Arc (`gsp_arc`)

Circular value indicator with an optional draggable range.

When to use

Use it for a value with a clear minimum and maximum.

Local interactive preview

First set up the commands from the compatibility guide, then run from an unpacked component or public repository root with gspc and gsp_sim_host:

arc-preview.sh

mkdir -p gsp-out/widget-preview
gspc pack \
  examples/usage/widgets/arc/arc.json \
  --deployable -o gsp-out/widget-preview/arc.gspb
gsp_sim_host \
  --bundle gsp-out/widget-preview/arc.gspb --frames 0

These commands compile the example and open it in the ESP-GSP simulator browser preview.

Runtime behavior

Clicking or dragging updates the retained value. Application code can update the same value through the generated setter.

start_angle is measured clockwise from the top: right is 90°, bottom 180°, left 270°. sweep is a clockwise span of 1–360°; increasing value from min to max fills in that direction.

If application code must read or update an object, give it a stable name. GSPC then generates the typed functions listed below.

Example scene

arc.json

{"screen":"widget_arc","w":480,"h":320,"screen_bg":"#101827","objects":[{"type":"arc","parent":-1,"name":"level","x":150,"y":55,"w":180,"h":180,"min":0,"max":100,"value":72,"start_angle":135,"sweep":270,"thickness":18,"bg_color":"#334155","fg_color":"#38BDF8"},{"type":"arc","parent":-1,"x":190,"y":95,"w":100,"h":100,"value":38,"start_angle":180,"sweep":180,"thickness":10,"bg_color":"#293548","fg_color":"#A78BFA"}]}

The canonical example is examples/usage/widgets/arc/arc.json. Copy any relative assets referenced by the scene with it.

Generated C API

const gsp_component_directory_t *const * gsp_arc_docs_component_directories(uint16_t *out_count)
esp_err_t gsp_widget_arc_level_get_effective_visible(esp_gsp_handle_t gsp, bool *out_visible)
esp_err_t gsp_widget_arc_level_get_info(esp_gsp_handle_t gsp, esp_gsp_component_info_t *out_info)
esp_err_t gsp_widget_arc_level_get_value(esp_gsp_handle_t gsp, int32_t *out_value)
esp_err_t gsp_widget_arc_level_set_value(esp_gsp_handle_t gsp, int32_t value)
esp_gsp_config_t gsp_arc_docs_config(void)
size_t gsp_arc_docs_dynamic_image_slots(void)

These signatures come from the actual compiler output for this JSON.

Fields in this example

Field	Type	Required	Default / range	Dynamic	Compiler definition
type	string	yes	—	—	widget type
parent	int	yes	default -1; -1…65534	—	parent object index (-1 = screen root)
x	int	yes	default 0; -32768…32767	scene: yes; template: —	x relative to parent
y	int	yes	default 0; -32768…32767	scene: yes; template: —	y relative to parent
w	int	yes	0…65535	scene: —; template: —	width in px
h	int	yes	0…65535	scene: —; template: —	height in px
name	identifier	—	—	—	stable component name; generates GSP_OBJ_KEY_<NAME>
fg_color	color	—	—	—	foreground color (text/knob/line/mark per type)
bg_color	color	—	—	yes	background/fill color (#RRGGBB or #RRGGBBAA)
value	int	—	—	yes	initial value (in min..max units)
min	int	—	default 0; -2147483648…2147483647	—	value range lower bound
max	int	—	default 100; -2147483648…2147483647	—	value range upper bound
start_angle	int	—	default 135; 0…359	scene: yes; template: —	arc start angle clockwise from top (0 top, 90 right)
sweep	int	—	default 270; 1…360	—	clockwise arc span in degrees
thickness	int	—	0…65535	—	stroke thickness; omitted = max(min(w,h)/8, 2); 0 clamps to 1

