[mutter/gbsneto/dmabuf-screencast: 1/8] cogl/context: Add cogl_context_capture_dma_buf() and family

[Georges Basile Stavracas Neto <gbsneto src gnome org>]

commit 8ae9f8c45b32bd5d58291e073a970fb3806cef5f
Author: Georges Basile Stavracas Neto <georges stavracas gmail com>
Date:   Mon Dec 9 10:03:07 2019 -0300

    cogl/context: Add cogl_context_capture_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-context.c               | 16 ++++++
 cogl/cogl/cogl-context.h               | 19 +++++++
 cogl/cogl/cogl-dma-buf-handle.c        | 95 ++++++++++++++++++++++++++++++++++
 cogl/cogl/cogl-dma-buf-handle.h        | 83 +++++++++++++++++++++++++++++
 cogl/cogl/cogl-types.h                 |  8 +++
 cogl/cogl/cogl.h                       |  1 +
 cogl/cogl/meson.build                  |  2 +
 cogl/cogl/winsys/cogl-winsys-private.h |  6 +++
 8 files changed, 230 insertions(+)
---
diff --git a/cogl/cogl/cogl-context.c b/cogl/cogl/cogl-context.c
index 5d9ea07be..117fc7f77 100644
--- a/cogl/cogl/cogl-context.c
+++ b/cogl/cogl/cogl-context.c
@@ -616,3 +616,19 @@ cogl_get_graphics_reset_status (CoglContext *context)
       return COGL_GRAPHICS_RESET_STATUS_NO_ERROR;
     }
 }
+
+CoglDmaBufHandle *
+cogl_context_capture_dma_buf (CoglContext  *context,
+                              int           width,
+                              int           height,
+                              GError      **error)
+{
+  const CoglWinsysVtable *winsys;
+
+  winsys = context->display->renderer->winsys_vtable;
+
+  if (winsys->context_capture_dma_buf)
+    return winsys->context_capture_dma_buf (context, width, height, error);
+
+  return NULL;
+}
diff --git a/cogl/cogl/cogl-context.h b/cogl/cogl/cogl-context.h
index 241a09bfb..a47d06d83 100644
--- a/cogl/cogl/cogl-context.h
+++ b/cogl/cogl/cogl-context.h
@@ -353,6 +353,25 @@ typedef enum _CoglGraphicsResetStatus
 CoglGraphicsResetStatus
 cogl_get_graphics_reset_status (CoglContext *context);
 
+/**
+ * cogl_context_capture_dma_buf: (skip)
+ * @context: A #CoglContext
+ * @width: width 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_framebuffer_dmabuf_handle_release()
+ * after use.
+ */
+CoglDmaBufHandle *
+cogl_context_capture_dma_buf (CoglContext  *context,
+                              int           width,
+                              int           height,
+                              GError      **error);
+
 G_END_DECLS
 
 #endif /* __COGL_CONTEXT_H__ */
diff --git a/cogl/cogl/cogl-dma-buf-handle.c b/cogl/cogl/cogl-dma-buf-handle.c
new file mode 100644
index 000000000..4d6c4b4a6
--- /dev/null
+++ b/cogl/cogl/cogl-dma-buf-handle.c
@@ -0,0 +1,95 @@
+/*
+ * 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 private_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->private_data = user_data;
+  dmabuf_handle->destroy_func = destroy_func;
+
+  return dmabuf_handle;
+}
+
+void
+cogl_dma_buf_handle_free (CoglDmaBufHandle *dmabuf_handle)
+{
+  if (!dmabuf_handle)
+    return;
+
+  g_clear_pointer (&dmabuf_handle->framebuffer, cogl_object_unref);
+
+  if (dmabuf_handle->destroy_func)
+    g_clear_pointer (&dmabuf_handle->private_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;
+}
+
diff --git a/cogl/cogl/cogl-dma-buf-handle.h b/cogl/cogl/cogl-dma-buf-handle.h
new file mode 100644
index 000000000..25b9b0ccb
--- /dev/null
+++ b/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__ */
diff --git a/cogl/cogl/cogl-types.h b/cogl/cogl/cogl-types.h
index f3d0b816d..d24683999 100644
--- a/cogl/cogl/cogl-types.h
+++ b/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)
diff --git a/cogl/cogl/cogl.h b/cogl/cogl/cogl.h
index 17c59d66e..a71d09fbf 100644
--- a/cogl/cogl/cogl.h
+++ b/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>
diff --git a/cogl/cogl/meson.build b/cogl/cogl/meson.build
index b9ff59b75..0297a2485 100644
--- a/cogl/cogl/meson.build
+++ b/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',
diff --git a/cogl/cogl/winsys/cogl-winsys-private.h b/cogl/cogl/winsys/cogl-winsys-private.h
index 1ed7bf4fb..f993150a1 100644
--- a/cogl/cogl/winsys/cogl-winsys-private.h
+++ b/cogl/cogl/winsys/cogl-winsys-private.h
@@ -97,6 +97,12 @@ typedef struct _CoglWinsysVtable
   void
   (*context_deinit) (CoglContext *context);
 
+  CoglDmaBufHandle *
+  (*context_capture_dma_buf) (CoglContext  *context,
+                              int           width,
+                              int           height,
+                              GError      **error);
+
   gboolean
   (*onscreen_init) (CoglOnscreen *onscreen, GError **error);