClass),
            (GtkClassInitFunc) grid_canvasitem_class_init,
            (GtkObjectInitFunc) grid_canvasitem_init,
            NULL, NULL,
            (GtkClassInitFunc) NULL
        };
        grid_canvasitem_type = gtk_type_unique (sp_canvas_item_get_type (), &grid_canvasitem_info);
    }
    return grid_canvasitem_type;
}

static void
grid_canvasitem_class_init (GridCanvasItemClass *klass)
{
    GtkObjectClass *object_class;
    SPCanvasItemClass *item_class;

    object_class = (GtkObjectClass *) klass;
    item_class = (SPCanvasItemClass *) klass;

    parent_class = (SPCanvasItemClass*)gtk_type_class (sp_canvas_item_get_type ());

    object_class->destroy = grid_canvasitem_destroy;

    item_class->update = grid_canvasitem_update;
    item_class->render = grid_canvasitem_render;
}

static void
grid_canvasitem_init (GridCanvasItem *griditem)
{
    griditem->grid = NULL;
}

static void
grid_canvasitem_destroy (GtkObject *object)
{
    g_return_if_fail (object != NULL);
    g_return_if_fail (INKSCAPE_IS_GRID_CANVASITEM (object));

    if (GTK_OBJECT_CLASS (parent_class)->destroy)
        (* GTK_OBJECT_CLASS (parent_class)->destroy) (object);
}

/**
*/
static void
grid_canvasitem_render (SPCanvasItem * item, SPCanvasBuf * buf)
{
    GridCanvasItem *gridcanvasitem = INKSCAPE_GRID_CANVASITEM (item);

    sp_canvas_prepare_buffer (buf);

    if (gridcanvasitem->grid) gridcanvasitem->grid->Render(buf);
}

static void
grid_canvasitem_update (SPCanvasItem *item, NR::Matrix const &affine, unsigned int flags)
{
    GridCanvasItem *gridcanvasitem = INKSCAPE_GRID_CANVASITEM (item);

    if (parent_class->update)
        (* parent_class->update) (item, affine, flags);

    if (gridcanvasitem->grid) {
        gridcanvasitem->grid->Update(affine, flags);

        sp_canvas_request_redraw (item->canvas,
                         -1000000, -1000000,
                         1000000, 1000000);

        item->x1 = item->y1 = -1000000;
        item->x2 = item->y2 = 1000000;
    }
}



// ##########################################################
//   CanvasGrid

    static Inkscape::XML::NodeEventVector const _repr_events = {
        NULL, /* child_added */
        NULL, /* child_removed */
        CanvasGrid::on_repr_attr_changed,
        NULL, /* content_changed */
        NULL  /* order_changed */
    };

CanvasGrid::CanvasGrid(SPDesktop *desktop, Inkscape::XML::Node * in_repr)
{
    //create canvasitem
    // FIXME: probably this creation has to be done on demand. I think for multiple desktops it is best if each has their own canvasitem, but share the same CanvasGrid object.
    canvasitem = INKSCAPE_GRID_CANVASITEM( sp_canvas_item_new(sp_desktop_grid(desktop), INKSCAPE_TYPE_GRID_CANVASITEM, NULL) );
    gtk_object_ref(GTK_OBJECT(canvasitem));    // since we're keeping a copy, we need to bump up the ref count
    canvasitem->grid = this;

    enabled = false;
    visible = false;

//    sp_canvas_item_hide(canvasitem);

    repr = in_repr;
    if (repr) {
        repr->addListener (&_repr_events, this);
    }
    
    namedview = sp_desktop_namedview(desktop);
}

CanvasGrid::~CanvasGrid()
{
    if (repr) {
        repr->removeListenerByData (this);
    }

    sp_canvas_item_hide(canvasitem);
   // deref canvasitem
   gtk_object_unref(GTK_OBJECT(canvasitem));
   g_free(canvasitem);
   g_message("~CanvasGrid");
}

/*
*  writes an <inkscape:grid> child to repr. 
*/
void 
CanvasGrid::writeNewGridToRepr(Inkscape::XML::Node * repr, const char * gridtype)
{
    if (!repr) return;
    if (!gridtype) return;
    
    // first create the child xml node, then hook it to repr. This order is important, to not set off listeners to repr before the new node is complete.
    
