[cogl/wip/cogl-1.14: 60/177] Use cogl_buffer_map_range from the journal

[Robert Bragg <rbragg src gnome org>]

commit e2dc60faba872c8d97b8bbff435cda4b8a1503a8
Author: Neil Roberts <neil linux intel com>
Date:   Wed Oct 17 21:36:10 2012 +0100

    Use cogl_buffer_map_range from the journal
    
    The journal maintains a cache of attribute buffers to upload the
    vertices for the rectangles. The buffers are mapped to fill in the
    data. However, if the previous journal was larger than the one being
    flushed now then the buffers may be larger than is actually needed. In
    that case we might as well only map the range that is actually used so
    that the driver can potentially avoid having to set up a mapping for
    the entire buffer. The COGL_BUFFER_MAP_HINT_DISCARD flag is still set
    so that the driver is free to discard the entire buffer, not just the
    subrange.
    
    The _cogl_buffer_map_for_fill_or_fallback has been replaced with
    _cogl_buffer_map_range_for_fill_or_fallback so that the range
    parameters can be passed. The original function is now just a wrapper
    around the latter.
    
    Reviewed-by: Robert Bragg <robert linux intel com>
    
    (cherry picked from commit 27769e54806dcfc1a12fdc4b07b054b8f2f4215b)

 cogl/cogl-buffer-private.h  |    8 ++++++--
 cogl/cogl-buffer.c          |   24 ++++++++++++++++++------
 cogl/cogl-context-private.h |    1 +
 cogl/cogl-journal.c         |    4 +++-
 4 files changed, 28 insertions(+), 9 deletions(-)
---
diff --git a/cogl/cogl-buffer-private.h b/cogl/cogl-buffer-private.h
index cf2d9b9..4b21fa3 100644
--- a/cogl/cogl-buffer-private.h
+++ b/cogl/cogl-buffer-private.h
@@ -137,13 +137,17 @@ _cogl_buffer_immutable_ref (CoglBuffer *buffer);
 void
 _cogl_buffer_immutable_unref (CoglBuffer *buffer);
 
-/* This is a wrapper around cogl_buffer_map for internal use when we
-   want to map the buffer for write only to replace the entire
+/* This is a wrapper around cogl_buffer_map_range for internal use
+   when we want to map the buffer for write only to replace the entire
    contents. If the map fails then it will fallback to writing to a
    temporary buffer. When _cogl_buffer_unmap_for_fill_or_fallback is
    called the temporary buffer will be copied into the array. Note
    that these calls share a global array so they can not be nested. */
 void *
+_cogl_buffer_map_range_for_fill_or_fallback (CoglBuffer *buffer,
+                                             size_t offset,
+                                             size_t size);
+void *
 _cogl_buffer_map_for_fill_or_fallback (CoglBuffer *buffer);
 
 void
diff --git a/cogl/cogl-buffer.c b/cogl/cogl-buffer.c
index 7a1a084..72fd3f8 100644
--- a/cogl/cogl-buffer.c
+++ b/cogl/cogl-buffer.c
@@ -262,6 +262,14 @@ cogl_buffer_unmap (CoglBuffer *buffer)
 void *
 _cogl_buffer_map_for_fill_or_fallback (CoglBuffer *buffer)
 {
+  return _cogl_buffer_map_range_for_fill_or_fallback (buffer, 0, buffer->size);
+}
+
+void *
+_cogl_buffer_map_range_for_fill_or_fallback (CoglBuffer *buffer,
+                                             size_t offset,
+                                             size_t size)
+{
   CoglContext *ctx = buffer->context;
   void *ret;
 
@@ -269,9 +277,11 @@ _cogl_buffer_map_for_fill_or_fallback (CoglBuffer *buffer)
 
   ctx->buffer_map_fallback_in_use = TRUE;
 
-  ret = cogl_buffer_map (buffer,
-                         COGL_BUFFER_ACCESS_WRITE,
-                         COGL_BUFFER_MAP_HINT_DISCARD);
+  ret = cogl_buffer_map_range (buffer,
+                               offset,
+                               size,
+                               COGL_BUFFER_ACCESS_WRITE,
+                               COGL_BUFFER_MAP_HINT_DISCARD);
 
   if (ret)
     return ret;
@@ -281,7 +291,8 @@ _cogl_buffer_map_for_fill_or_fallback (CoglBuffer *buffer)
          the data and then upload it using cogl_buffer_set_data when
          the buffer is unmapped. The temporary buffer is shared to
          avoid reallocating it every time */
-      g_byte_array_set_size (ctx->buffer_map_fallback_array, buffer->size);
+      g_byte_array_set_size (ctx->buffer_map_fallback_array, size);
+      ctx->buffer_map_fallback_offset = offset;
 
       buffer->flags |= COGL_BUFFER_FLAG_MAPPED_FALLBACK;
 
@@ -300,9 +311,10 @@ _cogl_buffer_unmap_for_fill_or_fallback (CoglBuffer *buffer)
 
   if ((buffer->flags & COGL_BUFFER_FLAG_MAPPED_FALLBACK))
     {
-      cogl_buffer_set_data (buffer, 0,
+      cogl_buffer_set_data (buffer,
+                            ctx->buffer_map_fallback_offset,
                             ctx->buffer_map_fallback_array->data,
-                            buffer->size);
+                            ctx->buffer_map_fallback_array->len);
       buffer->flags &= ~COGL_BUFFER_FLAG_MAPPED_FALLBACK;
     }
   else
diff --git a/cogl/cogl-context-private.h b/cogl/cogl-context-private.h
index 7321455..788cf3d 100644
--- a/cogl/cogl-context-private.h
+++ b/cogl/cogl-context-private.h
@@ -269,6 +269,7 @@ struct _CoglContext
      data */
   GByteArray       *buffer_map_fallback_array;
   CoglBool          buffer_map_fallback_in_use;
+  size_t            buffer_map_fallback_offset;
 
   CoglWinsysRectangleState rectangle_state;
 
diff --git a/cogl/cogl-journal.c b/cogl/cogl-journal.c
index e8eee79..c762a0b 100644
--- a/cogl/cogl-journal.c
+++ b/cogl/cogl-journal.c
@@ -1079,7 +1079,9 @@ upload_vertices (CoglJournal *journal,
   buffer = COGL_BUFFER (attribute_buffer);
   cogl_buffer_set_update_hint (buffer, COGL_BUFFER_UPDATE_HINT_STATIC);
 
-  vout = _cogl_buffer_map_for_fill_or_fallback (buffer);
+  vout = _cogl_buffer_map_range_for_fill_or_fallback (buffer,
+                                                      0, /* offset */
+                                                      needed_vbo_len * 4);
   vin = &g_array_index (vertices, float, 0);
 
   /* Expand the number of vertices from 2 to 4 while uploading */