callbacks: use a callback to draw at GtkDrawingAreagtk3_improvements

Gtk 3 supports wayland, but there's a catch: while the
current code works properly with X11, it doesn't draw
anything inside the GtkDrawingArea on Wayland.

The fix is trivial, but incompatible with Gtk2: instead of
updating the drawing aea inside the main loop, a callback
has to be used in order to handle gtk draw logic.

As, at least for now, we want to keep supporting Gtk 2,
let's add a compatibility code.

That fixes drawing with Wayland.

Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>

5 files changed, 70 insertions, 41 deletions

diff --git a/data/camorama.ui b/data/camorama.ui
index 9f99b38..8a19cbe 100644
--- a/data/camorama.ui
+++ b/data/camorama.ui
@@ -1372,6 +1372,7 @@
                     <property name="height_request">240</property>
                     <property name="visible">True</property>
                     <property name="can_focus">False</property>
+                    <signal name="draw" handler="show_buffer" swapped="no"/>
                   </object>
                 </child>
               </object>
diff --git a/src/callbacks.c b/src/callbacks.c
index f8a378e..a38a1dc 100644
--- a/src/callbacks.c
+++ b/src/callbacks.c
@@ -497,12 +497,10 @@ static void apply_filters(cam_t *cam)
  *    https://github.com/bratsche/gtk-/blob/master/gdk/gdkcairo.c
  * With a small backport.
  */
+#if GTK_MAJOR_VERSION < 3
 static cairo_surface_t *create_from_pixbuf(const GdkPixbuf *pixbuf,
                                            GdkWindow *for_window)
 {
-#if GTK_MAJOR_VERSION >= 3
-    return gdk_cairo_surface_create_from_pixbuf(pixbuf, 1, for_window);
-#else
     gint width = gdk_pixbuf_get_width(pixbuf);
     gint height = gdk_pixbuf_get_height(pixbuf);
     guchar *gdk_pixels = gdk_pixbuf_get_pixels(pixbuf);
@@ -567,82 +565,92 @@ static cairo_surface_t *create_from_pixbuf(const GdkPixbuf *pixbuf,
 
     cairo_surface_mark_dirty(surface);
     return surface;
-#endif
 }
 
 static void show_buffer(cam_t *cam)
 {
-    GdkPixbuf *pb;
     GtkWidget *widget;
     GdkWindow *window;
     cairo_surface_t *surface;
     cairo_t *cr;
-    unsigned char *pic_buf = cam->pic_buf;
-
     const GdkRectangle rect = {
         .x = 0, .y = 0,
         .width = cam->width, .height = cam->height
     };
-#if GTK_MAJOR_VERSION >= 3 && GTK_MINOR_VERSION >= 22
-    GdkDrawingContext *context;
-    cairo_region_t *region;
-#endif
 
-    /*
-     * refer the frame
-     */
-    if (cam->pixformat == V4L2_PIX_FMT_YUV420) {
-        yuv420p_to_rgb(cam->pic_buf, cam->tmp, cam->width, cam->height,
-                       cam->bpp / 8);
-        pic_buf = cam->tmp;
-    }
-
-    apply_filters(cam);
-
-    /* Use cairo to display the pixel buffer */
-
-    pb = gdk_pixbuf_new_from_data(pic_buf, GDK_COLORSPACE_RGB, FALSE, 8,
-                                  cam->width, cam->height,
-                                  (cam->width * cam->bpp / 8), NULL, NULL);
+    if (!cam->pb)
+        return;
 
     widget = GTK_WIDGET(gtk_builder_get_object(cam->xml, "da"));
     window = gtk_widget_get_window(widget);
 
-    surface = create_from_pixbuf(pb, window);
-
-#if GTK_MAJOR_VERSION >= 3 && GTK_MINOR_VERSION >= 22
-    region = cairo_region_create();
-    context = gdk_window_begin_draw_frame(window, region);
-    cr = gdk_drawing_context_get_cairo_context(context);
-#else
+    surface = create_from_pixbuf(cam->pb, window);
     cr = gdk_cairo_create(window);
-#endif
-
     cairo_set_source_surface(cr, surface, 0, 0);
+
     gdk_cairo_rectangle(cr, &rect);
+
     cairo_fill(cr);
+    cairo_destroy(cr);
+    cairo_surface_destroy(surface);
 
