BitmapUtil【縮放bitmap以及將bitmap保存成圖片到SD卡中】

版權聲明：本文為HaiyuKing原創文章，轉載請注明出處！

前言

用於縮放bitmap以及將bitmap保存成圖片到SD卡中

效果圖

代碼分析

bitmapZoomByHeight(Bitmap srcBitmap, float newHeight)： 根據指定的高度進行縮放（src是bitmap）

bitmapZoomByHeight(Drawable drawable, float newHeight) ：根據指定的高度進行縮放（src是drawable）

bitmapZoomByScale(Bitmap srcBitmap, float scaleWidth, float scaleHeight)： 根據指定的寬度比例值和高度比例值進行縮放

drawableToBitmap(Drawable drawable) ：將drawable對象轉成bitmap對象

drawableToBitmap2(Drawable drawable) ：將drawable對象轉成bitmap對象

saveBitmapToSDCard(Bitmap bitmap, String path)： 將bitmap對象保存成圖片到sd卡中

getBitmapFromSDCard(String path) ：從sd卡中去除圖片的bitmap對象

使用步驟

一、項目組織結構圖

 

注意事項：

1、  導入類文件后需要change包名以及重新import R文件路徑

2、  Values目錄下的文件（strings.xml、dimens.xml、colors.xml等），如果項目中存在，則復制里面的內容，不要整個覆蓋

二、導入步驟

將BitmapUtil復制到項目中

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;

    /**根據指定的高度進行縮放（source是bitmap）*/
    public static Bitmap bitmapZoomByHeight(Bitmap srcBitmap, float newHeight) {
        float scale = newHeight / (((float)srcBitmap.getHeight()));
        return BitmapUtil.bitmapZoomByScale(srcBitmap, scale, scale);
    }
    /**根據指定的高度進行縮放（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);
    }

    /**根據指定的寬度比例值和高度比例值進行縮放*/
    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;
        }
    }

    /**將drawable對象轉成bitmap對象*/
    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;
    }

    /**將drawable對象轉成bitmap對象*/
    public static Bitmap drawableToBitmap2(Drawable drawable) {
        BitmapDrawable bd = (BitmapDrawable) drawable;
        Bitmap bm= bd.getBitmap();
        return bm;
    }

    /**將bitmap對象保存成圖片到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));//設置PNG的話，透明區域不會變成黑色

            fileOutputStream.close();
            System.out.println("----------save success-------------------");
        }
        catch(Exception v0) {
            v0.printStackTrace();
        }

    }
    /**從sd卡中獲取圖片的bitmap對象*/
    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; //當圖片資源太大的適合，會出現內存溢出。圖片寬高都為原來的二分之一，即圖片為原來的四分一
                bitmap = BitmapFactory.decodeStream(((InputStream) fileInputStream), null, options);
            }
        } catch(Exception e) {
            return null;
        }

        return bitmap;
    }


}

在AndroidMainfest.xml文件中聲明權限

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
          package="com.why.project.bitmaputildemo">

    <!-- =================BitmapUtil用到的權限========================== -->
    <!-- 允許程序讀取外部存儲文件 -->
    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
    <!-- 允許程序寫入外部存儲，如SD卡上寫文件 -->
    <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>

添加運行時權限的處理（本demo中采用的是修改targetSDKVersion=22）

三、使用方法

本Demo搭配《AppDir【創建緩存目錄】》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

無

參考資料

Android常用的Drawable和Bitmap之間的轉化方法

項目demo下載地址

https://github.com/haiyuKing/BitmapUtilDemo