Android 线性布局(LinearLayout)相关官方文档 - 参考部分


Android 线性布局(LinearLayout)相关官方文档 - 参考部分

太阳火神的美丽人生 (http://blog.csdn.net/opengl_es)

本文遵循“署名-非商业用途-保持一致”创作公用协议

转载请保留此句:太阳火神的美丽人生 -  本博客专注于 敏捷开发及移动和物联设备研究:iOS、Android、Html5、Arduino、pcDuino否则,出自本博客的文章拒绝转载或再转载,谢谢合作。



Android 官方文档线性布局相关资源链接汇总如下:

android-sdk-macosx-4.4.2/docs/guide/topics/ui/layout/linear.html

android-sdk-macosx-4.4.2/docs/reference/android/widget/LinearLayout.html

android-sdk-macosx-4.4.2/docs/reference/android/widget/LinearLayout.LayoutParams.html



由于在线文档访问困难,这里给出的是本地文档的相对路径。



重点摘要:




译文来源:reference/android/widget/LinearLayout.html



Added in  API level 1

官方文档的参考文档,这么多年来总是会把我看晕了,每次都得细细地分析页面布局结构,现在这个 Summary ,有有些让人头疼,不过还好,我对照一下,感觉还是满清晰的,也许是真正掌握了文档的结构,也或许熟能生巧吧。
下面把这份 Summary 重新整理一下,其实也是按内容的组织结构,只不过,内容组织结构中用了一些表格嵌套不太明显而已。
近五年,研究一些文档或技术,我总是爱从上往下看,可能是岁数的关系,没有力量了,但我有法术,像拘小鬼儿一样,法台一搭,使其 无所遁形 。
希望这种方法会帮助到更多的猿人们!

该 Summary 把该类所有的可能的内容,包括自身声明的和继承或从接口实现的,均列出来,使开发人员能对该类的来龙去脉,细节关系了如指掌。
但后面的详细字段、常量以方法等的描述,仅限该类自身的,至于从其它来源继承、实现的,可以通过 Summary 部分跳转至相应链接进行阅读。


1、嵌套类 
      Nested Classes

2、XML 属性 
    XML Attrs 

    2.1、继承的 XML 属性 
        Inherited XML Attrs 

       2.1.1、From class android.view.ViewGroup
       2.1.2、From class android.view.View

3、常量 
    Constants 

    3.1、继承的常量  
        Inherited Constants  

        3.1.1、From class android.view.ViewGroup

    3.1.2、From class android.view.View

4字段
    Fields

    4.1、继承的字段 
    Inherited Fields

        4.1.1、From class android.view.View

5公共构造器
    Ctors

6、方法
    7.1、公共方法 
        Methods 

    7.2、保护方法
                Protected Methods

    7.3、继承的方法
               Inherited Methods 






public class

线性布局 LinearLayout

extends  ViewGroup
java.lang.Object
   ↳ android.view.View
     ↳ android.view.ViewGroup
       ↳ android.widget.LinearLayout
Known Direct Subclasses

类概述
Class Overview

一个在单行或单行排列其子视图的布局。行的方向可以通过调用 setOrientation() 来设置。也可以指定重力(gravity),它会通过调用  setOrientation() 来指定所有子元素的对齐方式;或通过设置 LinearLayout.LayoutParams 的权重(weight)成员变量来指定特定的子视图扩展以填充布局中的余下空间。默认方向是水平方向(horizontal)。
A Layout that arranges its children in a single column or a single row. The direction of the row can be set by calling setOrientation(). You can also specify gravity, which specifies the alignment of all the child elements by calling setGravity() or specify that specific children grow to fill up any remaining space in the layout by setting the weight member of LinearLayout.LayoutParams. The default orientation is horizontal.

查看 线性布局指南
See the Linear Layout guide.

也可以查看 android.widget.LinearLayout.LayoutParams 获得布局属性。
Also see android.widget.LinearLayout.LayoutParams for layout attributes。





XML 属性
XML Attributes

android:baselineAligned(基线对齐)

当设置为 false,避勉布局对齐其子视图的基线。该特性在子视图使用不同重力(gravity)值时特别有用。默认值是 true。
When set to false, prevents the layout from aligning its children's baselines. This attribute is particularly useful when the children use different values for gravity. The default value is true.

