android Region 类介绍

文章目录

1、简介
2、构造函数
2、常用方法
- 1） setEmpty()
- 2）set（）
- 3） isEmpty（）
- 4） isRect（)
- 5） isComplex（）
- 6） contains（）
- 7) getBounds()
- 8）quickContains（）
- 9）op（）

1、简介

Region意思是区域,范围.先了解有啥api给我们使用,然后每个api啥意思,我们就可以根据这个做出我们想要的效果出来,自定义view学习一般是这样的吧,至少个人是这么认为的.

2、构造函数

public Region() {this(nativeConstructor());
}/** Return a copy of the specified region
*/
public Region(Region region) {this(nativeConstructor());nativeSetRegion(mNativeRegion, region.mNativeRegion);
}/** Return a region set to the specified rectangle
*/
public Region(Rect r) {mNativeRegion = nativeConstructor();nativeSetRect(mNativeRegion, r.left, r.top, r.right, r.bottom);
}/** Return a region set to the specified rectangle
*/
public Region(int left, int top, int right, int bottom) {mNativeRegion = nativeConstructor();nativeSetRect(mNativeRegion, left, top, right, bottom);
}

我们发现有四个构造函数,先每个函数试试什么意思,

package com.simple;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.graphics.Region;
import android.graphics.RegionIterator;
import android.util.AttributeSet;
import android.view.View;
/*** Created by admin on 2017/7/11.*/
public class RegionView extends View {private Paint mPaint;public RegionView(Context context) {this(context,null);}public RegionView(Context context, AttributeSet attrs) {this(context, attrs,0);}public RegionView(Context context, AttributeSet attrs, int defStyleAttr) {super(context, attrs, defStyleAttr);initPaint();  //初始化 画笔}private void initPaint() {mPaint = new Paint();mPaint.setColor(Color.GREEN);mPaint.setStrokeWidth(3);}@Overrideprotected void onDraw(Canvas canvas) {super.onDraw(canvas);Region region = new Region(); //创建一个 Region  对象drawRegion(canvas,region,mPaint); //自定义方法 绘制 Region}private void drawRegion(Canvas canvas,Region rgn,Paint paint){RegionIterator iter = new RegionIterator(rgn);Rect r = new Rect();while (iter.next(r)) {canvas.drawRect(r, paint);}}
}

上面是使用空的构造函数创建Region对象,如图:

用崔健的一首歌来形容是一无所有啊,对,没错,确实是什么都没有,因为空的构造函数是没指定区域的,哪它就相当于是(0,0)坐标位置了.

现在构造函数改变一下:

@Override
protected void onDraw(Canvas canvas) {super.onDraw(canvas);Region region = new Region(0,0,100,100); //创建一个 有区域参数的 Region  对象drawRegion(canvas,region,mPaint);
}
private void drawRegion(Canvas canvas,Region rgn,Paint paint)
{RegionIterator iter = new RegionIterator(rgn);Rect r = new Rect();while (iter.next(r)) {canvas.drawRect(r, paint);}
}

效果图:

另外也可以用 region 对象来赋值传递

@Override
protected void onDraw(Canvas canvas) {super.onDraw(canvas);Region region1 = new Region(0,0,100,100); //创建一个 region  对象Region region = new Region(region1); //用已有对象 创建另一个drawRegion(canvas,region,mPaint);
}
private void drawRegion(Canvas canvas,Region rgn,Paint paint)
{RegionIterator iter = new RegionIterator(rgn);Rect r = new Rect();while (iter.next(r)) {canvas.drawRect(r, paint);}
}

2、常用方法

1） setEmpty()

就是把之前的区域给置空

@Override
protected void onDraw(Canvas canvas) {super.onDraw(canvas);Region region = new Region(0,0,100,100);//region.setEmpty();  //打开函数 将什么也看不到drawRegion(canvas,regi on,mPaint);
}
private void drawRegion(Canvas canvas,Region rgn,Paint paint)
{RegionIterator iter = new RegionIterator(rgn);Rect r = new Rect();while (iter.next(r)) {canvas.drawRect(r, paint);}
}

2）set（）

用新的区域覆盖原来的区域

例子:@Override
protected void onDraw(Canvas canvas) {super.onDraw(canvas);Region region = new Region(0,0,100,100);region.setEmpty();Region region1 = new Region(0,0,100,100);region.set(region1);drawRegion(canvas,region,mPaint);
}
private void drawRegion(Canvas canvas,Region rgn,Paint paint)
{RegionIterator iter = new RegionIterator(rgn);Rect r = new Rect();while (iter.next(r)) {canvas.drawRect(r, paint);}
}

我显示给Region设置了一个矩形,然后又置为空了,然后又给它设置了一个矩形,相当于是在原来空的区域地方设置了一个矩形。
图:

public boolean set(Rect r)把原来的区域用矩形来代替

@Override
protected void onDraw(Canvas canvas) {super.onDraw(canvas);Region region = new Region(0,0,100,100);region.setEmpty();region.set(new Rect(100,100,400,400)); //传递 矩形对象drawRegion(canvas,region,mPaint);
}
private void drawRegion(Canvas canvas,Region rgn,Paint paint)
{RegionIterator iter = new RegionIterator(rgn);Rect r = new Rect();while (iter.next(r)) {canvas.drawRect(r, paint);}
}

这是先给了一个矩形(0,0),(100,100)然后设置为空了,再然后给他设置了一个矩形(100,100)，(400,400).
图:

这个方法public boolean set(int left, int top, int right, int bottom)和上面的是同一个意思.不多讲

3） isEmpty（）

判断区域是否是空的

4） isRect（)

