Android图片缩放123

图片缩放中常用的有：

1.BitmapFactory.Options

eg:// 特点：图片原始尺寸的固定比例缩小（不能进行放大）
public Bitmap optionCompressBitmap() {
// 获取原始图片的尺寸
BitmapFactory.Options srcOption = new BitmapFactory.Options();
srcOption.inJustDecodeBounds = true;
BitmapFactory
.decodeResource(getResources(), R.drawable.test, srcOption);
int srcWidth = srcOption.outWidth;
int srcHeight = srcOption.outHeight;
int scale = (int) Math.max((srcWidth / destWidth),
(srcHeight / destHeight));
// 修改原始图片的option
srcOption.inSampleSize = scale;
srcOption.inJustDecodeBounds = false;
return BitmapFactory.decodeResource(getResources(), R.drawable.test,
srcOption);
}

2.Matrix

eg:// matrix:缩放非常灵活(如果需要不按照原始比例，这个是非常恰当的) 当图片所在的资源文件夹与手机的不对应，会出现奇葩的现象
public Bitmap matrixCompressBitmap() {
// 获取原始图片的尺寸
BitmapFactory.Options srcOption = new BitmapFactory.Options();
srcOption.inJustDecodeBounds = true;
BitmapFactory
.decodeResource(getResources(), R.drawable.test, srcOption);
int srcWidth = srcOption.outWidth;
int srcHeight = srcOption.outHeight;
float scaleWidth = destWidth / srcWidth;
float scaleHeight = destHeight / srcHeight;
// 修改原始图片的缩放比
Matrix matrix = new Matrix();
matrix.postScale(scaleWidth, scaleHeight);
Bitmap srcBitmap = BitmapFactory.decodeResource(getResources(),
R.drawable.test);
Bitmap bitmap = Bitmap.createBitmap(srcBitmap, 0, 0,
srcBitmap.getWidth(), srcBitmap.getHeight(), matrix, false);
return bitmap;
}

/**
 * 一般情况下，我们倾向于指定较长的一个边缩放情况（较短的进行等比例缩放）
 * @param resId
 * @param lastLongerLength
 * @return
 */
public Bitmap scaleBitmap(Bitmap srcBitmap, int lastLongerLength) {
    int srcWidth = srcBitmap.getWidth();
    int srcHeight = srcBitmap.getHeight();
    float scaleWidth = (float) lastLongerLength / srcWidth;
    float scaleHeight = (float) lastLongerLength / srcHeight;
    Matrix matrix = new Matrix();
    float scaleRatio = Math.min(scaleWidth, scaleHeight);
    matrix.postScale(scaleRatio, scaleRatio);
    Bitmap bitmap = Bitmap.createBitmap(srcBitmap, 0, 0,
            srcBitmap.getWidth(), srcBitmap.getHeight(), matrix, false);

    return bitmap;
}

3.有图有真相：

![看一下效果](http://img.blog.csdn.net/20150215153857005)

4.给一下Demo的地下地址：

http://download.csdn.net/detail/guchuanhang/8448117