gtk/gdk/gdkcursor.c
Matthias Clasen d1aa0a74e4 gdk: Add callback cursors
Add a variant of GdkCursor that obtains the texture for the cursor
via a callback. The callback gives us the flexibility to handle
fractional scales and update the cursor for cursor theme size
changes as well as scale changes.
2024-04-04 01:07:28 +02:00

532 lines
17 KiB
C

/* GDK - The GIMP Drawing Kit
* Copyright (C) 1995-1997 Peter Mattis, Spencer Kimball and Josh MacDonald
*
* 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/>.
*/
/*
* Modified by the GTK+ Team and others 1997-2000. See the AUTHORS
* file for a list of people on the GTK+ Team. See the ChangeLog
* files for a list of changes. These files are distributed with
* GTK+ at ftp://ftp.gtk.org/pub/gtk/.
*/
#include "config.h"
#define GDK_PIXBUF_ENABLE_BACKEND
#include <gdk-pixbuf/gdk-pixbuf.h>
#include "gdkcursor.h"
#include "gdkcursorprivate.h"
#include "gdktexture.h"
#include <glib/gi18n-lib.h>
#include <math.h>
#include <errno.h>
/**
* GdkCursor:
*
* `GdkCursor` is used to create and destroy cursors.
*
* Cursors are immutable objects, so once you created them, there is no way
* to modify them later. You should create a new cursor when you want to change
* something about it.
*
* Cursors by themselves are not very interesting: they must be bound to a
* window for users to see them. This is done with [method@Gdk.Surface.set_cursor]
* or [method@Gdk.Surface.set_device_cursor]. Applications will typically
* use higher-level GTK functions such as [gtk_widget_set_cursor()](../gtk4/method.Widget.set_cursor.html)
* instead.
*
* Cursors are not bound to a given [class@Gdk.Display], so they can be shared.
* However, the appearance of cursors may vary when used on different
* platforms.
*
* ## Named and texture cursors
*
* There are multiple ways to create cursors. The platform's own cursors
* can be created with [ctor@Gdk.Cursor.new_from_name]. That function lists
* the commonly available names that are shared with the CSS specification.
* Other names may be available, depending on the platform in use. On some
* platforms, what images are used for named cursors may be influenced by
* the cursor theme.
*
* Another option to create a cursor is to use [ctor@Gdk.Cursor.new_from_texture]
* and provide an image to use for the cursor.
*
* To ease work with unsupported cursors, a fallback cursor can be provided.
* If a [class@Gdk.Surface] cannot use a cursor because of the reasons mentioned
* above, it will try the fallback cursor. Fallback cursors can themselves have
* fallback cursors again, so it is possible to provide a chain of progressively
* easier to support cursors. If none of the provided cursors can be supported,
* the default cursor will be the ultimate fallback.
*/
enum {
PROP_0,
PROP_FALLBACK,
PROP_HOTSPOT_X,
PROP_HOTSPOT_Y,
PROP_NAME,
PROP_TEXTURE,
};
G_DEFINE_TYPE (GdkCursor, gdk_cursor, G_TYPE_OBJECT)
static void
gdk_cursor_get_property (GObject *object,
guint prop_id,
GValue *value,
GParamSpec *pspec)
{
GdkCursor *cursor = GDK_CURSOR (object);
switch (prop_id)
{
case PROP_FALLBACK:
g_value_set_object (value, cursor->fallback);
break;
case PROP_HOTSPOT_X:
g_value_set_int (value, cursor->hotspot_x);
break;
case PROP_HOTSPOT_Y:
g_value_set_int (value, cursor->hotspot_y);
break;
case PROP_NAME:
g_value_set_string (value, cursor->name);
break;
case PROP_TEXTURE:
g_value_set_object (value, cursor->texture);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
gdk_cursor_set_property (GObject *object,
guint prop_id,
const GValue *value,
GParamSpec *pspec)
{
GdkCursor *cursor = GDK_CURSOR (object);
switch (prop_id)
{
case PROP_FALLBACK:
cursor->fallback = g_value_dup_object (value);
break;
case PROP_HOTSPOT_X:
cursor->hotspot_x = g_value_get_int (value);
break;
case PROP_HOTSPOT_Y:
cursor->hotspot_y = g_value_get_int (value);
break;
case PROP_NAME:
cursor->name = g_value_dup_string (value);
break;
case PROP_TEXTURE:
cursor->texture = g_value_dup_object (value);
break;
default:
G_OBJECT_WARN_INVALID_PROPERTY_ID (object, prop_id, pspec);
break;
}
}
static void
gdk_cursor_finalize (GObject *object)
{
GdkCursor *cursor = GDK_CURSOR (object);
g_free (cursor->name);
g_clear_object (&cursor->texture);
g_clear_object (&cursor->fallback);
if (cursor->destroy)
cursor->destroy (cursor->data);
G_OBJECT_CLASS (gdk_cursor_parent_class)->finalize (object);
}
static void
gdk_cursor_class_init (GdkCursorClass *cursor_class)
{
GObjectClass *object_class = G_OBJECT_CLASS (cursor_class);
object_class->get_property = gdk_cursor_get_property;
object_class->set_property = gdk_cursor_set_property;
object_class->finalize = gdk_cursor_finalize;
/**
* GdkCursor:fallback: (attributes org.gtk.Property.get=gdk_cursor_get_fallback)
*
* Cursor to fall back to if this cursor cannot be displayed.
