LayoutParams from support libraries and custom views

[zserge]

Layout params are not handled by generated DSL now. They are handled by hand-written BaseDSL in anvil base library. There are custom views that use their own layout params that BaseDSL knows nothing about. So far there is no way to set such layout params except for calling layoutParams method directly.

Here's a list of all ViewGroup.LayoutParams implementations:

• AbsListView.LayoutParams - same as normal LayoutParams
• AbsoluteLayout.LayoutParams - adds x and y to LayoutParams, but AbsoluteLayout is deprecated
• ActionBar.LayoutParams - adds gravity to MarginLayoutParams, not via XML
• ActionMenuView.LayoutParams - adds cellsUsed, expandable, extraPixels, isOverflowButton, preventEdgeOffset to MarginLayoutParams, not via XML
• AppBarLayout.LayoutParams - same as LinearLayout.LayoutParams
• BaseCardView.LayoutParams - adds viewType to FrameLayout.LayoutParams, not via XML
• CollapsingToolbarLayout.LayoutParams - adds CollapseMode and parallax multiplier to FrameLayout.LayoutParams, not via XML
• CoordinatorLayout.LayoutParams - adds anchorGravity, gravity and keyline to MarginLayoutParams
• DrawerLayout.LayoutParams - adds gravity to MarginLayoutParams
• FrameLayout.LayoutParams - adds gravity to MarginLayoutParams
• Gallery.LayoutParams - same as normal LayoutParams
• GridLayout.LayoutParams - adds row and column spec to MarginLayoutParams
• GridLayoutManager.LayoutParams - same as MarginLayoutParams
• LinearLayout.LayoutParams - adds weight and gravity to MarginLayoutParams
• LinearLayoutCompat.LayoutParams - also adds weight and gravity to MarginLayoutParams, rarely used and not via XML
• PercentFrameLayout.LayoutParams - same as FrameLayout.LayoutParams
• PercentRelativeLayout.LayoutParams - same as RelativeLayout.LayoutParams
• RadioGroup.LayoutParams - same as LinearLayout.LayoutParams
• RecyclerView.LayoutParams - same as MarginLayoutParams
• RelativeLayout.LayoutParams - adds rules to MarginLayoutParams
• SlidingPaneLayout.LayoutParams - adds weight to MarginLayoutParams
• StaggeredGridLayoutManager.LayoutParams - same as MarginLayoutParams
• TableLayout.LayoutParams - same as LinearLayout.LayoutParams
• TableRow.LayoutParams - adds column and span to LinearLayout.LayoutParams
• Toolbar.LayoutParams - same as ActionBar.LayoutParams, not via XML
• ViewGroup.LayoutParams (base) has width and height
• ViewGroup.MarginLayoutParams - adds margin to base LayoutParams
• ViewPager.LayoutParams - adds gravity and isDecor to base LayoutParams, not via XML
• WindowManager.LayoutParams - adds lots of fields, but none of them exporeted via XML

[zserge]

Also, here's a list of XML properties related to layout params:

• layout_above
• layout_alignBaseline
• layout_alignBottom
• layout_alignEnd
• layout_alignLeft
• layout_alignParentBottom
• layout_alignParentEnd
• layout_alignParentLeft
• layout_alignParentRight
• layout_alignParentStart
• layout_alignParentTop
• layout_alignRight
• layout_alignStart
• layout_alignTop
• layout_alignWithParentIfMissing
• layout_below
• layout_centerHorizontal
• layout_centerInParent
• layout_centerVertical
• layout_gravity - should be also supported in v4/v7 libraries
• layout_height
• layout_margin
• layout_marginBottom
• layout_marginEnd
• layout_marginLeft
• layout_marginRight
• layout_marginStart
• layout_marginTop
• layout_scale - what view uses this XML attr?
• layout_span - specific to TableRow, can be part of BaseDSL
• layout_toEndOf
• layout_toLeftOf
• layout_toRightOf
• layout_toStartOf
• layout_weight - should be also supported in v4/v7 libraries
• layout_width

Specific to GridLayout (API level 14, can be part of BaseDSL):

• layout_column
• layout_columnSpan
• layout_columnWeight
• layout_row
• layout_rowSpan
• layout_rowWeight

Specific to AppBarLayout (Design support library):

• android.support.design:layout_scrollFlags
• android.support.design:layout_scrollInterpolator

Specific to AbsoluteLayout (deprecated):

• layout_x
• layout_y

[zserge]

This narrows down the scope to:

• Design DSL: support anchor view ID and anchor gravity for CoordinatorLayout
• Base DSL: support DrawerLayout and CoordinatorLayout and Toolbar gravity
• Base DSL: support SlidingPaneLayout weight
• BaseDSL: support TableRow span (easy, but seems to be rarely used)
• BaseDSL: support GridLayout (also, easy but seems to be rarely used)

The only possible way to mutate property of the class not known at compile time is via reflection. The performance should be an issue, since it's a one-time operation in app lifecycle (most apps have only one navigation drawer or sliding pane).

[aaronpoweruser]

AppBarLayout.LayoutParams has a layout_scrollFlags and layout_scrollInterpolator layout param

http://developer.android.com/reference/android/support/design/widget/AppBarLayout.LayoutParams.html#attr_android.support.design:layout_scrollFlags