File: ev-document-misc.c

package info (click to toggle)
evince 3.38.2-1
  • links: PTS, VCS
  • area: main
  • in suites: bullseye
  • size: 18,428 kB
  • sloc: ansic: 81,222; cpp: 6,108; xml: 707; sh: 91; makefile: 25; python: 10
file content (679 lines) | stat: -rw-r--r-- 20,396 bytes parent folder | download | duplicates (2)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
/*
 *  Copyright (C) 2009 Juanjo Marín <juanj.marin@juntadeandalucia.es>
 *  Copyright (c) 2007 Carlos Garcia Campos <carlosgc@gnome.org>
 *  Copyright (C) 2000-2003 Marco Pesenti Gritti
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2, or (at your option)
 *  any later version.
 *
 *  This program 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 General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 */

#include <config.h>

#include <string.h>
#include <math.h>

#include <gtk/gtk.h>

#include "ev-document-misc.h"

/* Returns a new GdkPixbuf that is suitable for placing in the thumbnail view.
 * It is four pixels wider and taller than the source.  If source_pixbuf is not
 * NULL, then it will fill the return pixbuf with the contents of
 * source_pixbuf.
 */
static GdkPixbuf *
create_thumbnail_frame (int        width,
			int        height,
			GdkPixbuf *source_pixbuf,
			gboolean   fill_bg)
{
	GdkPixbuf *retval;
	guchar *data;
	gint rowstride;
	int i;
	int width_r, height_r;

	if (source_pixbuf)
		g_return_val_if_fail (GDK_IS_PIXBUF (source_pixbuf), NULL);

	if (source_pixbuf) {
		width_r = gdk_pixbuf_get_width (source_pixbuf);
		height_r = gdk_pixbuf_get_height (source_pixbuf);
	} else {
		width_r = width;
		height_r = height;
	}

	/* make sure no one is passing us garbage */
	g_return_val_if_fail (width_r >= 0 && height_r >= 0, NULL);

	retval = gdk_pixbuf_new (GDK_COLORSPACE_RGB,
				 TRUE, 8,
				 width_r + 4,
				 height_r + 4);

	/* make it black and fill in the middle */
	data = gdk_pixbuf_get_pixels (retval);
	rowstride = gdk_pixbuf_get_rowstride (retval);

	gdk_pixbuf_fill (retval, 0x000000ff);
	if (fill_bg) {
		for (i = 1; i < height_r + 1; i++)
			memset (data + (rowstride * i) + 4, 0xff, width_r * 4);
	}

	/* copy the source pixbuf */
	if (source_pixbuf)
		gdk_pixbuf_copy_area (source_pixbuf, 0, 0,
				      width_r,
				      height_r,
				      retval,
				      1, 1);
	/* Add the corner */
	data [(width_r + 2) * 4 + 3] = 0;
	data [(width_r + 3) * 4 + 3] = 0;
	data [(width_r + 2) * 4 + (rowstride * 1) + 3] = 0;
	data [(width_r + 3) * 4 + (rowstride * 1) + 3] = 0;

	data [(height_r + 2) * rowstride + 3] = 0;
	data [(height_r + 3) * rowstride + 3] = 0;
	data [(height_r + 2) * rowstride + 4 + 3] = 0;
	data [(height_r + 3) * rowstride + 4 + 3] = 0;

	return retval;
}

/**
 * ev_document_misc_get_thumbnail_frame:
 * @width: the desired width
 * @height: the desired height
 * @source_pixbuf: a #GdkPixbuf
 *
 * Returns: (transfer full): a #GdkPixbuf
 */
GdkPixbuf *
ev_document_misc_get_thumbnail_frame (int        width,
				      int        height,
				      GdkPixbuf *source_pixbuf)
{
	return create_thumbnail_frame (width, height, source_pixbuf, TRUE);
}

/**
 * ev_document_misc_get_loading_thumbnail:
 * @width: the desired width
 * @height: the desired height
 * @inverted_colors: whether to invert colors
 *
 * Returns: (transfer full): a #GdkPixbuf
 */
GdkPixbuf *
ev_document_misc_get_loading_thumbnail (int      width,
					int      height,
					gboolean inverted_colors)
{
	return create_thumbnail_frame (width, height, NULL, !inverted_colors);
}

