android Region 類介紹

文章目錄

1、簡介

Region意思是區域,範圍.先了解有啥api給我們使用,然後每個api啥意思,我們就可以根據這個做出我們想要的效果出來,自定義view學習一般是這樣的吧,至少個人是這麼認爲的.

2、構造函數

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);
}

我們發現有四個構造函數,先每個函數試試什麼意思,

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 畫筆
    }
    private void initPaint() {
        mPaint = new Paint();
        mPaint.setColor(Color.GREEN);
        mPaint.setStrokeWidth(3);
    }
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        Region region = new Region(); //創建一個 Region  對象
        drawRegion(canvas,region,mPaint); //自定義方法 繪製 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);
        }
    }
}

上面是使用空的構造函數創建Region對象,如圖:

用崔健的一首歌來形容是一無所有啊,對,沒錯,確實是什麼都沒有,因爲空的構造函數是沒指定區域的,哪它就相當於是(0,0)座標位置了.

現在構造函數改變一下:

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    Region region = new Region(0,0,100,100); //創建一個 有區域參數的 Region  對象
    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);
    }
}

效果圖:

另外也可以用 region 對象來賦值傳遞

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    Region region1 = new Region(0,0,100,100); //創建一個 region  對象
    Region region = new Region(region1); //用已有對象 創建另一個
    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()

就是把之前的區域給置空

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    Region region = new Region(0,0,100,100);
    //region.setEmpty();  //打開函數 將什麼也看不到
    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（）

用新的區域覆蓋原來的區域

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);
    }
}

我顯示給Region設置了一個矩形,然後又置爲空了,然後又給它設置了一個矩形,相當於是在原來空的區域地方設置了一個矩形。
圖:

public boolean set(Rect r)把原來的區域用矩形來代替

@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)); //傳遞 矩形對象
    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);
    }
}

這是先給了一個矩形(0,0),(100,100)然後設置爲空了,再然後給他設置了一個矩形(100,100)，(400,400).
圖:

這個方法public boolean set(int left, int top, int right, int bottom)和上面的是同一個意思.不多講

3） isEmpty（）

判斷區域是否是空的

4） isRect（)

判斷這個區域是否是矩形

5） isComplex（）

判斷這個區域是否是多個矩形構建而成

6） contains（）

判斷一個點是否在某個區域內
public native boolean contains(int x, int y) 判斷這個點是否在這區域內

@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(),"這個點在這個區域內",Toast.LENGTH_LONG).show();
    }else{
        Toast.makeText(getContext(),"這個點不在這個區域內",Toast.LENGTH_LONG).show();
    }
    return true;
}

效果圖:

7) getBounds()

返回的是區域的矩形位置

@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區域賦值給這個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)

從log發現rect原來是(200,200),(240,240)現在變成了(0,0),(10,10),倒推就是region的區域賦值給了rect,相等於rect = region.getRect(),

8）quickContains（）

quickContains(Rect r)這個方法是判斷r這個矩形是否在區域內

@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)

第一個參數是Rect

第二個參數是op

查看源代碼:

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;
}

寫例子去證明每個啥意思:


@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);
    //繪製二個矩形
    canvas.drawRect(rect1, paint);
    canvas.drawRect(rect2, paint);
    //構造兩個Region
    Region region1 = new Region(rect1);
    Region region2= new Region(rect2);
    **region1**.op(region2, Region.Op.DIFFERENCE);  //設置兩個 區域操作爲 DIFFERENCE
    paint.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) 補集

INTERSECT
INTERSECT就是region1和region2的交集

UNION
UNION就是region1和region2的並集

XOR
XOR就是region1和region2的並集並減去region1和region2的交集異並集

REVERSE_DIFFERENCE
REVERSE_DIFFERENCE就是region2減去region2和region1的交集反轉補集

REPLACE
REPLACE:就是顯示region2的區域替換

android Region 類介紹

文章目錄

1、簡介

2、構造函數

2、常用方法

1） setEmpty()

2）set（）

3） isEmpty（）

4） isRect（)

5） isComplex（）

6） contains（）

7) getBounds()

8）quickContains（）

9）op（）

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