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GridLayout

open class GridLayout : ViewGroup
kotlin.Any
   ↳ android.view.View
   ↳ android.view.ViewGroup
   ↳ androidx.gridlayout.widget.GridLayout

A layout that places its children in a rectangular grid.

The grid is composed of a set of infinitely thin lines that separate the viewing area into cells. Throughout the API, grid lines are referenced by grid indices. A grid with N columns has N + 1 grid indices that run from 0 through N inclusive. Regardless of how GridLayout is configured, grid index 0 is fixed to the leading edge of the container and grid index N is fixed to its trailing edge (after padding is taken into account).

Row and Column Specs

Children occupy one or more contiguous cells, as defined by their rowSpec and columnSpec layout parameters. Each spec defines the set of rows or columns that are to be occupied; and how children should be aligned within the resulting group of cells. Although cells do not normally overlap in a GridLayout, GridLayout does not prevent children being defined to occupy the same cell or group of cells. In this case however, there is no guarantee that children will not themselves overlap after the layout operation completes.

Default Cell Assignment

If a child does not specify the row and column indices of the cell it wishes to occupy, GridLayout assigns cell locations automatically using its: orientation, rowCount and columnCount properties.

Space

Space between children may be specified either by using instances of the dedicated android.widget.Space view or by setting the leftMargin, topMargin, rightMargin and bottomMargin layout parameters. When the useDefaultMargins property is set, default margins around children are automatically allocated based on the prevailing UI style guide for the platform. Each of the margins so defined may be independently overridden by an assignment to the appropriate layout parameter. Default values will generally produce a reasonable spacing between components but values may change between different releases of the platform.

Excess Space Distribution

GridLayout's distribution of excess space accommodates the principle of weight. In the event that no weights are specified, columns and rows are taken as flexible if their views specify some form of alignment within their groups.

The flexibility of a view is therefore influenced by its alignment which is, in turn, typically defined by setting the gravity property of the child's layout parameters. If either a weight or alignment were defined along a given axis then the component is taken as flexible in that direction. If no weight or alignment was set, the component is instead assumed to be inflexible.

Multiple components in the same row or column group are considered to act in parallel. Such a group is flexible only if all of the components within it are flexible. Row and column groups that sit either side of a common boundary are instead considered to act in series. The composite group made of these two elements is flexible if one of its elements is flexible.

To make a column stretch, make sure all of the components inside it define a weight or a gravity. To prevent a column from stretching, ensure that one of the components in the column does not define a weight or a gravity.

When the principle of flexibility does not provide complete disambiguation, GridLayout's algorithms favour rows and columns that are closer to its right and bottom edges. To be more precise, GridLayout treats each of its layout parameters as a constraint in the a set of variables that define the grid-lines along a given axis. During layout, GridLayout solves the constraints so as to return the unique solution to those constraints for which all variables are less-than-or-equal-to the corresponding value in any other valid solution.

Interpretation of GONE

For layout purposes, GridLayout treats views whose visibility status is GONE, as having zero width and height. This is subtly different from the policy of ignoring views that are marked as GONE outright. If, for example, a gone-marked view was alone in a column, that column would itself collapse to zero width if and only if no gravity was defined on the view. If gravity was defined, then the gone-marked view has no effect on the layout and the container should be laid out as if the view had never been added to it. GONE views are taken to have zero weight during excess space distribution.

These statements apply equally to rows as well as columns, and to groups of rows or columns.

See GridLayout.LayoutParams for a full description of the layout parameters used by GridLayout.

Summary

Nested classes
abstract

Alignments specify where a view should be placed within a cell group and what size it should be.

open

Layout information associated with each of the children of a GridLayout.

open

A Spec defines the horizontal or vertical characteristics of a group of cells.

Constants
static Int

This constant is an alignmentMode.

static Int

This constant is an alignmentMode.

static Int

The horizontal orientation.

static Int

The constant used to indicate that a value is undefined.

static Int

The vertical orientation.

Public constructors
<init>(context: Context!, attrs: AttributeSet!, defStyle: Int)

<init>(context: Context!, attrs: AttributeSet!)

