Android 使用View类绘图

View类是Android的一个超类，这个类几乎包含了所有的屏幕类型，每一个View都有一个用户绘画的画布。任何一个View类都只要重写onDraw方法来实现界面显示。

package com.Aina.Android;import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.view.View;public class ImageView extends View {public static int x = 20;public static int y = 20;public ImageView(Context context) {super(context);}/** * 绘制方法. */@Overrideprotected void onDraw(Canvas canvas) {super.onDraw(canvas);Paint paint = new Paint();paint.setColor(Color.RED);//设置颜色canvas.drawRect(x, y, x+40, y+40, paint);//绘制一个矩形}}

package com.Aina.Android;import android.app.Activity;import android.os.Bundle;import android.os.Handler;import android.os.Message;import android.view.KeyEvent;import android.view.MotionEvent;import android.view.Window;import android.view.WindowManager;import android.util.DisplayMetrics;import android.util.Log;public class Test_View extends Activity {/** Called when the activity is first created. */private ImageView iv = null;private static final int MSG = 0x0000001;private int DisplayWidth = 0, DisplayHeight = 0;@Overridepublic void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);//隐藏标题栏和状态栏也可以设置主题（Theme）在AndridManifest.xml里面设置：android:theme="@android:style/Theme.Black.NoTitleBar.Fullscreen"Window window = this.getWindow();window.setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,WindowManager.LayoutParams.FLAG_FULLSCREEN);//隐藏状态栏this.requestWindowFeature(Window.FEATURE_NO_TITLE);//隐藏标题栏iv = new ImageView(this);setContentView(iv);// 获得屏幕宽带和高度DisplayMetrics dm = new DisplayMetrics();this.getWindowManager().getDefaultDisplay().getMetrics(dm);DisplayWidth = dm.widthPixels;// 屏幕宽带DisplayHeight = dm.heightPixels;// 屏幕高度MyThread th = new MyThread();th.start();}private Handler handle = new Handler() {public void handleMessage(Message msg) {super.handleMessage(msg);if (msg.what == MSG) {iv.invalidate();// 更新界面}}};class MyThread extends Thread {public void run() {while (!Thread.currentThread().isInterrupted()) {// 当前线程没有中断try {Message msg = new Message();msg.what = MSG;Test_View.this.handle.sendMessage(msg);// 发送消息Thread.sleep(100);} catch (Exception ex) {ex.printStackTrace();Thread.currentThread().interrupt();// 中断当前线程.}}}}/*使用postInvalidate()方法更新界面，可以直接在线程里面更新。 * class MyThread extends Thread { public void run() { while * (!Thread.currentThread().isInterrupted()) {// 当前线程没有中断 try { * Thread.sleep(100); iv.postInvalidate(); } catch (Exception ex) { * ex.printStackTrace(); Thread.currentThread().interrupt();// 中断当前线程. } } } * } *//** * 触笔事件 */@Overridepublic boolean onTouchEvent(MotionEvent event) {int x = (int) event.getX();int y = (int) event.getY();ImageView.x = x;ImageView.y=y;Log.d("EVENT", x+"|"+y);return super.onTouchEvent(event);}/** * 键盘按下事件 */@Overridepublic boolean onKeyDown(int keyCode, KeyEvent event) {switch (keyCode) {case KeyEvent.KEYCODE_DPAD_DOWN:// 向下Log.d("y", ImageView.y + "");if (ImageView.y + 40 >= DisplayHeight) {ImageView.y = DisplayHeight - 40;} else {ImageView.y += 5;}break;case KeyEvent.KEYCODE_DPAD_UP:// 向上if (ImageView.y <= 0) {ImageView.y = 0;} else {ImageView.y -= 5;}break;case KeyEvent.KEYCODE_DPAD_LEFT:// 向左if (ImageView.x <= 0) {ImageView.x = 0;} else {ImageView.x -= 5;}break;case KeyEvent.KEYCODE_DPAD_RIGHT:// 向右if (ImageView.x + 40 >= DisplayWidth) {ImageView.x = DisplayWidth - 40;} else {ImageView.x += 5;}break;default:break;}return super.onKeyDown(keyCode, event);}/** * 键盘按下之后弹起事件 */@Overridepublic boolean onKeyUp(int keyCode, KeyEvent event) {return super.onKeyUp(keyCode, event);}}

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