mutter/cogl/cogl-path-private.h
Neil Roberts 067a520f26 cogl: Support retained paths
This adds three new API calls:

  CoglHandle cogl_path_get()
  void cogl_path_set(CoglHandle path)
  CoglHandle cogl_path_copy(CoglHandle path)

All of the fields relating to the path have been moved from the Cogl
context to a new CoglPath handle type. The cogl context now just
contains a CoglPath handle. All of the existing path commands
manipulate the data in the current path handle. cogl_path_new now just
creates a new path handle and unrefs the old one.

The path handle can be stored for later with cogl_path_get. The path
can then be copied with cogl_path_copy. Internally it implements
copy-on-write semantics with an extra optimisation that it will only
copy the data if the new path is modified, but not if the original
path is modified. It can do this because the only way to modify a path
is by appending to it so the copied path is able to store its own path
length and only render the nodes up to that length. For this to work
the copied path also needs to keep its own copies of the path extents
because the parent path may change these by adding nodes.

The clip stack now uses the cogl_path_copy mechanism to store paths in
the stack instead of directly copying the data. This should save some
memory and processing time.
2010-04-08 19:53:38 +01:00

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2.5 KiB
C

/*
* Cogl
*
* An object oriented GL/GLES Abstraction/Utility Layer
*
* Copyright (C) 2010 Intel Corporation.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*
*
*/
#ifndef __COGL_PATH_PRIVATE_H
#define __COGL_PATH_PRIVATE_H
#include "cogl-handle.h"
#define COGL_PATH(tex) ((CoglPath *)(tex))
typedef struct _floatVec2
{
float x;
float y;
} floatVec2;
typedef struct _CoglPathNode
{
float x;
float y;
unsigned int path_size;
} CoglPathNode;
typedef struct _CoglBezQuad
{
floatVec2 p1;
floatVec2 p2;
floatVec2 p3;
} CoglBezQuad;
typedef struct _CoglBezCubic
{
floatVec2 p1;
floatVec2 p2;
floatVec2 p3;
floatVec2 p4;
} CoglBezCubic;
typedef struct _CoglPath CoglPath;
struct _CoglPath
{
CoglHandleObject _parent;
/* If this path was created with cogl_path_copy then parent_path
will point to the copied path. Otherwise it will be
COGL_INVALID_HANDLE to indicate that we own path_nodes. */
CoglHandle parent_path;
/* Pointer to the path nodes array. This will point directly into
the parent path if this path is a copy */
GArray *path_nodes;
/* Number of nodes to render from the data. This may be different
from path_nodes->len if this is a copied path and the parent path
was appended to. If that is the case then we need to be careful
to check that the size of a sub path doesn't extend past
path_size */
unsigned int path_size;
floatVec2 path_start;
floatVec2 path_pen;
unsigned int last_path;
floatVec2 path_nodes_min;
floatVec2 path_nodes_max;
};
/* This is an internal version of cogl_path_new that doesn't affect
the current path and just creates a new handle */
CoglHandle
_cogl_path_new (void);
void
_cogl_add_path_to_stencil_buffer (CoglHandle path,
gboolean merge,
gboolean need_clear);
#endif /* __COGL_PATH_PRIVATE_H */