// SPDX-License-Identifier: GPL-2.0-or-later
/**
 * @file
 * A light-weight widget containing an SPCanvas for rendering an SVG.
 */
/*
 * Authors:
 *   Tavmjong Bah <tavmjong@free.fr>
 *
 * Includes code moved from svg-view.cpp authored by:
 *   MenTaLGuy
 *   Ralf Stephan <ralf@ark.in-berlin.de>
 *   Jon A. Cruz <jon@joncruz.org>
 *
 * Copyright (C) 2018 Authors
 *
 * The contents of this file may be used under the GNU General Public License Version 2 or later.
 * Read the file 'COPYING' for more information.
 *
 */

#include <iostream>

#include "svg-view-widget.h"

#include "document.h"

#include "2geom/transforms.h"

#include "display/sp-canvas.h"
#include "display/sp-canvas-group.h"
#include "display/sp-canvas-item.h"
#include "display/canvas-arena.h"

#include "object/sp-item.h"
#include "object/sp-root.h"

#include "util/units.h"

namespace Inkscape {
namespace UI {
namespace View {

/**
 * Callback connected with arena_event.
 */
// This hasn't worked since at least 0.48. It should result in a cursor change over <a></a> links.
// There should be a better way of doing this. See note in canvas-arena.cpp.
static gint arena_handler(SPCanvasArena */*arena*/, Inkscape::DrawingItem *ai,
                          GdkEvent *event, SVGViewWidget *svgview)
{
    static gdouble x, y;
    static gboolean active = FALSE;
    SPEvent spev;

    SPItem *spitem = (ai) ? ai->getItem() : nullptr;

    switch (event->type) {
        case GDK_BUTTON_PRESS:
            if (event->button.button == 1) {
                active = TRUE;
                x = event->button.x;
                y = event->button.y;
            }
            break;
        case GDK_BUTTON_RELEASE:
            if (event->button.button == 1) {
                if (active && (event->button.x == x) &&
                    (event->button.y == y)) {
                    spev.type = SPEvent::ACTIVATE;
                    if ( spitem != nullptr )
                    {
                        spitem->emitEvent (spev);
                    }
                }
            }
            active = FALSE;
            break;
        case GDK_MOTION_NOTIFY:
            active = FALSE;
            break;
        case GDK_ENTER_NOTIFY:
            spev.type = SPEvent::MOUSEOVER;
            spev.view = svgview;
            if ( spitem != nullptr )
            {
                spitem->emitEvent (spev);
            }
            break;
        case GDK_LEAVE_NOTIFY:
            spev.type = SPEvent::MOUSEOUT;
            spev.view = svgview;
            if ( spitem != nullptr )
            {
                spitem->emitEvent (spev);
            }
            break;
        default:
            break;
    }

    return TRUE;
}


/**
 * A light-weight widget containing an SPCanvas for rendering an SVG.
 * It's derived from a Gtk::ScrolledWindow like the previous C version, but that doesn't seem to be
 * too useful.
 */
SVGViewWidget::SVGViewWidget(SPDocument* document)
    : _document(nullptr)
    , _dkey(0)
    , _parent(nullptr)
    , _drawing(nullptr)
    , _hscale(1.0)
    , _vscale(1.0)
    , _rescale(false)
    , _keepaspect(false)
    , _width(0.0)
    , _height(0.0)
{
    _canvas = SPCanvas::createAA();
    add(*Glib::wrap(_canvas));

    SPCanvasItem* item =
        sp_canvas_item_new(SP_CANVAS(_canvas)->getRoot(), SP_TYPE_CANVAS_GROUP, nullptr);
    _parent = SP_CANVAS_GROUP(item);

    _drawing = sp_canvas_item_new (_parent, SP_TYPE_CANVAS_ARENA, nullptr);
    g_signal_connect (G_OBJECT (_drawing), "arena_event", G_CALLBACK (arena_handler), this);

    setDocument(document);

    signal_size_allocate().connect(sigc::mem_fun(*this, &SVGViewWidget::size_allocate));
}

SVGViewWidget::~SVGViewWidget()
{
    if (_document) {
        _document = nullptr;
    }
}

void
SVGViewWidget::setDocument(SPDocument* document)
{
    // Clear old document
    if (_document) {
        _document->getRoot()->invoke_hide(_dkey); // Removed from display tree
    }

    // Add new document
    if (document) {
        _document = document;

        Inkscape::DrawingItem *ai = document->getRoot()->invoke_show(
                SP_CANVAS_ARENA (_drawing)->drawing,
                _dkey,
                SP_ITEM_SHOW_DISPLAY);

        if (ai) {
            SP_CANVAS_ARENA (_drawing)->drawing.root()->prependChild(ai);
        }

        doRescale ();
    }
}

void
SVGViewWidget::setResize(int width, int height)
{
    // Triggers size_allocation which calls SVGViewWidget::size_allocate.
    set_size_request(width, height);
    queue_resize();
}

void
SVGViewWidget::size_allocate(Gtk::Allocation& allocation)
{
    double width  = allocation.get_width();
    double height = allocation.get_height();

    if (width < 0.0 || height < 0.0) {
        std::cerr << "SVGViewWidget::size_allocate: negative dimensions!" << std::endl;
        return;
    }

    _rescale = true;
    _keepaspect = true;
    _width = width;
    _height = height;

    doRescale ();
}

void
SVGViewWidget::doRescale()
{
    if (!_document) {
        std::cerr << "SVGViewWidget::doRescale: No document!" << std::endl;
        return;
    }

    if (_document->getWidth().value("px") < 1e-9) {
        std::cerr << "SVGViewWidget::doRescale: Width too small!" << std::endl;
        return;
    }

    if (_document->getHeight().value("px") < 1e-9) {
        std::cerr << "SVGViewWidget::doRescale: Height too small!" << std::endl;
        return;
    }

    double x_offset = 0.0;
    double y_offset = 0.0;
    if (_rescale) {
        _hscale = _width / _document->getWidth().value("px");
        _vscale = _height / _document->getHeight().value("px");
        if (_keepaspect) {
            if (_hscale > _vscale) {
                _hscale = _vscale;
                x_offset = (_width  - _document->getWidth().value("px")  * _vscale)/2.0;
            } else {
                _vscale = _hscale;
                y_offset = (_height - _document->getHeight().value("px") * _hscale)/2.0;
            }
        }
    }

    if (_drawing) {
        sp_canvas_item_affine_absolute (_drawing, Geom::Scale(_hscale, _vscale) * Geom::Translate(x_offset, y_offset));
    }
}

void
SVGViewWidget::mouseover()
{
    GdkDisplay *display = gdk_display_get_default();
    GdkCursor  *cursor  = gdk_cursor_new_for_display(display, GDK_HAND2);
    GdkWindow *window = gtk_widget_get_window (GTK_WIDGET(SP_CANVAS_ITEM(_drawing)->canvas));
    gdk_window_set_cursor(window, cursor);
    g_object_unref(cursor);
}

void
SVGViewWidget::mouseout()
{
    GdkWindow *window = gtk_widget_get_window (GTK_WIDGET(SP_CANVAS_ITEM(_drawing)->canvas));
    gdk_window_set_cursor(window, nullptr);
}

} // Namespace View
} // Namespace UI
} // 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:fileencoding=utf-8 :