必须为布尔值,或是 "true" 或是 "false"。
Must be a boolean value, either "true" or "false".

也可以是包含这一类型值的资源的引用(格式如:"@[package:]type:name")或主题属性(格式如:"?[package:][type:]name"
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.

其相当于全局属性资源标志  baselineAligned。
This corresponds to the global attribute resource symbol baselineAligned.

相关方法
Related Methods
  • setBaselineAligned(boolean)

android:baselineAlignedChildIndex

When a linear layout is part of another layout that is baseline aligned, it can specify which of its children to baseline align to (that is, which child TextView).

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 baselineAlignedChildIndex.

Related Methods
  • setBaselineAlignedChildIndex(int)

android:divider

Drawable to use as a vertical divider between buttons.

May be a reference to another resource, in the form "@[+][package:]type:name" or to a theme attribute in the form "?[package:][type:]name".

May be a color value, in the form of "#rgb", "#argb", "#rrggbb", or "#aarrggbb".

This corresponds to the global attribute resource symbol divider.

Related Methods
  • setDividerDrawable(Drawable)

android:gravity

Specifies how an object should position its content, on both the X and Y axes, within its own bounds.

Must be one or more (separated by '|') of the following constant values.

Constant Value Description
top 0x30 Push object to the top of its container, not changing its size.
bottom 0x50 Push object to the bottom of its container, not changing its size.
left 0x03 Push object to the left of its container, not changing its size.
right 0x05 Push object to the right of its container, not changing its size.
center_vertical 0x10 Place object in the vertical center of its container, not changing its size.
fill_vertical 0x70 Grow the vertical size of the object if needed so it completely fills its container.
center_horizontal 0x01 Place object in the horizontal center of its container, not changing its size.
fill_horizontal 0x07 Grow the horizontal size of the object if needed so it completely fills its container.
center 0x11 Place the object in the center of its container in both the vertical and horizontal axis, not changing its size.
fill 0x77 Grow the horizontal and vertical size of the object if needed so it completely fills its container.
clip_vertical 0x80 Additional option that can be set to have the top and/or bottom edges of the child clipped to its container's bounds. The clip will be based on the vertical gravity: a top gravity will clip the bottom edge, a bottom gravity will clip the top edge, and neither will clip both edges.
clip_horizontal 0x08 Additional option that can be set to have the left and/or right edges of the child clipped to its container's bounds. The clip will be based on the horizontal gravity: a left gravity will clip the right edge, a right gravity will clip the left edge, and neither will clip both edges.
start 0x00800003 Push object to the beginning of its container, not changing its size.
end 0x00800005 Push object to the end of its container, not changing its size.

This corresponds to the global attribute resource symbol gravity.

Related Methods
  • setGravity(int)

android:measureWithLargestChild

When set to true, all children with a weight will be considered having the minimum size of the largest child. If false, all children are measured normally.

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 measureWithLargestChild.

Related Methods
  • setMeasureWithLargestChildEnabled(boolean)

android:orientation

Should the layout be a column or a row? Use "horizontal" for a row, "vertical" for a column. The default is horizontal.

Must be one of the following constant values.

Constant Value Description
horizontal 0 Defines an horizontal widget.
vertical 1 Defines a vertical widget.

This corresponds to the global attribute resource symbol orientation.

Related Methods
  • setOrientation(int)

android:weightSum

Defines the maximum weight sum. If unspecified, the sum is computed by adding the layout_weight of all of the children. This can be used for instance to give a single child 50% of the total available space by giving it a layout_weight of 0.5 and setting the weightSum to 1.0.

Must be a floating point value, such as "1.2".

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 weightSum.

Related Methods

    Constants

    public static final int HORIZONTAL

    Added in  API level 1

    Constant Value: 0 (0x00000000)

    public static final int SHOW_DIVIDER_BEGINNING

    Added in  API level 11

    Show a divider at the beginning of the group.

    Constant Value: 1 (0x00000001)

    public static final int SHOW_DIVIDER_END

    Added in  API level 11

    Show a divider at the end of the group.

