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：
1 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 2 xmlns:tools="http://schemas.android.com/tools" 3 android:layout_width="match_parent" 4 android:layout_height="match_parent" 5 android:orientation="vertical"> 6 7 <ImageView 8 android:id="@+id/iv" 9 android:layout_width="wrap_content" 10 android:layout_height="wrap_content" 11 android:background="@drawable/bg" 12 /> 13 <TextView 14 android:layout_width="wrap_content" 15 android:layout_height="wrap_content" 16 android:text="画笔的粗细" 17 /> 18 <SeekBar 19 android:id="@+id/sb" 20 android:layout_width="match_parent" 21 android:layout_height="wrap_content" 22 android:max="256" 23 /> 24 <TextView 25 android:layout_width="wrap_content" 26 android:layout_height="wrap_content" 27 android:text="颜色" 28 /> 29 <Spinner 30 android:id="@+id/sp" 31 android:layout_width="wrap_content" 32 android:layout_height="wrap_content" 33 android:entries="@array/color" 34 /> 35 <Button 36 android:id="@+id/btn" 37 android:layout_width="wrap_content" 38 android:layout_height="wrap_content" 39 android:text="保存" 40 /> 41 42 43 44 </LinearLayout>
然后书写主页的代码MainActivity.java代码如下
1 package com.xunfang.drawing;
2
3 import java.io.File;
4 import java.io.FileNotFoundException;
5 import java.io.FileOutputStream;
6
7 import android.app.Activity;
8 import android.content.Intent;
9 import android.graphics.Bitmap;
10 import android.graphics.Bitmap.CompressFormat;
11 import android.graphics.BitmapFactory;
12 import android.graphics.Canvas;
13 import android.graphics.Color;
14 import android.graphics.Matrix;
15 import android.graphics.Paint;
16 import android.net.Uri;
17 import android.os.Bundle;
18 import android.os.Environment;
19 import android.util.MonthDisplayHelper;
20 import android.view.Menu;
21 import android.view.MenuItem;
22 import android.view.MotionEvent;
23 import android.view.View;
24 import android.view.View.OnClickListener;
25 import android.view.View.OnTouchListener;
26 import android.widget.AdapterView;
27 import android.widget.AdapterView.OnItemClickListener;
28 import android.widget.AdapterView.OnItemSelectedListener;
29 import android.widget.Button;
30 import android.widget.ImageView;
31 import android.widget.SeekBar;
32 import android.widget.Spinner;
33 import android.widget.Toast;
34
35
36 public class MainActivity extends Activity {
37 private SeekBar sb;
38 private ImageView iv;
39 private Button btn;
40 private Spinner sp;
41 private String[] color ;
42
43 private Bitmap bm;
44 private Bitmap copy;
45 private Canvas canvas;
46 private Paint paint;
47 private File file;
48 private int yanse;
49
50 @Override
51 protected void onCreate(Bundle savedInstanceState) {
52 super.onCreate(savedInstanceState);
53 setContentView(R.layout.activity_main);
54
55 //拿到在xml文件中定义的颜色数组
56 color = getResources().getStringArray(R.array.color) ;
57 //实例化
58 initData();
59 //设置监听器
60 setLister();
61 //画画
62 loadingImage();
63
64 }
65 private void loadingImage() {
66 // 加载原始图片
67 bm = BitmapFactory.decodeResource(getResources(), R.drawable.bg);
68 // 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)
69 copy = bm.createBitmap(bm.getWidth(), bm.getHeight(), bm.getConfig());
70 // 需要一个画板,画板上铺上白纸
71 canvas= new Canvas(copy);
72 // 创建画笔
73 paint= new Paint();
74
75 // 给imageView空间加载一个滑动监听器
76 iv.setOnTouchListener(new OnTouchListener() {
77 int startx;
78 int starty;
79 @Override
80 public boolean onTouch(View v, MotionEvent event) {
81 // 拿到动作
82 int type = event.getAction();
83 switch (type) {
84 case MotionEvent.ACTION_DOWN:
85 startx = (int) event.getX();
86 starty = (int) event.getY();
87 break;
88 case MotionEvent.ACTION_MOVE:
89 int endx = (int) event.getX();
90 int endy = (int) event.getY();
91 //画画
92 canvas.drawLine(startx, starty, endx, endy, paint);
93 startx = (int) event.getX();
94 starty = (int) event.getY();
95 iv.setImageBitmap(copy);
96 break;
97 case MotionEvent.ACTION_UP:
98
99 break;
100 }
101 return true;
102 }
103 });
104
105 }
106 private void setLister() {
107 //下拉框
108 sp.setOnItemSelectedListener(new OnItemSelectedListener() {
109 @Override
110 public void onItemSelected(AdapterView<?> parent, View view,
111 int position, long id) {
112 Toast.makeText(getApplicationContext(), "你点击的是：" + color[position], 0).show();
113 switch (position) {
114 case 1:
115 paint.setColor(Color.GREEN);
116 break;
117 case 2:
118 paint.setColor(Color.BLUE);
119 break;
120 case 3:
121 paint.setColor(Color.BLACK);
122 break;
123 case 4:
124 paint.setColor(Color.YELLOW);
125 break;
126 case 0:
127 paint.setColor(Color.RED);
128 break;
129 }
130 }
131 @Override
132 public void onNothingSelected(AdapterView<?> parent) {
133 }
134 });
135 //保存
136 btn.setOnClickListener(new OnClickListener() {
137 @Override
138 public void onClick(View v) {
139 try {
140 //指定图片的存储路径
141 file = new File(Environment.getExternalStorageDirectory().getAbsoluteFile()+"/draw.png");
142 FileOutputStream fos = new FileOutputStream(file);
143 copy.compress(CompressFormat.PNG, 100, fos);
144 Toast.makeText(getApplicationContext(), "保存成功", 0).show() ;
145 } catch (Exception e) {
146 }
147 //欺骗系统,告诉系统插入一个sd卡
148 Intent intent = new Intent();
149 intent.setAction(intent.ACTION_MEDIA_MOUNTED);
150 intent.setData(Uri.fromFile(file));
151 sendBroadcast(intent);
152 }
153 });
154 }
155 private void initData() {
156 sb = (SeekBar) findViewById(R.id.sb);
157 btn = (Button) findViewById(R.id.btn);
158 sp = (Spinner) findViewById(R.id.sp);
159 iv = (ImageView) findViewById(R.id.iv);
160 }
161
162
163 }
AndroidManifest.xml配置文件如下：
1 <?xml version="1.0" encoding="utf-8"?> 2 <manifest xmlns:android="http://schemas.android.com/apk/res/android" 3 package="com.xunfang.drawing" 4 android:versionCode="1" 5 android:versionName="1.0" > 6 7 <uses-sdk 8 android:minSdkVersion="16" 9 android:targetSdkVersion="21" /> 10 11 <application 12 android:allowBackup="true" 13 android:icon="@drawable/ic_launcher" 14 android:label="@string/app_name" 15 android:theme="@style/AppTheme" > 16 <activity 17 android:name=".MainActivity" 18 android:label="@string/app_name" > 19 <intent-filter> 20 <action android:name="android.intent.action.MAIN" /> 21 22 <category android:name="android.intent.category.LAUNCHER" /> 23 </intent-filter> 24 </activity> 25 </application> 26 27 </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
时间： 2024-08-03 09:14:02