static cairo_surface_t *
ev_document_misc_render_thumbnail_frame (GtkWidget       *widget,
                                         int              width,
                                         int              height,
                                         gboolean         inverted_colors,
                                         GdkPixbuf       *source_pixbuf,
                                         cairo_surface_t *source_surface)
{
        GtkStyleContext *context = gtk_widget_get_style_context (widget);
        GtkStateFlags    state = gtk_widget_get_state_flags (widget);
        double           width_r, height_r;
        double           width_f, height_f;
        cairo_surface_t *surface;
        cairo_t         *cr;
        double           device_scale_x = 1;
        double           device_scale_y = 1;
        GtkBorder        border = {0, };

        if (source_surface) {
                width_r = cairo_image_surface_get_width (source_surface);
                height_r = cairo_image_surface_get_height (source_surface);
#ifdef HAVE_HIDPI_SUPPORT
                cairo_surface_get_device_scale (source_surface, &device_scale_x, &device_scale_y);
#endif
        } else if (source_pixbuf) {
                g_return_val_if_fail (GDK_IS_PIXBUF (source_pixbuf), NULL);

                width_r = gdk_pixbuf_get_width (source_pixbuf);
                height_r = gdk_pixbuf_get_height (source_pixbuf);
#ifdef HAVE_HIDPI_SUPPORT
                device_scale_x = device_scale_y = gtk_widget_get_scale_factor (widget);
#endif
        } else {
                width_r = width;
                height_r = height;
#ifdef HAVE_HIDPI_SUPPORT
                device_scale_x = device_scale_y = gtk_widget_get_scale_factor (widget);
#endif
        }

        width_r /= device_scale_x;
        height_r /= device_scale_y;

        gtk_style_context_save (context);

        gtk_style_context_add_class (context, "page-thumbnail");
        if (inverted_colors)
                gtk_style_context_add_class (context, "inverted");

        gtk_style_context_get_border (context, state, &border);
        width_f = width_r + border.left + border.right;
        height_f = height_r + border.top + border.bottom;

        surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32,
                                              device_scale_x * width_f,
                                              device_scale_y * height_f);

#ifdef HAVE_HIDPI_SUPPORT
        cairo_surface_set_device_scale (surface, device_scale_x, device_scale_y);
#endif

        cr = cairo_create (surface);
        if (source_surface) {
                cairo_set_source_surface (cr, source_surface, border.left, border.top);
                cairo_paint (cr);
        } else if (source_pixbuf) {
                gdk_cairo_set_source_pixbuf (cr, source_pixbuf, border.left, border.top);
                cairo_paint (cr);
        } else {
                gtk_render_background (context, cr, 0, 0, width_f, height_f);
        }
        gtk_render_frame (context, cr, 0, 0, width_f, height_f);
        cairo_destroy (cr);

        gtk_style_context_restore (context);

        return surface;
}

/**
 * ev_document_misc_render_loading_thumbnail:
 * @widget: a #GtkWidget to use for style information
 * @width: the desired width
 * @height: the desired height
 * @inverted_colors: whether to invert colors
 *
 * Returns: (transfer full): a #GdkPixbuf
 *
 * Since: 3.8
 */
GdkPixbuf *
ev_document_misc_render_loading_thumbnail (GtkWidget *widget,
                                           int        width,
                                           int        height,
                                           gboolean   inverted_colors)
{
        GdkPixbuf *retval;
        cairo_surface_t *surface;

        surface = ev_document_misc_render_thumbnail_frame (widget, width, height, inverted_colors, NULL, NULL);
        retval = gdk_pixbuf_get_from_surface (surface, 0, 0, width, height);
        cairo_surface_destroy (surface);

        return retval;
}

/**
 * ev_document_misc_render_loading_thumbnail_surface:
 * @widget: a #GtkWidget to use for style information
 * @width: the desired width
 * @height: the desired height
 * @inverted_colors: whether to invert colors
 *
 * Returns: (transfer full): a #cairo_surface_t
 *
 * Since: 3.14
 */
cairo_surface_t *
ev_document_misc_render_loading_thumbnail_surface (GtkWidget *widget,
                                                   int        width,
                                                   int        height,
                                                   gboolean   inverted_colors)
{
        return ev_document_misc_render_thumbnail_frame (widget, width, height, inverted_colors, NULL, NULL);
}

