cogl/context: Add cogl_renderer_create_dma_buf() and family

This is a winsys-specific API that allows exporting a DMA buffer fd.
The CoglDmaBufHandle structure allows passing the ownership of the
DMA buffer to whoever is using it, so the winsys doesn't need to
manually track it.

https://gitlab.gnome.org/GNOME/mutter/merge_requests/1086

cogl/cogl/cogl-dma-buf-handle.c

@@ -0,0 +1,94 @@
+/*
+ * Cogl
+ *
+ * A Low Level GPU Graphics and Utilities API
+ *
+ * Copyright (C) 2020 Endless, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ * Authors:
+ *   Georges Basile Stavracas Neto <georges.stavracas@gmail.com>
+ */
+
+#include "cogl-config.h"
+
+#include "cogl-dma-buf-handle.h"
+#include "cogl-object.h"
+
+#include <unistd.h>
+
+struct _CoglDmaBufHandle
+{
+  CoglFramebuffer *framebuffer;
+  int dmabuf_fd;
+  gpointer user_data;
+  GDestroyNotify destroy_func;
+};
+
+CoglDmaBufHandle *
+cogl_dma_buf_handle_new (CoglFramebuffer *framebuffer,
+                         int              dmabuf_fd,
+                         gpointer         user_data,
+                         GDestroyNotify   destroy_func)
+{
+  CoglDmaBufHandle *dmabuf_handle;
+
+  g_assert (framebuffer);
+  g_assert (dmabuf_fd != -1);
+
+  dmabuf_handle = g_new0 (CoglDmaBufHandle, 1);
+  dmabuf_handle->framebuffer = cogl_object_ref (framebuffer);
+  dmabuf_handle->dmabuf_fd = dmabuf_fd;
+  dmabuf_handle->user_data = user_data;
+  dmabuf_handle->destroy_func = destroy_func;
+
+  return dmabuf_handle;
+}
+
+void
+cogl_dma_buf_handle_free (CoglDmaBufHandle *dmabuf_handle)
+{
+  g_return_if_fail (dmabuf_handle != NULL);
+
+  g_clear_pointer (&dmabuf_handle->framebuffer, cogl_object_unref);
+
+  if (dmabuf_handle->destroy_func)
+    g_clear_pointer (&dmabuf_handle->user_data, dmabuf_handle->destroy_func);
+
+  if (dmabuf_handle->dmabuf_fd != -1)
+    close (dmabuf_handle->dmabuf_fd);
+
+  g_free (dmabuf_handle);
+}
+
+CoglFramebuffer *
+cogl_dma_buf_handle_get_framebuffer (CoglDmaBufHandle *dmabuf_handle)
+{
+  return dmabuf_handle->framebuffer;
+}
+
+int
+cogl_dma_buf_handle_get_fd (CoglDmaBufHandle *dmabuf_handle)
+{
+  return dmabuf_handle->dmabuf_fd;
+}
+

cogl/cogl/cogl-dma-buf-handle.h

@@ -0,0 +1,83 @@
+/*
+ * Cogl
+ *
+ * A Low Level GPU Graphics and Utilities API
+ *
+ * Copyright (C) 2020 Endless, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use, copy,
+ * modify, merge, publish, distribute, sublicense, and/or sell copies
+ * of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
+ * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
+ * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ * Authors:
+ *   Georges Basile Stavracas Neto <georges.stavracas@gmail.com>
+ */
+
+
+#if !defined(__COGL_H_INSIDE__) && !defined(COGL_COMPILATION)
+#error "Only <cogl/cogl.h> can be included directly."
+#endif
+
+#ifndef __COGL_DMA_BUF_HANDLE_H__
+#define __COGL_DMA_BUF_HANDLE_H__
+
+#include <cogl/cogl-types.h>
+#include <cogl/cogl-framebuffer.h>
+
+/**
+ * cogl_dma_buf_handle_new: (skip)
+ */
+CoglDmaBufHandle *
+cogl_dma_buf_handle_new (CoglFramebuffer *framebuffer,
+                         int              dmabuf_fd,
+                         gpointer         data,
+                         GDestroyNotify   destroy_func);
+
+/**
+ * cogl_dma_buf_handle_free: (skip)
+ *
+ * Releases @dmabuf_handle; it is a programming error to release
+ * an already released handle.
+ */
+void
+cogl_dma_buf_handle_free (CoglDmaBufHandle *dmabuf_handle);
+
+/**
+ * cogl_dma_buf_handle_get_framebuffer: (skip)
+ *
+ * Retrieves the #CoglFramebuffer, backed by an exported DMABuf buffer,
+ * of @dmabuf_handle.
+ *
+ * Returns: (transfer none): a #CoglFramebuffer
+ */
+CoglFramebuffer *
+cogl_dma_buf_handle_get_framebuffer (CoglDmaBufHandle *dmabuf_handle);
+
+/**
+ * cogl_dma_buf_handle_get_fd: (skip)
+ *
+ * Retrieves the file descriptor of @dmabuf_handle.
+ *
+ * Returns: a valid file descriptor
+ */
+int
+cogl_dma_buf_handle_get_fd (CoglDmaBufHandle *dmabuf_handle);
+
+
+#endif /* __COGL_DMA_BUF_HANDLE_H__ */

