android.graphics.Rect类的详解

标签： AndroidRect

  分类：

 

Android中文API（5） 

public final class

Rect

extends  Object
implements  Parcelable

java.lang.Object
↳	android.graphics.Rect

Public Constructors
	Rect() Create a new empty Rect.
	Rect(int left, int top, int right, int bottom) Create a new rectangle with the specified coordinates.
	Rect( Rect r) Create a new rectangle, initialized with the values in the specified rectangle (which is left unmodified).

Public Methods
final int	centerX()获取矩阵中心点（x，y）
final int	centerY()
boolean	contains(int x, int y)是否包含（x,y）点 Returns true if (x,y) is inside the rectangle.
boolean	contains(int left, int top, int right, int bottom)是否包含（int left, int top, int right, int bottom）矩阵 Returns true iff the 4 specified sides of a rectangle are inside or equal to this rectangle.
boolean	contains( Rect r) Returns true iff the specified rectangle r is inside or equal to this rectangle.
int	describeContents() Parcelable interface methods
boolean	equals( Object obj) Compares this instance with the specified object and indicates if they are equal.
final float	exactCenterX()该方法和CenterX()类似，只是该方法精确度比它高（返回float类型）
final float	exactCenterY()
String	flattenToString() Return a string representation of the rectangle in a well-defined format.
final int	height()
void	inset(int dx, int dy) Inset the rectangle by (dx,dy).
boolean	intersect( Rect r) If the specified rectangle intersects this rectangle, return true and set this rectangle to that intersection, otherwise return false and do not change this rectangle.
boolean	intersect(int left, int top, int right, int bottom) If the rectangle specified by left,top,right,bottom intersects this rectangle, return true and set this rectangle to that intersection, otherwise return false and do not change this rectangle.
boolean	intersects(int left, int top, int right, int bottom) Returns true if this rectangle intersects the specified rectangle.
static boolean	intersects( Rect a,  Rect b) Returns true iff the two specified rectangles intersect.
final boolean	isEmpty() Returns true if the rectangle is empty (left >= right or top >= bottom)
void	offset(int dx, int dy)该矩阵在x轴和y轴分别发生的偏移量（很有用，可以上下移动矩阵） Offset the rectangle by adding dx to its left and right coordinates, and adding dy to its top and bottom coordinates.
void	offsetTo(int newLeft, int newTop)保持矩阵的宽高，矩阵的左上角偏移到（newLeft,newTop）该点 Offset the rectangle to a specific (left, top) position, keeping its width and height the same.
void	readFromParcel( Parcel in) Set the rectangle's coordinates from the data stored in the specified parcel.
void	set(int left, int top, int right, int bottom) Set the rectangle's coordinates to the specified values.
void	set( Rect src) Copy the coordinates from src into this rectangle.
void	setEmpty() Set the rectangle to (0,0,0,0)
boolean	setIntersect( Rect a,  Rect b) If rectangles a and b intersect, return true and set this rectangle to that intersection, otherwise return false and do not change this rectangle.
void	sort() Swap top/bottom or left/right if there are flipped (i.e.
String	toShortString() Return a string representation of the rectangle in a compact form.
String	toString() Returns a string containing a concise, human-readable description of this object.
static  Rect	unflattenFromString( String str) Returns a Rect from a string of the form returned by  flattenToString(), or null if the string is not of that form.
void	union(int left, int top, int right, int bottom) Update this Rect to enclose itself and the specified rectangle.
void	union( Rect r) Update this Rect to enclose itself and the specified rectangle.
void	union(int x, int y) Update this Rect to enclose itself and the [x,y] coordinate.
final int	width()
void	writeToParcel( Parcel out, int flags) Write this rectangle to the specified parcel.

1.   new Rect(150, 75, 260, 120)  

  这个构造方法需要四个参数这四个参数 指明了什么位置 ？我们就来解释怎么画 这个 矩形 
这四个 参数 分别代表的意思是：left   top   right   bottom  上下左右呗。啊，不是 是 左 上 右 下。 下面给大家解释  
left ： 矩形左边的X坐标  150  
top:    矩形顶部的Y坐标   75     
right :  矩形右边的X坐标   260    
bottom： 矩形底部的Y坐标 120    

说白了就是左上角的坐标是（150,75），右下角的坐标是（260,120），这样就好理解了

2、Rect类与RectF类（android.graphics.RectF）的区别??

答：主要还是在精度上的不同，他们分别是：int、float类型的