[gtk+/wip/otte/snapshot: 1/30] gtk: Add gtk_widget_snapshot()

[Benjamin Otte <otte src gnome org>]

commit b58a5a533022ea8ac807f1bac05291140509e347
Author: Benjamin Otte <otte redhat com>
Date:   Mon Nov 7 19:10:49 2016 +0100

    gtk: Add gtk_widget_snapshot()
    
    It's functionally equivalent to gtk_widget_get_render_node() but uses a
    GtkSnapshot argument to carry the state.

 gtk/Makefile.am          |    5 ++-
 gtk/gtk.h                |    1 +
 gtk/gtksnapshot.c        |   80 ++++++++++++++++++++++++++++++++++++++++++++++
 gtk/gtksnapshot.h        |   50 ++++++++++++++++++++++++++++
 gtk/gtksnapshotprivate.h |   43 ++++++++++++++++++++++++
 gtk/gtkwidget.c          |   44 +++++++++++++++----------
 gtk/gtkwidgetprivate.h   |    3 ++
 7 files changed, 207 insertions(+), 19 deletions(-)
---
diff --git a/gtk/Makefile.am b/gtk/Makefile.am
index 34bfab7..d11ba0c 100644
--- a/gtk/Makefile.am
+++ b/gtk/Makefile.am
@@ -293,6 +293,7 @@ gtk_public_h_sources =              \
        gtkstacksidebar.h       \
        gtksizegroup.h          \
        gtksizerequest.h        \
+       gtksnapshot.h           \
        gtkspinbutton.h         \
        gtkspinner.h            \
        gtkstack.h              \
@@ -540,6 +541,7 @@ gtk_private_h_sources =             \
        gtksidebarrowprivate.h  \
        gtksizegroup-private.h  \
        gtksizerequestcacheprivate.h    \
+       gtksnapshotprivate.h    \
        gtkstyleanimationprivate.h \
        gtkstylecascadeprivate.h \
        gtkstylecontextprivate.h \
@@ -871,10 +873,11 @@ gtk_base_c_sources =              \
        gtksizerequest.c        \
        gtksizerequestcache.c   \
        gtkshow.c               \
-       gtkstacksidebar.c       \
+       gtksnapshot.c           \
        gtkspinbutton.c         \
        gtkspinner.c            \
        gtkstack.c              \
+       gtkstacksidebar.c       \
        gtkstackswitcher.c      \
        gtkstatusbar.c          \
        gtkstyleanimation.c     \
diff --git a/gtk/gtk.h b/gtk/gtk.h
index a3f903d..8d13dfd 100644
--- a/gtk/gtk.h
+++ b/gtk/gtk.h
@@ -193,6 +193,7 @@
 #include <gtk/gtkshortcutsshortcut.h>
 #include <gtk/gtkshortcutswindow.h>
 #include <gtk/gtkshow.h>
+#include <gtk/gtksnapshot.h>
 #include <gtk/gtkstacksidebar.h>
 #include <gtk/gtksizegroup.h>
 #include <gtk/gtksizerequest.h>
diff --git a/gtk/gtksnapshot.c b/gtk/gtksnapshot.c
new file mode 100644
index 0000000..0dbc3d1
--- /dev/null
+++ b/gtk/gtksnapshot.c
@@ -0,0 +1,80 @@
+/* GTK - The GIMP Toolkit
+ * Copyright (C) 2016 Benjamin Otte <otte gnome org>
+ *
+ * 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/>.
+ */
+
+#include "config.h"
+
+#include "gtksnapshot.h"
+#include "gtksnapshotprivate.h"
+
+void
+gtk_snapshot_init (GtkSnapshot             *state,
+                   const GtkSnapshot       *parent,
+                   const graphene_matrix_t *transform)
+{
+  state->parent = parent;
+  state->renderer = parent->renderer;
+  
+  graphene_matrix_init_from_matrix (&state->transform, transform);
+}
+
+void
+gtk_snapshot_init_root (GtkSnapshot *state,
+                        GskRenderer *renderer)
+{
+  state->parent = NULL;
+  state->renderer = renderer;