cogl/cogl/cogl-renderer.c

@@ -756,3 +756,17 @@ cogl_renderer_foreach_output (CoglRenderer *renderer,
   for (l = renderer->outputs; l; l = l->next)
     callback (l->data, user_data);
 }
+
+CoglDmaBufHandle *
+cogl_renderer_create_dma_buf (CoglRenderer  *renderer,
+                              int            width,
+                              int            height,
+                              GError       **error)
+{
+  const CoglWinsysVtable *winsys = _cogl_renderer_get_winsys (renderer);
+
+  if (winsys->renderer_create_dma_buf)
+    return winsys->renderer_create_dma_buf (renderer, width, height, error);
+
+  return NULL;
+}

cogl/cogl/cogl-renderer.h

@@ -398,6 +398,27 @@ cogl_renderer_foreach_output (CoglRenderer *renderer,
                               CoglOutputCallback callback,
                               void *user_data);
 
+/**
+ * cogl_renderer_create_dma_buf: (skip)
+ * @renderer: A #CoglRenderer
+ * @width: width of the new
+ * @height: height of the new
+ * @error: (nullable): return location for a #GError
+ *
+ * Creates a new #CoglFramebuffer with @width x @height, and format
+ * hardcoded to XRGB, and exports the new framebuffer's DMA buffer
+ * handle.
+ *
+ * Returns: (nullable)(transfer full): a #CoglDmaBufHandle. The
+ * return result must be released with cogl_dma_buf_handle_free()
+ * after use.
+ */
+CoglDmaBufHandle *
+cogl_renderer_create_dma_buf (CoglRenderer  *renderer,
+                              int            width,
+                              int            height,
+                              GError       **error);
+
 G_END_DECLS
 
 #endif /* __COGL_RENDERER_H__ */

cogl/cogl/cogl-types.h

@@ -101,6 +101,14 @@ typedef int32_t CoglAngle;
 typedef struct _CoglColor               CoglColor;
 typedef struct _CoglTextureVertex       CoglTextureVertex;
 
+/**
+ * CoglDmaBufHandle: (skip)
+ *
+ * An opaque type that tracks the lifetime of a DMA buffer fd. Release
+ * with cogl_dma_buf_handle_free().
+ */
+typedef struct _CoglDmaBufHandle CoglDmaBufHandle;
+
 /* Enum declarations */
 
 #define COGL_A_BIT              (1 << 4)

cogl/cogl/cogl.h

@@ -61,6 +61,7 @@
 #include <cogl/cogl1-context.h>
 #include <cogl/cogl-bitmap.h>
 #include <cogl/cogl-color.h>
+#include <cogl/cogl-dma-buf-handle.h>
 #include <cogl/cogl-matrix.h>
 #include <cogl/cogl-matrix-stack.h>
 #include <cogl/cogl-offscreen.h>

cogl/cogl/meson.build

@@ -96,6 +96,7 @@ cogl_nonintrospected_headers = [
   'cogl-renderer.h',
   'cogl-swap-chain.h',
   'cogl-onscreen-template.h',
+  'cogl-dma-buf-handle.h',
   'cogl-display.h',
   'cogl-snippet.h',
   'cogl-index-buffer.h',
@@ -203,6 +204,7 @@ cogl_sources = [
   'cogl-i18n-private.h',
   'cogl-debug.h',
   'cogl-debug-options.h',
+  'cogl-dma-buf-handle.c',
   'cogl-gpu-info.c',
   'cogl-gpu-info-private.h',
   'cogl-context-private.h',

cogl/cogl/winsys/cogl-winsys-private.h

@@ -91,6 +91,12 @@ typedef struct _CoglWinsysVtable
   void
   (*display_destroy) (CoglDisplay *display);
 
+  CoglDmaBufHandle *
+  (*renderer_create_dma_buf) (CoglRenderer  *renderer,
+                              int            width,
+                              int            height,
+                              GError       **error);
+
   gboolean
   (*context_init) (CoglContext *context, GError **error);