Stroke operations

This part of the API performs stroke operations. (from March 2022)

Stroke enumerations

This section gives details on stroke enumerations.

vg_lite_cap_style_t enumeration

Defines the style of cap at the end of a stroke (from March 2022).

Used in structure: vg_lite_stroke_t.

Used in function: vg_lite_set_stroke.

vg_lite_cap_style_t values	Description
VG_LITE_CAP_BUTT	The butt end cap style terminates each segment with a line perpendicular to the tangent at each endpoint.
VG_LITE_CAP_ROUND	The round end cap style appends a semicircle with a diameter equal to the line width centered around each endpoint.
VG_LITE_CAP_SQUARE	The square end cap style appends a rectangle with two sides of length equal to the line width perpendicular to the tangent, and two sides of length equal to half the line width parallel to the tangent, at each endpoint.

Parent topic:Stroke enumerations

vg_lite_path_type_t enumeration

Defines the type of draw path (from March 2022).

Used in structure: vg_lite_path_t, vg_lite_stroke_t.

Used in function: vg_lite_set_path_type.

vg_lite_path_type_t string values	Description
VG_LITE_DRAW_FILL_PATH	Draw path is fill.
VG_LITE_DRAW_STROKE_PATH	Draw path is stroke.
VG_LITE_DRAW_FILL_STROKE_PATH	Draw path is both fill and stroke.

Parent topic:Stroke enumerations

vg_lite_join_style_t enumeration

Defines the type of styles available for line joints. (from March 2022)

Used in structure: vg_lite_stroke_t.

Used in function: vg_lite_set_stroke.

vg_lite_join_style_t string values	Description
VG_LITE_JOIN_MITER	The miter join style appends a trapezoid with one vertex at the intersection point of the two original lines, two adjacent vertices at the outer endpoints of the two “thickened” lines and a fourth vertex at the extrapolated intersection point of the outer perimeters of the two “thickened” lines.
VG_LITE_JOIN_ROUND	The round join style appends a wedge-shaped portion of a circle, centered at the intersection point of the two original lines, having a radius equal to half the line width.
VG_LITE_JOIN_BEVEL	The bevel type join style appends a triangle with two vertices at the outer endpoints of the two “thickened” lines and a third vertex at the intersection point of the two original lines.

Parent topic:Stroke enumerations

Parent topic:Stroke operations

Stroke structures

This section gives details on stroke structures.

vg_lite_path_t structure

Defined under Vector Path Structures - vg_lite_path_t structure.

(additional members added for stroke from March 2022)

Parent topic:Stroke structures

vg_lite_path_list_t structure

The structure vg_lite_path_list_ptr points to the vg_lite_path_list structure that provides divided path data according to MOVE/MOVE_REL. (from Aug 2023)

Used (vg_lite_path_list_ptr) in structures: vg_lite_stroke_t.

vg_lite_path_list_t members	Type	Description
path_points	vg_lite_path_point_ptr
path_end	vg_lite_path_point_ptr
point_count	vg_lite_uint32_t
next	vg_lite_path_list_ptr
closed	vg_lite_uint8_t

Parent topic:Stroke structures

vg_lite_path_point_t structure

The structure vg_lite_path_point_ptr points to the vg_lite_path_point structure which provides path detail (from March 2022)

Used (vg_lite_path_point_ptr) in structures: vg_lite_path_point_t, vg_lite_stroke_conversion. vg_lite_sub_path_t.

vg_lite_path_point_t members	Type	Description
x	vg_lite_float_t	X coordinate
y	vg_lite_float_t	Y coordinate
flatten_flag	vg_lite_uint8_t	Flatten flag for flattened path
curve_type	vg_lite_uint8_t	Curve type for the stroke path
tangentX	vg_lite_float_t	X tangent (Note: #define centerX tangent)
tangentY	vg_lite_float_t	Y tangent (Note: #define centerX tangent)
length	vg_lite_float_t	Line length
prev	vg_lite_path_point_ptr	Pointer to the previous point node

Parent topic:Stroke structures

vg_lite_stroke_t structure

The structure provides stroke parameters and pointers to temp storage for a stroke sub path. Refer to the function vg_lite_set_stroke parameter descriptions for additional description for some members. (from March 2022)

Used in structure: vg_lite_path_t.

vg_lite_stroke_t members	Type	Description
cap_style	vg_lite_cap_style_t	Stroke cap style
join_style	vg_lite_join_style_t	Stroke joint style
line_width	vg_lite_float_t	Stroke line width
miter_limit	vg_lite_float_t	Stroke miter limit
*dash_pattern	vg_lite_float_t	Pointer to stroke dash pattern
pattern_count	vg_lite_uint32_t	Number of dash pattern repetitions
dash_phase	vg_lite_float_t	Stroke dash phrase
dash_length	vg_lite_float_t	Stroke dash initial length
dash_index	vg_lite_uint32_t	Stroke dash initial index
half_width	vg_lite_float_t	Half line width
pattern_length	vg_lite_float_t	Total length of stroke dash patterns.
miter_square	vg_lite_float_t	For fast checking
path_points	vg_lite_path_point_ptr	Temp storage for stroke sub path
path_end	vg_lite_path_point_ptr	Temp storage for stroke sub path
point_count	unint32_t	Temp storage for stroke sub path
left_point	vg_lite_path_point_ptr	Temp storage for stroke sub path
right_pont	vg_lite_path_point_ptr	Temp storage for stroke sub path
stroke_points	vg_lite_path_point_ptr	Temp storage for stroke sub path
stroke_end	vg_lite_path_point_ptr	Temp storage for stroke sub path
stroke_count	vg_lite_uint32_t	Temp storage for stroke sub path
path_list_divide	vg_lite_path_list_ptr	Divide stroke path according to move or move_rel for avoiding implicit closure. (from Aug 2023)
cur_list	vg_lite_path_list_ptr	Pointer to current divided path data. (from Aug 2023)
add_end	vg_lite_uint8_t	Flag that adds end_path in driver (from Aug 2023)
dash_reset	vg_lite_uint8_t	(from Aug 2023)
stroke_paths	vg_lite_sub_path_ptr
last_stroke	vg_lite_sub_path_ptr
swing_handling	vg_lite_uint32_t
swing_deltax	vg_lite_float_t
swing_deltay	vg_lite_float_t
swing_start	vg_lite_path_point_ptr
swing_stroke	vg_lite_path_point_ptr
swing_length	vg_lite_float_t
swing_centlen	vg_lite_float_t
swing_count	vg_lite_uint32_t
need_swing	vg_lite_uint8_t
swing_ccw	vg_lite_uint8_t
stroke_length	vg_lite_float_t
stroke_size	vg_lite_uint32_t
fattened	vg_lite_uint8_t	The stroke line is a fat line.
closed	vg_lite_uint8_t

