mutter/cogl/cogl-path.h
2010-12-22 09:52:35 +00:00

492 lines
15 KiB
C

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