+
+  graphene_matrix_init_identity (&state->transform);
+}
+
+void
+gtk_snapshot_finish (GtkSnapshot *state)
+{
+  /* nothing to do so far */
+}
+
+GskRenderer *
+gtk_snapshot_get_renderer (const GtkSnapshot *state)
+{
+  return state->renderer;
+}
+
+GskRenderNode *
+gtk_snapshot_create_render_node (const GtkSnapshot *state,
+                                 const char *name,
+                                 ...)
+{
+  GskRenderNode *node;
+
+  node = gsk_renderer_create_render_node (state->renderer);
+
+  if (name)
+    {
+      va_list args;
+      char *str;
+
+      va_start (args, name);
+      str = g_strdup_vprintf (name, args);
+      va_end (args);
+
+      gsk_render_node_set_name (node, str);
+
+      g_free (str);
+    }
+
+  return node;
+}
diff --git a/gtk/gtksnapshot.h b/gtk/gtksnapshot.h
new file mode 100644
index 0000000..2d4e826
--- /dev/null
+++ b/gtk/gtksnapshot.h
@@ -0,0 +1,50 @@
+/* GTK - The GIMP Toolkit
+ * Copyright (C) 2016 Benjamin Otte <otte gnome org>
+ *
+ * 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/.
+ */
+
+#ifndef __GTK_SNAPSHOT_H__
+#define __GTK_SNAPSHOT_H__
+
+
+#if !defined (__GTK_H_INSIDE__) && !defined (GTK_COMPILATION)
+#error "Only <gtk/gtk.h> can be included directly."
+#endif
+
+#include <gsk/gsk.h>
+
+G_BEGIN_DECLS
+
+typedef struct _GtkSnapshot GtkSnapshot;
+
+
+GDK_AVAILABLE_IN_3_90
+GskRenderer *   gtk_snapshot_get_renderer               (const GtkSnapshot *state);
+
+GDK_AVAILABLE_IN_3_90
+GskRenderNode * gtk_snapshot_create_render_node         (const GtkSnapshot *state,
+                                                         const char *name,
+                                                         ...) G_GNUC_PRINTF(2, 3);
+
+G_END_DECLS
+
+#endif /* __GTK_SNAPSHOT_H__ */
diff --git a/gtk/gtksnapshotprivate.h b/gtk/gtksnapshotprivate.h
new file mode 100644
index 0000000..5b238b7
--- /dev/null
+++ b/gtk/gtksnapshotprivate.h
@@ -0,0 +1,43 @@
+/* GTK - The GIMP Toolkit
+ * Copyright (C) 2016 Benjamin Otte <otte gnome org>
+ *
+ * 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/>.
+ */
+
+#ifndef __GTK_SNAPSHOT_PRIVATE_H__
+#define __GTK_SNAPSHOT_PRIVATE_H__
+
+#include "gtksnapshot.h"
+
+G_BEGIN_DECLS
+
+struct _GtkSnapshot {
+  const GtkSnapshot     *parent;
+  
+  GskRenderer           *renderer;
+
+  graphene_matrix_t      transform;
+};
+
+void            gtk_snapshot_init               (GtkSnapshot             *state,
+                                                 const GtkSnapshot       *parent,
+                                                 const graphene_matrix_t *transform);
+void            gtk_snapshot_init_root          (GtkSnapshot             *state,
+                                                 GskRenderer             *renderer);
+
+void            gtk_snapshot_finish             (GtkSnapshot             *state);
+
+G_END_DECLS
+
+#endif /* __GTK_SNAPSHOT_PRIVATE_H__ */
diff --git a/gtk/gtkwidget.c b/gtk/gtkwidget.c
index f74104b..f051175 100644
--- a/gtk/gtkwidget.c
+++ b/gtk/gtkwidget.c
@@ -67,6 +67,7 @@
 #include "gtkapplicationprivate.h"
 #include "gtkgestureprivate.h"
 #include "gtkwidgetpathprivate.h"
+#include "gtksnapshotprivate.h"
 
