BitmapUtil【缩放bitmap以及将bitmap保存成图片到SD卡中】

前言

用于缩放bitmap以及将bitmap保存成图片到SD卡中

效果图

代码分析

bitmapZoomByHeight(Bitmap srcBitmap, float newHeight)：根据指定的高度进行缩放（src是bitmap）

bitmapZoomByHeight(Drawable drawable, float newHeight) ：根据指定的高度进行缩放（src是drawable）

bitmapZoomByScale(Bitmap srcBitmap, float scaleWidth, float scaleHeight)：根据指定的宽度比例值和高度比例值进行缩放

drawableToBitmap(Drawable drawable) ：将drawable对象转成bitmap对象

drawableToBitmap2(Drawable drawable) ：将drawable对象转成bitmap对象

saveBitmapToSDCard(Bitmap bitmap, String path)：将bitmap对象保存成图片到sd卡中

getBitmapFromSDCard(String path) ：从sd卡中去除图片的bitmap对象

使用步骤

一、项目组织结构图

注意事项：

1、导入类文件后需要change包名以及重新import R文件路径

2、 Values目录下的文件（strings.xml、dimens.xml、colors.xml等），如果项目中存在，则复制里面的内容，不要整个覆盖

二、导入步骤

将BitmapUtil复制到项目中

package com.why.project.bitmaputildemo.utils;

import android.graphics.Bitmap;

import android.graphics.BitmapFactory;

import android.graphics.Canvas;

import android.graphics.Matrix;

import android.graphics.PixelFormat;

import android.graphics.drawable.BitmapDrawable;

import android.graphics.drawable.Drawable;

import java.io.File;

import java.io.FileInputStream;

import java.io.FileOutputStream;

import java.io.InputStream;

import java.io.OutputStream;

/**

 * Created by HaiyuKing

 * Used

 */

public class BitmapUtil {

    public static Bitmap temp;

    /**根据指定的高度进行缩放（source是bitmap）*/

    public static Bitmap bitmapZoomByHeight(Bitmap srcBitmap, float newHeight) {

        float scale = newHeight / (((float)srcBitmap.getHeight()));

        return BitmapUtil.bitmapZoomByScale(srcBitmap, scale, scale);

    }

    /**根据指定的高度进行缩放（source是drawable）*/

    public static Bitmap bitmapZoomByHeight(Drawable drawable, float newHeight) {

        Bitmap bitmap = BitmapUtil.drawableToBitmap(drawable);

        float scale = newHeight / (((float)bitmap.getHeight()));

        return BitmapUtil.bitmapZoomByScale(bitmap, scale, scale);

    }

    /**根据指定的宽度比例值和高度比例值进行缩放*/

    public static Bitmap bitmapZoomByScale(Bitmap srcBitmap, float scaleWidth, float scaleHeight) {

        int width = srcBitmap.getWidth();

        int height = srcBitmap.getHeight();

        Matrix matrix = new Matrix();

        matrix.postScale(scaleWidth, scaleHeight);

        Bitmap bitmap = Bitmap.createBitmap(srcBitmap, 0, 0, width, height, matrix, true);

        if(bitmap != null) {

            return bitmap;

        }else {

            return srcBitmap;

        }

    }

    /**将drawable对象转成bitmap对象*/

    public static Bitmap drawableToBitmap(Drawable drawable) {

        int width = drawable.getIntrinsicWidth();

        int height = drawable.getIntrinsicHeight();

        Bitmap.Config config = drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888 : Bitmap.Config.RGB_565;

        Bitmap bitmap = Bitmap.createBitmap(width, height, config);

        Canvas canvas = new Canvas(bitmap);

        drawable.setBounds(0, 0, width, height);

        drawable.draw(canvas);

        return bitmap;

    }

    /**将drawable对象转成bitmap对象*/

    public static Bitmap drawableToBitmap2(Drawable drawable) {

        BitmapDrawable bd = (BitmapDrawable) drawable;

        Bitmap bm= bd.getBitmap();

        return bm;

    }

    /**将bitmap对象保存成图片到sd卡中*/

    public static void saveBitmapToSDCard(Bitmap bitmap, String path) {

        File file = new File(path);

        if(file.exists()) {

            file.delete();

        }

        try {

            FileOutputStream fileOutputStream = new FileOutputStream(file);

            bitmap.compress(Bitmap.CompressFormat.PNG, 100, ((OutputStream)fileOutputStream));//设置PNG的话，透明区域不会变成黑色

            fileOutputStream.close();

            System.out.println("----------save success-------------------");

