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Kavyansh Tyagi 7ca36d9c50
Merge pull request #27408 from KAVYANSHTYAGI:Umat-vector-contructor 
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
2025-06-09 16:02:38 +03:00
.github Removed Android test as it's broken for now. 2025-02-18 12:52:24 +03:00
3rdparty Merge pull request #27403 from CodeLinaro:apreetam_6thPost 2025-06-06 12:27:13 +03:00
apps Merge pull request #27338 from omahs:patch-1 2025-05-21 12:13:50 +03:00
cmake Try to add FastCV to OpenCV4AndroidSDK 2025-05-24 18:49:11 +03:00
data Merge pull request #22727 from su77ungr:patch-1 2022-11-17 06:54:25 +00:00
doc Merge pull request #27396 from abhishek-gola:hdr_bug_fix 2025-06-05 09:02:58 +03:00
hal Fix remap16s to pass Imgproc_WarpPerspective. 2025-06-08 15:09:37 +08:00
include exclude opencv_contrib modules 2020-02-26 15:12:45 +03:00
modules Merge pull request #27408 from KAVYANSHTYAGI:Umat-vector-contructor 2025-06-09 16:02:38 +03:00
platforms Use older version of IPP for Android x86 32bit to resolve linkage issues. 2025-06-05 13:11:05 +03:00
samples Merge pull request #27396 from abhishek-gola:hdr_bug_fix 2025-06-05 09:02:58 +03:00
.editorconfig add .editorconfig 2018-10-11 17:57:51 +00:00
.gitattributes cmake: generate and install ffmpeg-download.ps1 2018-06-09 13:19:48 +03:00
.gitignore Merge pull request #17165 from komakai:objc-binding 2020-06-08 18:32:53 +00:00
CMakeLists.txt Merge pull request #27301 from fengyuentau:4x/hal/riscv_rvv/refactor_build 2025-05-14 14:04:58 +03:00
CONTRIBUTING.md migration: github.com/opencv/opencv 2016-07-12 12:51:12 +03:00
COPYRIGHT copyright: 2023 (update) 2023-01-09 09:49:22 +00:00
LICENSE Merge pull request #18073 from vpisarev:apache2_license 2020-08-17 11:49:11 +00:00
README.md Space mistake in README.md 2024-03-03 23:37:07 +05:30
SECURITY.md Updated PGP key for security reports 2023-04-19 19:16:55 +03:00

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OpenCV: Open Source Computer Vision Library

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