<init>(context: Context!)

Public methods
open GridLayout.LayoutParams!

open Int

Returns the alignment mode.

open Int

Returns the current number of columns.

open Int

Returns the current orientation.

open Printer!

Return the printer that will log diagnostics from this layout.

open Int

Returns the current number of rows.

open Boolean

Returns whether or not this GridLayout will allocate default margins when no corresponding layout parameters are defined.

open Boolean

Returns whether or not column boundaries are ordered by their grid indices.

open Boolean

Returns whether or not row boundaries are ordered by their grid indices.

open Unit

open Unit
setAlignmentMode(alignmentMode: Int)

Sets the alignment mode to be used for all of the alignments between the children of this container.

open Unit
setColumnCount(columnCount: Int)

ColumnCount is used only to generate default column/column indices when they are not specified by a component's layout parameters.

open Unit
setColumnOrderPreserved(columnOrderPreserved: Boolean)

When this property is true, GridLayout is forced to place the column boundaries so that their associated grid indices are in ascending order in the view.

open Unit
setOrientation(orientation: Int)

GridLayout uses the orientation property for two purposes:

  • To control the 'direction' in which default row/column indices are generated when they are not specified in a component's layout parameters.
  • To control which axis should be processed first during the layout operation: when orientation is HORIZONTAL the horizontal axis is laid out first.
The order in which axes are laid out is important if, for example, the height of one of GridLayout's children is dependent on its width - and its width is, in turn, dependent on the widths of other components.

open Unit
setPrinter(printer: Printer!)

Set the printer that will log diagnostics from this layout.

open Unit
setRowCount(rowCount: Int)

RowCount is used only to generate default row/column indices when they are not specified by a component's layout parameters.

open Unit
setRowOrderPreserved(rowOrderPreserved: Boolean)

When this property is true, GridLayout is forced to place the row boundaries so that their associated grid indices are in ascending order in the view.

open Unit
setUseDefaultMargins(useDefaultMargins: Boolean)

When true, GridLayout allocates default margins around children based on the child's visual characteristics.

open static GridLayout.Spec!
spec(start: Int, size: Int, alignment: GridLayout.Alignment!, weight: Float)

Return a Spec, spec, where:

  • spec.span = [start, start + size]
  • spec.alignment = alignment
  • spec.weight = weight

open static GridLayout.Spec!
spec(start: Int, alignment: GridLayout.Alignment!, weight: Float)

Equivalent to: spec(start, 1, alignment, weight).

open static GridLayout.Spec!
spec(start: Int, size: Int, weight: Float)

Equivalent to: spec(start, 1, default_alignment, weight) - where default_alignment is specified in android.widget.GridLayout.LayoutParams.

open static GridLayout.Spec!
spec(start: Int, weight: Float)

Equivalent to: spec(start, 1, weight).

open static GridLayout.Spec!
spec(start: Int, size: Int, alignment: GridLayout.Alignment!)

Equivalent to: spec(start, size, alignment, 0f).

open static GridLayout.Spec!
spec(start: Int, alignment: GridLayout.Alignment!)

Return a Spec, spec, where:

  • spec.span = [start, start + 1]
  • spec.alignment = alignment

open static GridLayout.Spec!
spec(start: Int, size: Int)

Return a Spec, spec, where:

  • spec.span = [start, start + size]

open static GridLayout.Spec!
spec(start: Int)

Return a Spec, spec, where:

  • spec.span = [start, start + 1]

Protected methods
open Boolean

open GridLayout.LayoutParams!

open GridLayout.LayoutParams!

open Unit
onLayout(changed: Boolean, left: Int, top: Int, right: Int, bottom: Int)

open Unit
onMeasure(widthSpec: Int, heightSpec: Int)

Properties
static GridLayout.Alignment!

Indicates that a view should be aligned with the baselines of the other views in its cell group.

static GridLayout.Alignment!

Indicates that a view should be aligned with the bottom edges of the other views in its cell group.

static GridLayout.Alignment!

Indicates that a view should be centered with the other views in its cell group.

static GridLayout.Alignment!