    Inkscape::XML::Document *xml_doc = sp_document_repr_doc(sp_desktop_document(SP_ACTIVE_DESKTOP));
    Inkscape::XML::Node *newnode;
    newnode = xml_doc->createElement("inkscape:grid");
    newnode->setAttribute("type",gridtype);
    
    repr->appendChild(newnode);

    // FIXME: add this to history?
//    sp_document_done(current_document, SP_VERB_DIALOG_XML_EDITOR,
//                     _("Create new element node"));
}

/*
* Creates a new CanvasGrid object of type gridtype 
*/
CanvasGrid* 
CanvasGrid::NewGrid(SPDesktop *desktop, Inkscape::XML::Node * in_repr, const char * gridtype)
{
    if (!desktop) return NULL;
    if (!in_repr) return NULL;
    if (!gridtype) return NULL;
    
    if (!strcmp(gridtype,"xygrid")) {
        return (CanvasGrid*) new CanvasXYGrid(desktop, in_repr);
    } else if (!strcmp(gridtype,"axonometric")) {
        return (CanvasGrid*) new CanvasAxonomGrid(desktop, in_repr);
    }
    
    return NULL;
}


void
CanvasGrid::hide()
{
    sp_canvas_item_hide(canvasitem);
    visible = false;
}

void
CanvasGrid::show()
{
    sp_canvas_item_show(canvasitem);
    visible = true;
}

void
CanvasGrid::on_repr_attr_changed (Inkscape::XML::Node * repr, const gchar *key, const gchar *oldval, const gchar *newval, bool is_interactive, void * data)
{
    if (!data)
        return;

    ((CanvasGrid*) data)->onReprAttrChanged(repr, key, oldval, newval, is_interactive);
}



// ##########################################################
//   CanvasXYGrid

static void grid_hline (SPCanvasBuf *buf, gint y, gint xs, gint xe, guint32 rgba);
static void grid_vline (SPCanvasBuf *buf, gint x, gint ys, gint ye, guint32 rgba);


/**
* A DIRECT COPY-PASTE FROM DOCUMENT-PROPERTIES.CPP  TO QUICKLY GET RESULTS
*
 * Helper function that attachs widgets in a 3xn table. The widgets come in an
 * array that has two entries per table row. The two entries code for four
 * possible cases: (0,0) means insert space in first column; (0, non-0) means
 * widget in columns 2-3; (non-0, 0) means label in columns 1-3; and
 * (non-0, non-0) means two widgets in columns 2 and 3.
**/
#define SPACE_SIZE_X 15
#define SPACE_SIZE_Y 10
static inline void
attach_all (Gtk::Table &table, const Gtk::Widget *arr[], unsigned size, int start = 0)
{
    for (unsigned i=0, r=start; i<size/sizeof(Gtk::Widget*); i+=2)
    {
        if (arr[i] && arr[i+1])
        {
            table.attach (const_cast<Gtk::Widget&>(*arr[i]),   1, 2, r, r+1,
                      Gtk::FILL|Gtk::EXPAND, (Gtk::AttachOptions)0,0,0);
            table.attach (const_cast<Gtk::Widget&>(*arr[i+1]), 2, 3, r, r+1,
                      Gtk::FILL|Gtk::EXPAND, (Gtk::AttachOptions)0,0,0);
        }
        else
        {
            if (arr[i+1])
                table.attach (const_cast<Gtk::Widget&>(*arr[i+1]), 1, 3, r, r+1,
                      Gtk::FILL|Gtk::EXPAND, (Gtk::AttachOptions)0,0,0);
            else if (arr[i])
            {
                Gtk::Label& label = reinterpret_cast<Gtk::Label&> (const_cast<Gtk::Widget&>(*arr[i]));
                label.set_alignment (0.0);
                table.attach (label, 0, 3, r, r+1,
                      Gtk::FILL|Gtk::EXPAND, (Gtk::AttachOptions)0,0,0);
            }
            else
            {
                Gtk::HBox *space = manage (new Gtk::HBox);
                space->set_size_request (SPACE_SIZE_X, SPACE_SIZE_Y);
                table.attach (*space, 0, 1, r, r+1,
                      (Gtk::AttachOptions)0, (Gtk::AttachOptions)0,0,0);
            }
        }
        ++r;
    }
}

