小案例的原理:
1、new Thread(mCustomView).start();
2、public class CustomView extends View implements Runnable
3、
<strong> public void run() { /*确保线程不断执行不断刷新界面*/ while (true) { try { /*如果半径小于200则自加否则大于200后重置半径值以实现往复*/ if (radiu <= 200) { radiu += 10; //刷新View postInvalidate(); } else { radiu = 0; } // 每执行一次暂停40毫秒 Thread.sleep(40); } catch (InterruptedException e) { e.printStackTrace(); } } }</strong>
activity_main.xml
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#FFFFFF" android:orientation="vertical" > <com.aigestudio.customviewdemo.views.CustomView android:id="@+id/main_cv" android:layout_width="match_parent" android:layout_height="match_parent" /> </LinearLayout>
package com.aigestudio.customviewdemo.activities; import android.app.Activity; import android.os.Bundle; import com.aigestudio.customviewdemo.R; import com.aigestudio.customviewdemo.views.CustomView; /** * 主界面 */ public class MainActivity extends Activity { private CustomView mCustomView;// 我们的自定义View @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); // 获取控件 mCustomView = (CustomView) findViewById(R.id.main_cv); /* * 开线程 */ new Thread(mCustomView).start(); } }
package com.aigestudio.customviewdemo.views; import android.app.Activity; import android.util.DisplayMetrics; /** * 测绘工具类 */ public final class MeasureUtil { /** * 获取屏幕尺寸 * * @param activity * Activity * @return 屏幕尺寸像素值,下标为0的值为宽,下标为1的值为高 */ public static int[] getScreenSize(Activity activity) { DisplayMetrics metrics = new DisplayMetrics(); activity.getWindowManager().getDefaultDisplay().getMetrics(metrics); return new int[] { metrics.widthPixels, metrics.heightPixels }; } }
package com.aigestudio.customviewdemo.views; import android.app.Activity; import android.content.Context; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.util.AttributeSet; import android.view.View; /** * 自定义View */ public class CustomView extends View implements Runnable { private Paint mPaint;// 画笔 private Context mContext;// 上下文环境引用 private int radiu;// 圆环半径 public CustomView(Context context) { this(context, null); } public CustomView(Context context, AttributeSet attrs) { super(context, attrs); mContext = context; // 初始化画笔 initPaint(); } /** * 初始化画笔 */ private void initPaint() { // 实例化画笔并打开抗锯齿 mPaint = new Paint(Paint.ANTI_ALIAS_FLAG); /* * 设置画笔样式为描边,圆环嘛……当然不能填充不然就么意思了 * * 画笔样式分三种: * 1.Paint.Style.STROKE:描边 * 2.Paint.Style.FILL_AND_STROKE:描边并填充 * 3.Paint.Style.FILL:填充 */ mPaint.setStyle(Paint.Style.STROKE); // 设置画笔颜色为浅灰色 mPaint.setColor(Color.LTGRAY); /* * 设置描边的粗细,单位:像素px * 注意:当setStrokeWidth(0)的时候描边宽度并不为0而是只占一个像素 */ mPaint.setStrokeWidth(10); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); // 绘制圆环 canvas.drawCircle(MeasureUtil.getScreenSize((Activity) mContext)[0] / 2, MeasureUtil.getScreenSize((Activity) mContext)[1] / 2, radiu, mPaint); } @Override public void run() { /* * 确保线程不断执行不断刷新界面 */ while (true) { try { /* * 如果半径小于200则自加否则大于200后重置半径值以实现往复 */ if (radiu <= 200) { radiu += 10; // 刷新View postInvalidate(); } else { radiu = 0; } // 每执行一次暂停40毫秒 Thread.sleep(40); } catch (InterruptedException e) { e.printStackTrace(); } } } }