Add hi-dpi support for main view.

Based on Evince commits 8b965e769808815df9c75a10a0e4972c0904d26a
and a612f809e4e23d88a661a9604ce84f332189a658.

https://github.com/linuxmint/xreader/commit/4eccf6b

3 files changed, 91 insertions, 22 deletions

diff --git a/configure.ac b/configure.ac
index ba57b81c..36c7fe26 100644
--- a/configure.ac
+++ b/configure.ac
@@ -123,6 +123,23 @@ PKG_CHECK_MODULES(GMODULE, gmodule-2.0 >= $GLIB_REQUIRED)
 
 PKG_CHECK_MODULES([SHELL_CORE],[libxml-2.0 >= $LIBXML_REQUIRED gtk+-3.0 >= $GTK_REQUIRED gio-2.0 >= $GLIB_REQUIRED gthread-2.0 x11])
 
+# Although GTK+ 3.10 includes hi-dpi functionality, it does not require a cairo with
+# cairo_surface_set_device_scale(), which we also need if we're to support hi-dpi,
+# so we need check for that explicity.
+
+atril_save_LIBS=$LIBS
+LIBS="$LIBS $LIBVIEW_LIBS"
+AC_CHECK_FUNCS(cairo_surface_set_device_scale)
+LIBS=$atril_save_LIBS
+
+AC_MSG_CHECKING([for hi-dpi support])
+if test "$ac_cv_func_cairo_surface_set_device_scale" = yes ; then
+   AC_DEFINE([HAVE_HIDPI_SUPPORT], [1], [Define if cairo and GTK+ have necessary functions for hi-dpi])
+   AC_MSG_RESULT([yes])
+else
+   AC_MSG_RESULT([no])
+fi
+
 dnl
 dnl zlib support
 dnl
diff --git a/libview/ev-pixbuf-cache.c b/libview/ev-pixbuf-cache.c
index 409b9c39..506d1316 100644
--- a/libview/ev-pixbuf-cache.c
+++ b/libview/ev-pixbuf-cache.c
@@ -14,6 +14,9 @@ typedef struct _CacheJobInfo
 	/* Data we get from rendering */
 	cairo_surface_t *surface;
 
+	/* Device scale factor of target widget */
+	int device_scale;
+
 	/* Selection data. 
 	 * Selection_points are the coordinates encapsulated in selection.
 	 * target_points is the target selection size. */
@@ -235,6 +238,27 @@ ev_pixbuf_cache_set_max_size (EvPixbufCache *pixbuf_cache,
 	pixbuf_cache->max_size = max_size;
 }
 
+static int
+get_device_scale (EvPixbufCache *pixbuf_cache)
+{
+#ifdef HAVE_HIDPI_SUPPORT
+	return gtk_widget_get_scale_factor (pixbuf_cache->view);
+#else
+	return 1;
+#endif
+}
+
+static void
+set_device_scale_on_surface (cairo_surface_t *surface,
+                             int              device_scale)
+{
+#ifdef HAVE_HIDPI_SUPPORT
+	cairo_surface_set_device_scale (surface, device_scale, device_scale);
+#else
+	g_return_if_fail (device_scale != 1);
+#endif
+}
+
 static void
 copy_job_to_job_info (EvJobRender   *job_render,
 		      CacheJobInfo  *job_info,
@@ -244,6 +268,7 @@ copy_job_to_job_info (EvJobRender   *job_render,
 		cairo_surface_destroy (job_info->surface);
 	}
 	job_info->surface = cairo_surface_reference (job_render->surface);
+	set_device_scale_on_surface (job_info->surface, job_info->device_scale);
 	if (pixbuf_cache->inverted_colors) {
 		ev_document_misc_invert_surface (job_info->surface);
 	}
@@ -262,6 +287,7 @@ copy_job_to_job_info (EvJobRender   *job_render,
 		job_info->selection_points = job_render->selection_points;
 		job_info->selection_region = cairo_region_reference (job_render->selection_region);
 		job_info->selection = cairo_surface_reference (job_render->selection);
+		set_device_scale_on_surface (job_info->selection, job_info->device_scale);
 		g_assert (job_info->selection_points.x1 >= 0);
 		job_info->points_set = TRUE;
 	}
@@ -307,20 +333,24 @@ check_job_size_and_unref (EvPixbufCache *pixbuf_cache,
 			  gfloat         scale)
 {
 	gint width, height;
+	gint device_scale;
 
 	g_assert (job_info);
 
 	if (job_info->job == NULL)
 		return;
 
