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/*
* A class for handling shape interaction with libavoid.
*
* Authors:
* Michael Wybrow <mjwybrow@users.sourceforge.net>
*
* Copyright (C) 2005 Michael Wybrow
*
* Released under GNU GPL, read the file 'COPYING' for more information
*/
#include "sp-item.h"
#include "conn-avoid-ref.h"
#include "libnr/nr-rect-ops.h"
#include "libavoid/polyutil.h"
#include "libavoid/incremental.h"
#include "xml/simple-node.cpp"
#include "document.h"
static Avoid::Polygn avoid_item_poly(SPItem const *item);
static void avoid_item_move(NR::Matrix const *mp, SPItem *moved_item);
SPAvoidRef::SPAvoidRef(SPItem *spitem)
: shapeRef(NULL)
, item(spitem)
, setting(false)
, new_setting(false)
, _transformed_connection()
{
}
SPAvoidRef::~SPAvoidRef()
{
_transformed_connection.disconnect();
if (shapeRef) {
// shapeRef is finalised by delShape,
// so no memory is lost here.
Avoid::delShape(shapeRef);
shapeRef = NULL;
}
}
void SPAvoidRef::setAvoid(char const *value)
{
if (SP_OBJECT_IS_CLONED(item)) {
// Don't keep avoidance information for cloned objects.
return;
}
new_setting = false;
if (value && (strcmp(value, "true") == 0)) {
new_setting = true;
}
}
void SPAvoidRef::handleSettingChange(void)
{
if (new_setting == setting) {
// Don't need to make any changes
return;
}
_transformed_connection.disconnect();
if (new_setting) {
_transformed_connection = item->connectTransformed(
sigc::ptr_fun(&avoid_item_move));
Avoid::Polygn poly = avoid_item_poly(item);
if (poly.pn > 0) {
const char *id = SP_OBJECT_REPR(item)->attribute("id");
g_assert(id != NULL);
// Get a unique ID for the item.
GQuark itemID = g_quark_from_string(id);
shapeRef = new Avoid::ShapeRef(itemID, poly);
Avoid::freePoly(poly);
Avoid::addShape(shapeRef);
}
}
else
{
g_assert(shapeRef);
// shapeRef is finalised by delShape,
// so no memory is lost here.
Avoid::delShape(shapeRef);
shapeRef = NULL;
}
setting = new_setting;
}
static Avoid::Polygn avoid_item_poly(SPItem const *item)
{
Avoid::Polygn poly;
// TODO: The right way to do this is to return the convex hull of
// the object, or an approximation in the case of a rounded
// object. Specific SPItems will need to have a new
// function that returns points for the convex hull.
// For some objects it is enough to feed the snappoints to
// some convex hull code, though not NR::ConvexHull as this
// only keeps the bounding box of the convex hull currently.
// TODO: SPItem::invokeBbox gives the wrong result for some objects
// that have internal representations that are updated later
// by the sp_*_update functions, e.g., text.
sp_document_ensure_up_to_date(item->document);
NR::Rect rHull = item->invokeBbox(sp_item_i2doc_affine(item));
// Add a little buffer around the edge of each object.
NR::Rect rExpandedHull = NR::expand(rHull, -10.0);
poly = Avoid::newPoly(4);
for (unsigned n = 0; n < 4; ++n) {
// TODO: I think the winding order in libavoid or inkscape might
// be backwards, probably due to the inverse y co-ordinates
// used for the screen. The '3 - n' reverses the order.
/* On "correct" winding order: Winding order of NR::Rect::corner is in a positive
* direction, like libart. "Positive direction" means the same as in most of Inkscape and
* SVG: if you visualize y as increasing upwards, as is the convention in mathematics, then
* positive angle is visualized as anticlockwise, as in mathematics; so if you visualize y
* as increasing downwards, as is common outside of mathematics, then positive angle
* direction is visualized as clockwise, as is common outside of mathematics. This
* convention makes it easier mix pure mathematics code with graphics code: the important
* thing when mixing code is that the number values stored in variables (representing y
* coordinate, angle) match up; variables store numbers, not visualized positions, and the
* programmer is free to switch between visualizations when thinking about a given piece of
* code.
*
* MathWorld, libart and NR::Rect::corner all seem to take positive winding (i.e. winding
* that yields +1 winding number inside a simple closed shape) to mean winding in a
* positive angle. This, together with the observation that variables store numbers rather
* than positions, suggests that NR::Rect::corner uses the right direction.
*/
NR::Point hullPoint = rExpandedHull.corner(3 - n);
poly.ps[n].x = hullPoint[NR::X];
poly.ps[n].y = hullPoint[NR::Y];
}
return poly;
}
static void avoid_item_move(NR::Matrix const *mp, SPItem *moved_item)
{
Avoid::ShapeRef *shapeRef = moved_item->avoidRef->shapeRef;
g_assert(shapeRef);
Avoid::Polygn poly = avoid_item_poly(moved_item);
if (poly.pn > 0) {
// moveShape actually destroys the old shapeRef and returns a new one.
moved_item->avoidRef->shapeRef = Avoid::moveShape(shapeRef, &poly);
Avoid::freePoly(poly);
}
}
/*
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 :
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