CanvasXYGrid::CanvasXYGrid (SPDesktop *desktop, Inkscape::XML::Node * in_repr)
    : CanvasGrid(desktop, in_repr), table(1, 1)
{
    origin[NR::X] = origin[NR::Y] = 0.0;
//            nv->gridcolor = (nv->gridcolor & 0xff) | (DEFAULTGRIDCOLOR & 0xffffff00);
//	case SP_ATTR_GRIDOPACITY:
//            nv->gridcolor = (nv->gridcolor & 0xffffff00) | (DEFAULTGRIDCOLOR & 0xff);
    color = 0xff3f3f20;
    empcolor = 0xFF3F3F40;
    empspacing = 5;
    spacing[NR::X] = spacing[NR::Y] = 8.0;
    gridunit = &sp_unit_get_by_id(SP_UNIT_PX);
    
    snapper = new CanvasXYGridSnapper(this, namedview, 0);
    
    // initialize widgets:
    vbox.set_border_width(2);
    table.set_spacings(2);
    vbox.pack_start(table, false, false, 0);

    _rumg.init (_("Grid _units:"), "units", _wr, repr);
    _rsu_ox.init (_("_Origin X:"), _("X coordinate of grid origin"),
                  "originx", _rumg, _wr, repr);
    _rsu_oy.init (_("O_rigin Y:"), _("Y coordinate of grid origin"),
                  "originy", _rumg, _wr, repr);
    _rsu_sx.init (_("Spacing _X:"), _("Distance between vertical grid lines"),
                  "spacingx", _rumg, _wr, repr);
    _rsu_sy.init (_("Spacing _Y:"), _("Distance between horizontal grid lines"),
                  "spacingy", _rumg, _wr, repr);
    _rcp_gcol.init (_("Grid line _color:"), _("Grid line color"),
                    _("Color of grid lines"), "color", "opacity", _wr, repr);
    _rcp_gmcol.init (_("Ma_jor grid line color:"), _("Major grid line color"),
                     _("Color of the major (highlighted) grid lines"),
                     "empcolor", "empopacity", _wr, repr);
    _rsi.init (_("_Major grid line every:"), _("lines"), "empspacing", _wr, repr);

    const Gtk::Widget* widget_array[] =
    {
        0,                  _rcbgrid._button,
        _rumg._label,       _rumg._sel,
        0,                  _rsu_ox.getSU(),
        0,                  _rsu_oy.getSU(),
        0,                  _rsu_sx.getSU(),
        0,                  _rsu_sy.getSU(),
        _rcp_gcol._label,   _rcp_gcol._cp,
        0,                  0,
        _rcp_gmcol._label,  _rcp_gmcol._cp,
        _rsi._label,        &_rsi._hbox,
    };

    attach_all (table, widget_array, sizeof(widget_array));

    vbox.show();

    if (repr) readRepr();
    updateWidgets();
}

CanvasXYGrid::~CanvasXYGrid ()
{
   if (snapper) delete snapper;
}


/* fixme: Collect all these length parsing methods and think common sane API */

static gboolean sp_nv_read_length(const gchar *str, guint base, gdouble *val, const SPUnit **unit)
{
    if (!str) {
        return FALSE;
    }

    gchar *u;
    gdouble v = g_ascii_strtod(str, &u);
    if (!u) {
        return FALSE;
    }
    while (isspace(*u)) {
        u += 1;
    }

    if (!*u) {
        /* No unit specified - keep default */
        *val = v;
        return TRUE;
    }

    if (base & SP_UNIT_DEVICE) {
        if (u[0] && u[1] && !isalnum(u[2]) && !strncmp(u, "px", 2)) {
            *unit = &sp_unit_get_by_id(SP_UNIT_PX);
            *val = v;
            return TRUE;
        }
    }

