Compositing layers with cairo_push_group and pop_group_to_source
Render a watermark or shadow into an offscreen Cairo group, then paint it as a single blended layer over your surface.
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cairoUndefined Behavior during pointer arithmetic on stack-allocated arrays
In C (ISO/IEC 9899), pointer arithmetic is permitted within the bounds of an array, including one element past the end. However, dereferencing a pointer that has moved beyond this boundary triggers Undefined Behavior (UB). A specific concern arises when compiler optimizations (such as -O2 or -O3 ) are applied. Because the compiler assumes UB never occurs, it
C static linkage: choosing the export boundary for internal helpers in a shared library
In C, functions and file-scope variables have external linkage by default, so any translation unit can reach them through an extern declaration. Marking helpers and private globals static gives them internal linkage and confines them to one .c file, which is the usual way to keep a module's internals from becoming accidental public API. The boundary breaks d
cUnspecified evaluation order for function arguments in C
C leaves the order in which function arguments and operands of most operators are evaluated unspecified, and it leaves sequencing of side effects to sequence points. This documented unspecified behavior means the same source can be legal yet produce different observable results across implementations and optimization levels. The goal is to characterize the p
Can __STDC_VERSION__ be trusted to guarantee full C standard support?
Goal Determine whether a program can rely on the __STDC_VERSION__ macro to detect that a compiler fully implements a target C standard and safely fall back when an upgrade fails. Constraints and uncertainty The macro expands to an integer encoding the advertised standard version (e.g., 202311L for C23). Compilers may define the macro even when they only part