feat: Adds Progress and Cancel API support#195
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Exposes the progress/cancel feature added to c2pa-rs in PR #1927 (merged to main 2026-03-24, not yet on crates.io). Public API additions (c2pa.hpp): - `c2pa::ProgressCallbackFunc` — std::function alias for the callback. Signature: `bool(C2paProgressPhase phase, uint32_t step, uint32_t total)`. Return false to request cancellation. - `Context::ContextBuilder::with_progress_callback(ProgressCallbackFunc)` Attaches a progress callback to the context being built. Chainable with with_settings(), with_json(), and with_signer(). The heap-allocated std::function is owned by the resulting Context and freed on destruction. - `Context::cancel() noexcept` Requests cancellation of the current in-progress operation. Safe to call from another thread. Implementation (c2pa_context.cpp): - `progress_callback_trampoline` — static C-compatible trampoline that forwards (user_data, phase, step, total) to the stored std::function. - `ContextBuilder::pending_callback_` — unique_ptr holding the heap-allocated callback between with_progress_callback() and create_context(). - `Context::callback_owner_` — void* that takes ownership of the raw pointer on create_context(); deleted in ~Context() and forwarded by move ops. Tests (context.test.cpp): - ProgressCallback_InvokedDuringSigning / _InvokedDuringReading - ProgressCallback_StepAndTotalValues - ProgressCallback_ReturnFalseCancels - ProgressCallback_CancelMethodAbortsOperation - CancelWithoutCallback_IsNoOp - ProgressCallback_ChainWithSettings - ProgressCallback_SurvivesContextMove / _SurvivesBuilderMove Requires: c2pa-rs >= 0.79.0 built from source (C2PA_BUILD_FROM_SOURCE=ON) pointing to a c2pa-rs checkout containing the progress/cancel feature. Made-with: Cursor
Bump c2pa-rs dependency from pre-release 0.78.4 to published 0.78.7; bump project to 0.18.3 Replace C2paProgressPhase (C unscoped enum) with c2pa::ProgressPhase scoped enum class in the public API; add static_asserts to catch any future C/C++ enum divergence at compile time Fix trampoline signature to match published ABI (const void*, int return, enum-typed phase) Update tests and remove stale @note Requires c2pa-rs >= 0.79.0 comments Add progress/cancel section to context-settings.md
tmathern
reviewed
Mar 28, 2026
tmathern
approved these changes
Mar 28, 2026
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Update progress/cancel API to published c2pa-rs 0.78.7
Bump c2pa-rs dependency from pre-release 0.78.4 to published 0.78.7; bump project to 0.18.3
Replace C2paProgressPhase (C unscoped enum) with c2pa::ProgressPhase scoped enum class in the public API; add static_asserts to catch any future C/C++ enum divergence at compile time
Fix trampoline signature to match published ABI (const void*, int return, enum-typed phase)
Update tests and remove stale @note Requires c2pa-rs >= 0.79.0 comments
Add progress/cancel section to context-settings.md