Expose layout hints and hide-label metadata

Read OFX layout hints and propagate them into generated parameter metadata
so UIs can better preserve plugin-authored control layout.

- map OFX layout hint values to metadata:
  - no_new_line
  - divider
- mark label-style string params as hide-label in addition to readonly
- extend metadata schema with:
  - layout-hint enum
  - hide-label boolean (default: false)
- include the Nuke OFX public extensions header for layout-hint constants

Author: bmatherly

src/framework/metaschema.yaml

@@ -154,6 +154,14 @@ mapping:
               - text
               - textbox # multi-line
               - timecode
+          "layout-hint": # A hint to the UI for relative control placement
+            type: str
+            enum:
+              - divider
+              - no_new_line
+          "hide-label": # A hint to the UI to suppress the field label; omitted means false
+            type: bool
+            default: no
           "minimum": # For numeric types, the minimal value
             type: number
           "maximum": # For numeric types, the maximal value 

src/modules/openfx/mlt_openfx.c

@@ -35,6 +35,7 @@
 #endif
 
 /* OpenFX Header files https://github.com/AcademySoftwareFoundation/openfx/tree/main/include */
+#include <nuke/fnPublicOfxExtensions.h>
 #include <ofxDrawSuite.h>
 #include <ofxGPURender.h>
 #include <ofxImageEffect.h>
@@ -3094,6 +3095,22 @@ void *mltofx_fetch_params(OfxPlugin *plugin, mlt_properties params, mlt_properti
             mlt_properties_set(p, "type", "integer");
         }
 
+        int layout_hint = 0;
+        if (propGetInt((OfxPropertySetHandle) ppp, kOfxParamPropLayoutHint, 0, &layout_hint)
+            == kOfxStatOK) {
+            switch (layout_hint) {
+            case kOfxParamPropLayoutHintNoNewLine:
+                mlt_properties_set(p, "layout-hint", "no_new_line");
+                break;
+            case kOfxParamPropLayoutHintDivider:
+                mlt_properties_set(p, "layout-hint", "divider");
+                break;
+            default:
+                // Add new layout-hint cases here as they are supported.
+                break;
+            }
+        }
+
         if (strcmp(param_type, kOfxParamTypeGroup) != 0) {
             int animation = 1;
             propGetInt((OfxPropertySetHandle) ppp, kOfxParamPropAnimates, 0, &animation);
@@ -3262,6 +3279,7 @@ void *mltofx_fetch_params(OfxPlugin *plugin, mlt_properties params, mlt_properti
                 propGetString((OfxPropertySetHandle) ppp, p_name, 0, &str_value);
                 if (strcmp(str_value, kOfxParamStringIsLabel) == 0) {
                     mlt_properties_set(p, "readonly", "yes");
+                    mlt_properties_set_int(p, "hide-label", 1);
                 }
             } else if (strcmp(p_name, kOfxParamPropParent) == 0) {
                 char *str_value = "";

src/modules/openfx/openfx/include/nuke/fnPublicOfxExtensions.h

@@ -0,0 +1,37 @@
+#ifndef _fnPublicOfxExtensions_h_
+#define _fnPublicOfxExtensions_h_
+
+#include "ofxImageEffect.h"
+
+/** @brief Layout hint for hierarchical layouts.
+ *
+ * - Type - int X 1
+ * - Property Set - plugin parameter descriptor (read/write) and instance (read only)
+ * - Default - 0
+ * - Valid Values - 0, 1, or 2
+ *   - 0 - for a new line after the parameter
+ *   - 1 - for a separator between this parameter and the one to follow
+ *   - 2 - for no new line, continue the next parameter on the same horizontal level
+ */
+#define kOfxParamPropLayoutHint "OfxParamPropLayoutHint"
+
+// lay out as normal
+#define kOfxParamPropLayoutHintNormal 0
+
+// put a divider after parameter
+#define kOfxParamPropLayoutHintDivider 1
+
+// have the next parameter start on the same line as this
+#define kOfxParamPropLayoutHintNoNewLine 2
+
+/** @brief Layout padding for hierarchical views, only pertinent when
+ * kOfxParamPropLayoutHint == 2.
+ *
+ * - Type - int X 1
+ * - Property Set - plugin parameter descriptor (read/write) and instance (read only)
+ * - Default - 0
+ * - Valid Values - any positive integer value
+ */
+#define kOfxParamPropLayoutPadWidth "OfxParamPropLayoutPadWidth"
+
+#endif