Python API: Expose CurveMapping Reset View function

The Python API for the curve mapping widget offers the `update`
function, but no way to reset the view to the clipping rectangle.

This commit adds a blenkernel function for this operation,
and exposes it to the CurvMapping RNA API. This allows addons
to display a more user-friendly view of the data in this widget.

Differential Revision: https://developer.blender.org/D10561

source/blender/blenkernel/BKE_colortools.h

@@ -59,6 +59,7 @@ enum {
   CURVEMAP_SLOPE_POS_NEG = 2,
 };
 
+void BKE_curvemapping_reset_view(struct CurveMapping *cumap);
 void BKE_curvemap_reset(struct CurveMap *cuma, const struct rctf *clipr, int preset, int slope);
 void BKE_curvemap_remove(struct CurveMap *cuma, const short flag);
 bool BKE_curvemap_remove_point(struct CurveMap *cuma, struct CurveMapPoint *cmp);

source/blender/blenkernel/intern/colortools.c

@@ -965,6 +965,12 @@ void BKE_curvemapping_changed_all(CurveMapping *cumap)
   cumap->cur = cur;
 }
 
+/* Reset the view for current curve. */
+void BKE_curvemapping_reset_view(CurveMapping *cumap)
+{
+  cumap->curr = cumap->clipr;
+}
+
 /* table should be verified */
 float BKE_curvemap_evaluateF(const CurveMapping *cumap, const CurveMap *cuma, float value)
 {

source/blender/editors/interface/interface_templates.c

@@ -3987,7 +3987,7 @@ static void curvemap_tools_dofunc(bContext *C, void *cumap_v, int event)
       BKE_curvemapping_changed(cumap, false);
       break;
     case UICURVE_FUNC_RESET_VIEW:
-      cumap->curr = cumap->clipr;
+      BKE_curvemapping_reset_view(cumap);
       break;
     case UICURVE_FUNC_HANDLE_VECTOR: /* set vector */
       BKE_curvemap_handle_set(cuma, HD_VECT);

source/blender/makesrna/intern/rna_color.c

@@ -896,6 +896,9 @@ static void rna_def_curvemapping(BlenderRNA *brna)
   func = RNA_def_function(srna, "update", "BKE_curvemapping_changed_all");
   RNA_def_function_ui_description(func, "Update curve mapping after making changes");
 
+  func = RNA_def_function(srna, "reset_view", "BKE_curvemapping_reset_view");
+  RNA_def_function_ui_description(func, "Reset the curve mapping grid to its clipping size");
+
   func = RNA_def_function(srna, "initialize", "rna_CurveMap_initialize");
   RNA_def_function_ui_description(func, "Initialize curve");