-	_get_page_size_for_scale_and_rotation (job_info->job->document,
-					       EV_JOB_RENDER (job_info->job)->page,
-					       scale,
-					       EV_JOB_RENDER (job_info->job)->rotation,
-					       &width, &height);
-	if (width == EV_JOB_RENDER (job_info->job)->target_width &&
-	    height == EV_JOB_RENDER (job_info->job)->target_height)
-		return;
+	device_scale = get_device_scale (pixbuf_cache);
+	if (job_info->device_scale == device_scale) {
+		_get_page_size_for_scale_and_rotation (job_info->job->document,
+						       EV_JOB_RENDER (job_info->job)->page,
+						       scale,
+						       EV_JOB_RENDER (job_info->job)->rotation,
+						       &width, &height);
+		if (width * device_scale == EV_JOB_RENDER (job_info->job)->target_width &&
+		    height * device_scale == EV_JOB_RENDER (job_info->job)->target_height)
+			return;
+	}
 
 	g_signal_handlers_disconnect_by_func (job_info->job,
 					      G_CALLBACK (job_finished_cb),
@@ -634,6 +664,7 @@ add_job (EvPixbufCache  *pixbuf_cache,
 	 gfloat          scale,
 	 EvJobPriority   priority)
 {
+	job_info->device_scale = get_device_scale (pixbuf_cache);
 	job_info->page_ready = FALSE;
 
 	if (job_info->region)
@@ -641,8 +672,10 @@ add_job (EvPixbufCache  *pixbuf_cache,
 	job_info->region = region ? cairo_region_reference (region) : NULL;
 
 	job_info->job = ev_job_render_new (pixbuf_cache->document,
-					   page, rotation, scale,
-					   width, height);
+	                                   page, rotation,
+	                                   scale * job_info->device_scale,
+	                                   width * job_info->device_scale,
+	                                   height * job_info->device_scale);
 
 	if (new_selection_surface_needed (pixbuf_cache, job_info, page, scale)) {
 		GdkColor text, base;
@@ -667,6 +700,7 @@ add_job_if_needed (EvPixbufCache *pixbuf_cache,
 		   gfloat         scale,
 		   EvJobPriority  priority)
 {
+	gint device_scale = get_device_scale (pixbuf_cache);
 	gint width, height;
 
 	if (job_info->job)
@@ -677,8 +711,9 @@ add_job_if_needed (EvPixbufCache *pixbuf_cache,
 					       &width, &height);
 
 	if (job_info->surface &&
-	    cairo_image_surface_get_width (job_info->surface) == width &&
-	    cairo_image_surface_get_height (job_info->surface) == height)
+	    job_info->device_scale == device_scale &&
+	    cairo_image_surface_get_width (job_info->surface) == width * device_scale &&
+	    cairo_image_surface_get_height (job_info->surface) == height * device_scale)
 		return;
 
 	/* Free old surfaces for non visible pages */
@@ -949,7 +984,7 @@ ev_pixbuf_cache_get_selection_surface (EvPixbufCache   *pixbuf_cache,
 
 	/* Now, lets see if we need to resize the image.  If we do, we clear the
 	 * old one. */
-	clear_selection_if_needed (pixbuf_cache, job_info, page, scale);
+	clear_selection_if_needed (pixbuf_cache, job_info, page, scale * job_info->device_scale);
 
