Android简易实战教程--第二十四话《画画板》

今天完成一个画画板。

首先来个布局：

<RelativeLayout 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:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context=".MainActivity" >    <ImageView        android:id="@+id/iv"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="@string/hello_world"         /><LinearLayout     android:layout_width="match_parent"    android:layout_height="wrap_content"    android:orientation="horizontal"    android:layout_alignParentBottom="true"    >    <Button         android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="红色"        android:onClick="red"        />    <Button         android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="绿色"        android:onClick="green"        />    <Button         android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="刷子"        android:onClick="brush"        />    <Button         android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:text="保存"        android:onClick="save"        /></LinearLayout></RelativeLayout>

可见，要分红绿色，而且还要保存最后画的图片。

看一下主活动代码：

package com.itydl.paintban;import java.io.File;import java.io.FileNotFoundException;import java.io.FileOutputStream;import android.net.Uri;import android.os.Bundle;import android.os.Environment;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.view.Menu;import android.view.MotionEvent;import android.view.View;import android.view.View.OnTouchListener;import android.widget.ImageView;public class MainActivity extends Activity {private ImageView iv;int startX;int startY;private Canvas canvas;private Paint paint;private Bitmap bmCopy;@Overrideprotected void onCreate(Bundle savedInstanceState) {super.onCreate(savedInstanceState);setContentView(R.layout.activity_main);//加载画画板的背景图Bitmap bmSrc = BitmapFactory.decodeResource(getResources(), R.drawable.bg);bmCopy = Bitmap.createBitmap(bmSrc.getWidth(), bmSrc.getHeight(), bmSrc.getConfig());paint = new Paint();canvas = new Canvas(bmCopy);//绘制canvas.drawBitmap(bmSrc, new Matrix(), paint);iv = (ImageView) findViewById(R.id.iv);iv.setImageBitmap(bmCopy);//设置触摸侦听iv.setOnTouchListener(new OnTouchListener() {//触摸屏幕时，触摸事件产生时，此方法调用@Overridepublic boolean onTouch(View v, MotionEvent event) {int action = event.getAction();switch (action) {//用户手指摸到屏幕case MotionEvent.ACTION_DOWN:startX = (int) event.getX();startY = (int) event.getY();break;//用户手指正在滑动case MotionEvent.ACTION_MOVE:int x = (int) event.getX();int y = (int) event.getY();canvas.drawLine(startX, startY, x, y, paint);//每次绘制完毕之后，本次绘制的结束坐标变成下一次绘制的初始坐标startX = x;startY = y;iv.setImageBitmap(bmCopy);break;//用户手指离开屏幕case MotionEvent.ACTION_UP:break;}//true：告诉系统，这个触摸事件由我来处理//false：告诉系统，这个触摸事件我不处理，这时系统会把触摸事件传递给imageview的父节点return true;}});}public void red(View v){paint.setColor(Color.RED);}public void green(View v){paint.setColor(Color.GREEN);}public void brush(View v){paint.setStrokeWidth(7);}public void save(View v){File file = new File("sdcard/dazuo.png");FileOutputStream fos = null;try {fos = new FileOutputStream(file);} catch (FileNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();}bmCopy.compress(CompressFormat.PNG, 100, fos);//发送sd卡就绪广播Intent intent = new Intent();intent.setAction(Intent.ACTION_MEDIA_MOUNTED);intent.setData(Uri.fromFile(Environment.getExternalStorageDirectory()));sendBroadcast(intent);}}

运行看一下结果：

画了个绿帽子，哈哈。欢迎关注本博客点击打开链接  http://blog.csdn.net/qq_32059827，每天花上5分钟，阅读一篇有趣的安卓小文哦。