--- /dev/null
+/* GTK - The GIMP Toolkit
+ * Copyright (C) 2023 Benjamin Otte
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+
+/**
+ * GtkScrollInfo:
+ *
+ * The `GtkScrollInfo` can be used to provide more accurate data on how a scroll
+ * operation should be performed.
+ *
+ * Scrolling functions usually allow passing a %NULL scroll info which will cause
+ * the default values to be used and just scroll the element into view.
+ *
+ * Since: 4.12
+ */
+
+#include "config.h"
+
+#include "gtkscrollinfoprivate.h"
+
+#include <math.h>
+
+struct _GtkScrollInfo
+{
+ guint ref_count;
+
+ gboolean enabled[2]; /* directions */
+};
+
+static GtkScrollInfo default_scroll_info = {
+ 1,
+ { TRUE, TRUE }
+};
+
+G_DEFINE_BOXED_TYPE (GtkScrollInfo, gtk_scroll_info,
+ gtk_scroll_info_ref,
+ gtk_scroll_info_unref)
+
+
+/**
+ * gtk_scroll_info_new:
+ *
+ * Creates a new scroll info for scrolling an element into view.
+ *
+ * Returns: A new scroll info
+ *
+ * Since: 4.12
+ **/
+GtkScrollInfo *
+gtk_scroll_info_new (void)
+{
+ GtkScrollInfo *self;
+
+ self = g_new0 (GtkScrollInfo, 1);
+ self->ref_count = 1;
+ self->enabled[GTK_ORIENTATION_HORIZONTAL] = TRUE;
+ self->enabled[GTK_ORIENTATION_VERTICAL] = TRUE;
+
+ return self;
+}
+
+/**
+ * gtk_scroll_info_ref:
+ * @self: a `GtkScrollInfo`
+ *
+ * Increases the reference count of a `GtkScrollInfo` by one.
+ *
+ * Returns: the passed in `GtkScrollInfo`.
+ *
+ * Since: 4.12
+ */
+GtkScrollInfo *
+gtk_scroll_info_ref (GtkScrollInfo *self)
+{
+ g_return_val_if_fail (self != NULL, NULL);
+
+ self->ref_count++;
+
+ return self;
+}
+
+/**
+ * gtk_scroll_info_unref:
+ * @self: a `GtkScrollInfo`
+ *
+ * Decreases the reference count of a `GtkScrollInfo` by one.
+ *
+ * If the resulting reference count is zero, frees the self.
+ *
+ * Since: 4.12
+ */
+void
+gtk_scroll_info_unref (GtkScrollInfo *self)
+{
+ g_return_if_fail (self != NULL);
+ g_return_if_fail (self->ref_count > 0);
+
+ self->ref_count--;
+ if (self->ref_count > 0)
+ return;
+
+ g_free (self);
+}
+
+/**
+ * gtk_scroll_info_set_enable_horizontal:
+ * @self: a `GtkScrollInfo`
+ * @horizontal: if scrolling in the horizontal direction
+ * should happen
+ *
+ * Turns horizontal scrolling on or off.
+ *
+ * Since: 4.12
+ **/
+void
+gtk_scroll_info_set_enable_horizontal (GtkScrollInfo *self,
+ gboolean horizontal)
+{
+ g_return_if_fail (self != NULL);
+
+ self->enabled[GTK_ORIENTATION_HORIZONTAL] = horizontal;
+}
+
+/**
+ * gtk_scroll_info_get_enable_horizontal:
+ * @self: a `GtkScrollInfo`
+ *
+ * Checks if horizontal scrolling is enabled.
+ *
+ * Returns: %TRUE if horizontal scrolling is enabled.
+ *
+ * Since: 4.12
+ **/
+gboolean
+gtk_scroll_info_get_enable_horizontal (GtkScrollInfo *self)
+{
+ g_return_val_if_fail (self != NULL, FALSE);
+
+ return self->enabled[GTK_ORIENTATION_HORIZONTAL];
+}
+
+/**
+ * gtk_scroll_info_set_enable_vertical:
+ * @self: a `GtkScrollInfo`
+ * @vertical: if scrolling in the vertical direction
+ * should happen
+ *
+ * Turns vertical scrolling on or off.
+ *
+ * Since: 4.12
+ **/
+void
+gtk_scroll_info_set_enable_vertical (GtkScrollInfo *self,
+ gboolean vertical)
+{
+ g_return_if_fail (self != NULL);
+
+ self->enabled[GTK_ORIENTATION_VERTICAL] = vertical;
+}
+
+/**
+ * gtk_scroll_info_get_enable_vertical:
+ * @self: a `GtkScrollInfo`
+ *
+ * Checks if vertical scrolling is enabled.
+ *
+ * Returns: %TRUE if vertical scrolling is enabled.
