Text measurement and layout helpers for mode UIs. More...

Functions
void	format_uint (uint32_t v, char *out, uint8_t out_size)
	Overwrite out with the decimal digits of v, NUL-terminated.
void	format_int (int32_t v, char *out, uint8_t out_size, bool force_plus=false)
	Overwrite out with the signed decimal of v, NUL-terminated.
void	append_uint (char *buf, uint8_t buf_size, uint32_t v)
	Append the decimal digits of v at the existing NUL of buf.
void	append_int (char *buf, uint8_t buf_size, int32_t v, bool force_plus=false)
	Append the signed decimal of v at the existing NUL of buf.
void	format_str (const char s, char out, uint8_t out_size)
	Overwrite out with a bounded copy of s (freestanding strlcpy).
void	append_str (char buf, uint8_t buf_size, const char s)
	Append a bounded copy of s at the existing NUL of buf (freestanding strcat).
void	append_enum (char buf, uint8_t buf_size, uint32_t idx, const char const labels, uint32_t count, const char fallback="?")
	Append labels[idx] at the existing NUL of buf, bounds-checked.
void	append_fixed (char *buf, uint8_t buf_size, int32_t value, uint8_t decimals)
	Append value as a fixed-point decimal with decimals fractional digits at the existing NUL of buf.
uint16_t	strlen_chars (const char *s)
	Count the characters in a NUL-terminated string.
uint16_t	text_width (const char *s)
	Pixel width of a string rendered in the standard 5x7 font.
uint16_t	large_text_width (const char *s)
	Pixel width of a string rendered in the large 8x12 font.
uint16_t	align_center_x (const char *s, uint16_t total_w)
	X-offset that horizontally centers a standard-font string inside a box.
uint16_t	large_align_center_x (const char *s, uint16_t total_w)
	X-offset that horizontally centers a large-font string inside a box.
void	truncate_with_ellipsis (const char s, uint16_t max_chars, char out, uint16_t out_size)
	Copy s into out, appending "..." when it exceeds max_chars.
uint8_t	word_wrap (const char s, uint16_t width_px, const char *line_starts, uint8_t max_lines)
	Greedy word-wrap a NUL-terminated string into lines no wider than width_px pixels (standard font).

Variables
constexpr uint8_t	kFontStdAdvance = 6
	Horizontal advance (pixels) of one standard-font glyph.
constexpr uint8_t	kFontStdSpaceAdvance = 4
	Horizontal advance (pixels) of the standard-font space glyph.
constexpr uint8_t	kFontStdHeight = 8
	Line height (pixels) of the standard font.
constexpr uint8_t	kFontLargeAdvance = 8
	Horizontal advance (pixels) of one large-font glyph.
constexpr uint8_t	kFontLargeSpaceAdvance = 6
	Horizontal advance (pixels) of the large-font space glyph.
constexpr uint8_t	kFontLargeHeight = 13
	Line height (pixels) of the large font.

Detailed Description

Text measurement and layout helpers for mode UIs.

Function Documentation

◆ align_center_x()

uint16_t op::sdk::text::align_center_x	(	const char *	s,
		uint16_t	total_w )

inline

X-offset that horizontally centers a standard-font string inside a box.

Parameters

s	Text to measure.
total_w	Width of the containing box in pixels.

Returns: Offset; 0 if the text is wider than the box.

◆ append_enum()

void op::sdk::text::append_enum	(	char *	buf,
		uint8_t	buf_size,
		uint32_t	idx,
		const char const	labels,
		uint32_t	count,
		const char *	fallback = "?" )

inline

Append labels[idx] at the existing NUL of buf, bounds-checked.

Parameters

buf	NUL-terminated buffer to extend in place. Non-null.
buf_size	Total capacity of buf in bytes. The appended label truncates to fit; buf stays NUL-terminated.
idx	Index into labels. If idx >= count the fallback string is appended instead (no out-of-range read).
labels	Caller-owned label table (count entries). This helper only indexes it safely. The mode owns the storage.
count	Number of entries in labels.
fallback	Appended when idx is out of range (default "?").

Composes e.g. char b[24] = "Rate: "; append_enum(b, sizeof b, r, kRateLabels, kRateCount); -> "Rate: 1/4". Implemented via append_str. Freestanding: no libc, no double.

