Android利用canvas画画板
cg4f
9年前
首先新建一个项目工程，建立文件，如下图所示
首先配置页面布局文件activity_main.xml，如下图所示：
<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"> <ImageView android:id="@+id/iv" android:layout_width="wrap_content" android:layout_height="wrap_content" android:background="@drawable/bg" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="画笔的粗细" /> <SeekBar android:id="@+id/sb" android:layout_width="match_parent" android:layout_height="wrap_content" android:max="256" /> <TextView android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="颜色" /> <Spinner android:id="@+id/sp" android:layout_width="wrap_content" android:layout_height="wrap_content" android:entries="@array/color" /> <Button android:id="@+id/btn" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="保存" /> </LinearLayout>
然后书写主页的代码MainActivity.java代码如下
package com.xunfang.drawing; import java.io.File; import java.io.FileNotFoundException; import java.io.FileOutputStream; import android.app.Activity; import android.content.Intent; import android.graphics.Bitmap; import android.graphics.Bitmap.CompressFormat; import android.graphics.BitmapFactory; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Matrix; import android.graphics.Paint; import android.net.Uri; import android.os.Bundle; import android.os.Environment; import android.util.MonthDisplayHelper; import android.view.Menu; import android.view.MenuItem; import android.view.MotionEvent; import android.view.View; import android.view.View.OnClickListener; import android.view.View.OnTouchListener; import android.widget.AdapterView; import android.widget.AdapterView.OnItemClickListener; import android.widget.AdapterView.OnItemSelectedListener; import android.widget.Button; import android.widget.ImageView; import android.widget.SeekBar; import android.widget.Spinner; import android.widget.Toast; public class MainActivity extends Activity { private SeekBar sb; private ImageView iv; private Button btn; private Spinner sp; private String[] color ; private Bitmap bm; private Bitmap copy; private Canvas canvas; private Paint paint; private File file; private int yanse; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); //拿到在xml文件中定义的颜色数组 color = getResources().getStringArray(R.array.color) ; //实例化 initData(); //设置监听器 setLister(); //画画 loadingImage(); } private void loadingImage() { // 加载原始图片 bm = BitmapFactory.decodeResource(getResources(), R.drawable.bg); // 需要创建一个和原始的图片大小一样的空白图片(一张纸,上面没有任何数据) copy = bm.createBitmap(bm.getWidth(), bm.getHeight(), bm.getConfig()); // 需要一个画板,画板上铺上白纸 canvas= new Canvas(copy); // 创建画笔 paint= new Paint(); // 给imageView空间加载一个滑动监听器 iv.setOnTouchListener(new OnTouchListener() { int startx; int starty; @Override public boolean onTouch(View v, MotionEvent event) { // 拿到动作 int type = event.getAction(); switch (type) { case MotionEvent.ACTION_DOWN: startx = (int) event.getX(); starty = (int) event.getY(); break; case MotionEvent.ACTION_MOVE: int endx = (int) event.getX(); int endy = (int) event.getY(); //画画 canvas.drawLine(startx, starty, endx, endy, paint); startx = (int) event.getX(); starty = (int) event.getY(); iv.setImageBitmap(copy); break; case MotionEvent.ACTION_UP: break; } return true; } }); } private void setLister() { //下拉框 sp.setOnItemSelectedListener(new OnItemSelectedListener() { @Override public void onItemSelected(AdapterView<?> parent, View view, int position, long id) { Toast.makeText(getApplicationContext(), "你点击的是：" + color[position], 0).show(); switch (position) { case 1: paint.setColor(Color.GREEN); break; case 2: paint.setColor(Color.BLUE); break; case 3: paint.setColor(Color.BLACK); break; case 4: paint.setColor(Color.YELLOW); break; case 0: paint.setColor(Color.RED); break; } } @Override public void onNothingSelected(AdapterView<?> parent) { } }); //保存 btn.setOnClickListener(new OnClickListener() { @Override public void onClick(View v) { try { //指定图片的存储路径 file = new File(Environment.getExternalStorageDirectory().getAbsoluteFile()+"/draw.png"); FileOutputStream fos = new FileOutputStream(file); copy.compress(CompressFormat.PNG, 100, fos); Toast.makeText(getApplicationContext(), "保存成功", 0).show() ; } catch (Exception e) { } //欺骗系统,告诉系统插入一个sd卡 Intent intent = new Intent(); intent.setAction(intent.ACTION_MEDIA_MOUNTED); intent.setData(Uri.fromFile(file)); sendBroadcast(intent); } }); } private void initData() { sb = (SeekBar) findViewById(R.id.sb); btn = (Button) findViewById(R.id.btn); sp = (Spinner) findViewById(R.id.sp); iv = (ImageView) findViewById(R.id.iv); } }AndroidManifest.xml配置文件如下：
<?xml version="1.0" encoding="utf-8"?> <manifest xmlns:android="http://schemas.android.com/apk/res/android" package="com.xunfang.drawing" android:versionCode="1" android:versionName="1.0" > <uses-sdk android:minSdkVersion="16" android:targetSdkVersion="21" /> <application android:allowBackup="true" android:icon="@drawable/ic_launcher" android:label="@string/app_name" android:theme="@style/AppTheme" > <activity android:name=".MainActivity" android:label="@string/app_name" > <intent-filter> <action android:name="android.intent.action.MAIN" /> <category android:name="android.intent.category.LAUNCHER" /> </intent-filter> </activity> </application> </manifest>
然后用虚拟机测试如下所示：
可以在模拟器看一下，生成的文件
表示验证成功了
来自：http://www.cnblogs.com/ouysq/p/4641869.html