如何在Android中實用地縮小圖像的寬度和高度？

Question

我的要求是存儲在數據庫中的圖像的大小（寬度，高度而不是文件大小），我需要檢索圖像的簡單護照大小。

我的代碼是：

byte[] imgByte=null; 

在onCreate方法

imageview=new ImageView(this); 
imageview.setLayoutParams(llp2); 
imgByte=cursor.getBlob(cursor.getColumnIndex("imagestore")); 
imageview.setScaleType(ScaleType.CENTER); 
imageview.setImageBitmap(BitmapFactory.decodeByteArray(imgByte, 0, imgByte.length)); 
layout.addView(imageview) 

當我顯示該只顯示什麼都大小之前進入。所以我需要在android中適應該圖像大小。

我想這些鏈接

Reduce size of Bitmap to some specified pixel in Android

但這裏的問題是，我在字節得到的圖像。但所有代碼圖像數據類型只有int。我可以得到正確的解決方案來務實降低圖像尺寸嗎？

Answer 1

您可以使用以下代碼來創建示例大小的圖像。這將返回Bitmap。

public static Bitmap decodeSampledBitmapFromResource(Resources res, 
     int resId, int reqWidth, int reqHeight) { 

    // First decode with inJustDecodeBounds=true to check dimensions 
    final BitmapFactory.Options options = new BitmapFactory.Options(); 
    options.inJustDecodeBounds = true; 
    BitmapFactory.decodeResource(res, resId, options); 

    // Calculate inSampleSize 
    options.inSampleSize = calculateInSampleSize(options, reqWidth, 
      reqHeight); 

    // Decode bitmap with inSampleSize set 
    options.inJustDecodeBounds = false; 
    return BitmapFactory.decodeResource(res, resId, options); 
} 

public static int calculateInSampleSize(BitmapFactory.Options options, 
     int reqWidth, int reqHeight) { 
    // Raw height and width of image 
    final int height = options.outHeight; 
    final int width = options.outWidth; 
    int inSampleSize = 1; 

    if (height > reqHeight || width > reqWidth) { 

     // Calculate ratios of height and width to requested height and 
     // width 
     final int heightRatio = Math.round((float) height 
       /(float) reqHeight); 
     final int widthRatio = Math.round((float) width/(float) reqWidth); 

     // Choose the smallest ratio as inSampleSize value, this will 
     // guarantee 
     // a final image with both dimensions larger than or equal to the 
     // requested height and width. 
     inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio; 
    } 

    return inSampleSize; 
} 

使用此代碼，

decodeSampledBitmapFromResource(getResources(),R.drawable.xyz, 100, 100); 

在這裏，100 * 100的樣本大小您提供。所以這樣大小的縮略圖將被創建。

編輯

要使用字節[]中的代碼，使用以下短的代碼。

public static Bitmap decodeSampledBitmap(byte[] data, int reqWidth, 
     int reqHeight) { 

    // First decode with inJustDecodeBounds=true to check dimensions 
    final BitmapFactory.Options options = new BitmapFactory.Options(); 
    options.inJustDecodeBounds = true; 
    BitmapFactory.decodeByteArray(data, 0, data.length, options); 

    // Calculate inSampleSize 
    options.inSampleSize = calculateInSampleSize(options, reqWidth, 
      reqHeight); 

    // Decode bitmap with inSampleSize set 
    options.inJustDecodeBounds = false; 
    return BitmapFactory.decodeByteArray(data, 0, data.length, options); 
}