java.lang.Object | |||
↳ | android.view.View | ||
↳ | android.view.ViewGroup | ||
↳ | android.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).
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.
orientation
,
rowCount
and
columnCount
properties.
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.
A child's ability to stretch is inferred from the alignment properties of its row and column groups (which are typically set by setting the gravity
property of the child's layout parameters). If alignment was defined along a given axis then the component is taken as flexible in that direction. If no 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 gravity. To prevent a column from stretching, ensure that one of the components in the column does not define 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.
weight
. In general, it is not therefore possible to configure a GridLayout to distribute excess space between multiple components.
Some common use-cases may nevertheless be accommodated as follows. To place equal amounts of space around a component in a cell group; use CENTER
alignment (or gravity
). For complete control over excess space distribution in a row or column; use a LinearLayout
subview to hold the components in the associated cell group. When using either of these techniques, bear in mind that cell groups may be defined to overlap.
See GridLayout.LayoutParams
for a full description of the layout parameters used by GridLayout.
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GridLayout.Alignment | Alignments specify where a view should be placed within a cell group and what size it should be. | |||||||||
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GridLayout.LayoutParams | Layout information associated with each of the children of a GridLayout. | |||||||||
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GridLayout.Spec | A Spec defines the horizontal or vertical characteristics of a group of cells. |
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android:alignmentMode | setAlignmentMode(int) | When set to alignMargins, causes alignment to take place between the outer boundary of a view, as defined by its margins. | |||||||||
android:columnCount | setColumnCount(int) | The maxmimum number of columns to create when automatically positioning children. | |||||||||
android:columnOrderPreserved | setColumnOrderPreserved(boolean) | When set to true, forces column boundaries to appear in the same order as column indices. | |||||||||
android:orientation | setOrientation(int) | The orientation property is not used during layout. | |||||||||
android:rowCount | setRowCount(int) | The maxmimum number of rows to create when automatically positioning children. | |||||||||
android:rowOrderPreserved | setRowOrderPreserved(boolean) | When set to true, forces row boundaries to appear in the same order as row indices. | |||||||||
android:useDefaultMargins | setUseDefaultMargins(boolean) | When set to true, tells GridLayout to use default margins when none are specified in a view's layout parameters. |
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Inherited XML Attributes
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Constants | |||||||||||
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int | ALIGN_BOUNDS | This constant is an alignmentMode . |
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int | ALIGN_MARGINS | This constant is an alignmentMode . |
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int | HORIZONTAL | The horizontal orientation. | |||||||||
int | UNDEFINED | The constant used to indicate that a value is undefined. | |||||||||
int | VERTICAL | The vertical orientation. |
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Fields | |||||||||||
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BASELINE | Indicates that a view should be aligned with the baselines of the other views in its cell group. | |||||||||
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BOTTOM | Indicates that a view should be aligned with the bottom edges of the other views in its cell group. | |||||||||
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CENTER | Indicates that a view should be centered with the other views in its cell group. | |||||||||
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END | Indicates that a view should be aligned with the end edges of the other views in its cell group. | |||||||||
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FILL | Indicates that a view should expanded to fit the boundaries of its cell group. | |||||||||
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LEFT | Indicates that a view should be aligned with the left edges of the other views in its cell group. | |||||||||
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RIGHT | Indicates that a view should be aligned with the right edges of the other views in its cell group. | |||||||||
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START | Indicates that a view should be aligned with the start edges of the other views in its cell group. | |||||||||
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TOP | Indicates that a view should be aligned with the top edges of the other views in its cell group. |
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Public Constructors | |||||||||||
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Public Methods | |||||||||||
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Returns a new set of layout parameters based on the supplied attributes set.
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Returns the alignment mode.
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Returns the current number of columns.
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Returns the current orientation.
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Returns the current number of rows.
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Returns whether or not this GridLayout will allocate default margins when no corresponding layout parameters are defined.
