Android learning notes: graffiti on pictures (clear screen)

Handwritingactivity. Java

package xiaosi.handWriting;import android.app.Activity;import android.app.AlertDialog;import android.content.DialogInterface;import android.os.Bundle;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;public class HandWritingActivity extends Activity{/** Called when the activity is first created. */private HandWrite handWrite = null;private Button clear = null;@Overridepublic void onCreate(Bundle savedInstanceState){super.onCreate(savedInstanceState);setContentView(R.layout.main);handWrite = (HandWrite)findViewById(R.id.handwriteview);clear = (Button)findViewById(R.id.clear);clear.setOnClickListener(new clearListener());}     private class clearListener implements OnClickListener{public void onClick(View v){handWrite.clear();}}}

Handwrite. Java

public class HandWrite extends View{    private Paint paint = null;    private Bitmap originalBitmap = null;    private Bitmap new1Bitmap = null;    private Bitmap new2Bitmap = null;    private float clickX = 0,clickY = 0;    private float startX = 0,startY = 0;    private boolean isMove = true;    private boolean isClear = false;    private int color = Color.GREEN;    private float strokeWidth = 2.0f;public HandWrite(Context context, AttributeSet attrs){super(context, attrs);originalBitmap = BitmapFactory.decodeResource(getResources(), R.drawable.girl_a);new1Bitmap = Bitmap.createBitmap(originalBitmap);}    public void clear(){    isClear = true;    new2Bitmap = Bitmap.createBitmap(originalBitmap);    invalidate();    }    public void setstyle(float strokeWidth){    this.strokeWidth = strokeWidth;    }@Overrideprotected void onDraw(Canvas canvas){super.onDraw(canvas);canvas.drawBitmap(HandWriting(new1Bitmap), 0, 0,null);}public Bitmap HandWriting(Bitmap originalBitmap){Canvas canvas = null;if(isClear){canvas = new Canvas(new2Bitmap);}else{canvas = new Canvas(originalBitmap);}paint = new Paint();paint.setStyle(Style.STROKE);paint.setAntiAlias(true);paint.setColor(color);paint.setStrokeWidth(strokeWidth);if(isMove){canvas.drawLine(startX, startY, clickX, clickY, paint);}startX = clickX;startY = clickY;if(isClear){return new2Bitmap;}return originalBitmap;}@Overridepublic boolean onTouchEvent(MotionEvent event){clickX = event.getX();clickY = event.getY();if(event.getAction() == MotionEvent.ACTION_DOWN){isMove = false;invalidate();return true;}else if(event.getAction() == MotionEvent.ACTION_MOVE){isMove = true;invalidate();return true;}return super.onTouchEvent(event);}   }

Main. xml

<? XML version = "1.0" encoding = "UTF-8"?> <Linearlayout xmlns: Android = "http://schemas.android.com/apk/res/android" Android: layout_width = "fill_parent" Android: layout_height = "fill_parent" Android: Orientation = "vertical"> <xiaosi. handwriting. handwrite Android: Id = "@ + ID/handwriteview" Android: layout_width = "fill_parent" Android: layout_height = "380dp"/> <linearlayout Android: layout_width = "fill_parent" Android: layout_height = "fill_parent" Android: Orientation = "horizontal" Android: gravity = "center_horizontal"> <button Android: Id = "@ + ID/clear" Android: layout_width = "200dp" Android: layout_height = "wrap_content" Android: text = "clear screen"/> </linearlayout>