BitmapFactory.Options操作图片显示大小

来源：互联网发布：python 多任务处理编辑：程序博客网时间：2024/06/10 04:59

加载和显示图片是很消耗内存的一件事，BitmapFactory.Options 类, 允许我们定义图片以何种方式如何读到内存，

BitmapFactory.Options bmpFactoryOptions = new BitmapFactory.Options();
bmpFactoryOptions.inSampleSize = 8;
Bitmap bmp = BitmapFactory.decodeFile(imageFilePath, bmpFactoryOptions);
imv.setImageBitmap(bmp);
    上面的代码使图片变成原来的1/8.

//imv = (ImageView) findViewById(R.id.ReturnedImageView);
        Display currentDisplay = getWindowManager().getDefaultDisplay();
        int dw = currentDisplay.getWidth();
        int dh = currentDisplay.getHeight();
          try
       {
        BitmapFactory.Options bmpFactoryOptions = new BitmapFactory.Options();
        bmpFactoryOptions.inJustDecodeBounds = true;
        Bitmap bmp = BitmapFactory.decodeStream(getContentResolver().
        openInputStream(imageFileUri), null,  bmpFactoryOptions);
        int heightRatio = (int)Math.ceil(bmpFactoryOptions.outHeight/(float)dh);
        int widthRatio = (int)Math.ceil(bmpFactoryOptions.outWidth/(float)dw);
        Log.v("HEIGHRATIO", ""+heightRatio);
        Log.v("WIDTHRATIO", ""+widthRatio);
        if (heightRatio > 1 && widthRatio > 1)
        {
            bmpFactoryOptions.inSampleSize =  heightRatio > widthRatio ? heightRatio:widthRatio;
        }
       bmpFactoryOptions.inJustDecodeBounds = false;
       bmp = BitmapFactory.decodeStream(getContentResolver().
       openInputStream(imageFileUri), null,  bmpFactoryOptions);
       returnedImageView.setImageBitmap(bmp);
       }
       catch (FileNotFoundException e)
       {
           Log.v("ERROR", e.toString());
       }

上面的代码让图片根据窗口大小改变

bmpFactoryOptions.inJustDecodeBounds = true;
这一行让代码只解码图片的Bounds

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