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Returns whether or not column boundaries are ordered by their grid indices.
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Returns whether or not row boundaries are ordered by their grid indices.
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Initializes an
AccessibilityEvent with information about this View which is the event source.
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Initializes an
AccessibilityNodeInfo with information about this view.
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Call this when something has changed which has invalidated the layout of this view.
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Sets the alignment mode to be used for all of the alignments between the children of this container.
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ColumnCount is used only to generate default column/column indices when they are not specified by a component's layout parameters.
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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.
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GridLayout uses the orientation property for two purposes:
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RowCount is used only to generate default row/column indices when they are not specified by a component's layout parameters.
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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.
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When
true , GridLayout allocates default margins around children based on the child's visual characteristics.
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Return a Spec,
spec , where:
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Return a Spec,
spec , where:
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Return a Spec,
spec , where:
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Return a Spec,
spec , where:
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Returns a set of default layout parameters.
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Returns a safe set of layout parameters based on the supplied layout params.
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Called from layout when this view should assign a size and position to each of its children.
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Measure the view and its content to determine the measured width and the measured height. |
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When set to alignMargins, causes alignment to take place between the outer boundary of a view, as defined by its margins. When set to alignBounds, causes alignment to take place between the edges of the view. The default is alignMargins. See setAlignmentMode(int)
.
Must be one of the following constant values.
Constant | Value | Description |
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alignBounds |
0 | Align the bounds of the children. See ALIGN_BOUNDS . |
alignMargins |
1 | Align the margins of the children. See ALIGN_MARGINS . |
This corresponds to the global attribute resource symbol alignmentMode
.
The maxmimum number of columns to create when automatically positioning children.
Must be an integer value, such as "100
".
This may also be a reference to a resource (in the form "@[package:]type:name
") or theme attribute (in the form "?[package:][type:]name
") containing a value of this type.
This corresponds to the global attribute resource symbol columnCount
.
When set to true, forces column boundaries to appear in the same order as column indices. The default is true. See setColumnOrderPreserved(boolean)
.
Must be a boolean value, either "true
" or "false
".
This may also be a reference to a resource (in the form "@[package:]type:name
") or theme attribute (in the form "?[package:][type:]name
") containing a value of this type.
This corresponds to the global attribute resource symbol columnOrderPreserved
.
The orientation property is not used during layout. It is only used to allocate row and column parameters when they are not specified by its children's layout paramters. GridLayout works like LinearLayout in this case; putting all the components either in a single row or in a single column - depending on the value of this flag. In the horizontal case, a columnCount property may be additionally supplied to force new rows to be created when a row is full. The rowCount attribute may be used similarly in the vertical case. The default is horizontal.
Must be one of the following constant values.
Constant | Value | Description |
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horizontal |
0 | Defines an horizontal widget. |
vertical |
1 | Defines a vertical widget. |
This corresponds to the global attribute resource symbol orientation
.
The maxmimum number of rows to create when automatically positioning children.
Must be an integer value, such as "100
".
This may also be a reference to a resource (in the form "@[package:]type:name
") or theme attribute (in the form "?[package:][type:]name
") containing a value of this type.
This corresponds to the global attribute resource symbol rowCount
.
When set to true, forces row boundaries to appear in the same order as row indices. The default is true. See setRowOrderPreserved(boolean)
.
Must be a boolean value, either "true
" or "false
".
This may also be a reference to a resource (in the form "@[package:]type:name
") or theme attribute (in the form "?[package:][type:]name
") containing a value of this type.
This corresponds to the global attribute resource symbol rowOrderPreserved
.
When set to true, tells GridLayout to use default margins when none are specified in a view's layout parameters. The default value is false. See setUseDefaultMargins(boolean)
.
Must be a boolean value, either "true
" or "false
".
This may also be a reference to a resource (in the form "@[package:]type:name
") or theme attribute (in the form "?[package:][type:]name
") containing a value of this type.
