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When COGL_ENABLE_EXPERIMENTAL_2_0_API is defined cogl.h will now include
cogl2-path.h which changes cogl_path_new() so it can directly return a
CoglPath pointer; it no longer exposes a prototype for
cogl_{get,set}_path and all the remaining cogl_path_ functions now take
an explicit path as their first argument.
The idea is that we want to encourage developers to retain path objects
for as long as possible so they can take advantage of us uploading the
path geometry to the GPU. Currently although it is possible to start a
new path and query the current path, it is not convenient.
The other thing is that we want to get Cogl to the point where nothing
depends on a global, current context variable. This will allow us to one
day define a sensible threading model if/when that is ever desired.
492 lines
15 KiB
C
492 lines
15 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) 2008,2009 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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#if !defined(__COGL_H_INSIDE__) && !defined(CLUTTER_COMPILATION)
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#error "Only <cogl/cogl.h> can be included directly."
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#endif
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#ifndef __COGL_PATH_H__
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#define __COGL_PATH_H__
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#include <cogl/cogl-types.h>
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G_BEGIN_DECLS
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/**
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* SECTION:cogl-paths
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* @short_description: Functions for constructing and drawing 2D paths.
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*
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* There are two levels on which drawing with cogl-paths can be used.
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* The highest level functions construct various simple primitive
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* shapes to be either filled or stroked. Using a lower-level set of
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* functions more complex and arbitrary paths can be constructed by
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* concatenating straight line, bezier curve and arc segments.
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*
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* When constructing arbitrary paths, the current pen location is
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* initialized using the move_to command. The subsequent path segments
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* implicitly use the last pen location as their first vertex and move
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* the pen location to the last vertex they produce at the end. Also
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* there are special versions of functions that allow specifying the
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* vertices of the path segments relative to the last pen location
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* rather then in the absolute coordinates.
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*/
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typedef struct _CoglPath CoglPath;
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#define COGL_PATH(obj) ((CoglPath *)(obj))
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/**
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* CoglPathFillRule:
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* @COGL_PATH_FILL_RULE_NON_ZERO: Each time the line crosses an edge of
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* the path from left to right one is added to a counter and each time
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* it crosses from right to left the counter is decremented. If the
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* counter is non-zero then the point will be filled. See <xref
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* linkend="fill-rule-non-zero"/>.
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* @COGL_PATH_FILL_RULE_EVEN_ODD: If the line crosses an edge of the
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* path an odd number of times then the point will filled, otherwise
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* it won't. See <xref linkend="fill-rule-even-odd"/>.
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*
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* #CoglPathFillRule is used to determine how a path is filled. There
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* are two options - 'non-zero' and 'even-odd'. To work out whether any
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* point will be filled imagine drawing an infinetely long line in any
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* direction from that point. The number of times and the direction
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* that the edges of the path crosses this line determines whether the
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* line is filled as described below. Any open sub paths are treated
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* as if there was an extra line joining the first point and the last
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* point.
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*
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* The default fill rule is %COGL_PATH_FILL_RULE_EVEN_ODD. The fill
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* rule is attached to the current path so preserving a path with
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* cogl_get_path() also preserves the fill rule. Calling
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* cogl_path_new() resets the current fill rule to the default.
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*
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* <figure id="fill-rule-non-zero">
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* <title>Example of filling various paths using the non-zero rule</title>
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* <graphic fileref="fill-rule-non-zero.png" format="PNG"/>
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* </figure>
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*
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* <figure id="fill-rule-even-odd">
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* <title>Example of filling various paths using the even-odd rule</title>
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* <graphic fileref="fill-rule-even-odd.png" format="PNG"/>
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* </figure>
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*
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* Since: 1.4
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*/
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typedef enum {
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COGL_PATH_FILL_RULE_NON_ZERO,
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COGL_PATH_FILL_RULE_EVEN_ODD
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} CoglPathFillRule;
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/**
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* cogl_is_path:
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* @handle: A CoglHandle
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*
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* Gets whether the given handle references an existing path object.
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*
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* Return value: %TRUE if the handle references a #CoglPath,
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* %FALSE otherwise
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*/
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gboolean
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cogl_is_path (CoglHandle handle);
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/**
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* cogl_path_set_fill_rule:
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* @fill_rule: The new fill rule.
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*
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* Sets the fill rule of the current path to @fill_rule. This will
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* affect how the path is filled when cogl_path_fill() is later
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* called. Note that the fill rule state is attached to the path so
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* calling cogl_get_path() will preserve the fill rule and calling
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* cogl_path_new() will reset the fill rule back to the default.
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*
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* Since: 1.4
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*/
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void
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cogl_path_set_fill_rule (CoglPathFillRule fill_rule);
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/**
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* cogl_path_get_fill_rule:
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*
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* Retrieves the fill rule set using cogl_path_set_fill_rule().
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*
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* Return value: the fill rule that is used for the current path.
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*
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* Since: 1.4
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*/
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CoglPathFillRule
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cogl_path_get_fill_rule (void);
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/**
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* cogl_path_fill:
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*
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* Fills the interior of the constructed shape using the current
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* drawing color. The current path is then cleared. To use the path
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* again, call cogl_path_fill_preserve() instead.