-#if GTK_MAJOR_VERSION >= 3 && GTK_MINOR_VERSION >= 22
-    gdk_window_end_draw_frame(window, context);
+    frames++;
+    frames2++;
+}
 #else
-    cairo_destroy(cr);
-    cairo_region_destroy(region);
-#endif
+/*
+ * GTK 3 way: use a drawing callback
+ */
+void draw_callback(GtkWidget *widget, cairo_t *cr, cam_t *cam)
+{
+    GdkWindow *window;
+    cairo_surface_t *surface;
+    const GdkRectangle rect = {
+        .x = 0, .y = 0,
+        .width = cam->width, .height = cam->height
+    };
 
+    if (!cam->pb)
+        return;
+
+    window = gtk_widget_get_window(widget);
+    surface = gdk_cairo_surface_create_from_pixbuf(cam->pb, 1, window);
+    cairo_set_source_surface(cr, surface, 0, 0);
+    gdk_cairo_rectangle(cr, &rect);
+    cairo_fill(cr);
     cairo_surface_destroy(surface);
 
     frames++;
     frames2++;
 }
 
+static inline void show_buffer(cam_t *cam)
+{
+    gtk_widget_queue_draw(GTK_WIDGET(gtk_builder_get_object(cam->xml, "da")));
+}
+#endif
+
 /*
 * get image from cam - does all the work ;)
 */
 gint read_timeout_func(cam_t *cam)
 {
+    unsigned char *pic_buf = cam->pic_buf;
+
     v4l2_read(cam->dev, cam->pic_buf,
               (cam->width * cam->height * cam->bpp / 8));
 
+    if (cam->pixformat == V4L2_PIX_FMT_YUV420) {
+        yuv420p_to_rgb(cam->pic_buf, cam->tmp, cam->width, cam->height,
+                       cam->bpp / 8);
+        pic_buf = cam->tmp;
+    }
+    apply_filters(cam);
+    cam->pb = gdk_pixbuf_new_from_data(pic_buf, GDK_COLORSPACE_RGB, FALSE, 8,
+                                       cam->width, cam->height,
+                                       (cam->width * cam->bpp / 8),
+                                       NULL, NULL);
+
     show_buffer(cam);
 
     return TRUE;
@@ -650,9 +658,22 @@ gint read_timeout_func(cam_t *cam)
 
 gint timeout_func(cam_t *cam)
 {
+    unsigned char *pic_buf = cam->pic_buf;
+
     capture_buffers(cam, cam->pic_buf,
                     cam->width * cam->height * cam->bytesperline);
 
+    if (cam->pixformat == V4L2_PIX_FMT_YUV420) {
+        yuv420p_to_rgb(cam->pic_buf, cam->tmp, cam->width, cam->height,
+                       cam->bpp / 8);
+        pic_buf = cam->tmp;
+    }
+    apply_filters(cam);
+    cam->pb = gdk_pixbuf_new_from_data(pic_buf, GDK_COLORSPACE_RGB, FALSE, 8,
+                                       cam->width, cam->height,
+                                       (cam->width * cam->bpp / 8),
+                                       NULL, NULL);
+
     show_buffer(cam);
 
     return TRUE;
diff --git a/src/callbacks.h b/src/callbacks.h
index c0c2e1b..30e15b2 100644
--- a/src/callbacks.h
+++ b/src/callbacks.h
@@ -33,6 +33,7 @@ void ppm_func(GtkWidget *, cam_t *);
 void rts_func(GtkWidget *, cam_t *);
 void rjpg_func(GtkWidget *, cam_t *);
 void rpng_func(GtkWidget *, cam_t *);
+void draw_callback(GtkWidget *, cairo_t *, cam_t *cam);
 
 gint(*pt2Function) (cam_t *);
 void rppm_func(GtkWidget *, cam_t *);
diff --git a/src/main.c b/src/main.c
index 5b434e3..257e4ee 100644
--- a/src/main.c
+++ b/src/main.c
@@ -217,6 +217,11 @@ int main(int argc, char *argv[])
     load_interface(cam);
 
     widget = GTK_WIDGET(gtk_builder_get_object(cam->xml, "da"));
+
+#if GTK_MAJOR_VERSION >= 3
+    g_signal_connect(G_OBJECT(widget), "draw", G_CALLBACK(draw_callback), cam);
+#endif
+
     gtk_widget_show(widget);
 
     cam->idle_id = g_idle_add((GSourceFunc) pt2Function, (gpointer) cam);
diff --git a/src/v4l.h b/src/v4l.h
index d991a63..1d4fa1f 100644
--- a/src/v4l.h
+++ b/src/v4l.h
@@ -79,6 +79,7 @@ typedef struct camera {
     guint32 timeout_interval;
     GConfClient *gc;
     GtkBuilder *xml;
+    GdkPixbuf *pb;
     GtkStatusIcon *tray_icon;
 
     CamoramaFilterChain *filter_chain;