G26: Add 'Repeat' Option

- Allows for specifying number of points to print/validate, using 'R' code like with G29 P4 Rx
- Moved the code for Random to 'M' so we could be consistent with G29 P4
- G26 instructions indenting/cleanup

Marlin/G26_Mesh_Validation_Tool.cpp

@@ -69,7 +69,7 @@
    *   B #  Bed         Set the Bed Temperature.  If not specified, a default of 60 C. will be assumed.
    *
    *   C    Current     When searching for Mesh Intersection points to draw, use the current nozzle location
-   *        as the base for any distance comparison.
+                        as the base for any distance comparison.
    *
    *   D    Disable     Disable the Unified Bed Leveling System.  In the normal case the user is invoking this
    *                    command to see how well a Mesh as been adjusted to match a print surface.  In order to do
@@ -91,6 +91,11 @@
    *   Q #  Multiplier  Retraction Multiplier.  Normally not needed.  Retraction defaults to 1.0mm and
    *                    un-retraction is at 1.2mm   These numbers will be scaled by the specified amount
    *
+   *   M #  Random      Randomize the order that the circles are drawn on the bed.  The search for the closest
+   *                    undrawn cicle is still done.  But the distance to the location for each circle has a
+   *                    random number of the size specified added to it.  Specifying R50 will give an interesting
+   *                    deviation from the normal behaviour on a 10 x 10 Mesh.
+
    *   N #  Nozzle      Used to control the size of nozzle diameter.  If not specified, a .4mm nozzle is assumed.
    *                    'n' can be used instead if your host program does not appreciate you using 'N'.
    *
@@ -106,14 +111,13 @@
    *                    printing the Mesh.  You can carefully remove the spent filament with a needle nose
    *                    pliers while holding the LCD Click wheel in a depressed state.
    *
-   *   R #  Random    Randomize the order that the circles are drawn on the bed.  The search for the closest
-   *        undrawn cicle is still done.  But the distance to the location for each circle has a
-   *        random number of the size specified added to it.  Specifying R50 will give an interesting
-   *        deviation from the normal behaviour on a 10 x 10 Mesh.
+   *   R #  Repeat      Prints the number of patterns given as a parameter, starting at the current location.
+   *                    If a parameter isn't given, every point will be printed unless G26 is interrupted.
+   *                    This works the same way that the UBL G29 P4 R parameter works.
    *
-   *   X #  X coordinate  Specify the starting location of the drawing activity.
+   *   X #  X Coord.    Specify the starting location of the drawing activity.
    *
-   *   Y #  Y coordinate  Specify the starting location of the drawing activity.
+   *   Y #  Y Coord.    Specify the starting location of the drawing activity.
    */
 
   // External references
@@ -176,6 +180,8 @@
 
   static bool keep_heaters_on = false;
 
+  static int16_t g26_repeats;
+
   /**
    * G26: Mesh Validation Pattern generation.
    *
@@ -359,7 +365,7 @@
 
       //debug_current_and_destination(PSTR("Done with current circle."));
 
-    } while (location.x_index >= 0 && location.y_index >= 0);
+    } while (location.x_index >= 0 && location.y_index >= 0 && g26_repeats--);
 
     LEAVE:
     lcd_reset_alert_level();
@@ -722,11 +728,21 @@
       }
     }
 
-    if (code_seen('R')) {
+    if (code_seen('M')) {
       randomSeed(millis());
       random_deviation = code_has_value() ? code_value_float() : 50.0;
     }
 
+    if (code_seen('R')) {
+      g26_repeats = code_has_value() ? code_value_int() - 1 : 999;
+
+      if (g26_repeats <= 0) {
+        SERIAL_PROTOCOLLNPGM("?(R)epeat value not plausible; must be greater than 0.");
+        return UBL_ERR;
+      }
+    }
+
+
     x_pos = current_position[X_AXIS];
     y_pos = current_position[Y_AXIS];