oiiotool: new --layersplit action for splitting channel-name-based layers on the stack

Signed-off-by: Loïc Vital <[email protected]>

Author: mugulmd

src/oiiotool/oiiotool.cpp

@@ -2880,6 +2880,50 @@ action_subimage_split(Oiiotool& ot, cspan<const char*> argv)
 
 
 
+// --layersplit
+static void
+action_layer_split(Oiiotool& ot, cspan<const char*> argv)
+{
+    if (ot.postpone_callback(1, action_layer_split, argv))
+        return;
+    string_view command = ot.express(argv[0]);
+    OTScopedTimer timer(ot, command);
+
+    ImageRecRef A = ot.pop();
+    ot.read(A);
+
+    // Push the individual channel-name-based layers onto the stack
+    ImageSpec* spec = A->spec();
+    int chbegin = 0;
+    for (size_t i = 0; i < spec->channelnames.size(); ++i) {
+        const std::string & chname          = spec->channelnames[i];
+        const std::string::size_type dotpos = chname.find(".");
+        const std::string layername         = (dotpos == std::string::npos) ? "" : chname.substr(0, dotpos);
+
+        bool pushlayer = false;
+        if (i < spec->channelnames.size() - 1) {
+            const std::string & nextchname          = spec->channelnames[i + 1];
+            const std::string::size_type nextdotpos = nextchname.find(".");
+            const std::string nextlayername         = (nextdotpos == std::string::npos) ? "" : nextchname.substr(0, nextdotpos);
+            pushlayer                               = (nextlayername != layername);
+        } else {
+            pushlayer = true;
+        }
+
+        if (pushlayer) {
+            const int chend = i + 1; 
+            ImageBufRef img = std::make_shared<ImageBuf>();
+            std::vector<int> channelorder(chend - chbegin);
+            std::iota(channelorder.begin(), channelorder.end(), chbegin);
+            ImageBufAlgo::channels(*img, (*A)(), chend - chbegin, cspan<int>(channelorder));
+            ot.push(new ImageRec(img, true));
+            chbegin = chend;
+        }
+    }
+}
+
+
+
 static void
 action_subimage_append_n(Oiiotool& ot, int n, string_view command)
 {
@@ -6898,6 +6942,9 @@ Oiiotool::getargs(int argc, char* argv[])
     ap.arg("--siappendall")
       .help("Append all images on the stack into a single multi-subimage image")
       .OTACTION(action_subimage_append_all);
+    ap.arg("--layersplit")
+      .help("Split the top image's channel-name-based layers into separate images on the stack")
+      .OTACTION(action_layer_split);
     ap.arg("--deepen")
       .help("Deepen normal 2D image to deep")
       .OTACTION(action_deepen);