[gtk+/wip/ebassi/gsk-renderer: 422/545] gdk: Add utility for uploading Cairo surfaces to GL

[Emmanuele Bassi <ebassi src gnome org>]

commit 4c10e3cdff8dfd20356ffc506b4c17b82bd458f4
Author: Emmanuele Bassi <ebassi gnome org>
Date:   Mon Apr 25 11:29:14 2016 +0100

    gdk: Add utility for uploading Cairo surfaces to GL
    
    The surface-to-GL upload logic has become more complicated with the
    addition of the GLES code paths; it's more logical to have a public
    utility function that can be called from GDK users, instead of copy
    pasting the whole thing multiple times.

 gdk/gdkcairo.h |    7 +++++++
 gdk/gdkgl.c    |   48 ++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 55 insertions(+), 0 deletions(-)
---
diff --git a/gdk/gdkcairo.h b/gdk/gdkcairo.h
index dd874f7..8ba8baa 100644
--- a/gdk/gdkcairo.h
+++ b/gdk/gdkcairo.h
@@ -83,6 +83,13 @@ void       gdk_cairo_draw_from_gl (cairo_t              *cr,
 GDK_AVAILABLE_IN_3_22
 GdkDrawingContext *     gdk_cairo_get_drawing_context   (cairo_t *cr);
 
+GDK_AVAILABLE_IN_3_22
+void      gdk_cairo_surface_upload_to_gl (cairo_surface_t *surface,
+                                          int              target,
+                                          int              width,
+                                          int              height,
+                                          GdkGLContext    *context);
+
 G_END_DECLS
 
 #endif /* __GDK_CAIRO_H__ */
diff --git a/gdk/gdkgl.c b/gdk/gdkgl.c
index 51d2b02..58674c7 100644
--- a/gdk/gdkgl.c
+++ b/gdk/gdkgl.c
@@ -814,3 +814,51 @@ gdk_gl_texture_from_surface (cairo_surface_t *surface,
   glDisable (GL_SCISSOR_TEST);
   glDeleteTextures (1, &texture_id);
 }
+
+/**
+ * gdk_cairo_surface_upload_to_gl:
+ * @surface: a Cairo surface
+ * @target: a GL texture target
+ * @width: the width of the texture @target
+ * @height: the height of the texture @target
+ * @context: (nullable): a #GdkGLContext, or %NULL to use the currently
+ *   bound context
+ *
+ * Uploads the contents of a Cairo @surface to a GL texture @target.
+ *
+ * Since: 3.22
+ */
+void
+gdk_cairo_surface_upload_to_gl (cairo_surface_t *surface,
+                                int              target,
+                                int              width,
+                                int              height,
+                                GdkGLContext    *context)
+{
+  cairo_rectangle_int_t rect;
+  cairo_surface_t *tmp;
+  double sx, sy;
+  double device_x_offset, device_y_offset;
+
+  g_return_if_fail (surface != NULL);
+  g_return_if_fail (context == NULL || GDK_IS_GL_CONTEXT (context));
+
+  if (context == NULL)
+    context = gdk_gl_context_get_current ();
+
+  cairo_surface_flush (surface);
+
+  sx = sy = 1;
+  cairo_surface_get_device_scale (surface, &sx, &sy);
+  cairo_surface_get_device_offset (surface, &device_x_offset, &device_y_offset);
+
+  rect.x = (int) device_x_offset;
+  rect.y = (int) device_y_offset;
+  rect.width = width * sx;
+  rect.height = height * sx;
+  tmp = cairo_surface_map_to_image (surface, &rect);
+
+  gdk_gl_context_upload_texture (context, tmp, rect.width, rect.height, target);
+
+  cairo_surface_unmap_image (surface, tmp);
+}