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Android中怎么通過自定義View實(shí)現(xiàn)畫圓,很多新手對(duì)此不是很清楚,為了幫助大家解決這個(gè)難題,下面小編將為大家詳細(xì)講解,有這方面需求的人可以來學(xué)習(xí)下,希望你能有所收獲。
引入布局
<?xml version="1.0" encoding="utf-8"?> <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:id="@+id/activity_main" android:layout_width="match_parent" android:layout_height="match_parent" android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" tools:context="com.bwie.test.xuejian1508a20170928.MainActivity"> <com.bwie.test.xuejian1508a20170928.ViView android:layout_width="match_parent" android:layout_height="match_parent" /> </RelativeLayout>
自定義View的java類,繼承View
public class ViView extends View{ Paint paint; Context context; //構(gòu)造方法 public ViView(Context context) { super(context); } public ViView(Context context, AttributeSet attrs) { super(context, attrs); } public ViView(Context context, AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); } public ViView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) { super(context, attrs, defStyleAttr, defStyleRes); this.context=context; } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); } @Override protected void onLayout(boolean changed, int left, int top, int right, int bottom) { super.onLayout(changed, left, top, right, bottom); } /*繪圖*/ @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); //得到屏幕寬高 int width = getWidth(); int radius = width - 450/2; int height = getHeight(); // 創(chuàng)建畫筆 Paint paint1 = new Paint(); Paint paint2 = new Paint(); Paint paint3= new Paint(); // 消除鋸齒 paint1.setAntiAlias(true); paint2.setAntiAlias(true); paint3.setAntiAlias(true); //畫筆顏色 paint1.setColor(Color.RED); paint2.setColor(Color.WHITE); paint3.setColor(Color.BLUE); // 畫圓。確定位置 // canvas.drawRect(100,100,width/2,height/2,paint1); // canvas.drawCircle(100,100,100,paint1); // canvas.drawCircle(250,250,200,paint2); // canvas.drawCircle(500,500,300,paint3); //設(shè)置圓環(huán)形狀和大小 RectF oval = new RectF(width-radius,width-radius,width+radius,width+radius); paint1.setStrokeWidth(450); canvas.drawArc(oval,-90,90,false,paint1); canvas.drawCircle(width/2,height/2,450,paint1); canvas.drawCircle(width/2,height/2,300,paint2); canvas.drawCircle(width/2,height/2,200,paint3); } @Override public boolean onTouchEvent(MotionEvent event) { return super.onTouchEvent(event); } }
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