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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: (skip)
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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: (skip)
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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: (skip)
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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: (transfer full): 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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