Parent topic:Stroke structures

vg_lite_sub_path_t structure

The structure vg_lite_sub_path_ptr points to the vg_lite_sub_path structure that provides sub path detail and a pointer to the next sub path. (from March 2022)

Used in structure: vg_lite_stroke_conversion.

vg_lite_path_point_t members	Type	Description
next	vg_lite_sub_path_ptr	Pointer to the next sub path
point_count	vg_lite_uint32_t	Number of points in the sub path
point_list	vg_lite_path_point_ptr	Pointer to the point list.
end_point	vg_lite_path_point_ptr	Pointer to the last point.
closed	vg_lite_uint8_t	Indicates whether or not the path is closed.
length	vg_lite_float_t	Length of the sub path.

Parent topic:Stroke structures

Parent topic:Stroke operations

Stroke functions

All return vg_lite_error_t status.

vg_lite_set_path_type function

Description:

This function sets the path type*. (from March 2022)*

Syntax:

vg_lite_error_t vg_lite_set_path_type (
    vg_lite_path_t              *path,
    vg_lite_path_type_t         path_type
);  

Parameters:

Parameter	Description
*path	Pointer to the vg_lite_path_t structure that describes the vector path.
path_type	Pointer to a vg_lite_path_type_t structure that describes the path type.

Returns:

Returns VG_LITE_SUCCESS if successful. See vg_lite_error_t enum for other return codes.

Parent topic:Stroke functions

vg_lite_set_stroke function

Description:

This function uses input parameters to set stroke attributes (from March 2022).

Syntax:

vg_lite_error_t vg_lite_set_stroke (
    vg_lite_path_t              *path,
    vg_lite_cap_style_t         cap_style,
    vg_lite_join_style_t        join_style,
    vg_lite_float_t             line_width,
    vg_lite_float_t             miter_limit,
    vg_lite_float_t             *dash_pattern,
    vg_lite_uint32_t            pattern_count,
    vg_lite_float_t             dash_phase,
    vg_lite_color_t             color
);  

Parameters:

Parameter	Description
*path	Pointer to the vg_lite_path_t structure that describes the path.
cap_style	The end cap style is defined by the vg_lite_cap_style_t enum.
join_style	The line join style defined by the vg_lite_join_style_t enum.
line_width	The line width of the stroke path. A line width less than or equal to 0 prevents stroking from taking place.
miter_limit	When stroking using the Miter stroke vg_lite_join_style_t, the miter length (that is, the length between the intersection points of the inner and outer perimeters of the two “fattened” lines) is compared to the product of the user-set miter limit and the line width. If the miter length exceeds this product, the Miter join is not drawn and a Bevel join is substituted. Note: Miter limit values less than 1 are silently clamped to 1.
*dash_pattern	Pointer to a dash pattern that consists of a sequence of lengths of alternating “on” and “off” dash segments. The first value of the dash array defines the length, in user coordinates, of the first “on” dash segment. The second value defines the length of the following “off” segment. Each subsequent pair of values defines one “on” and one “off” segment. Note: If the dash pattern has an odd number of elements, the final element is ignored.
pattern_count	The count of dash on/off segments.
dash_phase	Defines the starting point in the dash pattern that is associated with the start of the first segment of the path. For example, if the dash pattern is [10 20 30 40] and the dash phase is 35, the path is stroked with an “on” segment of length 25 (skipping the first “on” segment of length 10, the following “off” segment of length 20, and the first 5 units of the next “on” segment), followed by an “off” segment of length 40. The pattern is then repeated from the beginning, with an “on” segment of length 10, an “off” segment of length 20, an “on” segment of length 30.
color	The stroke color.

Returns:

Returns VG_LITE_SUCCESS if successful. See vg_lite_error_t enum for other return codes.

Parent topic:Stroke functions

vg_lite_update_stroke function

Description:

This function uses the path and stroke attributes as specified with the function vg_lite_set_stroke to update the stroke path’s parameters and generate stroke path data . (from March 2022)

Syntax:

vg_lite_error_t vg_lite_update_stroke (
    vg_lite_path_t              *path,
);  

Parameters:

Parameter	Description
*path	Pointer to the vg_lite_path_t structure that describes the path.

Returns:

Returns VG_LITE_SUCCESS if successful. See vg_lite_error_t enum for other return codes.

Parent topic:Stroke functions

Parent topic:Stroke operations