/**
 * ev_document_misc_render_thumbnail_with_frame:
 * @widget: a #GtkWidget to use for style information
 * @source_pixbuf: a #GdkPixbuf
 *
 * Returns: (transfer full): a #GdkPixbuf
 *
 * Since: 3.8
 */
GdkPixbuf *
ev_document_misc_render_thumbnail_with_frame (GtkWidget *widget,
                                              GdkPixbuf *source_pixbuf)
{
        GdkPixbuf *retval;
        cairo_surface_t *surface;

        surface = ev_document_misc_render_thumbnail_frame (widget, -1, -1, FALSE, source_pixbuf, NULL);
        retval = gdk_pixbuf_get_from_surface (surface, 0, 0,
                                              cairo_image_surface_get_width (surface),
                                              cairo_image_surface_get_height (surface));
        cairo_surface_destroy (surface);

        return retval;
}

/**
 * ev_document_misc_render_thumbnail_surface_with_frame:
 * @widget: a #GtkWidget to use for style information
 * @source_surface: a #cairo_surface_t
 * @width: the desired width
 * @height: the desired height
 *
 * Returns: (transfer full): a #cairo_surface_t
 *
 * Since: 3.14
 */
cairo_surface_t *
ev_document_misc_render_thumbnail_surface_with_frame (GtkWidget       *widget,
                                                      cairo_surface_t *source_surface,
                                                      int              width,
                                                      int              height)
{
        return ev_document_misc_render_thumbnail_frame (widget, width, height, FALSE, NULL, source_surface);
}

void
ev_document_misc_get_page_border_size (gint       page_width,
				       gint       page_height,
				       GtkBorder *border)
{
	g_assert (border);

	border->left = 1;
	border->top = 1;
	if (page_width < 100) {
		border->right = 2;
		border->bottom = 2;
	} else if (page_width < 500) {
		border->right = 3;
		border->bottom = 3;
	} else {
		border->right = 4;
		border->bottom = 4;
	}
}

/**
 * ev_document_misc_paint_one_page:
 * @cr: a #cairo_tEvannotation
 * @widget a #GtkWidget
 * @area: a #GdkRectangle
 * @border: a #GtkBorder
 * @highlight: whether to highlight the text
 * @inverted_colors: whether to invert colors
 *
 * Deprecated: 3.10.
 */
void
ev_document_misc_paint_one_page (cairo_t      *cr,
				 GtkWidget    *widget,
				 GdkRectangle *area,
				 GtkBorder    *border,
				 gboolean      highlight,
				 gboolean      inverted_colors)
{
G_GNUC_BEGIN_IGNORE_DEPRECATIONS
	GtkStyleContext *context = gtk_widget_get_style_context (widget);
	GtkStateFlags state = gtk_widget_get_state_flags (widget);
        GdkRGBA fg, bg, shade_bg;

        gtk_style_context_get_background_color (context, state, &bg);
        gtk_style_context_get_color (context, state, &fg);
        gtk_style_context_get_color (context, GTK_STATE_FLAG_INSENSITIVE, &shade_bg);

	gdk_cairo_set_source_rgba (cr, highlight ? &fg : &shade_bg);
	gdk_cairo_rectangle (cr, area);
	cairo_fill (cr);

	if (inverted_colors)
		cairo_set_source_rgb (cr, 0, 0, 0);
	else
		cairo_set_source_rgb (cr, 1, 1, 1);
	cairo_rectangle (cr,
			 area->x + border->left,
			 area->y + border->top,
			 area->width - (border->left + border->right),
			 area->height - (border->top + border->bottom));
	cairo_fill (cr);

	gdk_cairo_set_source_rgba (cr, &bg);
	cairo_rectangle (cr,
			 area->x,
			 area->y + area->height - (border->bottom - border->top),
			 border->bottom - border->top,
			 border->bottom - border->top);
	cairo_fill (cr);

	cairo_rectangle (cr,
			 area->x + area->width - (border->right - border->left),
			 area->y,
			 border->right - border->left,
			 border->right - border->left);
	cairo_fill (cr);
G_GNUC_END_IGNORE_DEPRECATIONS
}

cairo_surface_t *
ev_document_misc_surface_from_pixbuf (GdkPixbuf *pixbuf)
{
	cairo_surface_t *surface;
	cairo_t         *cr;

	g_return_val_if_fail (GDK_IS_PIXBUF (pixbuf), NULL);

	surface = cairo_image_surface_create (gdk_pixbuf_get_has_alpha (pixbuf) ?
					      CAIRO_FORMAT_ARGB32 : CAIRO_FORMAT_RGB24,
					      gdk_pixbuf_get_width (pixbuf),
					      gdk_pixbuf_get_height (pixbuf));
	cr = cairo_create (surface);
	gdk_cairo_set_source_pixbuf (cr, pixbuf, 0, 0);
	cairo_paint (cr);
	cairo_destroy (cr);
	