    if (base & SP_UNIT_ABSOLUTE) {
        if (!strncmp(u, "pt", 2)) {
            *unit = &sp_unit_get_by_id(SP_UNIT_PT);
        } else if (!strncmp(u, "mm", 2)) {
            *unit = &sp_unit_get_by_id(SP_UNIT_MM);
        } else if (!strncmp(u, "cm", 2)) {
            *unit = &sp_unit_get_by_id(SP_UNIT_CM);
        } else if (!strncmp(u, "m", 1)) {
            *unit = &sp_unit_get_by_id(SP_UNIT_M);
        } else if (!strncmp(u, "in", 2)) {
            *unit = &sp_unit_get_by_id(SP_UNIT_IN);
        } else {
            return FALSE;
        }
        *val = v;
        return TRUE;
    }

    return FALSE;
}

static gboolean sp_nv_read_opacity(const gchar *str, guint32 *color)
{
    if (!str) {
        return FALSE;
    }

    gchar *u;
    gdouble v = g_ascii_strtod(str, &u);
    if (!u) {
        return FALSE;
    }
    v = CLAMP(v, 0.0, 1.0);

    *color = (*color & 0xffffff00) | (guint32) floor(v * 255.9999);

    return TRUE;
}



void
CanvasXYGrid::readRepr()
{
    gchar const* value;
    if ( (value = repr->attribute("originx")) ) {
        sp_nv_read_length(value, SP_UNIT_ABSOLUTE | SP_UNIT_DEVICE, &origin[NR::X], &gridunit);
        origin[NR::X] = sp_units_get_pixels(origin[NR::X], *(gridunit));
    }
    if ( (value = repr->attribute("originy")) ) {
        sp_nv_read_length(value, SP_UNIT_ABSOLUTE | SP_UNIT_DEVICE, &origin[NR::Y], &gridunit);
        origin[NR::Y] = sp_units_get_pixels(origin[NR::Y], *(gridunit));
    }

    if ( (value = repr->attribute("spacingx")) ) {
        sp_nv_read_length(value, SP_UNIT_ABSOLUTE | SP_UNIT_DEVICE, &spacing[NR::X], &gridunit);
        spacing[NR::X] = sp_units_get_pixels(spacing[NR::X], *(gridunit));
    }
    if ( (value = repr->attribute("spacingy")) ) {
        sp_nv_read_length(value, SP_UNIT_ABSOLUTE | SP_UNIT_DEVICE, &spacing[NR::Y], &gridunit);
        spacing[NR::Y] = sp_units_get_pixels(spacing[NR::Y], *(gridunit));
    }

    if ( (value = repr->attribute("color")) ) {
        color = (color & 0xff) | sp_svg_read_color(value, color);
    }

    if ( (value = repr->attribute("empcolor")) ) {
        empcolor = (empcolor & 0xff) | sp_svg_read_color(value, empcolor);
    }

    if ( (value = repr->attribute("opacity")) ) {
        sp_nv_read_opacity(value, &color);
    }
    if ( (value = repr->attribute("empopacity")) ) {
        sp_nv_read_opacity(value, &empcolor);
    }

    if ( (value = repr->attribute("empspacing")) ) {
        empspacing = atoi(value);
    }

    sp_canvas_item_request_update (canvasitem);

    return;
}

/**
 * Called when XML node attribute changed; updates dialog widgets if change was not done by widgets themselves.
 */
void
CanvasXYGrid::onReprAttrChanged (Inkscape::XML::Node * repr, const gchar *key, const gchar *oldval, const gchar *newval, bool is_interactive)
{
    readRepr();

    if ( ! (_wr.isUpdating()) )
        updateWidgets();
}




Gtk::Widget &
CanvasXYGrid::getWidget()
{
    return vbox;
}


/**
 * Update dialog widgets from object's values.
 */
void
CanvasXYGrid::updateWidgets()
{
    if (_wr.isUpdating()) return;

    _wr.setUpdating (true);

//    _rrb_gridtype.setValue (nv->gridtype);
    _rumg.setUnit (gridunit);

    gdouble val;
    val = origin[NR::X];
    val = sp_pixels_get_units (val, *(gridunit));
    _rsu_ox.setValue (val);
    val = origin[NR::Y];
    val = sp_pixels_get_units (val, *(gridunit));
    _rsu_oy.setValue (val);
    val = spacing[NR::X];
    double gridx = sp_pixels_get_units (val, *(gridunit));
    _rsu_sx.setValue (gridx);
    val = spacing[NR::Y];
    double gridy = sp_pixels_get_units (val, *(gridunit));
    _rsu_sy.setValue (gridy);