Show other fields supported by this Widget

Field	Type	Required	Default / range	Dynamic	Compiler definition
min_width	int	—	0…65535	—	compile-time minimum width in px
max_width	int	—	0…65535	—	compile-time maximum width in px
min_height	int	—	0…65535	—	compile-time minimum height in px
max_height	int	—	0…65535	—	compile-time maximum height in px
layout	enum	—	row, column, grid	—	child auto-layout: row/column/grid
layout_wrap	bool	—	default false	—	wrap row/column children into additional lines
grid_columns	int	—	1…65535	—	equal-width column count for grid layout
grid_column_span	int	—	default 1; 1…65535	—	column span in the parent grid layout
gap	int	—	default 0; 0…4096	—	auto-layout gap in px
padding	int	—	default 0; 0…4096	—	auto-layout padding in px
padding_left	int	—	0…4096	—	row layout: leading padding override
padding_right	int	—	0…4096	—	row layout: trailing padding override
padding_top	int	—	0…4096	—	column layout: leading padding override
padding_bottom	int	—	0…4096	—	column layout: trailing padding override
grow	int	—	default 0; 0…100	—	auto-layout grow weight
margin	int	—	default 0; 0…4096	—	auto-layout space on both child sides
margin_left	int	—	0…4096	—	auto-layout leading margin on the x axis
margin_right	int	—	0…4096	—	auto-layout trailing margin on the x axis
margin_top	int	—	0…4096	—	auto-layout leading margin on the y axis
margin_bottom	int	—	0…4096	—	auto-layout trailing margin on the y axis
align_main	enum	—	start, center, end, space_between	—	auto-layout main-axis placement
align_cross	enum	—	start, center, end, stretch	—	auto-layout cross-axis placement
hidden	bool	—	default false	yes	start hidden (show via actions or set_visible)
opacity	int	—	default 255; 0…255	scene: —; template: —	0-255 blend opacity
bg_gradient	color	—	—	—	second gradient stop (with bg_color)
gradient_dir	enum	—	default vertical; vertical, horizontal	—	gradient direction
radius	int	—	default 0; 0…65535	scene: —; template: —	corner radius in px
shadow_color	color	—	—	—	static hard-shadow color
shadow_opacity	int	—	default 96; 0…255	—	static hard-shadow opacity
shadow_offset_x	int	—	-32768…32767	—	static hard-shadow x offset
shadow_offset_y	int	—	-32768…32767	—	static hard-shadow y offset
shadow_spread	int	—	0…4096	—	static hard-shadow spread in px
shadow_radius	int	—	0…65535	—	static hard-shadow corner radius
border_color	color	—	—	—	border stroke color
border_width	int	—	0…65535	—	border stroke width (needs border_color)
border_opacity	int	—	default 255; 0…255	—	border stroke opacity
outline_color	color	—	—	—	outside outline color
outline_width	int	—	default 0; 0…65535	—	outside outline width
outline_opacity	int	—	default 255; 0…255	—	outside outline opacity
outline_pad	int	—	default 0; 0…4096	—	gap between the element and its outline
text_line_space	int	—	default 0; 0…4096	—	extra spacing between static text rows in px
text_vertical_align	enum	—	default auto; auto, top, center, bottom	—	static text block placement; auto preserves single-line center and multiline top
text	string	—	—	yes	static text content (UTF-8)
text_align	enum	—	left, center, right	—	text alignment
overflow	enum	—	default clip; clip, ellipsis	—	single-line overflow
font	path	—	—	—	per-object TTF/OTF override
font_size	int	—	1…255	—	per-object font pixel size
font_charset	string	—	—	—	glyphs available to runtime-bound text; static text is added automatically
font_charset_file	path	—	—	—	UTF-8 character corpus relative to the scene; combined with font_charset and static text
font_link	enum	—	embedded, external, auto	—	font storage policy: embedded/external/auto
input	bool	—	default false	—	text field: attaches the caret/keyboard flow
animation_codec	enum	—	lossless, jpeg, hardware_jpeg	—	animation frame policy: lossless patches, JPEG full frames, or JPEG when the target has hardware decoding
svg_layout	enum	—	content, canvas	—	SVG part placement: cropped content or original canvas
morph_to	path	—	—	—	SVG end shape with matching paths and paints
morph	int	—	0…100	—	SVG shape interpolation progress (percent); generates a runtime setter
svg_element	string	—	—	—	SVG element id; imports its painted bounds as an independent image
tint	color	—	—	—	SVG silhouette color; generates a runtime color setter
image	path	—	—	yes	image file path (raster or compiled SVG)
codec	enum	—	raw, lossless, jpeg, auto, speed, size, store, qoi, rle16, rle16_a8, rle32, default, hardware_jpeg	—	image codec
quality	int	—	1…100	—	JPEG quality 1-100 (omitted = profile default)
jpeg_quality	int	—	1…100	—	legacy JPEG quality alias
compress	bool	—	—	—	image compression toggle (legacy; prefer codec)
cache_policy	enum	—	mmap_direct, mmap, decode_lru, lru, preload	—	image cache policy: mmap_direct, decode_lru or preload
store_scale	number	—	0.05…1.0	—	pre-scale factor applied when encoding
max_fps	int	—	0…120	—	GIF/animation frame-rate cap (0 = uncapped)
fit	enum	—	default stretch; stretch, fill, contain, cover	—	image fit mode
position_x	number	—	default 0.5; 0.0…1.0	—	image fit horizontal alignment
position_y	number	—	default 0.5; 0.0…1.0	—	image fit vertical alignment
rotation	int	—	default 0; -32768…32767	scene: image; template: —	clockwise image rotation around the bounding-box center; source alpha is supported; clipped to the box
scalable	bool	—	default false	—	enable runtime image scaling
scale	number	—	default 1.0; 0.0625…16.0	—	initial runtime image scale
min_scale	number	—	default 0.5; 0.0625…16.0	—	minimum runtime image scale
max_scale	number	—	default 4.0; 0.0625…16.0	—	maximum runtime image scale
vertical	bool	—	default false	—	vertical orientation
enabled	bool	—	—	—	initial interaction state; when present, exposes a runtime enabled property inherited by descendant controls
disabled_color	color	—	default #808080	—	disabled-state overlay color
disabled_opacity	int	—	default 112; 0…255	—	disabled-state overlay opacity
bind	identifier	—	—	—	public state name; generates GSP_BIND_<NAME>
bind_target	enum	—	visible, value, color, text, resource, data	—	explicit bind state family
callback	identifier	—	—	—	app callback name; generates scene-qualified event helpers
events	action_list	—	—	—	input bindings: [{event, action, ...}]
template	identifier	—	—	—	declare this subtree as a render template
max_instances	int	—	1…65535	—	maximum simultaneously live template instances; included in the automatic pool requirement
dynamic_color	bool	—	—	—	template member exposes a per-instance color slot
dynamic_image	bool	—	—	—	template image exposes a per-instance resource slot
interactive	bool	—	default true	—	allow pointer interaction

Show fields shared by every Widget

Field	Type	Required	Default / range	Dynamic	Compiler definition
parent_name	string	—	—	—	parent by name instead of index