canvas画图

写一个class继承view

package com.example.myapplication.login;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.support.annotation.Nullable;
import android.util.AttributeSet;
import android.view.View;
public class CircleIView extends View {

public int width;
public int height;
public Paint paint;
public CircleIView(Context context) {
    super(context);
}

public CircleIView(Context context,  @Nullable AttributeSet attrs) {
    super(context, attrs);
    paint=new Paint();
    paint.setColor(Color.YELLOW);
}

public CircleIView(Context context,  @Nullable AttributeSet attrs, int defStyleAttr) {
    super(context, attrs, defStyleAttr);
}

@Override
protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    canvas.drawCircle(width/2,height/2,50,paint);
}

@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    super.onMeasure(widthMeasureSpec, heightMeasureSpec);
    width=getMeasuredWidth();
    height=getMeasuredHeight();
}

}

在Activity展示

    ObjectAnimator objectAnimator=ObjectAnimator.ofFloat(imageView,"translationY",0f,400f);
    objectAnimator.setDuration(5000);
    objectAnimator.start();