    _rcp_gcol.setRgba32 (color);
    _rcp_gmcol.setRgba32 (empcolor);
    _rsi.setValue (empspacing);

    _wr.setUpdating (false);
    
    return;
}



void
CanvasXYGrid::Update (NR::Matrix const &affine, unsigned int flags)
{
    ow = origin * affine;
    sw = spacing * affine;
    sw -= NR::Point(affine[4], affine[5]);

    for(int dim = 0; dim < 2; dim++) {
        gint scaling_factor = 5; //empspacing;

        if (scaling_factor <= 1)
            scaling_factor = 5;

        scaled[dim] = FALSE;
        sw[dim] = fabs (sw[dim]);
        while (sw[dim] < 8.0) {
            scaled[dim] = TRUE;
            sw[dim] *= scaling_factor;
            /* First pass, go up to the major line spacing, then
               keep increasing by two. */
            scaling_factor = 2;
        }
    }
}

void
CanvasXYGrid::Render (SPCanvasBuf *buf)
{
    const gdouble sxg = floor ((buf->rect.x0 - ow[NR::X]) / sw[NR::X]) * sw[NR::X] + ow[NR::X];
    const gint  xlinestart = (gint) Inkscape::round((sxg - ow[NR::X]) / sw[NR::X]);
    const gdouble syg = floor ((buf->rect.y0 - ow[NR::Y]) / sw[NR::Y]) * sw[NR::Y] + ow[NR::Y];
    const gint  ylinestart = (gint) Inkscape::round((syg - ow[NR::Y]) / sw[NR::Y]);

    gint ylinenum;
    gdouble y;
    for (y = syg, ylinenum = ylinestart; y < buf->rect.y1; y += sw[NR::Y], ylinenum++) {
        const gint y0 = (gint) Inkscape::round(y);

        if (!scaled[NR::Y] && (ylinenum % 5 /*empspacing*/) == 0) {
            grid_hline (buf, y0, buf->rect.x0, buf->rect.x1 - 1, empcolor);
        } else {
            grid_hline (buf, y0, buf->rect.x0, buf->rect.x1 - 1, color);
        }
    }

    gint xlinenum;
    gdouble x;
    for (x = sxg, xlinenum = xlinestart; x < buf->rect.x1; x += sw[NR::X], xlinenum++) {
        const gint ix = (gint) Inkscape::round(x);
        if (!scaled[NR::X] && (xlinenum % 5 /*empspacing*/) == 0) {
            grid_vline (buf, ix, buf->rect.y0, buf->rect.y1, empcolor);
        } else {
            grid_vline (buf, ix, buf->rect.y0, buf->rect.y1, color);
        }
    }
}












/**
 * \return x rounded to the nearest multiple of c1 plus c0.
 *
 * \note
 * If c1==0 (and c0 is finite), then returns +/-inf.  This makes grid spacing of zero
 * mean "ignore the grid in this dimention".  We're currently discussing "good" semantics
 * for guide/grid snapping.
 */

/* FIXME: move this somewhere else, perhaps */
static double round_to_nearest_multiple_plus(double x, double const c1, double const c0)
{
    return floor((x - c0) / c1 + .5) * c1 + c0;
}

CanvasXYGridSnapper::CanvasXYGridSnapper(CanvasXYGrid *grid, SPNamedView const *nv, NR::Coord const d) : LineSnapper(nv, d)
{
    this->grid = grid;
}

LineSnapper::LineList 
CanvasXYGridSnapper::_getSnapLines(NR::Point const &p) const
{
    LineList s;

    if ( grid == NULL ) {
        return s;
    }

    for (unsigned int i = 0; i < 2; ++i) {

        /* This is to make sure we snap to only visible grid lines */
        double scaled_spacing = grid->sw[i]; // this is spacing of visible lines if screen pixels

        // convert screen pixels to px
        // FIXME: after we switch to snapping dist in screen pixels, this will be unnecessary
        if (SP_ACTIVE_DESKTOP) {
            scaled_spacing /= SP_ACTIVE_DESKTOP->current_zoom();
        }

