Android之Canvas画画板

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前几篇都涉及到了Canvas，Paint，Bitmap的结合使用，这里就不多说了~

现在我要写的是画画板这个项目~

项目效果：

1.画笔的颜色的随意更改

2.画笔的大小也可以随着拖动条的拖动而改变

3.橡皮擦清除画的效果

4.画板的清空

效果图：

布局文件很简单：

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:orientation="vertical">    <LinearLayout         android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:orientation="horizontal">        <View        android:layout_width="50dp"        android:layout_height="50dp"        android:background="#ff0000"         android:id="@+id/red"/>    <View        android:layout_width="50dp"        android:layout_height="50dp"        android:background="#00ff00"         android:id="@+id/green"/>    <View        android:layout_width="50dp"        android:layout_height="50dp"        android:background="#0000ff"        android:id="@+id/blue"/>    <Button android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="橡皮擦"        android:onClick="click"/>    <Button         android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="清空"        android:onClick="clear"/>    </LinearLayout>    <SeekBar         android:layout_width="match_parent"        android:layout_height="wrap_content"        android:id="@+id/seek"/>    <ImageView         android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:id="@+id/iv"        android:background="@drawable/bg"/>    </LinearLayout>

MainActivity：

public class MainActivity extends Activity implements OnClickListener{private View red,green,blue;private SeekBar seek;private ImageView iv;private Bitmap baseBitmap,copyBitmap;private Canvas canvas;private Paint paint;private int startX,startY;public void click(View view){paint.setColor(Color.BLACK);paint.setStrokeWidth(40);}public void clear(View view){canvas.drawColor(Color.BLACK);paint.setColor(Color.BLACK);/*baseBitmap=BitmapFactory.decodeResource(getResources(), R.drawable.bg);iv.setImageBitmap(baseBitmap);*/}@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);red=(View)findViewById(R.id.red);green=(View)findViewById(R.id.green);blue=(View)findViewById(R.id.blue);iv=(ImageView) findViewById(R.id.iv);seek=(SeekBar) findViewById(R.id.seek);red.setOnClickListener(this);blue.setOnClickListener(this);green.setOnClickListener(this);baseBitmap=BitmapFactory.decodeResource(getResources(), R.drawable.bg);copyBitmap=Bitmap.createBitmap(baseBitmap.getWidth(), baseBitmap.getHeight(), baseBitmap.getConfig());canvas=new Canvas(copyBitmap);//画板的颜色canvas.drawColor(Color.BLACK);paint=new Paint();//画笔的颜色paint.setColor(Color.RED);iv.setOnTouchListener(new OnTouchListener() {@Overridepublic boolean onTouch(View v, MotionEvent event) {// TODO Auto-generated method stubswitch (event.getAction()) {case MotionEvent.ACTION_DOWN://落下startX=(int)event.getX();startY=(int)event.getY();break;case MotionEvent.ACTION_MOVE://移动int stopX=(int)event.getX();int stopY=(int)event.getY();canvas.drawLine(startX, startY, stopX, stopY, paint);startX=(int)event.getX();startY=(int)event.getY();iv.setImageBitmap(copyBitmap);break;case MotionEvent.ACTION_UP://离开default:break;}return true;}});seek.setOnSeekBarChangeListener(new OnSeekBarChangeListener() {@Overridepublic void onStopTrackingTouch(SeekBar seekBar) {// TODO Auto-generated method stubint progress=seekBar.getProgress();//使拖动条的取值为0f-2f，满足我们的取值要求float count=progress/50f;paint.setStrokeWidth(progress);}@Overridepublic void onStartTrackingTouch(SeekBar seekBar) {// TODO Auto-generated method stub}@Overridepublic void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {// TODO Auto-generated method stub}});}@Overridepublic void onClick(View v) {// TODO Auto-generated method stubswitch (v.getId()) {case R.id.red:paint.setColor(Color.RED);break;case R.id.green:paint.setColor(Color.GREEN);break;case R.id.blue:paint.setColor(Color.BLUE);break;default:break;}}}

因为代码不是很麻烦，所以现在不上传源码

有想要源码的可以联系我，到时候传上来~

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