ConstraintLayout （约束布局）属性详情
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app:layout_constraintLeft_toLeftOf
//Constrains the left side of a child to the left side of a target child (contains the target child id).
表示此控件的左边框与某个控件的左边框对齐或者在其右边
app:layout_constraintLeft_toRightOf
//Constrains the left side of a child to the right side of a target child (contains the target child id).
表示此控件的左边框与某个控件的右边框对齐或者在其右边
app:layout_constraintRight_toLeftOf
//Constrains the right side of a child to the left side of a target child (contains the target child id).
表示此控件的右边框与某个控件的左边框对齐或在其左边
app:layout_constraintRight_toRightOf
//Constrains the right side of a child to the right side of a target child (contains the target child id).
表示此控件的右边框与某个控件的右边框对齐或在其左边
app:layout_constraintTop_toTopOf
//Constrains the top side of a child to the top side of a target child (contains the target child id).
表示此控件的顶部边框与某个控件的顶部边框水平对齐或在其下边
app:layout_constraintTop_toBottomOf
//Constrains the top side of a child to the bottom side of a target child (contains the target child id).
表示此控件的顶部边框与某个控件的底部边框水平对齐或在其下边
app:layout_constraintBottom_toTopOf
//Constrains the bottom side of a child to the top side of a target child (contains the target child id).
表示此控件的底部边框与某个控件的顶部边框水平对齐或其上边
app:layout_constraintBottom_toBottomOf
//Constrains the bottom side of a child to the bottom side of a target child (contains the target child id).
表示此控件的底部边框与某个控件的底部边框水平对齐或其上边
app:layout_constraintBaseline_toBaselineOf
//Constrains the baseline of a child to the baseline of a target child (contains the target child id).
表示此控件与某个控件水平对齐
app:layout_editor_absoluteX
//The design time location of the left side of the child.
表示此控件在布局中X轴的绝对坐标点。如图代码3
app:layout_editor_absoluteY
//The design time location of the right side of the child.
表示此控件在布局中Y轴的绝对坐标点。如图代码3
app:layout_constraintGuide_begin
//The distance of child (guideline) to the top or left edge of its parent.
表示在布局中引导线距顶部或左边框的距离（如：20dp表示距顶部或者左边框20dp）
app:layout_constraintGuide_end
//The distance of child (guideline) to the top or left edge of its parent.
表示在布局中引导线距底部的距离（如：10dp表示距顶部10dp）
app:layout_constraintGuide_percent
//The ratio of the distance to the parent's sides
表示在整个布局中引导线距离左边框的百分百（如：app:layout_constraintGuide_percent="0.5"表示距离左边框50%的位置）
app:layout_constraintStart_toEndOf
//Constrains the start side of a child to the end side of a target child (contains the target child id).
表示此控件的左边界在某个控件右边界的右边，及表示此控件在某个控件的右边
app:layout_constraintStart_toStartOf
//Constrains the start side of a child to the start side of a target child (contains the target child id).
表示此控件的左边界与某个控件的左边界在同一垂直线上
app:layout_constraintEnd_toStartOf
//Constrains the end side of a child to the start side of a target child (contains the target child id).
表示此控件的右边界与某个控件的左边界在同一垂直线上
app:layout_constraintEnd_toEndOf
//Constrains the end side of a child to the end side of a target child (contains the target child id).
表示此控件的右边界与某个控件的右边界对齐
app:layout_constraintHorizontal_bias
//The ratio between two connections when the left and right (or start and end) sides are constrained.
表示此控件在布局中的水平方向上的偏移百分百。如视图16，代码16
app:layout_constraintVertical_bias
//The ratio between two connections when the top and bottom sides are constrained.
表示此控件在布局中的的垂直方向上的偏移百分百。如视图16，代码16
app:layout_constraintDimensionRatio
//The child's side to constrain using dimensRatio.
表示两个控件的纵横比，而使用则需要把宽（layout_width）或者高（layout_height）设置为0dp，根据另一个属性和比例, 计算当前属性, 如两个图片控件的显示大小，app:layout_constraintDimensionRatio="4:3"；
app:layout_goneMarginLeft
//The left margin to use when the target is gone.
app:layout_goneMarginTop
//The top margin to use when the target is gone.
app:layout_goneMarginRight
//The right margin to use when the target is gone
app:layout_goneMarginBottom
//The bottom margin to use when the target is gone.
app:layout_goneMarginStart
//The start margin to use when the target is gone.
app:layout_goneMarginEnd
//The end margin to use when the target is gone.