        }

        catch(Exception v0) {

            v0.printStackTrace();

        }

    }

    /**从sd卡中获取图片的bitmap对象*/

    public static Bitmap getBitmapFromSDCard(String path) {

        Bitmap bitmap = null;

        try {

            FileInputStream fileInputStream = new FileInputStream(path);

            if(fileInputStream != null) {

                BitmapFactory.Options options = new BitmapFactory.Options();

                options.inSampleSize = 2; //当图片资源太大的适合，会出现内存溢出。图片宽高都为原来的二分之一，即图片为原来的四分一

                bitmap = BitmapFactory.decodeStream(((InputStream) fileInputStream), null, options);

            }

        } catch(Exception e) {

            return null;

        }

        return bitmap;

    }

}

在AndroidMainfest.xml文件中声明权限

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

          package="com.why.project.bitmaputildemo">

    <!-- =================BitmapUtil用到的权限========================== -->

    <!-- 允许程序读取外部存储文件 -->

    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>

    <!-- 允许程序写入外部存储，如SD卡上写文件 -->

    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"></uses-permission>

    <application

        android:allowBackup="true"

        android:icon="@mipmap/ic_launcher"

        android:label="@string/app_name"

        android:supportsRtl="true"

        android:theme="@style/AppTheme">

        <activity android:name=".MainActivity">

            <intent-filter>

                <action android:name="android.intent.action.MAIN"/>

                <category android:name="android.intent.category.LAUNCHER"/>

            </intent-filter>

        </activity>

    </application>

</manifest>

添加运行时权限的处理（本demo中采用的是修改targetSDKVersion=22）

三、使用方法

本Demo搭配《AppDir【创建缓存目录】》使用

package com.why.project.bitmaputildemo;

import android.graphics.Bitmap;

import android.os.Bundle;

import android.support.v7.app.AppCompatActivity;

import android.view.View;

import android.widget.Button;

import android.widget.ImageView;

import com.why.project.bitmaputildemo.utils.AppDir;

import com.why.project.bitmaputildemo.utils.BitmapUtil;

import java.io.File;

public class MainActivity extends AppCompatActivity {

    private ImageView img_source;

    private ImageView img_scale1;

    private ImageView img_scale2;

    private Button btn_save;

    private Button btn_show;

    private ImageView img_show;

    private String pngFilePath;

    @Override

    protected void onCreate(Bundle savedInstanceState) {

        super.onCreate(savedInstanceState);

        setContentView(R.layout.activity_main);

        initViews();

        initDatas();

        initEvents();

    }

    private void initViews() {

        img_source = (ImageView) findViewById(R.id.img_source);

        img_scale1 = (ImageView) findViewById(R.id.img_scale1);

        img_scale2 = (ImageView) findViewById(R.id.img_scale2);

        btn_save = (Button) findViewById(R.id.btn_save);

        btn_show = (Button) findViewById(R.id.btn_show);

        img_show = (ImageView) findViewById(R.id.img_show);

    }

    private void initDatas() {

        img_source.setImageResource(R.mipmap.ic_launcher);

        Bitmap sourceBitmap = BitmapUtil.drawableToBitmap(getResources().getDrawable(R.mipmap.ic_launcher));

        Bitmap sacleBitmap1 = BitmapUtil.bitmapZoomByHeight(sourceBitmap,200);

        img_scale1.setImageBitmap(sacleBitmap1);

        Bitmap sacleBitmap2 = BitmapUtil.bitmapZoomByScale(sourceBitmap,2,1);

        img_scale2.setImageBitmap(sacleBitmap2);

    }

    private void initEvents() {

        btn_save.setOnClickListener(new View.OnClickListener() {

            @Override

            public void onClick(View v) {

                pngFilePath = AppDir.getInstance(MainActivity.this).IMAGE + File.separator + System.currentTimeMillis() + ".png";

                Bitmap sourceBitmap = BitmapUtil.drawableToBitmap(getResources().getDrawable(R.mipmap.ic_launcher));

                BitmapUtil.saveBitmapToSDCard(sourceBitmap,pngFilePath);

            }

        });

        btn_show.setOnClickListener(new View.OnClickListener() {

            @Override

            public void onClick(View v) {

                String pngPath = pngFilePath;

                Bitmap pngBitmap = BitmapUtil.getBitmapFromSDCard(pngPath);

                img_show.setImageBitmap(pngBitmap);

            }

        });

    }

}

混淆配置

无

参考资料

Android常用的Drawable和Bitmap之间的转化方法

项目demo下载地址

https://github.com/haiyuKing/BitmapUtilDemo