    Constant Value: 4 (0x00000004)

    public static final int SHOW_DIVIDER_MIDDLE

    Added in  API level 11

    Show dividers between each item in the group.

    Constant Value: 2 (0x00000002)

    public static final int SHOW_DIVIDER_NONE

    Added in  API level 11

    Don't show any dividers.

    Constant Value: 0 (0x00000000)

    public static final int VERTICAL

    Added in  API level 1

    Constant Value: 1 (0x00000001)

    Public Constructors

    public LinearLayout (Context context)

    Added in  API level 1

    public LinearLayout (Context context, AttributeSet attrs)

    Added in  API level 1

    public LinearLayout (Context context, AttributeSet attrs, int defStyle)

    Added in  API level 11

    Public Methods

    public LinearLayout.LayoutParams generateLayoutParams (AttributeSet attrs)

    Added in  API level 1

    Returns a new set of layout parameters based on the supplied attributes set.

    Parameters
    attrs the attributes to build the layout parameters from
    Returns
    • an instance of ViewGroup.LayoutParams or one of its descendants

    public int getBaseline ()

    Added in  API level 1

    Return the offset of the widget's text baseline from the widget's top boundary. If this widget does not support baseline alignment, this method returns -1.

    Returns
    • the offset of the baseline within the widget's bounds or -1 if baseline alignment is not supported

    public int getBaselineAlignedChildIndex ()

    Added in  API level 1

    Returns
    • The index of the child that will be used if this layout is part of a larger layout that is baseline aligned, or -1 if none has been set.

    public Drawable getDividerDrawable ()

    Added in  API level 16

    Related XML Attributes
    • android:divider
    Returns
    • the divider Drawable that will divide each item.
    See Also
    • setDividerDrawable(Drawable)

    public int getDividerPadding ()

    Added in  API level 14

    Get the padding size used to inset dividers in pixels

    See Also
    • setShowDividers(int)
    • setDividerDrawable(Drawable)
    • setDividerPadding(int)

    public int getOrientation ()

    Added in  API level 1

    Returns the current orientation.

    Returns
    • either HORIZONTAL or VERTICAL

    public int getShowDividers ()

    Added in  API level 11

    Returns
    • A flag set indicating how dividers should be shown around items.
    See Also
    • setShowDividers(int)

    public float getWeightSum ()

    Added in  API level 1

    Returns the desired weights sum.

    Returns
    • A number greater than 0.0f if the weight sum is defined, or a number lower than or equals to 0.0f if not weight sum is to be used.

    public boolean isBaselineAligned ()

    Added in  API level 1

    Indicates whether widgets contained within this layout are aligned on their baseline or not.

    Returns
    • true when widgets are baseline-aligned, false otherwise

    public boolean isMeasureWithLargestChildEnabled ()

    Added in  API level 11

    When true, all children with a weight will be considered having the minimum size of the largest child. If false, all children are measured normally.

    Related XML Attributes
    • android:measureWithLargestChild
    Returns
    • True to measure children with a weight using the minimum size of the largest child, false otherwise.

    public void onInitializeAccessibilityEvent (AccessibilityEvent event)

    Added in  API level 14

    Initializes 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.

    Parameters
    event The event to initialize.

    public void onInitializeAccessibilityNodeInfo (AccessibilityNodeInfo info)

    Added in  API level 14

    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.

    Parameters
    info The instance to initialize.

    public void setBaselineAligned (boolean baselineAligned)

    Added in  API level 1

    Defines whether widgets contained in this layout are baseline-aligned or not.

    Related XML Attributes
    • android:baselineAligned
    Parameters
    baselineAligned true to align widgets on their baseline, false otherwise

    public void setBaselineAlignedChildIndex (int i)

    Added in  API level 1

    Related XML Attributes
    • android:baselineAlignedChildIndex
    Parameters
    i The index of the child that will be used if this layout is part of a larger layout that is baseline aligned.

    public void setDividerDrawable (Drawable divider)

    Added in  API level 11

    Set a drawable to be used as a divider between items.

    Related XML Attributes
    • android:divider
    Parameters
    divider Drawable that will divide each item.
    See Also
    • setShowDividers(int)

    public void setDividerPadding (int padding)

    Added in  API level 14

    Set padding displayed on both ends of dividers.