◆ append_fixed()

void op::sdk::text::append_fixed	(	char *	buf,
		uint8_t	buf_size,
		int32_t	value,
		uint8_t	decimals )

inline

Append value as a fixed-point decimal with decimals fractional digits at the existing NUL of buf.

Parameters

buf	NUL-terminated buffer to extend in place. Non-null.
buf_size	Total capacity of buf in bytes. truncates to fit; buf stays NUL-terminated.
value	Integer carrying decimals fractional digits, the same fixed-point convention as a Numeric param's decimal_places.
decimals	Number of fractional digits. 0 appends a plain integer.

Composes e.g. append_fixed(buf, size, 1250, 2) -> "12.50" and append_fixed(buf, size, -5, 2) -> "-0.05". Freestanding: no libc, no double, 32-bit division only.

◆ append_int()

void op::sdk::text::append_int	(	char *	buf,
		uint8_t	buf_size,
		int32_t	v,
		bool	force_plus = false )

inline

Append the signed decimal of v at the existing NUL of buf.

Parameters

buf	NUL-terminated buffer to extend in place. Non-null.
buf_size	Total capacity in bytes. Appended text truncates to fit; buf stays NUL-terminated.
v	Value to append (INT32_MIN .. INT32_MAX); INT32_MIN-safe.
force_plus	When true, non-negative v appends a leading '+'.

Freestanding: no libc, no double, 32-bit division only.

◆ append_str()

void op::sdk::text::append_str	(	char *	buf,
		uint8_t	buf_size,
		const char *	s )

inline

Append a bounded copy of s at the existing NUL of buf (freestanding strcat).

Parameters

buf	NUL-terminated buffer to extend in place (compose "Label: " + value without a libc strcat). Non-null.
buf_size	Total capacity of buf in bytes. The appended text truncates to fit the remaining space; buf stays NUL-terminated.
s	Source string to append (nullptr is treated as the empty string).

Freestanding: no libc, no double.

◆ append_uint()

void op::sdk::text::append_uint	(	char *	buf,
		uint8_t	buf_size,
		uint32_t	v )

inline

Append the decimal digits of v at the existing NUL of buf.

Parameters

buf	NUL-terminated buffer to extend in place (compose "Label: " + number without a libc strcat). Non-null.
buf_size	Total capacity of buf in bytes. The appended digits truncate to fit the remaining space; buf stays NUL-terminated.
v	Value to append (0 .. 4294967295).

Freestanding: no libc, no double, 32-bit division only.

◆ format_int()

void op::sdk::text::format_int	(	int32_t	v,
		char *	out,
		uint8_t	out_size,
		bool	force_plus = false )

inline

Overwrite out with the signed decimal of v, NUL-terminated.

Parameters

v	Value to format (INT32_MIN .. INT32_MAX). INT32_MIN is handled correctly (magnitude taken via negation of an int64 temporary, then narrowed, no 64-bit divide).
out	Destination buffer, overwritten and NUL-terminated. Non-null, out_size >= 1.
out_size	Capacity in bytes. Result truncates to fit. Size for the widest output: 12 bytes holds "-2147483648" + NUL (or "+2147483647" with force_plus).
force_plus	When true, non-negative values get a leading '+' (+5 / -3). When false, non-negative values are bare (5 / -3). Negative values always get '-'.

Freestanding: no libc, no double, 32-bit division only.

◆ format_str()

void op::sdk::text::format_str	(	const char *	s,
		char *	out,
		uint8_t	out_size )

inline

Overwrite out with a bounded copy of s (freestanding strlcpy).

Parameters

s	Source string (nullptr is treated as the empty string "").
out	Destination buffer; out[0] is overwritten, NUL-terminated on return. Non-null with out_size >= 1.
out_size	Capacity of out in bytes. The copy truncates to fit (out_size - 1 characters max) and out is always NUL-terminated.

Freestanding: no libc, no double. Use for the runtime-string overwrite primitive (filenames, resolved labels).

◆ format_uint()

void op::sdk::text::format_uint	(	uint32_t	v,
		char *	out,
		uint8_t	out_size )

inline

Overwrite out with the decimal digits of v, NUL-terminated.

