gsk: Add gsk_renderer_render_texture()

... and implement it for the Cairo renderer.

It's an API that instructs a renderer to render to a texture.
So far this is mostly meant to be used for testing, but I could imagine
it being useful for rendering DND icons.

1 files changed, 52 insertions, 18 deletions

diff --git a/gsk/gskcairorenderer.c b/gsk/gskcairorenderer.c
index d112e4fca0..af23d610f6 100644
--- a/gsk/gskcairorenderer.c
+++ b/gsk/gskcairorenderer.c
@@ -45,17 +45,62 @@ gsk_cairo_renderer_unrealize (GskRenderer *renderer)
 }
 
 static void
-gsk_cairo_renderer_render (GskRenderer   *renderer,
-                           GskRenderNode *root)
+gsk_cairo_renderer_do_render (GskRenderer   *renderer,
+                              cairo_t       *cr,
+                              GskRenderNode *root)
 {
-  GskCairoRenderer *self = GSK_CAIRO_RENDERER (renderer);
-  GdkDrawingContext *context = gsk_renderer_get_drawing_context (renderer);
-  graphene_rect_t viewport;
 #ifdef G_ENABLE_DEBUG
+  GskCairoRenderer *self = GSK_CAIRO_RENDERER (renderer);
   GskProfiler *profiler;
   gint64 cpu_time;
 #endif
 
+#ifdef G_ENABLE_DEBUG
+  profiler = gsk_renderer_get_profiler (renderer);
+  gsk_profiler_timer_begin (profiler, self->profile_timers.cpu_time);
+#endif
+
+  gsk_render_node_draw (root, cr);
+
+#ifdef G_ENABLE_DEBUG
+  cpu_time = gsk_profiler_timer_end (profiler, self->profile_timers.cpu_time);
+  gsk_profiler_timer_set (profiler, self->profile_timers.cpu_time, cpu_time);
+
+  gsk_profiler_push_samples (profiler);
+#endif
+}
+
+static GskTexture *
+gsk_cairo_renderer_render_texture (GskRenderer           *renderer,
+                                   GskRenderNode         *root,
+                                   const graphene_rect_t *viewport)
+{
+  GskTexture *texture;
+  cairo_surface_t *surface;
+  cairo_t *cr;
+
+  surface = cairo_image_surface_create (CAIRO_FORMAT_ARGB32, ceil (viewport->size.width), ceil (viewport->size.height));
+  cr = cairo_create (surface);
+
+  cairo_translate (cr, - viewport->origin.x, - viewport->origin.y);
+
+  gsk_cairo_renderer_do_render (renderer, cr, root);
+
+  cairo_destroy (cr);
+
+  texture = gsk_texture_new_for_surface (surface);
+  cairo_surface_destroy (surface);
+
+  return texture;
+}
+
+static void
+gsk_cairo_renderer_render (GskRenderer   *renderer,
+                           GskRenderNode *root)
+{
+  GdkDrawingContext *context = gsk_renderer_get_drawing_context (renderer);
+  graphene_rect_t viewport;
+
   cairo_t *cr;
 
   cr = gdk_drawing_context_get_cairo_context (context);
@@ -78,19 +123,7 @@ gsk_cairo_renderer_render (GskRenderer   *renderer,
       cairo_restore (cr);
     }
 
-#ifdef G_ENABLE_DEBUG
-  profiler = gsk_renderer_get_profiler (renderer);
-  gsk_profiler_timer_begin (profiler, self->profile_timers.cpu_time);
-#endif
-
-  gsk_render_node_draw (root, cr);
-
-#ifdef G_ENABLE_DEBUG
-  cpu_time = gsk_profiler_timer_end (profiler, self->profile_timers.cpu_time);
-  gsk_profiler_timer_set (profiler, self->profile_timers.cpu_time, cpu_time);
-
-  gsk_profiler_push_samples (profiler);
-#endif
+  gsk_cairo_renderer_do_render (renderer, cr, root);
 }
 
 static void
@@ -101,6 +134,7 @@ gsk_cairo_renderer_class_init (GskCairoRendererClass *klass)
   renderer_class->realize = gsk_cairo_renderer_realize;
   renderer_class->unrealize = gsk_cairo_renderer_unrealize;
   renderer_class->render = gsk_cairo_renderer_render;
+  renderer_class->render_texture = gsk_cairo_renderer_render_texture;
 }
 
 static void