        NR::Coord const rounded = round_to_nearest_multiple_plus(p[i],
                                                                 scaled_spacing,
                                                                 grid->origin[i]);

        s.push_back(std::make_pair(NR::Dim2(i), rounded));
    }

    return s;
}































enum {
    ARG_0,
    ARG_ORIGINX,
    ARG_ORIGINY,
    ARG_SPACINGX,
    ARG_SPACINGY,
    ARG_COLOR,
    ARG_EMPCOLOR,
    ARG_EMPSPACING
};


static void cxygrid_class_init (CXYGridClass *klass);
static void cxygrid_init (CXYGrid *grid);
static void cxygrid_destroy (GtkObject *object);
static void cxygrid_set_arg (GtkObject *object, GtkArg *arg, guint arg_id);

static void cxygrid_update (SPCanvasItem *item, NR::Matrix const &affine, unsigned int flags);
static void cxygrid_render (SPCanvasItem *item, SPCanvasBuf *buf);

//static SPCanvasItemClass * parent_class;

GtkType
cxygrid_get_type (void)
{
    static GtkType cxygrid_type = 0;

    if (!cxygrid_type) {
        GtkTypeInfo cxygrid_info = {
            "CXYGrid",
            sizeof (CXYGrid),
            sizeof (CXYGridClass),
            (GtkClassInitFunc) cxygrid_class_init,
            (GtkObjectInitFunc) cxygrid_init,
            NULL, NULL,
            (GtkClassInitFunc) NULL
        };
        cxygrid_type = gtk_type_unique (sp_canvas_item_get_type (), &cxygrid_info);
    }
    return cxygrid_type;
}

static void
cxygrid_class_init (CXYGridClass *klass)
{
    GtkObjectClass *object_class;
    SPCanvasItemClass *item_class;

    object_class = (GtkObjectClass *) klass;
    item_class = (SPCanvasItemClass *) klass;

    parent_class = (SPCanvasItemClass*)gtk_type_class (sp_canvas_item_get_type ());

    gtk_object_add_arg_type ("CXYGrid::originx", GTK_TYPE_DOUBLE, GTK_ARG_WRITABLE, ARG_ORIGINX);
    gtk_object_add_arg_type ("CXYGrid::originy", GTK_TYPE_DOUBLE, GTK_ARG_WRITABLE, ARG_ORIGINY);
    gtk_object_add_arg_type ("CXYGrid::spacingx", GTK_TYPE_DOUBLE, GTK_ARG_WRITABLE, ARG_SPACINGX);
    gtk_object_add_arg_type ("CXYGrid::spacingy", GTK_TYPE_DOUBLE, GTK_ARG_WRITABLE, ARG_SPACINGY);
    gtk_object_add_arg_type ("CXYGrid::color", GTK_TYPE_INT, GTK_ARG_WRITABLE, ARG_COLOR);
    gtk_object_add_arg_type ("CXYGrid::empcolor", GTK_TYPE_INT, GTK_ARG_WRITABLE, ARG_EMPCOLOR);
    gtk_object_add_arg_type ("CXYGrid::empspacing", GTK_TYPE_INT, GTK_ARG_WRITABLE, ARG_EMPSPACING);

    object_class->destroy = cxygrid_destroy;
    object_class->set_arg = cxygrid_set_arg;

    item_class->update = cxygrid_update;
    item_class->render = cxygrid_render;
}

static void
cxygrid_init (CXYGrid *grid)
{
    grid->origin[NR::X] = grid->origin[NR::Y] = 0.0;
    grid->spacing[NR::X] = grid->spacing[NR::Y] = 8.0;
    grid->color = 0x0000ff7f;
    grid->empcolor = 0x3F3FFF40;
    grid->empspacing = 5;
}

static void
cxygrid_destroy (GtkObject *object)
{
    g_return_if_fail (object != NULL);
    g_return_if_fail (INKSCAPE_IS_CXYGRID (object));

    if (GTK_OBJECT_CLASS (parent_class)->destroy)
        (* GTK_OBJECT_CLASS (parent_class)->destroy) (object);
}

static void
cxygrid_set_arg (GtkObject *object, GtkArg *arg, guint arg_id)
{
    SPCanvasItem *item = SP_CANVAS_ITEM (object);
    CXYGrid *grid = INKSCAPE_CXYGRID (object);

