二次取樣+質量壓縮
阿新 • • 發佈：2018-11-22
1.MainActivity頁面
package com.example.image; import android.content.Intent; import android.database.Cursor; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.net.Uri; import android.os.Environment; import android.provider.MediaStore; import android.support.annotation.Nullable; import android.support.v4.content.CursorLoader; import android.support.v7.app.AppCompatActivity; import android.os.Bundle; import android.util.Log; import android.view.View; import android.widget.Button; import android.widget.EditText; import android.widget.ImageView; import java.io.File; public class MainActivity extends AppCompatActivity { private EditText width;//寬 private EditText height;//高 private EditText quality;//質量 private Button getImage;//獲取圖片 private Button show;//顯示圖片 private ImageView image; private final int PICK_IMAGE = 100; private Uri uri; @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); //Bitmap bitmpa; //bitmpa.compress(Bitmap.CompressFormat.JPEG, 70, ); width = findViewById(R.id.width); height = findViewById(R.id.height); quality = findViewById(R.id.quality); getImage = findViewById(R.id.get_image); show = findViewById(R.id.show); image = findViewById(R.id.image); getImage.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { Intent intent = new Intent(Intent.ACTION_PICK); intent.setType("image/*"); startActivityForResult(intent, PICK_IMAGE); } }); show.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { String filePath = getRealPathFromURI(uri); //二次取樣 Log.i("TEST",filePath); Bitmap bitmap = ImageUtil.scaleBitmap(filePath, Integer.parseInt(width.getText().toString()), Integer.parseInt(height.getText().toString())); bitmap = ImageUtil.compress(bitmap, Integer.parseInt(quality.getText().toString()), new File(Environment.getExternalStorageDirectory(), "tmp2.jpg")); image.setImageBitmap(bitmap); //BitmapFactory.de //質量壓縮 //展示 } }); } private String getRealPathFromURI(Uri contentUri) { //傳入圖片uri地址 String[] proj = { MediaStore.Images.Media.DATA }; CursorLoader loader = new CursorLoader(this, contentUri, proj, null, null, null); Cursor cursor = loader.loadInBackground(); int column_index = cursor.getColumnIndexOrThrow(MediaStore.Images.Media.DATA); cursor.moveToFirst(); return cursor.getString(column_index); } @Override protected void onActivityResult(int requestCode, int resultCode, @Nullable Intent data) { if(requestCode == PICK_IMAGE) { if(resultCode == RESULT_OK) { //圖片uri uri = data.getData(); } return; } super.onActivityResult(requestCode, resultCode, data); } }
2.工具類
package com.example.image; import android.graphics.Bitmap; import android.graphics.BitmapFactory; import android.os.Environment; import java.io.File; import java.io.FileNotFoundException; import java.io.FileOutputStream; public class ImageUtil { //圖片二次取樣 public static Bitmap scaleBitmap(String filePath, int width, int height) { //進行兩次decode //第一次decode,只解析bitmap的寬高資訊 //縮小圖片大小, 降低記憶體佔用 BitmapFactory.Options opts = new BitmapFactory.Options(); //指定只解析bitmap的邊界資訊,不載入bitmap到記憶體中 opts.inJustDecodeBounds = true; BitmapFactory.decodeFile(filePath, opts); //寬高資訊 //1920 1080 //256 256 //opts.outWidth; //opts.outHeight; //通過圖片的真實寬高資訊 和 需要的寬高比,產生一個比例 opts.inSampleSize = Math.max(opts.outHeight / height, opts.outWidth / width); //第二次載入圖片: 真正載入圖片 opts.inJustDecodeBounds = false; Bitmap bitmap = BitmapFactory.decodeFile(filePath, opts); return bitmap; } //tup質量壓縮: 只改變檔案大小,基本不改變記憶體佔用 public static Bitmap compress(Bitmap bitmap, int qual, File output) { Bitmap result = bitmap; try { //縮放後的 //bitmap.compress(Bitmap.CompressFormat.JPEG, 100, new FileOutputStream(new File(Environment.getExternalStorageDirectory(), "tmp.jpg"))); //壓縮後的,儲存到output檔案 bitmap.compress(Bitmap.CompressFormat.JPEG, qual, new FileOutputStream(output)); //再次解析壓縮後的圖片 result = BitmapFactory.decodeFile(output.getAbsolutePath()); } catch (FileNotFoundException e) { e.printStackTrace(); }; return result; } }
3.佈局
<?xml version="1.0" encoding="utf-8"?> <android.support.constraint.ConstraintLayout 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=".MainActivity"> <Button android:layout_width="0dp" android:layout_height="wrap_content" android:text="選擇圖片" android:id="@+id/get_image" app:layout_constraintLeft_toLeftOf="parent" app:layout_constraintRight_toRightOf="parent" app:layout_constraintTop_toTopOf="parent" /> <EditText android:id="@+id/width" android:layout_width="wrap_content" android:layout_height="wrap_content" app:layout_constraintTop_toBottomOf="@id/get_image" app:layout_constraintLeft_toLeftOf="parent" app:layout_constraintRight_toLeftOf="@id/height" android:text="256" android:hint="輸入寬度"/> <EditText android:id="@+id/height" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="256" app:layout_constraintTop_toBottomOf="@id/get_image" app:layout_constraintLeft_toRightOf="@id/width" app:layout_constraintRight_toLeftOf="@id/quality" android:hint="輸入高度"/> <EditText android:id="@+id/quality" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="70" app:layout_constraintTop_toBottomOf="@id/get_image" app:layout_constraintLeft_toRightOf="@id/height" app:layout_constraintRight_toRightOf="parent" android:hint="輸入質量"/> <Button android:id="@+id/show" android:layout_width="0dp" android:layout_height="wrap_content" app:layout_constraintLeft_toLeftOf="parent" app:layout_constraintRight_toRightOf="parent" app:layout_constraintTop_toBottomOf="@id/height" android:text="生成"/> <ImageView android:id="@+id/image" android:layout_width="wrap_content" android:layout_height="wrap_content" app:layout_constraintLeft_toLeftOf="parent" app:layout_constraintRight_toRightOf="parent" app:layout_constraintTop_toBottomOf="@id/show" app:layout_constraintBottom_toBottomOf="parent"/> </android.support.constraint.ConstraintLayout>
4.配置檔案
<uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>