Merge branch 4.x

doc/js_tutorials/js_assets/js_image_arithmetics_bitwise.html

@@ -82,7 +82,7 @@ cv.bitwise_and(logo, logo, imgFg, mask);
 // Put logo in ROI and modify the main image
 cv.add(imgBg, imgFg, sum);
 
-dst = src.mat_clone();
+dst = src.clone();
 for (let i = 0; i < logo.rows; i++) {
     for (let j = 0; j < logo.cols; j++) {
         dst.ucharPtr(i, j)[0] = sum.ucharPtr(i, j)[0];

doc/js_tutorials/js_assets/js_imgproc_camera.html

@@ -248,7 +248,7 @@ function backprojection(src) {
         if (base instanceof cv.Mat) {
             base.delete();
         }
-        base = src.mat_clone();
+        base = src.clone();
         cv.cvtColor(base, base, cv.COLOR_RGB2HSV, 0);
     }
     cv.cvtColor(src, dstC3, cv.COLOR_RGB2HSV, 0);

doc/js_tutorials/js_assets/js_intelligent_scissors.html

@@ -53,7 +53,7 @@ canvas.addEventListener('click', e => {
 });
 canvas.addEventListener('mousemove', e => {
     let x = e.offsetX, y = e.offsetY; //console.log(x, y);
-    let dst = src.mat_clone();
+    let dst = src.clone();
     if (hasMap && x >= 0 && x < src.cols && y >= 0 && y < src.rows)
     {
         let contour = new cv.Mat();

doc/js_tutorials/js_core/js_basic_ops/js_basic_ops.markdown

@@ -77,14 +77,12 @@ How to copy Mat
 There are 2 ways to copy a Mat:
 
 @code{.js}
-// 1. Clone (deep copy)
-let dst = src.mat_clone();
+// 1. Clone
+let dst = src.clone();
 // 2. CopyTo(only entries indicated in the mask are copied)
 src.copyTo(dst, mask);
 @endcode
 
-@note In OpenCV.js, use `mat_clone()` instead of `clone()` to ensure deep copy behavior. The `clone()` method may perform shallow copy due to Emscripten embind limitations.
-
 How to convert the type of Mat
 ------------------------------
 

doc/js_tutorials/js_setup/js_setup/js_setup.markdown

@@ -84,7 +84,12 @@ Building OpenCV.js from Source
     @endcode
 
     @note
-    It requires `python` and `cmake` installed in your development environment.
+    - It requires `python` and `cmake` installed in your development environment.
+    - To build with Emscripten 4.0.20 or later, append --cmake_option="-DCMAKE_CXX_STANDARD=17" .
+      Embind requires C++17 or later since Emscripten 4.0.20.
+      @code{.bash}
+      emcmake python ./opencv/platforms/js/build_js.py build_js --cmake_option="-DCMAKE_CXX_STANDARD=17"
+      @endcode
 
 -#  [Optional] To build the OpenCV.js loader, append `--build_loader`.