	return surface;
}

/**
 * ev_document_misc_pixbuf_from_surface:
 * @surface: a #cairo_surface_t
 *
 * Returns: (transfer full): a #GdkPixbuf
 */
GdkPixbuf *
ev_document_misc_pixbuf_from_surface (cairo_surface_t *surface)
{
	g_return_val_if_fail (surface, NULL);	

        return gdk_pixbuf_get_from_surface (surface,
                                            0, 0,
                                            cairo_image_surface_get_width (surface),
                                            cairo_image_surface_get_height (surface));
}

cairo_surface_t *
ev_document_misc_surface_rotate_and_scale (cairo_surface_t *surface,
					   gint             dest_width,
					   gint             dest_height,
					   gint             dest_rotation)
{
	cairo_surface_t *new_surface;
	cairo_t         *cr;
	gint             width, height;
	gint             new_width = dest_width;
	gint             new_height = dest_height;

	width = cairo_image_surface_get_width (surface);
	height = cairo_image_surface_get_height (surface);
	
	if (dest_width == width &&
	    dest_height == height &&
	    dest_rotation == 0) {
		return cairo_surface_reference (surface);
	}

	if (dest_rotation == 90 || dest_rotation == 270) {
		new_width = dest_height;
		new_height = dest_width;
	}

	new_surface = cairo_surface_create_similar (surface,
						    cairo_surface_get_content (surface),
						    new_width, new_height);

	cr = cairo_create (new_surface);
	switch (dest_rotation) {
	        case 90:
			cairo_translate (cr, new_width, 0);
			break;
	        case 180:
			cairo_translate (cr, new_width, new_height);
			break;
	        case 270:
			cairo_translate (cr, 0, new_height);
			break;
	        default:
			cairo_translate (cr, 0, 0);
	}
	cairo_rotate (cr, dest_rotation * G_PI / 180.0);
	
	if (dest_width != width || dest_height != height) {
		cairo_pattern_set_filter (cairo_get_source (cr), CAIRO_FILTER_BILINEAR);
		cairo_scale (cr,
			     (gdouble)dest_width / width,
			     (gdouble)dest_height / height);
	}
	
	cairo_set_source_surface (cr, surface, 0, 0);
	cairo_paint (cr);
	cairo_destroy (cr);

	return new_surface;
}

void
ev_document_misc_invert_surface (cairo_surface_t *surface) {
	cairo_t *cr;

	cr = cairo_create (surface);

	/* white + DIFFERENCE -> invert */
	cairo_set_operator (cr, CAIRO_OPERATOR_DIFFERENCE);
	cairo_set_source_rgb (cr, 1., 1., 1.);
	cairo_paint(cr);
	cairo_destroy (cr);
}

void
ev_document_misc_invert_pixbuf (GdkPixbuf *pixbuf)
{
	guchar *data, *p;
	guint   width, height, x, y, rowstride, n_channels;

	n_channels = gdk_pixbuf_get_n_channels (pixbuf);
	g_assert (gdk_pixbuf_get_colorspace (pixbuf) == GDK_COLORSPACE_RGB);
	g_assert (gdk_pixbuf_get_bits_per_sample (pixbuf) == 8);

	/* First grab a pointer to the raw pixel data. */
	data = gdk_pixbuf_get_pixels (pixbuf);

	/* Find the number of bytes per row (could be padded). */
	rowstride = gdk_pixbuf_get_rowstride (pixbuf);

	width = gdk_pixbuf_get_width (pixbuf);
	height = gdk_pixbuf_get_height (pixbuf);
	for (x = 0; x < width; x++) {
		for (y = 0; y < height; y++) {
			/* Calculate pixel's offset into the data array. */
			p = data + x * n_channels + y * rowstride;
			/* Change the RGB values*/
			p[0] = 255 - p[0];
			p[1] = 255 - p[1];
			p[2] = 255 - p[2];
		}
	}
}

/**
 * ev_document_misc_get_screen_dpi:
 * @screen: a #GdkScreen
 *
 * Returns: The DPI of @screen, or 96 if the DPI is not available
 *
 * Deprecated: 3.36: This uses a deprecated GDK API. Use
 * ev_document_misc_get_widget_dpi() instead, which uses GDK's per-monitor
 * information.
 */
gdouble
ev_document_misc_get_screen_dpi (GdkScreen *screen)
{
G_GNUC_BEGIN_IGNORE_DEPRECATIONS
	gdouble dp, di;