    switch (arg_id) {
    case ARG_ORIGINX:
        grid->origin[NR::X] = GTK_VALUE_DOUBLE (* arg);
        sp_canvas_item_request_update (item);
        break;
    case ARG_ORIGINY:
        grid->origin[NR::Y] = GTK_VALUE_DOUBLE (* arg);
        sp_canvas_item_request_update (item);
        break;
    case ARG_SPACINGX:
        grid->spacing[NR::X] = GTK_VALUE_DOUBLE (* arg);
        if (grid->spacing[NR::X] < 0.01) grid->spacing[NR::X] = 0.01;
        sp_canvas_item_request_update (item);
        break;
    case ARG_SPACINGY:
        grid->spacing[NR::Y] = GTK_VALUE_DOUBLE (* arg);
        if (grid->spacing[NR::Y] < 0.01) grid->spacing[NR::Y] = 0.01;
        sp_canvas_item_request_update (item);
        break;
    case ARG_COLOR:
        grid->color = GTK_VALUE_INT (* arg);
        sp_canvas_item_request_update (item);
        break;
    case ARG_EMPCOLOR:
        grid->empcolor = GTK_VALUE_INT (* arg);
        sp_canvas_item_request_update (item);
        break;
    case ARG_EMPSPACING:
        grid->empspacing = GTK_VALUE_INT (* arg);
        // std::cout << "Emphasis Spacing: " << grid->empspacing << std::endl;
        sp_canvas_item_request_update (item);
        break;
    default:
        break;
    }
}

static void
grid_hline (SPCanvasBuf *buf, gint y, gint xs, gint xe, guint32 rgba)
{
    if ((y >= buf->rect.y0) && (y < buf->rect.y1)) {
        guint r, g, b, a;
        gint x0, x1, x;
        guchar *p;
        r = NR_RGBA32_R (rgba);
        g = NR_RGBA32_G (rgba);
        b = NR_RGBA32_B (rgba);
        a = NR_RGBA32_A (rgba);
        x0 = MAX (buf->rect.x0, xs);
        x1 = MIN (buf->rect.x1, xe + 1);
        p = buf->buf + (y - buf->rect.y0) * buf->buf_rowstride + (x0 - buf->rect.x0) * 3;
        for (x = x0; x < x1; x++) {
            p[0] = NR_COMPOSEN11_1111 (r, a, p[0]);
            p[1] = NR_COMPOSEN11_1111 (g, a, p[1]);
            p[2] = NR_COMPOSEN11_1111 (b, a, p[2]);
            p += 3;
        }
    }
}

static void
grid_vline (SPCanvasBuf *buf, gint x, gint ys, gint ye, guint32 rgba)
{
    if ((x >= buf->rect.x0) && (x < buf->rect.x1)) {
        guint r, g, b, a;
        gint y0, y1, y;
        guchar *p;
        r = NR_RGBA32_R(rgba);
        g = NR_RGBA32_G (rgba);
        b = NR_RGBA32_B (rgba);
        a = NR_RGBA32_A (rgba);
        y0 = MAX (buf->rect.y0, ys);
        y1 = MIN (buf->rect.y1, ye + 1);
        p = buf->buf + (y0 - buf->rect.y0) * buf->buf_rowstride + (x - buf->rect.x0) * 3;
        for (y = y0; y < y1; y++) {
            p[0] = NR_COMPOSEN11_1111 (r, a, p[0]);
            p[1] = NR_COMPOSEN11_1111 (g, a, p[1]);
            p[2] = NR_COMPOSEN11_1111 (b, a, p[2]);
            p += buf->buf_rowstride;
        }
    }
}

/**
    \brief  This function renders the grid on a particular canvas buffer
    \param  item  The grid to render on the buffer
    \param  buf   The buffer to render the grid on

    This function gets called a touch more than you might believe,
    about once per tile.  This means that it could probably be optimized
    and help things out.

    Basically this function has to determine where in the canvas it is,
    and how that associates with the grid.  It does this first by looking
    at the bounding box of the buffer, and then calculates where the grid
    starts in that buffer.  It will then step through grid lines until
    it is outside of the buffer.