This corresponds to the global attribute resource symbol useDefaultMargins
.
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 getTop()
method is called.
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.
The horizontal orientation.
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 MIN_VALUE
) is intended to avoid confusion between valid values whose sign may not be known.
The vertical orientation.
Indicates that a view should be aligned with the baselines of the other views in its cell group. This constant may only be used as an alignment in rowSpecs
.
Indicates that a view should be aligned with the bottom edges of the other views in its cell group.
Indicates that a view should be centered with the other views in its cell group. This constant may be used in both rowSpecs
and columnSpecs
.
Indicates that a view should be aligned with the end edges of the other views in its cell group.
Indicates that a view should expanded to fit the boundaries of its cell group. This constant may be used in both rowSpecs
and columnSpecs
.
Indicates that a view should be aligned with the left edges of the other views in its cell group.
Indicates that a view should be aligned with the right edges of the other views in its cell group.
Indicates that a view should be aligned with the start edges of the other views in its cell group.
Indicates that a view should be aligned with the top edges of the other views in its cell group.
Returns a new set of layout parameters based on the supplied attributes set.
attrs | the attributes to build the layout parameters from |
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ViewGroup.LayoutParams
or one of its descendants Returns the alignment mode.
ALIGN_BOUNDS
or ALIGN_MARGINS
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 columnSpec
.
Returns the current orientation.
HORIZONTAL
or VERTICAL
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 rowSpec
.
Returns whether or not this GridLayout will allocate default margins when no corresponding layout parameters are defined.
true
if default margins should be allocatedReturns whether or not column boundaries are ordered by their grid indices.
true
if column boundaries must appear in the order of their indices, false
otherwiseReturns whether or not row boundaries are ordered by their grid indices.
true
if row boundaries must appear in the order of their indices, false
otherwiseInitializes an AccessibilityEvent
with information about this View which is the event source. In other words, the source of an accessibility event is the view whose state change triggered firing the event.
Example: Setting the password property of an event in addition to properties set by the super implementation:
public void onInitializeAccessibilityEvent(AccessibilityEvent event) {
super.onInitializeAccessibilityEvent(event);
event.setPassword(true);
}
If an View.AccessibilityDelegate
has been specified via calling setAccessibilityDelegate(AccessibilityDelegate)
its onInitializeAccessibilityEvent(View, AccessibilityEvent)
is responsible for handling this call.
Note: Always call the super implementation before adding information to the event, in case the default implementation has basic information to add.
event | The event to initialize. |
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Initializes an AccessibilityNodeInfo
with information about this view. The base implementation sets:
setParent(View)
,setBoundsInParent(Rect)
,setBoundsInScreen(Rect)
,setPackageName(CharSequence)
,setClassName(CharSequence)
,setContentDescription(CharSequence)
,setEnabled(boolean)
,setClickable(boolean)
,setFocusable(boolean)
,setFocused(boolean)
,setLongClickable(boolean)
,setSelected(boolean)
,Subclasses should override this method, call the super implementation, and set additional attributes.
If an View.AccessibilityDelegate
has been specified via calling setAccessibilityDelegate(AccessibilityDelegate)
its onInitializeAccessibilityNodeInfo(View, AccessibilityNodeInfo)
is responsible for handling this call.
info | The instance to initialize. |
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Call this when something has changed which has invalidated the layout of this view. This will schedule a layout pass of the view tree.
Sets the alignment mode to be used for all of the alignments between the children of this container.
The default value of this property is ALIGN_MARGINS
.
alignmentMode | either ALIGN_BOUNDS or ALIGN_MARGINS |
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ColumnCount is used only to generate default column/column indices when they are not specified by a component's layout parameters.
columnCount | the number of columns. |
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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.
When this property is false
GridLayout is at liberty to place the horizontal column boundaries in whatever order best fits the given constraints.