Indicates that a view should be aligned with the end edges of the other views in its cell group.

static GridLayout.Alignment!

Indicates that a view should expanded to fit the boundaries of its cell group.

static GridLayout.Alignment!

Indicates that a view should be aligned with the left edges of the other views in its cell group.

static GridLayout.Alignment!

Indicates that a view should be aligned with the right edges of the other views in its cell group.

static GridLayout.Alignment!

Indicates that a view should be aligned with the start edges of the other views in its cell group.

static GridLayout.Alignment!

Indicates that a view should be aligned with the top edges of the other views in its cell group.

Constants

ALIGN_BOUNDS

static val ALIGN_BOUNDS: Int

This constant is an alignmentMode. When the alignmentMode is set to ALIGN_BOUNDS, alignment is made between the edges of each component's raw view boundary: i.e. the area delimited by the component's: top, left, bottom and right properties.

For example, when GridLayout is in ALIGN_BOUNDS mode, children that belong to a row group that uses TOP alignment will all return the same value when their android.view.View#getTop() method is called.

Value: 0

ALIGN_MARGINS

static val ALIGN_MARGINS: Int

This constant is an alignmentMode. When the alignmentMode is set to ALIGN_MARGINS, the bounds of each view are extended outwards, according to their margins, before the edges of the resulting rectangle are aligned.

For example, when GridLayout is in ALIGN_MARGINS mode, the quantity top - layoutParams.topMargin is the same for all children that belong to a row group that uses TOP alignment.

Value: 1

HORIZONTAL

static val HORIZONTAL: Int

The horizontal orientation.

Value: LinearLayout.HORIZONTAL

UNDEFINED

static val UNDEFINED: Int

The constant used to indicate that a value is undefined. Fields can use this value to indicate that their values have not yet been set. Similarly, methods can return this value to indicate that there is no suitable value that the implementation can return. The value used for the constant (currently Integer#MIN_VALUE) is intended to avoid confusion between valid values whose sign may not be known.

Value: Integer.MIN_VALUE

VERTICAL

static val VERTICAL: Int

The vertical orientation.

Value: LinearLayout.VERTICAL

Public constructors

<init>

GridLayout(
    context: Context!,
    attrs: AttributeSet!,
    defStyle: Int)

<init>

GridLayout(
    context: Context!,
    attrs: AttributeSet!)

<init>

GridLayout(context: Context!)

Public methods

generateLayoutParams

open fun generateLayoutParams(attrs: AttributeSet!): GridLayout.LayoutParams!

getAlignmentMode

open fun getAlignmentMode(): Int

Returns the alignment mode.

Return
Int the alignment mode; either ALIGN_BOUNDS or ALIGN_MARGINS

getColumnCount

open fun getColumnCount(): Int

Returns the current number of columns. This is either the last value that was set with setColumnCount(int) or, if no such value was set, the maximum value of each the upper bounds defined in LayoutParams#columnSpec.

Return
Int the current number of columns

getOrientation

open fun getOrientation(): Int

Returns the current orientation.

Return
Int either HORIZONTAL or VERTICAL

getPrinter

open fun getPrinter(): Printer!

Return the printer that will log diagnostics from this layout.

Return
Printer! the printer associated with this view

getRowCount

open fun getRowCount(): Int

Returns the current number of rows. This is either the last value that was set with setRowCount(int) or, if no such value was set, the maximum value of each the upper bounds defined in LayoutParams#rowSpec.

Return
Int the current number of rows

getUseDefaultMargins

open fun getUseDefaultMargins(): Boolean

Returns whether or not this GridLayout will allocate default margins when no corresponding layout parameters are defined.

Return
Boolean true if default margins should be allocated

isColumnOrderPreserved

open fun isColumnOrderPreserved(): Boolean

Returns whether or not column boundaries are ordered by their grid indices.

Return
Boolean true if column boundaries must appear in the order of their indices, false otherwise

isRowOrderPreserved

open fun isRowOrderPreserved(): Boolean

Returns whether or not row boundaries are ordered by their grid indices.