cairocontext: Move a function

A function of GdkDrawingContext is only used when drawing with Cairo, so
move it to GdkCairoContext.

1 files changed, 43 insertions, 0 deletions

diff --git a/gdk/gdkcairocontext.c b/gdk/gdkcairocontext.c
index 1954b3a339..596eaabfa6 100644
--- a/gdk/gdkcairocontext.c
+++ b/gdk/gdkcairocontext.c
@@ -223,3 +223,46 @@ gdk_cairo_context_init (GdkCairoContext *self)
 {
 }
 
+/**
+ * gdk_cairo_context_cairo_create:
+ * @context: a #GdkCairoContext that is currently drawing
+ *
+ * Retrieves a Cairo context to be used to draw on the #GdkSurface
+ * of @context. A call to gdk_surface_begin_draw_frame() with this
+ * @context must have been done or this function will return %NULL.
+ *
+ * The returned context is guaranteed to be valid until
+ * gdk_surface_end_draw_frame() is called.
+ *
+ * Returns: (transfer full) (nullable): a Cairo context to be used
+ *   to draw the contents of the #GdkSurface. %NULL is returned
+ *   when @contet is not drawing.
+ */
+cairo_t *
+gdk_cairo_context_cairo_create (GdkCairoContext *self)
+{
+  GdkSurface *surface;
+  cairo_region_t *region;
+  cairo_surface_t *cairo_surface;
+  cairo_t *cr;
+
+  g_return_val_if_fail (GDK_IS_CAIRO_CONTEXT (self), NULL);
+
+  surface = gdk_draw_context_get_surface (GDK_DRAW_CONTEXT (self));
+  if (surface->drawing_context == NULL ||
+      gdk_drawing_context_get_paint_context (surface->drawing_context) != GDK_DRAW_CONTEXT (self))
+    return NULL;
+
+  cairo_surface = _gdk_surface_ref_cairo_surface (surface);
+  cr = cairo_create (cairo_surface);
+
+  region = gdk_surface_get_current_paint_region (surface);
+  gdk_cairo_region (cr, region);
+  cairo_clip (cr);
+
+  cairo_region_destroy (region);
+  cairo_surface_destroy (cairo_surface);
+
+  return cr;
+}
+