+ *
+ * Since: 4.12
+ **/
+gboolean
+gtk_scroll_info_get_enable_vertical (GtkScrollInfo *self)
+{
+ g_return_val_if_fail (self != NULL, FALSE);
+
+ return self->enabled[GTK_ORIENTATION_VERTICAL];
+}
+
+int
+gtk_scroll_info_compute_for_orientation (GtkScrollInfo *self,
+ GtkOrientation orientation,
+ int area_origin,
+ int area_size,
+ int viewport_origin,
+ int viewport_size)
+{
+ float origin, size;
+ int delta;
+
+ if (self == NULL)
+ self = &default_scroll_info;
+
+ if (!self->enabled[orientation])
+ return viewport_origin;
+
+ origin = viewport_origin;
+ size = viewport_size;
+
+ if (area_origin <= origin)
+ delta = area_origin - ceil (origin);
+ else if (area_origin + area_size > origin + size)
+ delta = area_origin + area_size - floor (origin + size);
+ else
+ delta = 0;
+
+ return viewport_origin + delta;
+}
+
+/*<private>
+ * gtk_scroll_info_compute_scroll:
+ * @self: a `GtkScrollInfo`
+ * @area: area to scroll
+ * @viewport: viewport area to scroll into
+ * @out_x: (out): x coordinate to scroll viewport to
+ * @out_y: (out): y coordinate to scroll viewport to
+ *
+ * Computes The new x/y coordinate to move the viewport to
+ * according to this scroll info.
+ **/
+void
+gtk_scroll_info_compute_scroll (GtkScrollInfo *self,
+ const cairo_rectangle_int_t *area,
+ const cairo_rectangle_int_t *viewport,
+ int *out_x,
+ int *out_y)
+{
+ *out_x = gtk_scroll_info_compute_for_orientation (self,
+ GTK_ORIENTATION_HORIZONTAL,
+ area->x, area->width,
+ viewport->x, viewport->width);
+ *out_y = gtk_scroll_info_compute_for_orientation (self,
+ GTK_ORIENTATION_VERTICAL,
+ area->y, area->height,
+ viewport->y, viewport->height);
+}
+
--- /dev/null
+/* GTK - The GIMP Toolkit
+ * Copyright (C) 2023 Benjamin Otte
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#if !defined (__GTK_H_INSIDE__) && !defined (GTK_COMPILATION)
+#error "Only <gtk/gtk.h> can be included directly."
+#endif
+
+
+#include <gdk/gdk.h>
+#include <gtk/gtkenums.h>
+#include <gtk/gtktypes.h>
+
+#include <graphene.h>
+
+G_BEGIN_DECLS
+
+#define GTK_TYPE_SCROLL_INFO (gtk_scroll_info_get_type ())
+
+GDK_AVAILABLE_IN_4_12
+GType gtk_scroll_info_get_type (void) G_GNUC_CONST;
+GDK_AVAILABLE_IN_4_12
+GtkScrollInfo * gtk_scroll_info_new (void);
+
+GDK_AVAILABLE_IN_4_12
+GtkScrollInfo * gtk_scroll_info_ref (GtkScrollInfo *self);
+GDK_AVAILABLE_IN_4_12
+void gtk_scroll_info_unref (GtkScrollInfo *self);
+
+GDK_AVAILABLE_IN_4_12
+void gtk_scroll_info_set_enable_horizontal (GtkScrollInfo *self,
+ gboolean horizontal);
+GDK_AVAILABLE_IN_4_12
+gboolean gtk_scroll_info_get_enable_horizontal (GtkScrollInfo *self);
+
+GDK_AVAILABLE_IN_4_12
+void gtk_scroll_info_set_enable_vertical (GtkScrollInfo *self,
+ gboolean vertical);
+GDK_AVAILABLE_IN_4_12
+gboolean gtk_scroll_info_get_enable_vertical (GtkScrollInfo *self);
+
+
+G_DEFINE_AUTOPTR_CLEANUP_FUNC(GtkScrollInfo, gtk_scroll_info_unref)
+
+G_END_DECLS
+
--- /dev/null
+/* GTK - The GIMP Toolkit
+ * Copyright (C) 2023 Benjamin Otte
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ */
+
+#pragma once
+
+#if !defined (__GTK_H_INSIDE__) && !defined (GTK_COMPILATION)
+#error "Only <gtk/gtk.h> can be included directly."
+#endif
+
+
+#include <gtk/gtkscrollinfo.h>
+
+G_BEGIN_DECLS
+
+void gtk_scroll_info_compute_scroll (GtkScrollInfo *self,
+ const cairo_rectangle_int_t *area,
+ const cairo_rectangle_int_t *viewport,
+ int *out_x,
+ int *out_y);
+int gtk_scroll_info_compute_for_orientation (GtkScrollInfo *self,
+ GtkOrientation orientation,
+ int area_origin,
+ int area_size,
+ int viewport_origin,
+ int viewport_size);
+
+G_END_DECLS
+
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