    For each grid line it is drawn using the function \c sp_grid_hline
    or \c sp_grid_vline.  These are convience functions for the sake
    of making the function easier to read.

    Also, there are emphisized lines on the grid.  While the \c syg and
    \c sxg variable track grid positioning, the \c xlinestart and \c
    ylinestart variables track the 'count' of what lines they are.  If
    that count is a multiple of the line seperation between emphisis
    lines, then that line is drawn in the emphisis color.
*/
static void
cxygrid_render (SPCanvasItem * item, SPCanvasBuf * buf)
{
    CXYGrid *grid = INKSCAPE_CXYGRID (item);

    sp_canvas_prepare_buffer (buf);

    const gdouble sxg = floor ((buf->rect.x0 - grid->ow[NR::X]) / grid->sw[NR::X]) * grid->sw[NR::X] + grid->ow[NR::X];
    const gint  xlinestart = (gint) Inkscape::round((sxg - grid->ow[NR::X]) / grid->sw[NR::X]);
    const gdouble syg = floor ((buf->rect.y0 - grid->ow[NR::Y]) / grid->sw[NR::Y]) * grid->sw[NR::Y] + grid->ow[NR::Y];
    const gint  ylinestart = (gint) Inkscape::round((syg - grid->ow[NR::Y]) / grid->sw[NR::Y]);

    gint ylinenum;
    gdouble y;
    for (y = syg, ylinenum = ylinestart; y < buf->rect.y1; y += grid->sw[NR::Y], ylinenum++) {
        const gint y0 = (gint) Inkscape::round(y);

        if (!grid->scaled[NR::Y] && (ylinenum % grid->empspacing) == 0) {
            grid_hline (buf, y0, buf->rect.x0, buf->rect.x1 - 1, grid->empcolor);
        } else {
            grid_hline (buf, y0, buf->rect.x0, buf->rect.x1 - 1, grid->color);
        }
    }

    gint xlinenum;
    gdouble x;
    for (x = sxg, xlinenum = xlinestart; x < buf->rect.x1; x += grid->sw[NR::X], xlinenum++) {
        const gint ix = (gint) Inkscape::round(x);
        if (!grid->scaled[NR::X] && (xlinenum % grid->empspacing) == 0) {
            grid_vline (buf, ix, buf->rect.y0, buf->rect.y1, grid->empcolor);
        } else {
            grid_vline (buf, ix, buf->rect.y0, buf->rect.y1, grid->color);
        }
    }
}

static void
cxygrid_update (SPCanvasItem *item, NR::Matrix const &affine, unsigned int flags)
{
    CXYGrid *grid = INKSCAPE_CXYGRID (item);

    if (parent_class->update)
        (* parent_class->update) (item, affine, flags);

    grid->ow = grid->origin * affine;
    grid->sw = grid->spacing * affine;
    grid->sw -= NR::Point(affine[4], affine[5]);

    for(int dim = 0; dim < 2; dim++) {
        gint scaling_factor = grid->empspacing;

        if (scaling_factor <= 1)
            scaling_factor = 5;

        grid->scaled[dim] = FALSE;
        grid->sw[dim] = fabs (grid->sw[dim]);
        while (grid->sw[dim] < 8.0) {
            grid->scaled[dim] = TRUE;
            grid->sw[dim] *= scaling_factor;
            /* First pass, go up to the major line spacing, then
               keep increasing by two. */
            scaling_factor = 2;
        }
    }

    if (grid->empspacing == 0) {
        grid->scaled[NR::Y] = TRUE;
        grid->scaled[NR::X] = TRUE;
    }

    sp_canvas_request_redraw (item->canvas,
                     -1000000, -1000000,
                     1000000, 1000000);

    item->x1 = item->y1 = -1000000;
    item->x2 = item->y2 = 1000000;
}


}; /* namespace Inkscape */

/*
  Local Variables:
  mode:c++
  c-file-style:"stroustrup"
  c-file-offsets:((innamespace . 0)(inline-open . 0)(case-label . +))
  indent-tabs-mode:nil
  fill-column:99
  End:
*/
// vim: filetype=cpp:expandtab:shiftwidth=4:tabstop=8:softtabstop=4 :