*/
g_object_class_install_property (object_class,
PROP_FALLBACK,
g_param_spec_object ("fallback", NULL, NULL,
GDK_TYPE_CURSOR,
G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY |
G_PARAM_STATIC_STRINGS));
/**
* GdkCursor:hotspot-x: (attributes org.gtk.Property.get=gdk_cursor_get_hotspot_x)
*
* X position of the cursor hotspot in the cursor image.
*/
g_object_class_install_property (object_class,
PROP_HOTSPOT_X,
g_param_spec_int ("hotspot-x", NULL, NULL,
0, G_MAXINT, 0,
G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY |
G_PARAM_STATIC_STRINGS));
/**
* GdkCursor:hotspot-y: (attributes org.gtk.Property.get=gdk_cursor_get_hotspot_y)
*
* Y position of the cursor hotspot in the cursor image.
*/
g_object_class_install_property (object_class,
PROP_HOTSPOT_Y,
g_param_spec_int ("hotspot-y", NULL, NULL,
0, G_MAXINT, 0,
G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY |
G_PARAM_STATIC_STRINGS));
/**
* GdkCursor:name: (attributes org.gtk.Property.get=gdk_cursor_get_name)
*
* Name of this this cursor.
*
* The name will be %NULL if the cursor was created from a texture.
*/
g_object_class_install_property (object_class,
PROP_NAME,
g_param_spec_string ("name", NULL, NULL,
NULL,
G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY |
G_PARAM_STATIC_STRINGS));
/**
* GdkCursor:texture:
*
* The texture displayed by this cursor.
*
* The texture will be %NULL if the cursor was created from a name.
*/
g_object_class_install_property (object_class,
PROP_TEXTURE,
g_param_spec_object ("texture", NULL, NULL,
GDK_TYPE_TEXTURE,
G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY |
G_PARAM_STATIC_STRINGS));
}
static void
gdk_cursor_init (GdkCursor *cursor)
{
}
guint
gdk_cursor_hash (gconstpointer pointer)
{
const GdkCursor *cursor = pointer;
guint hash;
if (cursor->fallback)
hash = gdk_cursor_hash (cursor->fallback) << 16;
else
hash = 0;
if (cursor->name)
hash ^= g_str_hash (cursor->name);
else if (cursor->texture)
hash ^= g_direct_hash (cursor->texture);
else if (cursor->callback)
{
hash ^= g_direct_hash (cursor->callback);
hash ^= g_direct_hash (cursor->data);
}
hash ^= (cursor->hotspot_x << 8) | cursor->hotspot_y;
return hash;
}
gboolean
gdk_cursor_equal (gconstpointer a,
gconstpointer b)
{
const GdkCursor *ca = a;
const GdkCursor *cb = b;
if ((ca->fallback != NULL) != (cb->fallback != NULL))
return FALSE;
if (ca->fallback != NULL && !gdk_cursor_equal (ca->fallback, cb->fallback))
return FALSE;
if (g_strcmp0 (ca->name, cb->name) != 0)
return FALSE;
if (ca->texture != cb->texture)
return FALSE;
if (ca->hotspot_x != cb->hotspot_x ||
ca->hotspot_y != cb->hotspot_y)
return FALSE;
if (ca->callback != cb->callback ||
ca->data != cb->data)
return FALSE;
return TRUE;
}
/**
* gdk_cursor_new_from_name:
* @name: the name of the cursor
* @fallback: (nullable): %NULL or the `GdkCursor` to fall back to when
* this one cannot be supported
*
* Creates a new cursor by looking up @name in the current cursor
* theme.
