[gtk/wip/otte/lottie: 9/16] snapshot: Add gtk_snapshot_push_stroke()

[Benjamin Otte <otte src gnome org>]

commit bd635e79fc5f4b0f7cafe1c066a91106d8e9ec86
Author: Benjamin Otte <otte redhat com>
Date:   Wed Nov 11 07:37:08 2020 +0100

    snapshot: Add gtk_snapshot_push_stroke()

 docs/reference/gtk/gtk4-sections.txt |  1 +
 gtk/gtksnapshot.c                    | 69 ++++++++++++++++++++++++++++++++++++
 gtk/gtksnapshot.h                    |  4 +++
 3 files changed, 74 insertions(+)
---
diff --git a/docs/reference/gtk/gtk4-sections.txt b/docs/reference/gtk/gtk4-sections.txt
index 28f4911551..c4c1b44eda 100644
--- a/docs/reference/gtk/gtk4-sections.txt
+++ b/docs/reference/gtk/gtk4-sections.txt
@@ -4304,6 +4304,7 @@ gtk_snapshot_push_repeat
 gtk_snapshot_push_clip
 gtk_snapshot_push_rounded_clip
 gtk_snapshot_push_fill
+gtk_snapshot_push_stroke
 gtk_snapshot_push_cross_fade
 gtk_snapshot_push_blend
 gtk_snapshot_push_blur
diff --git a/gtk/gtksnapshot.c b/gtk/gtksnapshot.c
index 8cef253521..74a0e5eb98 100644
--- a/gtk/gtksnapshot.c
+++ b/gtk/gtksnapshot.c
@@ -31,6 +31,7 @@
 #include "gsktransformprivate.h"
 
 #include "gsk/gskrendernodeprivate.h"
+#include "gsk/gskstrokeprivate.h"
 
 #include "gtk/gskpango.h"
 
@@ -112,6 +113,10 @@ struct _GtkSnapshotState {
       GskPath *path;
       GskFillRule fill_rule;
     } fill;
+    struct {
+      GskPath *path;
+      GskStroke stroke;
+    } stroke;
     struct {
       gsize n_shadows;
       GskShadow *shadows;
@@ -1171,6 +1176,70 @@ gtk_snapshot_push_fill (GtkSnapshot *snapshot,
   state->data.fill.fill_rule = fill_rule;
 }
 
+static GskRenderNode *
+gtk_snapshot_collect_stroke (GtkSnapshot      *snapshot,
+                             GtkSnapshotState *state,
+                             GskRenderNode   **nodes,
+                             guint             n_nodes)
+{
+  GskRenderNode *node, *stroke_node;
+
+  node = gtk_snapshot_collect_default (snapshot, state, nodes, n_nodes);
+  if (node == NULL)
+    return NULL;
+
+  stroke_node = gsk_stroke_node_new (node,
+                                     state->data.stroke.path,
+                                     &state->data.stroke.stroke);
+
+  if (stroke_node->bounds.size.width == 0 ||
+      stroke_node->bounds.size.height == 0)
+    {
+      gsk_render_node_unref (node);
+      gsk_render_node_unref (stroke_node);
+      return NULL;
+    }
+
+  gsk_render_node_unref (node);
+
+  return stroke_node;
+}
+
+static void
+gtk_snapshot_clear_stroke (GtkSnapshotState *state)
+{
+  gsk_path_unref (state->data.stroke.path);
+  gsk_stroke_clear (&state->data.stroke.stroke);
+}
+
+/**
+ * gtk_snapshot_push_stroke:
+ * @snapshot: a #GtkSnapshot
+ * @path: The path to stroke
+ * @stroke: The stroke attributes
+ *
+ * Strokes the given @path with the attributes given by @stroke and the
+ * image being recorded until the next call to gtk_snapshot_pop().
+ */
+void
+gtk_snapshot_push_stroke (GtkSnapshot     *snapshot,
+                          GskPath         *path,
+                          const GskStroke *stroke)
+{
+  GtkSnapshotState *state;
+
+  /* FIXME: Is it worth calling ensure_affine() and transforming the path here? */
+  gtk_snapshot_ensure_identity (snapshot);
+
+  state = gtk_snapshot_push_state (snapshot,
+                                   gtk_snapshot_get_current_state (snapshot)->transform,
+                                   gtk_snapshot_collect_stroke,
+                                   gtk_snapshot_clear_stroke);
+
+  state->data.stroke.path = gsk_path_ref (path);
+  gsk_stroke_init_copy (&state->data.stroke.stroke, stroke);
+}
+
 static GskRenderNode *
 gtk_snapshot_collect_shadow (GtkSnapshot      *snapshot,
                              GtkSnapshotState *state,
diff --git a/gtk/gtksnapshot.h b/gtk/gtksnapshot.h
index d0077ca9a1..7f509aae04 100644
--- a/gtk/gtksnapshot.h
+++ b/gtk/gtksnapshot.h
@@ -93,6 +93,10 @@ void            gtk_snapshot_push_fill                  (GtkSnapshot
                                                          GskPath                *path,
                                                          GskFillRule             fill_rule);
 GDK_AVAILABLE_IN_ALL
+void            gtk_snapshot_push_stroke                (GtkSnapshot            *snapshot,
+                                                         GskPath                *path,
+                                                         const GskStroke        *stroke);
+GDK_AVAILABLE_IN_ALL
 void            gtk_snapshot_push_shadow                (GtkSnapshot            *snapshot,
                                                          const GskShadow        *shadow,
                                                          gsize                   n_shadows);