android - 位图变大

Answer 1

试试这个

public static Bitmap decodeFile(File f,int WIDTH,int HIGHT){
        try {
            //Decode image size
            BitmapFactory.Options o = new BitmapFactory.Options();
            o.inJustDecodeBounds = true;
            BitmapFactory.decodeStream(new FileInputStream(f),null,o);

            //The new size we want to scale to
            final int REQUIRED_WIDTH=WIDTH;
            final int REQUIRED_HIGHT=HIGHT;
            //Find the correct scale value. It should be the power of 2.
            int scale=1;
            while(o.outWidth/scale/2>=REQUIRED_WIDTH && o.outHeight/scale/2>=REQUIRED_HIGHT)
                scale*=2;

            //Decode with inSampleSize
            BitmapFactory.Options o2 = new BitmapFactory.Options();
            o2.inSampleSize=scale;
            return BitmapFactory.decodeStream(new FileInputStream(f), null, o2);
        }
            catch (FileNotFoundException e) {}
        return null;
    }

这将根据您传递的宽度和高度缩放位图

Answer 2

在将位图应用到图像视图之前，使用此类将位图缩小到所需的较小尺寸。

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;


class BitmapLoader
{
    public static int getScale(int originalWidth,int originalHeight,
    final int requiredWidth,final int requiredHeight)
    {
       //a scale of 1 means the original dimensions 
       //of the image are maintained
      int scale=1;

//calculate scale only if the height or width of 
//the image exceeds the required value. 
if((originalWidth>requiredWidth) || (originalHeight>requiredHeight)) 
{
    //calculate scale with respect to
    //the smaller dimension
    if(originalWidth<originalHeight)
        scale=Math.round((float)originalWidth/requiredWidth);
    else
      scale=Math.round((float)originalHeight/requiredHeight);

}

return scale;
}

public static BitmapFactory.Options getOptions(String filePath,
    int requiredWidth,int requiredHeight)
{

BitmapFactory.Options options=new BitmapFactory.Options();
//setting inJustDecodeBounds to true
//ensures that we are able to measure
//the dimensions of the image,without
//actually allocating it memory
options.inJustDecodeBounds=true;

//decode the file for measurement
BitmapFactory.decodeFile(filePath,options);

//obtain the inSampleSize for loading a 
//scaled down version of the image.
//options.outWidth and options.outHeight 
//are the measured dimensions of the 
//original image
options.inSampleSize=getScale(options.outWidth,
        options.outHeight, requiredWidth, requiredHeight);

//set inJustDecodeBounds to false again
//so that we can now actually allocate the
//bitmap some memory
options.inJustDecodeBounds=false;

return options;

}



public static Bitmap loadBitmap(String filePath,
    int requiredWidth,int requiredHeight){


BitmapFactory.Options options= getOptions(filePath,
        requiredWidth, requiredHeight);

return BitmapFactory.decodeFile(filePath,options);
}
}

然后从您的活动中调用

Bitmap reqBitmap = loadBitmap(String filePath,int requiredWidth,int requiredHeight) 

此类的方法提供从 sd 卡获取的位图的文件路径，并将 requiredWidth 和 requiredHeight 设置为您希望将位图缩放到的尺寸。现在使用 reqBitmap。