*
* A recommended set of cursor names that will work across different
* platforms can be found in the CSS specification:
*
* | | | | |
* | --- | --- | ---- | --- |
* | "none" | ![](default_cursor.png) "default" | ![](help_cursor.png) "help" | ![](pointer_cursor.png) "pointer" |
* | ![](context_menu_cursor.png) "context-menu" | ![](progress_cursor.png) "progress" | ![](wait_cursor.png) "wait" | ![](cell_cursor.png) "cell" |
* | ![](crosshair_cursor.png) "crosshair" | ![](text_cursor.png) "text" | ![](vertical_text_cursor.png) "vertical-text" | ![](alias_cursor.png) "alias" |
* | ![](copy_cursor.png) "copy" | ![](no_drop_cursor.png) "no-drop" | ![](move_cursor.png) "move" | ![](not_allowed_cursor.png) "not-allowed" |
* | ![](grab_cursor.png) "grab" | ![](grabbing_cursor.png) "grabbing" | ![](all_scroll_cursor.png) "all-scroll" | ![](col_resize_cursor.png) "col-resize" |
* | ![](row_resize_cursor.png) "row-resize" | ![](n_resize_cursor.png) "n-resize" | ![](e_resize_cursor.png) "e-resize" | ![](s_resize_cursor.png) "s-resize" |
* | ![](w_resize_cursor.png) "w-resize" | ![](ne_resize_cursor.png) "ne-resize" | ![](nw_resize_cursor.png) "nw-resize" | ![](sw_resize_cursor.png) "sw-resize" |
* | ![](se_resize_cursor.png) "se-resize" | ![](ew_resize_cursor.png) "ew-resize" | ![](ns_resize_cursor.png) "ns-resize" | ![](nesw_resize_cursor.png) "nesw-resize" |
* | ![](nwse_resize_cursor.png) "nwse-resize" | ![](zoom_in_cursor.png) "zoom-in" | ![](zoom_out_cursor.png) "zoom-out" | |
*
* Returns: (nullable): a new `GdkCursor`, or %NULL if there is no
* cursor with the given name
*/
GdkCursor *
gdk_cursor_new_from_name (const char *name,
GdkCursor *fallback)
{
g_return_val_if_fail (name != NULL, NULL);
g_return_val_if_fail (fallback == NULL || GDK_IS_CURSOR (fallback), NULL);
return g_object_new (GDK_TYPE_CURSOR,
"name", name,
"fallback", fallback,
NULL);
}
/**
* gdk_cursor_new_from_texture:
* @texture: the texture providing the pixel data
* @hotspot_x: the horizontal offset of the “hotspot” of the cursor
* @hotspot_y: the vertical offset of the “hotspot” of the cursor
* @fallback: (nullable): the `GdkCursor` to fall back to when
* this one cannot be supported
*
* Creates a new cursor from a `GdkTexture`.
*
* Returns: a new `GdkCursor`
*/
GdkCursor *
gdk_cursor_new_from_texture (GdkTexture *texture,
int hotspot_x,
int hotspot_y,
GdkCursor *fallback)
{
g_return_val_if_fail (GDK_IS_TEXTURE (texture), NULL);
g_return_val_if_fail (0 <= hotspot_x && hotspot_x < gdk_texture_get_width (texture), NULL);
g_return_val_if_fail (0 <= hotspot_y && hotspot_y < gdk_texture_get_height (texture), NULL);
g_return_val_if_fail (fallback == NULL || GDK_IS_CURSOR (fallback), NULL);
return g_object_new (GDK_TYPE_CURSOR,
"texture", texture,
"hotspot-x", hotspot_x,
"hotspot-y", hotspot_y,
"fallback", fallback,
NULL);
}
/**
* gdk_cursor_new_from_callback:
* @callback: the `GdkCursorGetTextureCallback`
* @data: data to pass to @callback
* @destroy: destroy notify for @data
* @fallback: (nullable): the `GdkCursor` to fall back to when
* this one cannot be supported
*
* Creates a new callback-based cursor object.
*
* Cursors of this kind produce textures for the cursor
* image on demand, when the @callback is called.
