/*

 *  Copyright (C) 2007, 2009 Holger Hans Peter Freyther zecke@selfish.org

 *  Copyright (C) 2010 Gustavo Noronha Silva <gns@gnome.org>

 *

 *  This library is free software; you can redistribute it and/or

 *  modify it under the terms of the GNU Lesser General Public

 *  License as published by the Free Software Foundation; either

 *  version 2 of the License, or (at your option) any later version.

 *

 *  This library 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

 *  Lesser General Public License for more details.

 *

 *  You should have received a copy of the GNU Lesser General Public

 *  License along with this library; if not, write to the Free Software

 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301  USA

 */

#include "config.h"

#include "ScrollbarGtk.h"

#include "GtkVersioning.h"

#include "IntRect.h"

#include "GraphicsContext.h"

#include "FrameView.h"

#include "ScrollbarTheme.h"

#include <gtk/gtk.h>

using namespace WebCore;

PassRefPtr<Scrollbar> Scrollbar::createNativeScrollbar(ScrollbarClient* client, ScrollbarOrientation orientation, ScrollbarControlSize size)

{

    return adoptRef(new ScrollbarGtk(client, orientation, size));

}

PassRefPtr<ScrollbarGtk> ScrollbarGtk::createScrollbar(ScrollbarClient* client, ScrollbarOrientation orientation, GtkAdjustment* adj)

{

    return adoptRef(new ScrollbarGtk(client, orientation, adj));

}

static gboolean gtkScrollEventCallback(GtkWidget* widget, GdkEventScroll* event, ScrollbarGtk*)

{

    /* Scroll only if our parent rejects the scroll event. The rationale for

     * this is that we want the main frame to scroll when we move the mouse

     * wheel over a child scrollbar in most cases. */

    return gtk_widget_event(gtk_widget_get_parent(widget), reinterpret_cast<GdkEvent*>(event));

}

ScrollbarGtk::ScrollbarGtk(ScrollbarClient* client, ScrollbarOrientation orientation,

                           ScrollbarControlSize controlSize)

    : Scrollbar(client, orientation, controlSize)

    , m_adjustment(GTK_ADJUSTMENT(gtk_adjustment_new(0.0, 0.0, 0.0, 0.0, 0.0, 0.0)))

{

    GtkWidget* scrollBar = orientation == HorizontalScrollbar ?

                           gtk_hscrollbar_new(m_adjustment):

                           gtk_vscrollbar_new(m_adjustment);

    gtk_widget_show(scrollBar);

    g_object_ref(m_adjustment);

    g_signal_connect(m_adjustment, "value-changed", G_CALLBACK(ScrollbarGtk::gtkValueChanged), this);

    g_signal_connect(scrollBar, "scroll-event", G_CALLBACK(gtkScrollEventCallback), this);

    setPlatformWidget(scrollBar);

    /*

     * assign a sane default width and height to the Scrollbar, otherwise

     * we will end up with a 0 width scrollbar.

     */

    resize(ScrollbarTheme::nativeTheme()->scrollbarThickness(),

           ScrollbarTheme::nativeTheme()->scrollbarThickness());

}

// Create a ScrollbarGtk on top of an existing GtkAdjustment but do not create a

// GtkScrollbar on top of this adjustment. The goal is to have a WebCore::Scrollbar

// that will manipulate the GtkAdjustment properties, will react to the changed

// value but will not consume any space on the screen and will not be painted

// at all. It is achieved by not calling setPlatformWidget.

ScrollbarGtk::ScrollbarGtk(ScrollbarClient* client, ScrollbarOrientation orientation, GtkAdjustment* adjustment)

    : Scrollbar(client, orientation, RegularScrollbar)

    , m_adjustment(adjustment)

{

    g_object_ref(m_adjustment);

    g_signal_connect(m_adjustment, "value-changed", G_CALLBACK(ScrollbarGtk::gtkValueChanged), this);

    // We have nothing to show as we are solely operating on the GtkAdjustment

    resize(0, 0);

}

ScrollbarGtk::~ScrollbarGtk()

{

    if (m_adjustment)

        detachAdjustment();

}

void ScrollbarGtk::attachAdjustment(GtkAdjustment* adjustment)

{

    if (platformWidget())

        return;

    if (m_adjustment)

        detachAdjustment();

    m_adjustment = adjustment;

    g_object_ref(m_adjustment);

    g_signal_connect(m_adjustment, "value-changed", G_CALLBACK(ScrollbarGtk::gtkValueChanged), this);

    updateThumbProportion();

    updateThumbPosition();

}

void ScrollbarGtk::detachAdjustment()

{

    if (!m_adjustment)

        return;

    g_signal_handlers_disconnect_by_func(G_OBJECT(m_adjustment), (gpointer)ScrollbarGtk::gtkValueChanged, this);

    // For the case where we only operate on the GtkAdjustment it is best to

    // reset the values so that the surrounding scrollbar gets updated, or

    // e.g. for a GtkScrolledWindow the scrollbar gets hidden.