	/*diagonal in pixels*/
	dp = hypot (gdk_screen_get_width (screen), gdk_screen_get_height (screen));
	if (dp == 0)
		return 96;

	/*diagonal in inches*/
	di = hypot (gdk_screen_get_width_mm(screen), gdk_screen_get_height_mm (screen)) / 25.4;
	if (di == 0)
		return 96;

	return (dp / di);
G_GNUC_END_IGNORE_DEPRECATIONS
}

/**
 * ev_document_misc_get_widget_dpi:
 * @widget: a #GtkWidget
 *
 * Returns sensible guess for DPI of monitor on which given widget has been
 * realized. If HiDPI display, use 192, else 96.
 * Returns 96 as fallback value.
 *
 * Returns: DPI as gdouble
 */
gdouble
ev_document_misc_get_widget_dpi (GtkWidget *widget)
{
	GdkRectangle  geometry;
	GdkDisplay   *display;
	GdkMonitor   *monitor;
	GdkWindow    *window;
	gboolean      is_landscape;

	display = gtk_widget_get_display (widget);
	window = gtk_widget_get_window (widget);
	if (window != NULL) {
		monitor = gdk_display_get_monitor_at_window (display, window);
	} else {
		monitor = gdk_display_get_primary_monitor (display);
		if (monitor == NULL)
			monitor = gdk_display_get_monitor (display, 0);
	}

	/* The only safe assumption you can make, on Unix-like/X11 and
	 * Linux/Wayland, is to always set the DPI to 96, regardless of
	 * physical/logical resolution, because that's the only safe
	 * guarantee we can make.
	 * https://gitlab.gnome.org/GNOME/gtk/-/issues/3115#note_904622 */
	if (monitor == NULL)
		return 96;

	gdk_monitor_get_geometry (monitor, &geometry);
	is_landscape = geometry.width > geometry.height;

	/* DPI is 192 if height ≥ 1080 and the orientation is not portrait,
	 * which is, incidentally, how GTK detects HiDPI displays and set a
	 * scaling factor for the logical output
	 * https://gitlab.gnome.org/GNOME/gtk/-/issues/3115#note_904622 */
	if (is_landscape && geometry.height >= 1080)
		return 192;
	else
		return 96;
}

/**
 * ev_document_misc_format_date:
 * @utime: a #GTime
 *
 * Returns: (transfer full): a locale specific date and time representation.
 *
 * Deprecated: 3.38: use ev_document_misc_format_datetime instead as GTime is
 *                   deprecated because it is not year-2038 safe.
 */
G_GNUC_BEGIN_IGNORE_DEPRECATIONS
gchar *
ev_document_misc_format_date (GTime utime)
{
	g_autoptr (GDateTime) dt = g_date_time_new_from_unix_utc ((gint64)utime);
	return ev_document_misc_format_datetime (dt);
}
G_GNUC_END_IGNORE_DEPRECATIONS

/**
 * ev_document_misc_format_datetime:
 * @dt: a #GDateTime
 *
 * Determine the preferred date and time representation for the current locale
 * for @dt.
 *
 * Returns: (transfer full): a new allocated string or NULL in the case
 * that there was an error (such as a format specifier not being supported
 * in the current locale). The string should be freed with g_free().
 *
 * Since: 3.38
 */
gchar *
ev_document_misc_format_datetime (GDateTime *dt)
{
	return g_date_time_format (dt, "%c");
}

/**
 * ev_document_misc_get_pointer_position:
 * @widget: a #GtkWidget
 * @x: (out): the pointer's "x" position, or -1 if the position is not
 *   available
 * @y: (out): the pointer's "y" position, or -1 if the position is not
 *   available
 *
 * Get the pointer's x and y position relative to @widget.
 */
void
ev_document_misc_get_pointer_position (GtkWidget *widget,
                                       gint      *x,
                                       gint      *y)
{
        GdkSeat      *seat;
        GdkDevice    *device_pointer;
        GdkRectangle  allocation;

        if (x)
                *x = -1;
        if (y)
                *y = -1;

        if (!gtk_widget_get_realized (widget))
                return;

        seat = gdk_display_get_default_seat (gtk_widget_get_display (widget));
        device_pointer = gdk_seat_get_pointer (seat);
        gdk_window_get_device_position (gtk_widget_get_window (widget),
                                        device_pointer,
                                        x, y, NULL);

        if (gtk_widget_get_has_window (widget))
                return;

        gtk_widget_get_allocation (widget, &allocation);
        if (x)
                *x -= allocation.x;
        if (y)
                *y -= allocation.y;
}