 #include "inspector/window.h"
 
@@ -15628,6 +15629,22 @@ GskRenderNode *
 gtk_widget_get_render_node (GtkWidget   *widget,
                             GskRenderer *renderer)
 {
+  GtkSnapshot snapshot;
+  GskRenderNode *node;
+
+  gtk_snapshot_init_root (&snapshot, renderer);
+
+  node = gtk_widget_snapshot (widget, &snapshot);
+
+  gtk_snapshot_finish (&snapshot);
+
+  return node;
+}
+
+GskRenderNode *
+gtk_widget_snapshot (GtkWidget         *widget,
+                     const GtkSnapshot *snapshot)
+{
   GtkWidgetClass *klass = GTK_WIDGET_GET_CLASS (widget);
   GskRenderNode *node;
   graphene_matrix_t m;
@@ -15651,27 +15668,21 @@ gtk_widget_get_render_node (GtkWidget   *widget,
     {
       GskRenderNode *tmp;
       cairo_t *cr;
-      char *str;
-
-      str = g_strconcat ("Fallback<", G_OBJECT_TYPE_NAME (widget), ">", NULL);
 
-      tmp = gsk_renderer_create_render_node (renderer);
-      gsk_render_node_set_name (tmp, str);
+      tmp = gtk_snapshot_create_render_node (snapshot, "Fallback<%s>", G_OBJECT_TYPE_NAME (widget));
       gsk_render_node_set_bounds (tmp, &bounds);
       gsk_render_node_set_transform (tmp, &m);
 
-      cr = gsk_render_node_get_draw_context (tmp, renderer);
+      cr = gsk_render_node_get_draw_context (tmp, gtk_snapshot_get_renderer (snapshot));
       cairo_translate (cr, alloc.x - clip.x, alloc.y - clip.y);
       gtk_widget_draw_internal (widget, cr, TRUE);
       cairo_destroy (cr);
 
-      g_free (str);
-
       node = tmp;
     }
   else
     {
-      node = klass->get_render_node (widget, renderer);
+      node = klass->get_render_node (widget, gtk_snapshot_get_renderer (snapshot));
 
       /* Compatibility mode: if there's a ::draw signal handler, we add a
        * child node with the contents of the handler
@@ -15681,21 +15692,15 @@ gtk_widget_get_render_node (GtkWidget   *widget,
           GskRenderNode *tmp;
           gboolean result;
           cairo_t *cr;
-          char *str;
-
-          str = g_strconcat ("DrawSignal<", G_OBJECT_TYPE_NAME (widget), ">", NULL);
 
-          tmp = gsk_renderer_create_render_node (renderer);
-          gsk_render_node_set_name (tmp, str);
+          tmp = gtk_snapshot_create_render_node (snapshot, "DrawSignal<%s>", G_OBJECT_TYPE_NAME (widget));
           gsk_render_node_set_bounds (tmp, &bounds);
 
-          cr = gsk_render_node_get_draw_context (tmp, renderer);
+          cr = gsk_render_node_get_draw_context (tmp, gtk_snapshot_get_renderer (snapshot));
           cairo_translate (cr, alloc.x - clip.x, alloc.y - clip.y);
           g_signal_emit (widget, widget_signals[DRAW], 0, cr, &result);
           cairo_destroy (cr);
 
-          g_free (str);
-
           if (node != NULL)
             {
               gsk_render_node_append_child (node, tmp);
@@ -15717,6 +15722,7 @@ gtk_widget_render (GtkWidget            *widget,
                    const cairo_region_t *region)
 {
   GdkDrawingContext *context;
+  GtkSnapshot snapshot;
   GskRenderer *renderer;
   GskRenderNode *root;
 
@@ -15728,7 +15734,9 @@ gtk_widget_render (GtkWidget            *widget,
   if (renderer == NULL)
     return;
 
-  root = gtk_widget_get_render_node (widget, renderer);
+  gtk_snapshot_init_root (&snapshot, renderer);
+  root = gtk_widget_snapshot (widget, &snapshot);
+  gtk_snapshot_finish (&snapshot);
   if (root == NULL)
     return;
 
diff --git a/gtk/gtkwidgetprivate.h b/gtk/gtkwidgetprivate.h
index 8169281..38c2e0a 100644
--- a/gtk/gtkwidgetprivate.h
+++ b/gtk/gtkwidgetprivate.h
@@ -31,6 +31,7 @@
 #include "gtkeventcontroller.h"
 #include "gtkactionmuxer.h"
 #include "gtksizerequestcacheprivate.h"
+#include "gtksnapshot.h"
 
 G_BEGIN_DECLS
 
@@ -285,6 +286,8 @@ void              gtk_widget_render                        (GtkWidget
 
 GskRenderNode *   gtk_widget_get_render_node               (GtkWidget   *widget,
                                                             GskRenderer *renderer);
+GskRenderNode *   gtk_widget_snapshot                      (GtkWidget            *widget,
+                                                            const GtkSnapshot    *snapshot);
 
 GskRenderNode *   gtk_widget_create_render_node            (GtkWidget   *widget,
                                                             GskRenderer *renderer,