#if GTK_CHECK_VERSION(2, 14, 0)

    gtk_adjustment_configure(m_adjustment, 0, 0, 0, 0, 0, 0);

#else

    m_adjustment->lower = 0;

    m_adjustment->upper = 0;

    m_adjustment->value = 0;

    gtk_adjustment_changed(m_adjustment);

    gtk_adjustment_value_changed(m_adjustment);

#endif

    g_object_unref(m_adjustment);

    m_adjustment = 0;

}

IntPoint ScrollbarGtk::getLocationInParentWindow(const IntRect& rect)

{

    IntPoint loc;

    if (parent()->isScrollViewScrollbar(this))

        loc = parent()->convertToContainingWindow(rect.location());

    else

        loc = parent()->contentsToWindow(rect.location());

    return loc;

}

void ScrollbarGtk::frameRectsChanged()

{

    if (!parent() || !platformWidget())

        return;

    IntPoint loc = getLocationInParentWindow(frameRect());

    // Don't allow the allocation size to be negative

    IntSize sz = frameRect().size();

    sz.clampNegativeToZero();

    GtkAllocation allocation = { loc.x(), loc.y(), sz.width(), sz.height() };

    gtk_widget_size_allocate(platformWidget(), &allocation);

}

void ScrollbarGtk::updateThumbPosition()

{

    if (gtk_adjustment_get_value(m_adjustment) != m_currentPos) {

#if GTK_CHECK_VERSION(2, 14, 0)

        gtk_adjustment_set_value(m_adjustment, m_currentPos);

#else

        m_adjustment->value = m_currentPos;

        gtk_adjustment_value_changed(m_adjustment);

#endif

    }

}

void ScrollbarGtk::updateThumbProportion()

{

#if GTK_CHECK_VERSION(2, 14, 0)

    gtk_adjustment_configure(m_adjustment,

                             gtk_adjustment_get_value(m_adjustment),

                             gtk_adjustment_get_lower(m_adjustment),

                             m_totalSize,

                             m_lineStep,

                             m_pageStep,

                             m_visibleSize);

#else

    m_adjustment->step_increment = m_lineStep;

    m_adjustment->page_increment = m_pageStep;

    m_adjustment->page_size = m_visibleSize;

    m_adjustment->upper = m_totalSize;

    gtk_adjustment_changed(m_adjustment);

#endif

}

void ScrollbarGtk::setFrameRect(const IntRect& rect)

{

    Widget::setFrameRect(rect);

    frameRectsChanged();

}

void ScrollbarGtk::gtkValueChanged(GtkAdjustment*, ScrollbarGtk* that)

{

    that->setValue(static_cast<int>(gtk_adjustment_get_value(that->m_adjustment)));

}

void ScrollbarGtk::setEnabled(bool shouldEnable)

{

    if (enabled() == shouldEnable)

        return;

    Scrollbar::setEnabled(shouldEnable);

    if (platformWidget()) 

        gtk_widget_set_sensitive(platformWidget(), shouldEnable);

}

/*

 * Strategy to painting a Widget:

 *  1.) do not paint if there is no GtkWidget set

 *  2.) We assume that the widget has no window and that frameRectsChanged positioned

 *      the widget correctly. ATM we do not honor the GraphicsContext translation.

 */

void ScrollbarGtk::paint(GraphicsContext* context, const IntRect& rect)

{

    if (!platformWidget())

        return;

    if (!context->gdkExposeEvent())

        return;

    GtkWidget* widget = platformWidget();

    ASSERT(!gtk_widget_get_has_window(widget));

    GdkEvent* event = gdk_event_new(GDK_EXPOSE);

    event->expose = *context->gdkExposeEvent();

    event->expose.area = static_cast<GdkRectangle>(rect);

    IntPoint loc = getLocationInParentWindow(rect);

    event->expose.area.x = loc.x();

    event->expose.area.y = loc.y();

#ifdef GTK_API_VERSION_2

    event->expose.region = gdk_region_rectangle(&event->expose.area);

#else

    event->expose.region = cairo_region_create_rectangle(&event->expose.area);

#endif

    /*

     * This will be unref'ed by gdk_event_free.

     */

    g_object_ref(event->expose.window);

    /*

     * If we are going to paint do the translation and GtkAllocation manipulation.

     */

#ifdef GTK_API_VERSION_2

    if (!gdk_region_empty(event->expose.region))

#else

    if (!cairo_region_is_empty(event->expose.region))

#endif

        gtk_widget_send_expose(widget, event);

    gdk_event_free(event);

}