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323adc0c14
There are a few places in Cogl that try to set the premult bit on a pixel format depending on whether it has an alpha channel. However this breaks if the pixel format is alpha-only because premultiplying data without any RGB components doesn't make any sense. This adds an internal macro to check for cases where we should add the premult bit called COGL_PIXEL_FORMAT_CAN_HAVE_PREMULT. This now gets used in all places that previously just checking for COGL_A_BIT. https://bugzilla.gnome.org/show_bug.cgi?id=671016 Reviewed-by: Robert Bragg <robert@linux.intel.com>
120 lines
3.7 KiB
C
120 lines
3.7 KiB
C
/*
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* Cogl
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*
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* An object oriented GL/GLES Abstraction/Utility Layer
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*
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* Copyright (C) 2010 Intel Corporation.
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library. If not, see <http://www.gnu.org/licenses/>.
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*
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*
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*/
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#ifndef __COGL_PRIVATE_H__
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#define __COGL_PRIVATE_H__
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#include <cogl/cogl-pipeline.h>
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#include "cogl-context.h"
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G_BEGIN_DECLS
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gboolean
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_cogl_gl_update_features (CoglContext *context,
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GError **error);
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gboolean
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_cogl_gles_update_features (CoglContext *context,
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GError **error);
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gboolean
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_cogl_check_extension (const char *name, const char *ext);
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void
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_cogl_clear (const CoglColor *color, unsigned long buffers);
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void
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_cogl_read_pixels_with_rowstride (int x,
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int y,
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int width,
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int height,
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CoglReadPixelsFlags source,
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CoglPixelFormat format,
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guint8 *pixels,
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int rowstride);
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void
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_cogl_init (void);
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void
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_cogl_push_source (CoglPipeline *pipeline, gboolean enable_legacy);
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gboolean
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_cogl_get_enable_legacy_state (void);
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/*
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* _cogl_pixel_format_get_bytes_per_pixel:
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* @format: a #CoglPixelFormat
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*
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* Queries how many bytes a pixel of the given @format takes.
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*
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* Return value: The number of bytes taken for a pixel of the given
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* @format.
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*/
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int
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_cogl_pixel_format_get_bytes_per_pixel (CoglPixelFormat format);
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/*
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* _cogl_pixel_format_has_aligned_components:
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* @format: a #CoglPixelFormat
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*
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* Queries whether the ordering of the components for the given
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* @format depend on the endianness of the host CPU or if the
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* components can be accessed using bit shifting and bitmasking by
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* loading a whole pixel into a word.
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*
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* XXX: If we ever consider making something like this public we
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* should really try to think of a better name and come up with
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* much clearer documentation since it really depends on what
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* point of view you consider this from whether a format like
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* COGL_PIXEL_FORMAT_RGBA_8888 is endian dependent. E.g. If you
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* read an RGBA_8888 pixel into a uint32
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* it's endian dependent how you mask out the different channels.
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* But If you already have separate color components and you want
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* to write them to an RGBA_8888 pixel then the bytes can be
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* written sequentially regardless of the endianness.
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*
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* Return value: %TRUE if you need to consider the host CPU
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* endianness when dealing with the given @format
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* else %FALSE.
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*/
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gboolean
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_cogl_pixel_format_is_endian_dependant (CoglPixelFormat format);
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/*
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* COGL_PIXEL_FORMAT_CAN_HAVE_PREMULT(format):
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* @format: a #CoglPixelFormat
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*
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* Returns TRUE if the pixel format can take a premult bit. This is
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* currently true for all formats that have an alpha channel except
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* COGL_PIXEL_FORMAT_A_8 (because that doesn't have any other
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* components to multiply by the alpha).
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*/
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#define COGL_PIXEL_FORMAT_CAN_HAVE_PREMULT(format) \
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(((format) & COGL_A_BIT) && (format) != COGL_PIXEL_FORMAT_A_8)
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G_END_DECLS
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#endif /* __COGL_PRIVATE_H__ */
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