5

Android 利用 Canvas 画画板

3 years ago

source link: http://www.androidchina.net/3008.html
Go to the source link to view the article. You can view the picture content, updated content and better typesetting reading experience. If the link is broken, please click the button below to view the snapshot at that time.

neoserver,ios ssh client

Android 利用 Canvas 画画板 – Android开发中文站

你的位置：Android开发中文站 > Android开发 > 开发进阶 > Android 利用 Canvas 画画板

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

转载请注明：Android开发中文站 » Android 利用 Canvas 画画板

Recommend

About Joyk

Aggregate valuable and interesting links.
Joyk means Joy of geeK