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*
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* The interior of the shape is determined using the fill rule of the
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* path. See %CoglPathFillRule for details.
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**/
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void
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cogl_path_fill (void);
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/**
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* cogl_path_fill_preserve:
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*
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* Fills the interior of the constructed shape using the current
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* drawing color and preserves the path to be used again. See
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* cogl_path_fill() for a description what is considered the interior
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* of the shape.
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*
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* Since: 1.0
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**/
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void
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cogl_path_fill_preserve (void);
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/**
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* cogl_path_stroke:
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*
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* Strokes the constructed shape using the current drawing color and a
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* width of 1 pixel (regardless of the current transformation
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* matrix). To current path is then cleared. To use the path again,
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* call cogl_path_stroke_preserve() instead.
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**/
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void
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cogl_path_stroke (void);
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/**
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* cogl_path_stroke_preserve:
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*
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* Strokes the constructed shape using the current drawing color and
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* preserves the path to be used again.
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*
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* Since: 1.0
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**/
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void
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cogl_path_stroke_preserve (void);
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/**
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* cogl_path_new:
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*
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* Clears the current path and starts a new one. Creating a new path
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* also resets the fill rule to the default which is
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* %COGL_PATH_FILL_RULE_EVEN_ODD.
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*
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* Since: 1.0
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*/
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void
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cogl_path_new (void);
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/**
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* cogl_path_move_to:
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* @x: X coordinate of the pen location to move to.
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* @y: Y coordinate of the pen location to move to.
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*
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* Moves the pen to the given location. If there is an existing path
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* this will start a new disjoint subpath.
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**/
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void
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cogl_path_move_to (float x,
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float y);
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/**
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* cogl_path_rel_move_to:
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* @x: X offset from the current pen location to move the pen to.
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* @y: Y offset from the current pen location to move the pen to.
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*
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* Moves the pen to the given offset relative to the current pen
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* location. If there is an existing path this will start a new
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* disjoint subpath.
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**/
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void
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cogl_path_rel_move_to (float x,
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float y);
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/**
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* cogl_path_line_to:
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* @x: X coordinate of the end line vertex
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* @y: Y coordinate of the end line vertex
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*
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* Adds a straight line segment to the current path that ends at the
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* given coordinates.
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**/
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void
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cogl_path_line_to (float x,
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float y);
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/**
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* cogl_path_rel_line_to:
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* @x: X offset from the current pen location of the end line vertex
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* @y: Y offset from the current pen location of the end line vertex
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*
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* Adds a straight line segment to the current path that ends at the
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* given coordinates relative to the current pen location.
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**/
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void
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cogl_path_rel_line_to (float x,
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float y);
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/**
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* cogl_path_arc:
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* @center_x: X coordinate of the elliptical arc center
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* @center_y: Y coordinate of the elliptical arc center
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* @radius_x: X radius of the elliptical arc
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* @radius_y: Y radius of the elliptical arc
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* @angle_1: Angle in degrees at which the arc begin
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* @angle_2: Angle in degrees at which the arc ends
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*
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* Adds an elliptical arc segment to the current path. A straight line
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* segment will link the current pen location with the first vertex
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* of the arc. If you perform a move_to to the arcs start just before
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* drawing it you create a free standing arc.
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*
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* The angles are measured in degrees where 0° is in the direction of
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* the positive X axis and 90° is in the direction of the positive Y
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* axis. The angle of the arc begins at @angle_1 and heads towards
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* @angle_2 (so if @angle_2 is less than @angle_1 it will decrease,
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* otherwise it will increase).
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**/
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void
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cogl_path_arc (float center_x,
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float center_y,
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float radius_x,
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float radius_y,
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float angle_1,
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float angle_2);
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/**
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* cogl_path_curve_to:
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* @x_1: X coordinate of the second bezier control point
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* @y_1: Y coordinate of the second bezier control point
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* @x_2: X coordinate of the third bezier control point
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* @y_2: Y coordinate of the third bezier control point
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* @x_3: X coordinate of the fourth bezier control point
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* @y_3: Y coordinate of the fourth bezier control point
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*
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* Adds a cubic bezier curve segment to the current path with the given
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* second, third and fourth control points and using current pen location
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* as the first control point.
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**/
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void
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cogl_path_curve_to (float x_1,
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float y_1,
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float x_2,
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float y_2,
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float x_3,
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float y_3);
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/**
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* cogl_path_rel_curve_to:
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* @x_1: X coordinate of the second bezier control point
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* @y_1: Y coordinate of the second bezier control point
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* @x_2: X coordinate of the third bezier control point
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* @y_2: Y coordinate of the third bezier control point
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* @x_3: X coordinate of the fourth bezier control point
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* @y_3: Y coordinate of the fourth bezier control point
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*
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* Adds a cubic bezier curve segment to the current path with the given
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* second, third and fourth control points and using current pen location
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* as the first control point. The given coordinates are relative to the
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* current pen location.
