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Android开发实例篇（1）-----简易涂鸦板
一、概述
这次要做一个简单的涂鸦板应用，以前在Qt上实现过，突然想到要把它在Android上实现，呵呵，既简单又有趣。
二、实现
新建工程MyWall，修改/res/layout/main.xml文件，在里面添加一个SurfaceView和两个Button，用到了RelativeLayout布局，完整的main.xml文件如下：-
- 1 <?xml version="1.0" encoding="utf-8"?> 2 3 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" 4 android:layout_width="fill_parent" 5 android:layout_height="fill_parent" 6 android:orientation="vertical" 7 > 8 9 <SurfaceView 10 android:id="@+id/surfaceview"11 android:layout_width="fill_parent"12 android:layout_height="wrap_content"13 android:layout_above="@+id/line"14 android:layout_alignParentTop="true"15 />16 17 <LinearLayout 18 android:id="@+id/line"19 android:layout_width="fill_parent"20 android:layout_height="wrap_content"21 android:layout_alignParentBottom="true"22 >23 24 <Button 25 android:id="@+id/flushbutton"26 android:layout_width="fill_parent"27 android:layout_height="wrap_content" 28 android:layout_weight="1"29 android:text="清屏"30 />31 32 <Button 33 android:id="@+id/colorbutton"34 android:layout_width="fill_parent"35 android:layout_height="wrap_content"36 android:layout_weight="1" 37 android:text="颜色"38 />39 </LinearLayout>40 </RelativeLayout>
- 复制代码
- 1 package com.nan.wall; 2 3 import android.app.Activity; 4 import android.app.AlertDialog; 5 import android.app.Dialog; 6 import android.content.DialogInterface; 7 import android.graphics.Canvas; 8 import android.graphics.Color; 9 import android.graphics.Paint; 10 import android.graphics.Rect; 11 import android.os.Bundle; 12 import android.view.MotionEvent; 13 import android.view.SurfaceHolder; 14 import android.view.SurfaceView; 15 import android.view.View; 16 import android.widget.Button; 17 18 public class MyWallActivity extends Activity 19 { 20 private SurfaceView mSurfaceView = null; 21 private SurfaceHolder mSurfaceHolder = null; 22 private Button cleanButton = null; 23 private Button colorButton = null; 24 25 private float oldX = 0f; 26 private float oldY = 0f; 27 28 private boolean canDraw = false; 29 private Paint mPaint = null; 30 //用来记录当前是哪一种颜色 31 private int whichColor = 0; 32 33 /** Called when the activity is first created. */ 34 @Override 35 public void onCreate(Bundle savedInstanceState) 36 { 37 super.onCreate(savedInstanceState); 38 setContentView(R.layout.main); 39 40 mSurfaceView = (SurfaceView)this.findViewById(R.id.surfaceview); 41 mSurfaceHolder = mSurfaceView.getHolder(); 42 43 mPaint = new Paint(); 44 //画笔的颜色 45 mPaint.setColor(Color.RED); 46 //画笔的粗细 47 mPaint.setStrokeWidth(2.0f); 48 49 cleanButton = (Button)this.findViewById(R.id.flushbutton); 50 //按钮监听 51 cleanButton.setOnClickListener(new View.OnClickListener() 52 { 53 54 @Override 55 public void onClick(View v) 56 { 57 // TODO Auto-generated method stub 58 //锁定整个SurfaceView 59 Canvas mCanvas = mSurfaceHolder.lockCanvas(); 60 mCanvas.drawColor(Color.BLACK); 61 //绘制完成，提交修改 62 mSurfaceHolder.unlockCanvasAndPost(mCanvas); 63 //重新锁一次 64 mSurfaceHolder.lockCanvas(new Rect(0, 0, 0, 0)); 65 mSurfaceHolder.unlockCanvasAndPost(mCanvas); 66 } 67 }); 68 69 colorButton = (Button)this.findViewById(R.id.colorbutton); 70 //按钮监听 71 colorButton.setOnClickListener(new View.OnClickListener() 72 { 73 74 @Override 75 public void onClick(View v) 76 { 77 // TODO Auto-generated method stub 78 Dialog mDialog = new AlertDialog.Builder(MyWallActivity.this) 79 .setTitle("颜色设置") 80 .setSingleChoiceItems(new String[]{"红色","绿色","蓝色"}, whichColor, new DialogInterface.OnClickListener() 81 { 82 83 @Override 84 public void onClick(DialogInterface dialog, int which) 85 { 86 // TODO Auto-generated method stub 87 switch(which) 88 { 89 case 0: 90 { 91 //画笔的颜色 92 mPaint.setColor(Color.RED); 93 whichColor = 0; 94 break; 95 } 96 case 1: 97 { 98 //画笔的颜色 99 mPaint.setColor(Color.GREEN);100 whichColor = 1;101 break;102 }103 case 2:104 {105 //画笔的颜色106 mPaint.setColor(Color.BLUE);107 whichColor = 2;108 break;109 }110 }111 }112 })113 .setPositiveButton("确定", new DialogInterface.OnClickListener() 114 {115 116 @Override117 public void onClick(DialogInterface dialog, int which) 118 {119 // TODO Auto-generated method stub120 dialog.dismiss();121 }122 })123 .create();124 mDialog.show();125 }126 });127 128 }129 130 131 @Override132 public boolean onTouchEvent(MotionEvent event)133 { 134 //获取x坐标135 float x = event.getX();136 //获取y坐标（不知道为什么要减去一个偏移值才对得准屏幕）137 float y = event.getY()-50;138 139 //第一次进来先不管140 if(canDraw)141 { 142 //获取触屏事件143 switch(event.getAction())144 {145 //如果是拖动事件146 case MotionEvent.ACTION_MOVE:147 {148 149 //锁定整个SurfaceView150 Canvas mCanvas = mSurfaceHolder.lockCanvas(); 151 mCanvas.drawLine(x, y, oldX, oldY, mPaint);152 mSurfaceHolder.unlockCanvasAndPost(mCanvas);153 //重新锁一次154 mSurfaceHolder.lockCanvas(new Rect(0, 0, 0, 0));155 mSurfaceHolder.unlockCanvasAndPost(mCanvas);156 break;157 }158 }159 160 }161 //保存目前的x坐标值162 oldX = x;163 //保存目前的y坐标值164 oldY = y;165 166 canDraw = true;167 168 return true;169 }170 171 }
- 复制代码
在真机上运行效果如下：
呵呵，写得比较丑。
在获取了Y坐标后减去一个偏移值50，这个值是我直接猜出来的，没想到在模拟器和真机上定位得还蛮准的，哈哈。当然这个应用的功能不多，不过有兴趣的话可以再完善它，希望能起到抛砖引玉的作用。
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发表于 2012-03-03 20:56
