From 703f0bb0f2bc64abd24a26a05971751f43ede0ff Mon Sep 17 00:00:00 2001
From: Alexander Smorkalov <2536374+asmorkalov@users.noreply.github.com>
Date: Thu, 16 Oct 2025 12:06:35 +0300
Subject: [PATCH] Merge pull request #27906 from asmorkalov:as/cairosvg

Use cairosvg for pattern rendering to get rid of double resize. #27906

Depends on https://github.com/opencv/ci-gha-workflow/pull/269

### Pull Request Readiness Checklist

See details at https://github.com/opencv/opencv/wiki/How_to_contribute#making-a-good-pull-request

- [x] I agree to contribute to the project under Apache 2 License.
- [x] To the best of my knowledge, the proposed patch is not based on a code under GPL or another license that is incompatible with OpenCV
- [ ] The PR is proposed to the proper branch
- [ ] There is a reference to the original bug report and related work
- [ ] There is accuracy test, performance test and test data in opencv_extra repository, if applicable
      Patch to opencv_extra has the same branch name.
- [ ] The feature is well documented and sample code can be built with the project CMake
---
 apps/pattern-tools/test_charuco_board.py | 16 ++++++----------
 1 file changed, 6 insertions(+), 10 deletions(-)

diff --git a/apps/pattern-tools/test_charuco_board.py b/apps/pattern-tools/test_charuco_board.py
index 7d5602705b..e92a38a216 100644
--- a/apps/pattern-tools/test_charuco_board.py
+++ b/apps/pattern-tools/test_charuco_board.py
@@ -11,10 +11,9 @@ class aruco_objdetect_test(NewOpenCVTests):
 
     def test_aruco_dicts(self):
         try:
-            from svglib.svglib import svg2rlg
-            from reportlab.graphics import renderPM
+            import cairosvg
         except:
-            raise self.skipTest("libraies svglib and reportlab not found")
+            raise self.skipTest("cairosvg library was not found")
         else:
             cols = 3
             rows = 5
@@ -49,8 +48,7 @@ class aruco_objdetect_test(NewOpenCVTests):
                                 os.path.join(basedir, aruco_type_str[aruco_type_i]+'.json.gz'), 0)
                     pm.make_charuco_board()
                     pm.save()
-                    drawing = svg2rlg(filesvg)
-                    renderPM.drawToFile(drawing, filepng, fmt='PNG', dpi=72)
+                    cairosvg.svg2png(url=filesvg, write_to=filepng, background_color="white")
                     from_svg_img = cv.imread(filepng)
                     _charucoCorners, _charuco_ids_svg, marker_corners_svg, marker_ids_svg = charuco_detector.detectBoard(from_svg_img)
                     _charucoCorners, _charuco_ids_cv, marker_corners_cv, marker_ids_cv = charuco_detector.detectBoard(from_cv_img)
@@ -72,10 +70,9 @@ class aruco_objdetect_test(NewOpenCVTests):
 
     def test_aruco_marker_sizes(self):
         try:
-            from svglib.svglib import svg2rlg
-            from reportlab.graphics import renderPM
+            import cairosvg
         except:
-            raise self.skipTest("libraies svglib and reportlab not found")
+            raise self.skipTest("cairosvg library was not found")
         else:
             cols = 3
             rows = 5
@@ -106,8 +103,7 @@ class aruco_objdetect_test(NewOpenCVTests):
                                 board_height, "charuco_checkboard", marker_size, os.path.join(basedir, aruco_type_str+'.json.gz'), 0)
                     pm.make_charuco_board()
                     pm.save()
-                    drawing = svg2rlg(filesvg)
-                    renderPM.drawToFile(drawing, filepng, fmt='PNG', dpi=72)
+                    cairosvg.svg2png(url=filesvg, write_to=filepng, background_color="white")
                     from_svg_img = cv.imread(filepng)
 
                     #test