bed_mesh: Implement adaptive bed mesh

Adaptive bed mesh allows the bed mesh algorithm
to probe only the area of the bed that is being
used by the current print.

It uses [exclude_objects] to get a list of the
printed objects and their area on the bed. It,
then, modifies the bed mesh parameters so only
the area used by the objects is measured.

Adaptive bed mesh works on both cartesian and
delta kinematics printers. On Delta printers,
the algorithm, adjusts the origin point and
radius in order to translate the area of the
bed being probe.

Signed-off-by: Mitko Haralanov <[email protected]>
Signed off-by: Kyle Hansen <[email protected]>

docs/Bed_Mesh.md

@@ -370,14 +370,54 @@ are identified in green.
 
 ![bedmesh_interpolated](img/bedmesh_faulty_regions.svg)
 
+### Adaptive Meshes
+
+Adaptive bed meshing is a way to speed up the bed mesh generation by only probing
+the area of the bed used by the objects being printed. When used, the method will
+automatically adjust the mesh parameters based on the area occupied by the defined
+print objects.
+
+The adapted mesh area will be computed from the area defined by the boundaries of all
+the defined print object so it covers every object, including any margins defined in
+the configuration. After the area is computed, the number of probe points will be
+scaled down based on the ratio of the default mesh area and the adapted mesh area. To
+illustrate this consider the following example:
+
+For a 150mmx150mm bed with `mesh_min` set to `25,25` and `mesh_max` set to `125,125`,
+the default mesh area is a 100mmx100mm square. An adapted mesh area of `50,50`
+means a ratio of `0.5x0.5` between the adapted area and default mesh area.
+
+If the `bed_mesh` configuration specified `probe_count` as `7x7`, the adapted bed
+mesh will use 4x4 probe points (roundUp(7 * 0.5)).
+
+![adaptive_bedmesh](img/adaptive_bed_mesh.svg)
+```
+[bed_mesh]
+speed: 120
+horizontal_move_z: 5
+mesh_min: 35, 6
+mesh_max: 240, 198
+probe_count: 5, 3
+mesh_margin: 5
+```
+
+- `mesh_margin` \
+  _Default Value: 0_ \
+  Margin (in mm) to add around the area of the bed used by the defined objects. The diagram
+  below shows the adapted bed mesh area with a `mesh_margin` set to 5mm. The adapted mesh area
+  (area in green) is computed as the used bed area (area in blue) plus the defined margin.
+
+  ![adaptive_bedmesh_margin](img/adaptive_bed_mesh_margin.svg)
 ## Bed Mesh Gcodes
 
 ### Calibration
 
 `BED_MESH_CALIBRATE PROFILE=<name> METHOD=[manual | automatic] [<probe_parameter>=<value>]
- [<mesh_parameter>=<value>]`\
+ [<mesh_parameter>=<value>] [ADAPTIVE=[0|1] [ADAPTIVE_MARGIN=<value>]`\
 _Default Profile:  default_\
-_Default Method:  automatic if a probe is detected, otherwise manual_
+_Default Method:  automatic if a probe is detected, otherwise manual_ \
+_Default Adaptive: 0_ \
+_Default Adaptive Margin: 0_
 
 Initiates the probing procedure for Bed Mesh Calibration.
 
@@ -399,6 +439,8 @@ following parameters are available:
   - `ROUND_PROBE_COUNT`
 - All beds:
   - `ALGORITHM`
+  - `ADAPTIVE`
+  - `ADAPTIVE_MARGIN`
 
 See the configuration documentation above for details on how each parameter
 applies to the mesh.