The default value of this property is true
.
columnOrderPreserved | use true to force GridLayout to respect the order of column boundaries. |
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GridLayout uses the orientation property for two purposes:
HORIZONTAL
the horizontal axis is laid out first. If your layout contains a TextView
(or derivative: Button
, EditText
, CheckBox
, etc.) which is in multi-line mode (the default) it is normally best to leave GridLayout's orientation as HORIZONTAL
- because TextView
is capable of deriving its height for a given width, but not the other way around.
Other than the effects above, orientation does not affect the actual layout operation of GridLayout, so it's fine to leave GridLayout in HORIZONTAL
mode even if the height of the intended layout greatly exceeds its width.
The default value of this property is HORIZONTAL
.
orientation | either HORIZONTAL or VERTICAL |
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RowCount is used only to generate default row/column indices when they are not specified by a component's layout parameters.
rowCount | the number of rows |
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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.
When this property is false
GridLayout is at liberty to place the vertical row boundaries in whatever order best fits the given constraints.
The default value of this property is true
.
rowOrderPreserved | true to force GridLayout to respect the order of row boundaries |
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When true
, GridLayout allocates default margins around children based on the child's visual characteristics. Each of the margins so defined may be independently overridden by an assignment to the appropriate layout parameter.
When false
, the default value of all margins is zero.
When setting to true
, consider setting the value of the alignmentMode
property to ALIGN_BOUNDS
.
The default value of this property is false
.
useDefaultMargins | use true to make GridLayout allocate default margins |
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Return a Spec, spec
, where:
spec.span = [start, start + 1]
spec.alignment = alignment
start | the start index |
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alignment | the alignment |
Return a Spec, spec
, where:
spec.span = [start, start + size]
start | the start |
---|---|
size | the size |
Return a Spec, spec
, where:
spec.span = [start, start + size]
spec.alignment = alignment
start | the start |
---|---|
size | the size |
alignment | the alignment |
Return a Spec, spec
, where:
spec.span = [start, start + 1]
start | the start index |
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Returns a set of default layout parameters. These parameters are requested when the View passed to addView(View)
has no layout parameters already set. If null is returned, an exception is thrown from addView.
Returns a safe set of layout parameters based on the supplied layout params. When a ViewGroup is passed a View whose layout params do not pass the test of checkLayoutParams(android.view.ViewGroup.LayoutParams)
, this method is invoked. This method should return a new set of layout params suitable for this ViewGroup, possibly by copying the appropriate attributes from the specified set of layout params.
p | The layout parameters to convert into a suitable set of layout parameters for this ViewGroup. |
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ViewGroup.LayoutParams
or one of its descendants Called from layout when this view should assign a size and position to each of its children. Derived classes with children should override this method and call layout on each of their children.
changed | This is a new size or position for this view |
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left | Left position, relative to parent |
top | Top position, relative to parent |
right | Right position, relative to parent |
bottom | Bottom position, relative to parent |
Measure the view and its content to determine the measured width and the measured height. This method is invoked by measure(int, int)
and should be overriden by subclasses to provide accurate and efficient measurement of their contents.
CONTRACT: When overriding this method, you must call setMeasuredDimension(int, int)
to store the measured width and height of this view. Failure to do so will trigger an IllegalStateException
, thrown by measure(int, int)
. Calling the superclass' onMeasure(int, int)
is a valid use.
The base class implementation of measure defaults to the background size, unless a larger size is allowed by the MeasureSpec. Subclasses should override onMeasure(int, int)
to provide better measurements of their content.
If this method is overridden, it is the subclass's responsibility to make sure the measured height and width are at least the view's minimum height and width (getSuggestedMinimumHeight()
and getSuggestedMinimumWidth()
).
widthSpec | horizontal space requirements as imposed by the parent. The requirements are encoded with View.MeasureSpec . |
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heightSpec | vertical space requirements as imposed by the parent. The requirements are encoded with View.MeasureSpec . |