关于图片压缩的一点方法和心得

最近在做公司应用的时候，那个分享到朋友圈，有的图片一直分享不过去（好吧，我只想说之前不是我做的），

后来去去看微信官方看了下，分享到朋友圈的图片的缩略图只能是32kb一下的图片，怎么办？当然得压缩了，压缩的话

，就得考虑是否失真啊，清晰度啊等等，好了 这些都是题外话，下面直接上代码吧

public static void shareToPengyou(Context ct, String p_w_picpathKey,
  String piccapText) {
 String path = LocalImageMaintain.getInstance().getLocalImageDir()
   + p_w_picpathKey + IMAGE_SUFFIX;
 try {
  Bitmap bmp = ImageTools.getBitmap(path, 2);
  WXImageObject imgObj = new WXImageObject(bmp);
  WXMediaMessage msg = new WXMediaMessage();
  msg.mediaObject = imgObj;
  Bitmap thumbBmp = Bitmap.createScaledBitmap(bmp, 120, 120, true);
  msg.thumbData = bmpToByteArray(thumbBmp, true); // 设置缩略图
  int tempSize = msg.thumbData.length;
  int temp = 1;

  while (tempSize > (32 * 1024)) {
   temp ++;
   bmp = ImageTools.getBitmap(path, (2 * temp));
   msg.mediaObject = imgObj;
   thumbBmp = Bitmap.createScaledBitmap(bmp, 120, 120, true);
   msg.thumbData = bmpToByteArray(thumbBmp, true); // 设置缩略图
   tempSize = msg.thumbData.length;
  }
  SendMessageToWX.Req req = new SendMessageToWX.Req();
  req.transaction = buildTransaction("img");
  req.message = msg;
  req.scene = SendMessageToWX.Req.WXSceneTimeline;
  IWXAPI api = WXAPIFactory.createWXAPI(ct, WXEntryActivity.APP_ID);
  api.sendReq(req);
 } catch (Exception e) {
  // TODO Auto-generated catch block
  e.printStackTrace();
 }
}


//图片压缩

public static byte[] bmpToByteArray(final Bitmap bmp,
  final boolean needRecycle) {
 ByteArrayOutputStream output = new ByteArrayOutputStream();
 bmp.compress(CompressFormat.PNG, 80, output);
 if (needRecycle) {
  bmp.recycle();
 }
 byte[] result = output.toByteArray();
 try {
  output.close();
 } catch (Exception e) {
  e.printStackTrace();
 }
 return result;
}

//简单的一个工具类，用来等比压缩的，size指的是压缩为原来的1/size

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.BitmapFactory.Options;
import android.util.FloatMath;

public class ImageTools {
// 指定大小載入圖片
public static Bitmap getBitmap(String path, int size) {
 Options op = new Options();
 op.inSampleSize = size;
 Bitmap bt = BitmapFactory.decodeFile(path, op);
 return bt;
}

// 按寬高壓縮載入圖片
public static Bitmap getBitmap(String path, int width, int heigh) {
 Options op = new Options();
 op.inJustDecodeBounds = true;
 Bitmap bt = BitmapFactory.decodeFile(path, op);
 int xScale = op.outWidth / width;
 int yScale = op.outHeight / heigh;
 op.inSampleSize = xScale > yScale ? xScale : yScale;
 op.inJustDecodeBounds = false;
 bt = BitmapFactory.decodeFile(path, op);
 return bt;
}

// 按寬高壓縮載入圖片方法2
public static Bitmap getBitmap2(String p_w_picpathFilePath, int displayWidth,
  int displayHeight) {
 BitmapFactory.Options bitmapOptions = new BitmapFactory.Options();
 bitmapOptions.inJustDecodeBounds = true;
 Bitmap bmp = BitmapFactory.decodeFile(p_w_picpathFilePath, bitmapOptions);
 // 编码后bitmap的宽高,bitmap除以屏幕宽度得到压缩比
 int widthRatio = (int) FloatMath.ceil(bitmapOptions.outWidth
   / (float) displayWidth);
 int heightRatio = (int) FloatMath.ceil(bitmapOptions.outHeight
   / (float) displayHeight);
 if (widthRatio > 1 && heightRatio > 1) {
  if (widthRatio > heightRatio) {
   // 压缩到原来的(1/widthRatios)
   bitmapOptions.inSampleSize = widthRatio;
  } else {
   bitmapOptions.inSampleSize = heightRatio;
  }
 }
 bitmapOptions.inJustDecodeBounds = false;
 bmp = BitmapFactory.decodeFile(p_w_picpathFilePath, bitmapOptions);
 return bmp;
}
}