Force empty output type where it's defined in API #27972
The PR replaces:
- https://github.com/opencv/opencv/pull/27936
- https://github.com/opencv/opencv/pull/21059
Empty matrix has undefined type, so user code should not relay on the output type, if it's empty. The PR introduces some exceptions:
- copyTo documentation defines, that the method re-create output buffer and set it's type.
- convertTo has output type as parameter and output type is defined and expected.
Deprecate copyData Parameter in UMat Construction from std::vector and Always Copy Data #27408
Overview
This PR simplifies and modernizes the construction of cv::UMat from std::vector by removing the legacy copyData parameter, always copying the data, and ensuring clearer, safer semantics. This brings UMat in line with current best practices and paves the way for the upcoming OpenCV 5.x series.
What Changed?
1. Header Documentation Update
Removed confusing or obsolete documentation about copyData and clarified the behavior:
Old: builds matrix from std::vector with or without copying the data
New: builds matrix from std::vector. The data is always copied. The copyData parameter is deprecated and will be removed in OpenCV 5.0.
2. Implementation Update
In UMat::UMat(const std::vector<_Tp>& vec, bool copyData), the copyData parameter:
Is now ignored and marked as deprecated.
Marked with CV_UNUSED(copyData) for backward compatibility and to avoid warnings.
The constructor always copies the data from the input vector, regardless of the value of copyData.
All branching logic around copyData has been removed. Any code for "not copying" was not implemented and is now dropped.
This guarantees data safety and predictable behavior.
3. Test Added
A new test construct_from_vector in test_umat_from_vector.cpp:
Verifies that UMat copies the vector data, not referencing it.
Modifies the source vector after construction to confirm that the UMat is unaffected (proving copy, not reference).
Checks matrix shape, type, and content to ensure correctness.
Why This Change?
1. Safety and Predictability
Always copying avoids dangling references and hard-to-debug lifetime issues with stack/heap-allocated vectors.
Removes an undocumented, unimplemented branch (copyData=false).
2. Backward Compatibility
The constructor signature remains for now, but the copyData parameter is marked as deprecated and ignored.
Codebases that pass the parameter will still compile and run as before (but always copy).
3. API Clarity and Maintenance
Documentation now matches the real implementation.
No misleading expectations about zero-copy.
Code is cleaner, future-proof, and easier to maintain.
4. Preparation for OpenCV 5.0
The copyData parameter is deprecated and will be removed in OpenCV 5.x.
Prepares users and downstream libraries for the planned change.
How This Helps OpenCV Users and Developers
Guarantees data safety and makes behavior explicit.
Removes legacy/ambiguous code.
Provides a clear path to OpenCV 5.x.
Minimizes future migration pain.
Ensures all users see the same, reliable behavior (copy semantics).
Refer:#27409
C-API cleanup: apps, imgproc_c and some constants #25075
Merge with https://github.com/opencv/opencv_contrib/pull/3642
* Removed obsolete apps - traincascade and createsamples (please use older OpenCV versions if you need them). These apps relied heavily on C-API
* removed all mentions of imgproc C-API headers (imgproc_c.h, types_c.h) - they were empty, included core C-API headers
* replaced usage of several C constants with C++ ones (error codes, norm modes, RNG modes, PCA modes, ...) - most part of this PR (split into two parts - all modules and calib+3d - for easier backporting)
* removed imgproc C-API headers (as separate commit, so that other changes could be backported to 4.x)
Most of these changes can be backported to 4.x.
* attempt to add 0d/1d mat support to OpenCV
* revised the patch; now 1D mat is treated as 1xN 2D mat rather than Nx1.
* a step towards 'green' tests
* another little step towards 'green' tests
* calib test failures seem to be fixed now
* more fixes _core & _dnn
* another step towards green ci; even 0D mat's (a.k.a. scalars) are now partly supported!
* * fixed strange bug in aruco/charuco detector, not sure why it did not work
* also fixed a few remaining failures (hopefully) in dnn & core
* disabled failing GAPI tests - too complex to dig into this compiler pipeline
* hopefully fixed java tests
* trying to fix some more tests
* quick followup fix
* continue to fix test failures and warnings
* quick followup fix
* trying to fix some more tests
* partly fixed support for 0D/scalar UMat's
* use updated parseReduce() from upstream
* trying to fix the remaining test failures
* fixed [ch]aruco tests in Python
* still trying to fix tests
* revert "fix" in dnn's CUDA tensor
* trying to fix dnn+CUDA test failures
* fixed 1D umat creation
* hopefully fixed remaining cuda test failures
* removed training whitespaces
- OpenCL kernel cleanup processing is asynchronous and can be called even after forced clFinish()
- buffers are released later in asynchronous mode
- silence these false positive cases for asynchronous cleanup
- removed tr1 usage (dropped in C++17)
- moved includes of vector/map/iostream/limits into ts.hpp
- require opencv_test + anonymous namespace (added compile check)
- fixed norm() usage (must be from cvtest::norm for checks) and other conflict functions
- added missing license headers
Alexander Smorkalov
Alexander Smorkalov
Kavyansh Tyagi
Maksim Shabunin
Vadim Pisarevsky
Suleyman TURKMEN
Dale Phurrough
Alexander Alekhin
clunietp
luz.paz
Dmitry Kurtaev
Vladislav Sovrasov
Alexander Alekhin
Alexander Alekhin
Maksim Shabunin
Andrey Pavlenko
Vitaliy Lyudvichenko
Vladimir Dudnik
Alexander Karsakov
Ilya Lavrenov