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分享Android涂鸦板，改变画笔颜色，之前画的颜色也变了？
自定义的MyView类：
MainActivity类：
主布局文件：
菜单布局：
package qieyi71.drawtool;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.CornerPathEffect;
import android.graphics.Paint;
import android.graphics.Path;
import android.media.MediaScannerConnection;
import android.net.Uri;
import android.os.Environment;
import android.util.AttributeSet;
import android.util.Log;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.View.OnTouchListener;
import android.widget.Toast;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.Date;
/**
* Created by Administrator on 2016/8/6.
*/
public class MyView extends SurfaceView implements SurfaceHolder.Callback,OnTouchListener{
private SurfaceHolder holder =null;
private Canvas canvas =null;
private Canvas canvasTemp =null;
private Bitmap bitmap =null;
public Paint p = null;
private Path path = new Path();
private boolean isfirst = true;
int color = Color.RED;
public MyView(Context context, AttributeSet attrs) {
super(context, attrs);
p= new Paint();
holder = getHolder();
holder.addCallback(this);
p.setColor(color);
p.setStrokeWidth(20);
p.setPathEffect(new CornerPathEffect(30));
p.setAntiAlias(true);
p.setStyle(Paint.Style.STROKE);
p.setStrokeCap(p.getStrokeCap().ROUND);
setOnTouchListener(this);
}
public void colorUpdate(int color){
canvas.save();
p.setColor(color);
canvas.restore();
}
public void draw(){
try {
canvas = holder.lockCanvas();
if (holder != null) {
canvasTemp.drawColor(Color.WHITE);
//p.setPathEffect(new CornerPathEffect(30));
canvasTemp.drawPath(path, p);
canvas.drawBitmap(bitmap, 0, 0, null);
}
} catch (Exception e) {
e.printStackTrace();
} finally {
if (holder != null) {
holder.unlockCanvasAndPost(canvas);
}
}
}
private String getTime(){
return new SimpleDateFormat("HHmmssSSS").format(new Date(System.currentTimeMillis()));
}
public void saveCanvas(View v) {
FileOutputStream fos = null;
try {
String fileName = getTime();
String filePath = Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_DCIM) + fileName + ".png";
fos = new FileOutputStream(new File(filePath));
bitmap.compress(Bitmap.CompressFormat.PNG, 100, fos);
MediaScannerConnection.scanFile(getContext(), new String[]{filePath}, null,
new MediaScannerConnection.OnScanCompletedListener() {
@Override
public void onScanCompleted(String path, Uri uri) {
Log.v("MediaScanWork", "file " + path
+ " was scanned seccessfully: " + uri);
}
});
Toast.makeText(getContext(), "保存成功,文件名:" + fileName + ".png", Toast.LENGTH_LONG).show();
clear();
} catch (IOException e) {
e.printStackTrace();
}
}
public void clear() {
path.reset();
isfirst=true;
draw();
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
bitmap = Bitmap.createBitmap(getWidth(), getHeight(),
Bitmap.Config.ARGB_8888);
canvasTemp = new Canvas(bitmap);
draw();
}
@Override
public void surfaceChanged(SurfaceHolder surfaceHolder, int i, int i1, int i2) {
}
@Override
public void surfaceDestroyed(SurfaceHolder surfaceHolder) {
}
@Override
public boolean onTouch(View v, MotionEvent motionEvent) {
switch (motionEvent.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
path.moveTo(motionEvent.getX(), motionEvent.getY());
draw();
break;
case MotionEvent.ACTION_MOVE:
if(motionEvent.getPointerCount()==1&&isfirst) {
path.lineTo(motionEvent.getX(), motionEvent.getY());
draw();
}
break;
case MotionEvent.ACTION_POINTER_DOWN:
isfirst=false;
break;
case MotionEvent.ACTION_UP:
isfirst = true;
break;
default:
break;
}
//invalidate();
return true;
}
}
MainActivity类：
package qieyi71.drawtool;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.graphics.Color;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.Menu;
import android.view.MenuInflater;
import android.view.MenuItem;
import android.view.View;
import android.widget.Button;
public class MainActivity extends AppCompatActivity {
private Button btn;
private MyView view;
private int whichColor = 0;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
btn = (Button) findViewById(R.id.btn);
view = (MyView)findViewById(R.id.draw);
btn.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
view.clear();
}
});
}
@Override
public boolean onCreateOptionsMenu(Menu menu) {
MenuInflater inflater = getMenuInflater();
inflater.inflate(R.menu.main_menu, menu);
return super.onCreateOptionsMenu(menu);
}
@Override
public boolean onOptionsItemSelected(MenuItem item) {
int item_id = item.getItemId();
switch (item_id) {
case R.id.menu1:
{
Dialog mDialog = new AlertDialog.Builder(MainActivity.this)
.setTitle("颜色设置")
.setSingleChoiceItems(new String[]{"白色","绿色","红色"}, whichColor, new DialogInterface.OnClickListener()
{
@Override
public void onClick(DialogInterface dialog, int which)
{
switch(which)
{
case 0:
{
view.p.setColor(Color.WHITE);
whichColor = 0;
break;
}
case 1:
{
view.colorUpdate(Color.GREEN);
whichColor = 1;
break;
}
case 2:
{
view.p.setColor(Color.RED);
whichColor = 2;
break;
}
}
}
})
.setPositiveButton("确定", new DialogInterface.OnClickListener()
{
@Override
public void onClick(DialogInterface dialog, int which)
{
dialog.dismiss();
}
})
.create();
mDialog.show();
break;
}
case R.id.menu2:
break;
case R.id.menu3:
view.saveCanvas(view);
break;
default:
return false;
}
return true;
}
}
主布局文件：
<?xml version="1.0" encoding="utf-8"?>
<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"
tools:context="qieyi71.drawtool.MainActivity">
<qieyi71.drawtool.MyView
android:id="@+id/draw"
android:layout_width="fill_parent"
android:layout_height="0dp"
android:layout_weight="1"
/>
<Button
android:id="@+id/btn"
android:layout_width="fill_parent"
android:layout_height="wrap_content"
android:text="清理画布"/>
</LinearLayout>
菜单布局：
<?xml version="1.0" encoding="utf-8"?>
<menu xmlns:android="http://schemas.android.com/apk/res/android">
<item android:id="@+id/menu1"
android:title="画笔颜色"
/>
<item android:id="@+id/menu2"
android:title="画笔大小"
/>
<item android:id="@+id/menu3"
android:title="保存"
/>
</menu>
...全文
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实质上这里的橡皮擦就是白色的画笔，根本不用使用到画笔的setXfermode方法，要搞一堆复杂的工程。 用户画完图之后可以保存图像。图像的文件名是当前的时间，保存的位置是sdcard的根目录。 制作过