    Parameters
    padding Padding value in pixels that will be applied to each end
    See Also
    • setShowDividers(int)
    • setDividerDrawable(Drawable)
    • getDividerPadding()

    public void setGravity (int gravity)

    Added in  API level 1

    Describes how the child views are positioned. Defaults to GRAVITY_TOP. If this layout has a VERTICAL orientation, this controls where all the child views are placed if there is extra vertical space. If this layout has a HORIZONTAL orientation, this controls the alignment of the children.

    Related XML Attributes
    • android:gravity
    Parameters
    gravity See Gravity

    public void setHorizontalGravity (int horizontalGravity)

    Added in  API level 1

    public void setMeasureWithLargestChildEnabled (boolean enabled)

    Added in  API level 11

    When set to true, all children with a weight will be considered having the minimum size of the largest child. If false, all children are measured normally. Disabled by default.

    Related XML Attributes
    • android:measureWithLargestChild
    Parameters
    enabled True to measure children with a weight using the minimum size of the largest child, false otherwise.

    public void setOrientation (int orientation)

    Added in  API level 1

    Should the layout be a column or a row.

    Related XML Attributes
    • android:orientation
    Parameters
    orientation Pass HORIZONTAL or VERTICAL. Default value is HORIZONTAL.

    public void setShowDividers (int showDividers)

    Added in  API level 11

    Set how dividers should be shown between items in this layout

    Parameters
    showDividers One or more of SHOW_DIVIDER_BEGINNINGSHOW_DIVIDER_MIDDLE, or SHOW_DIVIDER_END, or SHOW_DIVIDER_NONE to show no dividers.

    public void setVerticalGravity (int verticalGravity)

    Added in  API level 1

    public void setWeightSum (float weightSum)

    Added in  API level 1

    Defines the desired weights sum. If unspecified the weights sum is computed at layout time by adding the layout_weight of each child. This can be used for instance to give a single child 50% of the total available space by giving it a layout_weight of 0.5 and setting the weightSum to 1.0.

    Parameters
    weightSum a number greater than 0.0f, or a number lower than or equals to 0.0f if the weight sum should be computed from the children's layout_weight

    public boolean shouldDelayChildPressedState ()

    Added in  API level 14

    Return true if the pressed state should be delayed for children or descendants of this ViewGroup. Generally, this should be done for containers that can scroll, such as a List. This prevents the pressed state from appearing when the user is actually trying to scroll the content. The default implementation returns true for compatibility reasons. Subclasses that do not scroll should generally override this method and return false.

    Protected Methods

    protected boolean checkLayoutParams (ViewGroup.LayoutParams p)

    Added in  API level 1

    protected LinearLayout.LayoutParams generateDefaultLayoutParams ()

    Added in  API level 1

    Returns a set of layout parameters with a width of MATCH_PARENT and a height of WRAP_CONTENT when the layout's orientation is VERTICAL. When the orientation is HORIZONTAL, the width is set to WRAP_CONTENT and the height to WRAP_CONTENT.

    Returns
    • a set of default layout parameters or null

    protected LinearLayout.LayoutParams generateLayoutParams (ViewGroup.LayoutParams p)

    Added in  API level 1

    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.

    Parameters
    p The layout parameters to convert into a suitable set of layout parameters for this ViewGroup.
    Returns
    • an instance of ViewGroup.LayoutParams or one of its descendants

    protected void onDraw (Canvas canvas)

    Added in  API level 1

    Implement this to do your drawing.

    Parameters
    canvas the canvas on which the background will be drawn

    protected void onLayout (boolean changed, int l, int t, int r, int b)

    Added in  API level 1

    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.

    Parameters
    changed This is a new size or position for this view
    l Left position, relative to parent
    t Top position, relative to parent
    r Right position, relative to parent
    b Bottom position, relative to parent

    protected void onMeasure (int widthMeasureSpec, int heightMeasureSpec)

    Added in  API level 1

    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()).

    Parameters
    widthMeasureSpec horizontal space requirements as imposed by the parent. The requirements are encoded with View.MeasureSpec.
    heightMeasureSpec vertical space requirements as imposed by the parent. The requirements are encoded with View.MeasureSpec.







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