Android实现手绘功能

<?xml version="1.0" encoding="utf-8"? 
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:app="http://schemas.android.com/apk/res-auto"
 xmlns:tools="http://schemas.android.com/tools"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 tools:context="com.example.administrator.main.DrawActivity" 
 
 <ImageView
  android:id="@+id/iv"
  android:layout_width="1200px"
  android:layout_height="1500px"
  android:layout_alignParentLeft="true"
  android:layout_alignParentRight="true"
  android:layout_alignParentStart="true" / 
 
 <LinearLayout
  android:id="@+id/linearLayout4"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:layout_alignParentBottom="true"
  android:layout_gravity="center_horizontal"
  android:orientation="horizontal" 
 
 </LinearLayout 
 
 <Button
  android:id="@+id/btn_resume"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:layout_alignParentBottom="true"
  android:layout_alignParentEnd="true"
  android:layout_marginEnd="79dp"
  android:text="重绘" / 
 
 <Button
  android:id="@+id/btn_save"
  android:layout_width="wrap_content"
  android:layout_height="wrap_content"
  android:layout_alignBottom="@+id/linearLayout4"
  android:layout_marginStart="91dp"
  android:layout_toEndOf="@+id/linearLayout4"
  android:text="保存" / 
</RelativeLayout 

package com.example.administrator.main;
import android.content.Intent;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.net.Uri;
import android.os.Environment;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.Toast;
import java.io.File;
import java.io.FileOutputStream;
public class DrawActivity extends AppCompatActivity {
private ImageView iv;
private Bitmap baseBitmap;
private Button btn_resume;
private Button btn_save;
private Canvas canvas;
private Paint paint;
float radio;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_draw);
radio = 10;
iv = (ImageView) findViewById(R.id.iv);
// 初始化一个画笔，笔触宽度为5，颜色为红色
paint = new Paint();
paint.setStrokeWidth(radio);
paint.setColor(Color.BLACK);
iv = (ImageView) findViewById(R.id.iv);
btn_resume = (Button) findViewById(R.id.btn_resume);
btn_save = (Button) findViewById(R.id.btn_save);
btn_resume.setOnClickListener(click);
btn_save.setOnClickListener(click);
iv.setOnTouchListener(touch);
}
private View.OnTouchListener touch = new View.OnTouchListener() {
// 定义手指开始触摸的坐标
float startX;
float startY;
@Override
public boolean onTouch(View v, MotionEvent event) {
switch (event.getAction()) {
// 用户按下动作
case MotionEvent.ACTION_DOWN:
// 第一次绘图初始化内存图片，指定背景为白色
if (baseBitmap == null) {
baseBitmap = Bitmap.createBitmap(iv.getWidth(),
iv.getHeight(), Bitmap.Config.ARGB_8888);
canvas = new Canvas(baseBitmap);
canvas.drawColor(Color.WHITE);
}
// 记录开始触摸的点的坐标
startX = event.getX();
startY = event.getY();
break;
// 用户手指在屏幕上移动的动作
case MotionEvent.ACTION_MOVE:
// 记录移动位置的点的坐标
float stopX = event.getX();
float stopY = event.getY();
Thread t = new Thread(new Runnable() {
@Override
public void run() {
radio += 0.1;
try {
Thread.sleep(1000);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
});
t.start();
paint.setStrokeWidth(radio);
//根据两点坐标，绘制连线
canvas.drawLine(startX, startY, stopX, stopY, paint);
// 更新开始点的位置
startX = event.getX();
startY = event.getY();
// 把图片展示到ImageView中
iv.setImageBitmap(baseBitmap);
break;
case MotionEvent.ACTION_UP:
radio = 5;
break;
default:
break;
}
return true;
}
};
private View.OnClickListener click = new View.OnClickListener() {
@Override
public void onClick(View v) {
switch (v.getId()) {
case R.id.btn_save:
saveBitmap();
break;
case R.id.btn_resume:
resumeCanvas();
break;
default:
break;
}
}
};
/**
* 保存图片到SD卡上
*/
protected void saveBitmap() {
try {
// 保存图片到SD卡上
String fileName = "/sdcard/"+System.currentTimeMillis() + ".png";
File file = new File(fileName);
FileOutputStream stream = new FileOutputStream(file);
baseBitmap.compress(Bitmap.CompressFormat.PNG, 100, stream);
Toast.makeText(DrawActivity.this, "保存图片成功", Toast.LENGTH_SHORT).show();
// Android设备Gallery应用只会在启动的时候扫描系统文件夹
// 这里模拟一个媒体装载的广播，用于使保存的图片可以在Gallery中查看
Intent intent = new Intent();
intent.setAction(Intent.ACTION_MEDIA_MOUNTED);
intent.setData(Uri.fromFile(Environment
.getExternalStorageDirectory()));
sendBroadcast(intent);
} catch (Exception e) {
Toast.makeText(DrawActivity.this, "保存图片失败", Toast.LENGTH_SHORT).show();
e.printStackTrace();
}
}
// 手动清除画板的绘图，重新创建一个画板
protected void resumeCanvas() {
if (baseBitmap != null) {
baseBitmap = Bitmap.createBitmap(iv.getWidth(),
iv.getHeight(), Bitmap.Config.ARGB_8888);
canvas = new Canvas(baseBitmap);
canvas.drawColor(Color.WHITE);
iv.setImageBitmap(baseBitmap);
Toast.makeText(DrawActivity.this, "清除画板成功，可以重新开始绘图", Toast.LENGTH_SHORT).show();
}
}
}