Parameters

v	Value to format (0 .. 4294967295).
out	Destination buffer. out[0] is overwritten, NUL-terminated on return. Must be non-null with out_size >= 1.
out_size	Capacity of out in bytes. The result is truncated to fit (the least-significant digits are dropped if the buffer is too small), so size out for the widest value: 11 bytes holds any uint32 ("4294967295" + NUL).

Freestanding: no libc, no double, 32-bit division only. v == 0 yields "0".

◆ large_align_center_x()

uint16_t op::sdk::text::large_align_center_x	(	const char *	s,
		uint16_t	total_w )

inline

X-offset that horizontally centers a large-font string inside a box.

Parameters

s	Text to measure.
total_w	Width of the containing box in pixels.

Returns: Offset; 0 if the text is wider than the box.

◆ large_text_width()

uint16_t op::sdk::text::large_text_width ( const char * s )

inline

Pixel width of a string rendered in the large 8x12 font.

Parameters

s	NUL-terminated string (nullptr is treated as empty).

Returns: Sum of per-glyph advances (space counts as kFontLargeSpaceAdvance, every other glyph as kFontLargeAdvance), matching the firmware renderer. A flat strlen*advance over-measures strings with spaces.

◆ strlen_chars()

uint16_t op::sdk::text::strlen_chars ( const char * s )

inline

Count the characters in a NUL-terminated string.

Parameters

s	NUL-terminated string (may be nullptr, in which case 0 is returned).

Returns: Number of bytes preceding the terminator.

◆ text_width()

uint16_t op::sdk::text::text_width ( const char * s )

inline

Pixel width of a string rendered in the standard 5x7 font.

Parameters

s	NUL-terminated string (nullptr is treated as empty).

Returns: Sum of per-glyph advances (space counts as kFontStdSpaceAdvance, every other glyph as kFontStdAdvance), matching the firmware renderer so callers (centering, underlines, right-anchoring) align with the actual pixels. A flat strlen*advance over-measures any string containing spaces.

◆ truncate_with_ellipsis()

void op::sdk::text::truncate_with_ellipsis	(	const char *	s,
		uint16_t	max_chars,
		char *	out,
		uint16_t	out_size )

inline

Copy s into out, appending "..." when it exceeds max_chars.

Parameters

s	Source string (nullptr treated as empty).
max_chars	Maximum number of visible characters (including the ellipsis). Values below 4 behave like a plain truncate (no ellipsis).
out	Destination buffer; NUL-terminated on return.
out_size	Size of out in bytes (must be >= 1).

◆ word_wrap()

uint8_t op::sdk::text::word_wrap	(	const char *	s,
		uint16_t	width_px,
		const char **	line_starts,
		uint8_t	max_lines )

inline

Greedy word-wrap a NUL-terminated string into lines no wider than width_px pixels (standard font).

Parameters

s	Source string.
width_px	Maximum pixel width of a single line.
line_starts	Output array. Entry i points to the first character of line i inside the original buffer.
max_lines	Capacity of line_starts.

Returns: Number of lines populated (<= max_lines).

Note: the input string is not modified, so callers treat line_starts[i] as the start of a line whose length extends until the next line's start or end-of-string (space trimmed on line breaks). For destructive wrapping use your own routine. This implementation keeps the helper allocation-free.

Variable Documentation

◆ kFontLargeSpaceAdvance

uint8_t op::sdk::text::kFontLargeSpaceAdvance = 6

inlineconstexpr

Horizontal advance (pixels) of the large-font space glyph.

Space renders narrower (6px advance), matching the device's large-font renderer.

◆ kFontStdSpaceAdvance

uint8_t op::sdk::text::kFontStdSpaceAdvance = 4

inlineconstexpr

Horizontal advance (pixels) of the standard-font space glyph.

Space renders narrower than other glyphs (4px advance), matching the device's standard-font renderer.

Functions

Variables

Detailed Description

Function Documentation

◆ align_center_x()

◆ append_enum()

◆ append_fixed()

◆ append_int()

◆ append_str()

◆ append_uint()

◆ format_int()

◆ format_str()

◆ format_uint()

◆ large_align_center_x()

◆ large_text_width()

◆ strlen_chars()

◆ text_width()

◆ truncate_with_ellipsis()

◆ word_wrap()

Variable Documentation

◆ kFontLargeSpaceAdvance

◆ kFontStdSpaceAdvance