*
* Returns: (nullable): a new `GdkCursor`
*
* Since: 4.16
*/
GdkCursor *
gdk_cursor_new_from_callback (GdkCursorGetTextureCallback callback,
gpointer data,
GDestroyNotify destroy,
GdkCursor *fallback)
{
GdkCursor *cursor;
g_return_val_if_fail (callback != NULL, NULL);
g_return_val_if_fail (fallback == NULL || GDK_IS_CURSOR (fallback), NULL);
cursor = g_object_new (GDK_TYPE_CURSOR,
"fallback", fallback,
NULL);
cursor->callback = callback;
cursor->data = data;
cursor->destroy = destroy;
return cursor;
}
/**
* gdk_cursor_get_fallback: (attributes org.gtk.Method.get_property=fallback)
* @cursor: a `GdkCursor`
*
* Returns the fallback for this @cursor.
*
* The fallback will be used if this cursor is not available on a given
* `GdkDisplay`. For named cursors, this can happen when using nonstandard
* names or when using an incomplete cursor theme. For textured cursors,
* this can happen when the texture is too large or when the `GdkDisplay`
* it is used on does not support textured cursors.
*
* Returns: (transfer none) (nullable): the fallback of the cursor or %NULL
* to use the default cursor as fallback
*/
GdkCursor *
gdk_cursor_get_fallback (GdkCursor *cursor)
{
g_return_val_if_fail (GDK_IS_CURSOR (cursor), NULL);
return cursor->fallback;
}
/**
* gdk_cursor_get_name: (attributes org.gtk.Method.get_property=name)
* @cursor: a `GdkCursor`
*
* Returns the name of the cursor.
*
* If the cursor is not a named cursor, %NULL will be returned.
*
* Returns: (transfer none) (nullable): the name of the cursor or %NULL
* if it is not a named cursor
*/
const char *
gdk_cursor_get_name (GdkCursor *cursor)
{
g_return_val_if_fail (GDK_IS_CURSOR (cursor), NULL);
return cursor->name;
}
/**
* gdk_cursor_get_texture:
* @cursor: a `GdkCursor`
*
* Returns the texture for the cursor.
*
* If the cursor is a named cursor, %NULL will be returned.
*
* Returns: (transfer none) (nullable): the texture for cursor or %NULL
* if it is a named cursor
*/
GdkTexture *
gdk_cursor_get_texture (GdkCursor *cursor)
{
g_return_val_if_fail (GDK_IS_CURSOR (cursor), NULL);
return cursor->texture;
}
/**
* gdk_cursor_get_hotspot_x: (attributes org.gtk.Method.get_property=hotspot-x)
* @cursor: a `GdkCursor`
*
* Returns the horizontal offset of the hotspot.
*
* The hotspot indicates the pixel that will be directly above the cursor.
*
* Note that named cursors may have a nonzero hotspot, but this function
* will only return the hotspot position for cursors created with
* [ctor@Gdk.Cursor.new_from_texture].
*
* Returns: the horizontal offset of the hotspot or 0 for named cursors
*/
int
gdk_cursor_get_hotspot_x (GdkCursor *cursor)
{
g_return_val_if_fail (GDK_IS_CURSOR (cursor), 0);
return cursor->hotspot_x;
}
/**
* gdk_cursor_get_hotspot_y: (attributes org.gtk.Method.get_property=hotspot-y)
* @cursor: a `GdkCursor`
*
* Returns the vertical offset of the hotspot.
*
* The hotspot indicates the pixel that will be directly above the cursor.
*
* Note that named cursors may have a nonzero hotspot, but this function
* will only return the hotspot position for cursors created with
* [ctor@Gdk.Cursor.new_from_texture].
*
* Returns: the vertical offset of the hotspot or 0 for named cursors
*/
int
gdk_cursor_get_hotspot_y (GdkCursor *cursor)
{
g_return_val_if_fail (GDK_IS_CURSOR (cursor), 0);
return cursor->hotspot_y;
}
GdkTexture *
gdk_cursor_get_texture_for_size (GdkCursor *cursor,
int cursor_size,
double scale,
int *width,
int *height,
int *hotspot_x,
int *hotspot_y)
{
if (cursor->callback == NULL)
return NULL;
return cursor->callback (cursor,
cursor_size, scale,
width, height,
hotspot_x, hotspot_y,
cursor->data);
}