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*/
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void
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cogl_path_rel_curve_to (float x_1,
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float y_1,
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float x_2,
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float y_2,
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float x_3,
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float y_3);
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/**
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* cogl_path_close:
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*
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* Closes the path being constructed by adding a straight line segment
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* to it that ends at the first vertex of the path.
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**/
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void
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cogl_path_close (void);
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/**
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* cogl_path_line:
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* @x_1: X coordinate of the start line vertex
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* @y_1: Y coordinate of the start line vertex
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* @x_2: X coordinate of the end line vertex
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* @y_2: Y coordinate of the end line vertex
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*
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* Constructs a straight line shape starting and ending at the given
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* coordinates. If there is an existing path this will start a new
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* disjoint sub-path.
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**/
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void
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cogl_path_line (float x_1,
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float y_1,
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float x_2,
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float y_2);
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/**
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* cogl_path_polyline:
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* @coords: (in) (array) (transfer none): A pointer to the first element of an
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* array of fixed-point values that specify the vertex coordinates.
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* @num_points: The total number of vertices.
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*
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* Constructs a series of straight line segments, starting from the
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* first given vertex coordinate. If there is an existing path this
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* will start a new disjoint sub-path. Each subsequent segment starts
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* where the previous one ended and ends at the next given vertex
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* coordinate.
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*
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* The coords array must contain 2 * num_points values. The first value
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* represents the X coordinate of the first vertex, the second value
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* represents the Y coordinate of the first vertex, continuing in the same
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* fashion for the rest of the vertices. (num_points - 1) segments will
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* be constructed.
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**/
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void
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cogl_path_polyline (const float *coords,
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int num_points);
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/**
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* cogl_path_polygon:
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* @coords: (in) (array) (transfer none): A pointer to the first element of
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* an array of fixed-point values that specify the vertex coordinates.
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* @num_points: The total number of vertices.
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*
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* Constructs a polygonal shape of the given number of vertices. If
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* there is an existing path this will start a new disjoint sub-path.
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*
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* The coords array must contain 2 * num_points values. The first value
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* represents the X coordinate of the first vertex, the second value
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* represents the Y coordinate of the first vertex, continuing in the same
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* fashion for the rest of the vertices.
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**/
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void
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cogl_path_polygon (const float *coords,
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int num_points);
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/**
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* cogl_path_rectangle:
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* @x_1: X coordinate of the top-left corner.
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* @y_1: Y coordinate of the top-left corner.
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* @x_2: X coordinate of the bottom-right corner.
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* @y_2: Y coordinate of the bottom-right corner.
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*
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* Constructs a rectangular shape at the given coordinates. If there
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* is an existing path this will start a new disjoint sub-path.
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**/
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void
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cogl_path_rectangle (float x_1,
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float y_1,
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float x_2,
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float y_2);
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/**
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* cogl_path_ellipse:
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* @center_x: X coordinate of the ellipse center
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* @center_y: Y coordinate of the ellipse center
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* @radius_x: X radius of the ellipse
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* @radius_y: Y radius of the ellipse
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*
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* Constructs an ellipse shape. If there is an existing path this will
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* start a new disjoint sub-path.
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**/
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void
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cogl_path_ellipse (float center_x,
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float center_y,
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float radius_x,
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float radius_y);
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/**
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* cogl_path_round_rectangle:
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* @x_1: X coordinate of the top-left corner.
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* @y_1: Y coordinate of the top-left corner.
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* @x_2: X coordinate of the bottom-right corner.
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* @y_2: Y coordinate of the bottom-right corner.
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* @radius: Radius of the corner arcs.
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* @arc_step: Angle increment resolution for subdivision of
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* the corner arcs.
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*
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* Constructs a rectangular shape with rounded corners. If there is an
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* existing path this will start a new disjoint sub-path.
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**/
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void
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cogl_path_round_rectangle (float x_1,
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float y_1,
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float x_2,
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float y_2,
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float radius,
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float arc_step);
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/**
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* cogl_get_path:
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*
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* Gets a pointer to the current path. The path can later be used
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* again by calling cogl_path_set(). Note that the path isn't copied
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* so if you later call any functions to add to the path it will
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* affect the returned object too. No reference is taken on the path
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* so if you want to retain it you should take your own reference with
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* cogl_object_ref().
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*
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* Return value: a pointer to the current path.
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*
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* Since: 1.4
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*/
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CoglPath *
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cogl_get_path (void);
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/**
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* cogl_set_path:
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* @path: A #CoglPath object
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*
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* Replaces the current path with @path. A reference is taken on the
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* object so if you no longer need the path you should unref with
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* cogl_object_unref().
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*
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* Since: 1.4
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*/
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void
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cogl_set_path (CoglPath *path);
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/**
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* cogl_path_copy:
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* @path: A #CoglPath object
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*
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* Returns a new copy of the path in @path. The new path has a
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* reference count of 1 so you should unref it with
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* cogl_object_unref() if you no longer need it.
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*
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* Internally the path will share the data until one of the paths is
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* modified so copying paths should be relatively cheap.
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*
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* Return value: a copy of the path in @path.
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*/
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CoglPath *
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cogl_path_copy (CoglPath *path);
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G_END_DECLS
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#endif /* __COGL_PATH_H__ */
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