 	/* Finally, we see if the two scales are the same, and get a new pixbuf
 	 * if needed.  We do this synchronously for now.  At some point, we
@@ -973,7 +1008,7 @@ ev_pixbuf_cache_get_selection_surface (EvPixbufCache   *pixbuf_cache,
 		}
 
 		ev_page = ev_document_get_page (pixbuf_cache->document, page);
-		rc = ev_render_context_new (ev_page, 0, scale);
+		rc = ev_render_context_new (ev_page, 0, scale * job_info->device_scale);
 		g_object_unref (ev_page);
 
 		if (job_info->selection_region)
@@ -991,6 +1026,7 @@ ev_pixbuf_cache_get_selection_surface (EvPixbufCache   *pixbuf_cache,
 					       old_points,
 					       job_info->selection_style,
 					       &text, &base);
+		set_device_scale_on_surface (job_info->selection, job_info->device_scale);
 		job_info->selection_points = job_info->target_points;
 		g_object_unref (rc);
 		ev_document_doc_mutex_unlock ();
diff --git a/libview/ev-view.c b/libview/ev-view.c
index b7410d87..4584bd46 100644
--- a/libview/ev-view.c
+++ b/libview/ev-view.c
@@ -4463,6 +4463,7 @@ draw_one_page (EvView       *view,
 		cairo_surface_t *page_surface = NULL;
 		gint             selection_width, selection_height;
 		cairo_surface_t *selection_surface = NULL;
+		double device_scale_x = 1, device_scale_y = 1;
 
 		page_surface = ev_pixbuf_cache_get_surface (view->pixbuf_cache, page);
 
@@ -4475,6 +4476,10 @@ draw_one_page (EvView       *view,
 			return;
 		}
 
+#ifdef HAVE_HIDPI_SUPPORT
+		cairo_surface_get_device_scale (page_surface, &device_scale_x, &device_scale_y);
+#endif
+
 		if (page == current_page)
 			hide_loading_window (view);
 
@@ -4490,13 +4495,13 @@ draw_one_page (EvView       *view,
 			cairo_pattern_set_filter (cairo_get_source (cr),
 						  CAIRO_FILTER_FAST);
 			cairo_scale (cr,
-				     (gdouble)width / page_width,
-				     (gdouble)height / page_height);
+				     (gdouble)width / page_width * device_scale_x,
+				     (gdouble)height / page_height * device_scale_y);
 		}
 
 		cairo_surface_set_device_offset (page_surface,
-						 overlap.x - real_page_area.x,
-						 overlap.y - real_page_area.y);
+						 (overlap.x - real_page_area.x) * device_scale_x,
+						 (overlap.y - real_page_area.y) * device_scale_y);
 		cairo_set_source_surface (cr, page_surface, 0, 0);
 		cairo_paint (cr);
 		cairo_restore (cr);
@@ -4525,13 +4530,13 @@ draw_one_page (EvView       *view,
 			cairo_pattern_set_filter (cairo_get_source (cr),
 						  CAIRO_FILTER_FAST);
 			cairo_scale (cr,
-				     (gdouble)width / selection_width,
-				     (gdouble)height / selection_height);
+				     (gdouble)width / selection_width * device_scale_x,
+				     (gdouble)height / selection_height * device_scale_y);
 		}
 
 		cairo_surface_set_device_offset (selection_surface,
-						 overlap.x - real_page_area.x,
-						 overlap.y - real_page_area.y);
+						 (overlap.x - real_page_area.x) * device_scale_x,
+						 (overlap.y - real_page_area.y) * device_scale_y);
 
 		cairo_set_source_surface (cr, selection_surface, 0, 0);
 		cairo_paint (cr);
@@ -4873,6 +4878,14 @@ ev_view_class_init (EvViewClass *class)
 }
 
 static void
+on_notify_scale_factor (EvView     *view,
+			GParamSpec *pspec)
+{
+	if (view->document)
+		view_update_range_and_current_page (view);
+}
+
+static void
 ev_view_init (EvView *view)
 {
 	GtkStyleContext *context;
@@ -4918,6 +4931,9 @@ ev_view_init (EvView *view)
 	view->pending_scroll = SCROLL_TO_KEEP_POSITION;
 	view->jump_to_find_result = TRUE;
 	view->highlight_find_results = FALSE;
+
+	g_signal_connect (view, "notify::scale-factor",
+			  G_CALLBACK (on_notify_scale_factor), NULL);
 }
 
 /*** Callbacks ***/