判断这个区域是否是矩形

5） isComplex（）

判断这个区域是否是多个矩形构建而成

6） contains（）

判断一个点是否在某个区域内
public native boolean contains(int x, int y) 判断这个点是否在这区域内

@Override
protected void onDraw(Canvas canvas) {super.onDraw(canvas);region = new Region(0,0,100,100);region.setEmpty();region.set(new Rect(100,100,400,400));mPaint.setColor(Color.GREEN);region.translate(0,50,region);drawRegion(canvas,region,mPaint);
}
private void drawRegion(Canvas canvas,Region rgn,Paint paint)
{RegionIterator iter = new RegionIterator(rgn);Rect r = new Rect();while (iter.next(r)) {canvas.drawRect(r, paint);}
}
@Override
public boolean onTouchEvent(MotionEvent event) {int downX = (int)event.getX();int downY = (int)event.getY();boolean isContain =  region.contains(downX,downY);if(isContain){Toast.makeText(getContext(),"这个点在这个区域内",Toast.LENGTH_LONG).show();}else{Toast.makeText(getContext(),"这个点不在这个区域内",Toast.LENGTH_LONG).show();}return true;
}

效果图:

7) getBounds()

返回的是区域的矩形位置

@Override
protected void onDraw(Canvas canvas) {super.onDraw(canvas);region = new Region(0,0,100,100);drawRegion(canvas,region,mPaint);Rect rect =  region.getBounds();Log.e(TAG,"left="+rect.left);Log.e(TAG,"top="+rect.top);Log.e(TAG,"right="+rect.right);Log.e(TAG,"bottom="+rect.bottom);
}
private void drawRegion(Canvas canvas,Region rgn,Paint paint)
{RegionIterator iter = new RegionIterator(rgn);Rect r = new Rect();while (iter.next(r)) {canvas.drawRect(r, paint);}
}
log:
07-11 03:47:13.188 6873-6873/com.simple E/RegionView: left=0
07-11 03:47:13.188 6873-6873/com.simple E/RegionView: top=0
07-11 03:47:13.188 6873-6873/com.simple E/RegionView: right=100
07-11 03:47:13.188 6873-6873/com.simple E/RegionView: bottom=100

getBounds(Rect r) 是把Region区域赋值给这个r,

 @Override
protected void onDraw(Canvas canvas) {super.onDraw(canvas);region = new Region(0,0,10,10);Rect rect = new Rect(200,200,240,240);drawRegion(canvas,region,mPaint);boolean  a=  region.getBounds(rect);Log.e(TAG,"a="+a);Log.e(TAG, ""+rect);}

log：
07-11 04:11:55.014 30301-30301/com.simple E/RegionView: a=true
07-11 04:11:55.014 30301-30301/com.simple E/RegionView: Rect(0, 0 - 10, 10)

从log发现rect原来是(200,200),(240,240)现在变成了(0,0),(10,10),倒推就是region的区域赋值给了rect,相等于rect = region.getRect(),

8）quickContains（）

quickContains(Rect r)这个方法是判断r这个矩形是否在区域内

@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
region = new Region(0,0,100,100);
Rect rect = new Rect(0,0,101,101);
drawRegion(canvas,region,mPaint);
boolean b = region.quickContains(rect);
Log.e(TAG,“b=”+b);
rect = new Rect(0,0,100,100);
boolean c = region.quickContains(rect);
Log.e(TAG,“c=”+c);
}


log:
07-11 05:10:07.150 19374-19374/com.simple E/RegionView: b=false
07-11 05:10:07.150 19374-19374/com.simple E/RegionView: c=true

9）op（）

public boolean op(Rect r, Op op)

第一个参数是Rect

第二个参数是op

查看源代码:

public enum Op {DIFFERENCE(0),INTERSECT(1),UNION(2),XOR(3),REVERSE_DIFFERENCE(4),REPLACE(5);Op(int nativeInt) {this.nativeInt = nativeInt;}/*** @hide*/public final int nativeInt;
}

写例子去证明每个啥意思:@Override
protected void onDraw(Canvas canvas) {super.onDraw(canvas);Rect rect1 = new Rect(200,200,500,500);Rect rect2 = new Rect(300,300,600,600);Paint paint = new Paint();paint.setColor(Color.RED);paint.setStyle(Paint.Style.STROKE);paint.setStrokeWidth(2);//绘制二个矩形canvas.drawRect(rect1, paint);canvas.drawRect(rect2, paint);//构造两个RegionRegion region1 = new Region(rect1);Region region2= new Region(rect2);**region1**.op(region2, Region.Op.DIFFERENCE);  //设置两个 区域操作为 DIFFERENCEpaint.setColor(Color.GREEN);paint.setStyle(Paint.Style.FILL);drawRegion(canvas, **region1**, paint);
}
private void drawRegion(Canvas canvas,Region rgn,Paint paint)
{RegionIterator iter = new RegionIterator(rgn);Rect r = new Rect();while (iter.next(r)) {canvas.drawRect(r, paint);}
}

DIFFERENCE
DIFFERENCE就是region1-(region1和region2的交集) 补集

INTERSECT
INTERSECT就是region1和region2的交集

UNION
UNION就是region1和region2的并集

XOR
XOR就是region1和region2的并集并减去region1和region2的交集异并集

REVERSE_DIFFERENCE
REVERSE_DIFFERENCE就是region2减去region2和region1的交集反转补集

REPLACE
REPLACE:就是显示region2的区域替换