android 图片缩放

// 获得图片的宽高      int width = bm.getWidth();      int height = bm.getHeight();      // 设置想要的大小      int newWidth = 320;      int newHeight = 480;      // 计算缩放比例      float scaleWidth = ((float) newWidth) / width;      float scaleHeight = ((float) newHeight) / height;      // 取得想要缩放的matrix参数      Matrix matrix = new Matrix();      matrix.postScale(scaleWidth, scaleHeight);      // 得到新的图片      Bitmap newbm = Bitmap.createBitmap(bm, 0, 0, width, height, matrix,        true);  

为了使用方便，我们对bitmap方法进行封装

[java] view plain copy print?在CODE上查看代码片派生到我的代码片import java.io.ByteArrayInputStream;  import java.io.ByteArrayOutputStream;  import java.io.IOException;  import java.io.InputStream;  import android.content.Context;  import android.content.Intent;  import android.graphics.Bitmap;  import android.graphics.Bitmap.Config;  import android.graphics.BitmapFactory;  import android.graphics.Canvas;  import android.graphics.Matrix;  import android.net.Uri;  import android.util.Log;  public class Bitmaptest  {   private static final String TAG = "BitmapUtil";   /**   * 通过资源id转化成Bitmap   *   * @param context   * @param resId   * @return   */   public static Bitmap ReadBitmapById(Context context, int resId)   {    BitmapFactory.Options opt = new BitmapFactory.Options();    opt.inPreferredConfig = Bitmap.Config.RGB_565;    opt.inPurgeable = true;    opt.inInputShareable = true;    InputStream is = context.getResources().openRawResource(resId);    return BitmapFactory.decodeStream(is, null, opt);   }   /**   * 缩放Bitmap满屏   *   * @param bitmap   * @param screenWidth   * @param screenHight   * @return   */   public static Bitmap getBitmap(Bitmap bitmap, int screenWidth,     int screenHight)   {    int w = bitmap.getWidth();    int h = bitmap.getHeight();    Matrix matrix = new Matrix();    float scale = (float) screenWidth / w;    float scale2 = (float) screenHight / h;    // scale = scale < scale2 ? scale : scale2;    matrix.postScale(scale, scale);    Bitmap bmp = Bitmap.createBitmap(bitmap, 0, 0, w, h, matrix, true);    if (bitmap != null && !bitmap.equals(bmp) && !bitmap.isRecycled())    {     bitmap.recycle();     bitmap = null;    }    return bmp;// Bitmap.createBitmap(bitmap, 0, 0, w, h, matrix, true);   }   /**   * 按最大边按一定大小缩放图片   * */   public static Bitmap scaleImage(byte[] buffer, float size)   {    // 获取原图宽度    BitmapFactory.Options options = new BitmapFactory.Options();    options.inJustDecodeBounds = true;    options.inPurgeable = true;    options.inInputShareable = true;    Bitmap bm = BitmapFactory.decodeByteArray(buffer, 0, buffer.length,      options);    // 计算缩放比例    float reSize = options.outWidth / size;    if (options.outWidth < options.outHeight)    {     reSize = options.outHeight / size;    }    // 如果是小图则放大    if (reSize <= 1)    {     int newWidth = 0;     int newHeight = 0;     if (options.outWidth > options.outHeight)     {      newWidth = (int) size;      newHeight = options.outHeight * (int) size / options.outWidth;     } else     {      newHeight = (int) size;      newWidth = options.outWidth * (int) size / options.outHeight;     }     bm = BitmapFactory.decodeByteArray(buffer, 0, buffer.length);     bm = scaleImage(bm, newWidth, newHeight);     if (bm == null)     {      Log.e(TAG, "convertToThumb, decode fail:" + null);      return null;     }     return bm;    }    // 缩放    options.inJustDecodeBounds = false;    options.inSampleSize = (int) reSize;    bm = BitmapFactory.decodeByteArray(buffer, 0, buffer.length, options);    if (bm == null)    {     Log.e(TAG, "convertToThumb, decode fail:" + null);     return null;    }    return bm;   }   /**   * 检查图片是否超过一定值，是则缩小   *   * @param view   * @param strFileName   */   public static Bitmap convertToThumb(byte[] buffer, float size)   {    // 获取原图宽度    BitmapFactory.Options options = new BitmapFactory.Options();    options.inJustDecodeBounds = true;    options.inPurgeable = true;    options.inInputShareable = true;    Bitmap bm = BitmapFactory.decodeByteArray(buffer, 0, buffer.length,      options);    // 计算缩放比例    float reSize = options.outWidth / size;    if (options.outWidth > options.outHeight)    {     reSize = options.outHeight / size;    }    if (reSize <= 0)    {     reSize = 1;    }    Log.d(TAG, "convertToThumb, reSize:" + reSize);    // 缩放    options.inJustDecodeBounds = false;    options.inSampleSize = (int) reSize;    if (bm != null && !bm.isRecycled())    {     bm.recycle();     bm = null;     Log.e(TAG, "convertToThumb, recyle");    }    bm = BitmapFactory.decodeByteArray(buffer, 0, buffer.length, options);    if (bm == null)    {     Log.e(TAG, "convertToThumb, decode fail:" + null);     return null;    }    return bm;   }   /**   * Bitmap --> byte[]   *   * @param bmp   * @return   */   private static byte[] readBitmap(Bitmap bmp)   {    ByteArrayOutputStream baos = new ByteArrayOutputStream();    bmp.compress(Bitmap.CompressFormat.JPEG, 60, baos);    try    {     baos.flush();     baos.close();    } catch (IOException e)    {     e.printStackTrace();    }    return baos.toByteArray();   }   /**   * Bitmap --> byte[]   *   * @param bmp   * @return   */   public static byte[] readBitmapFromBuffer(byte[] buffer, float size)   {    return readBitmap(convertToThumb(buffer, size));   }   /**   * 以屏幕宽度为基准，显示图片   *   * @param iv   * @param path   * @param screenW   * @return   */   public static Bitmap decodeStream(Context context, Intent data, float size)   {    Bitmap image = null;    try    {     Uri dataUri = data.getData();     // 获取原图宽度     BitmapFactory.Options options = new BitmapFactory.Options();     options.inJustDecodeBounds = true;     options.inPurgeable = true;     options.inInputShareable = true;     BitmapFactory.decodeStream(context.getContentResolver()       .openInputStream(dataUri), null, options);     // 计算缩放比例     float reSize = (int) (options.outWidth / size);     if (reSize <= 0)     {      reSize = 1;     }     Log.d(TAG, "old-w:" + options.outWidth + ", llyt-w:" + size       + ", resize:" + reSize);     // 缩放     options.inJustDecodeBounds = false;     options.inSampleSize = (int) reSize;     image = BitmapFactory.decodeStream(context.getContentResolver()       .openInputStream(dataUri), null, options);    } catch (Exception e)    {     e.printStackTrace();    }    return image;   }   /**   * 按新的宽高缩放图片   *   * @param bm   * @param newWidth   * @param newHeight   * @return   */   public static Bitmap scaleImage(Bitmap bm, int newWidth, int newHeight)   {    if (bm == null)    {     return null;    }    int width = bm.getWidth();    int height = bm.getHeight();    float scaleWidth = ((float) newWidth) / width;    float scaleHeight = ((float) newHeight) / height;    Matrix matrix = new Matrix();    matrix.postScale(scaleWidth, scaleHeight);    Bitmap newbm = Bitmap.createBitmap(bm, 0, 0, width, height, matrix,      true);    if (bm != null & !bm.isRecycled())    {     bm.recycle();     bm = null;    }    return newbm;   }   /**   * fuction: 设置固定的宽度，高度随之变化，使图片不会变形   *   * @param target   * 需要转化bitmap参数   * @param newWidth   * 设置新的宽度   * @return   */   public static Bitmap fitBitmap(Bitmap target, int newWidth)   {    int width = target.getWidth();    int height = target.getHeight();    Matrix matrix = new Matrix();    float scaleWidth = ((float) newWidth) / width;    // float scaleHeight = ((float)newHeight) / height;    int newHeight = (int) (scaleWidth * height);    matrix.postScale(scaleWidth, scaleWidth);    // Bitmap result = Bitmap.createBitmap(target,0,0,width,height,    // matrix,true);    Bitmap bmp = Bitmap.createBitmap(target, 0, 0, width, height, matrix,      true);    if (target != null && !target.equals(bmp) && !target.isRecycled())    {     target.recycle();     target = null;    }    return bmp;// Bitmap.createBitmap(target, 0, 0, width, height, matrix,       // true);   }   /**   * 根据指定的宽度平铺图像   *   * @param width   * @param src   * @return   */   public static Bitmap createRepeater(int width, Bitmap src)   {    int count = (width + src.getWidth() - 1) / src.getWidth();    Bitmap bitmap = Bitmap.createBitmap(width, src.getHeight(),      Config.ARGB_8888);    Canvas canvas = new Canvas(bitmap);    for (int idx = 0; idx < count; ++idx)    {     canvas.drawBitmap(src, idx * src.getWidth(), 0, null);    }    return bitmap;   }   /**   * 图片的质量压缩方法   *   * @param image   * @return   */   public static Bitmap compressImage(Bitmap image)   {    ByteArrayOutputStream baos = new ByteArrayOutputStream();    image.compress(Bitmap.CompressFormat.JPEG, 100, baos);// 质量压缩方法，这里100表示不压缩，把压缩后的数据存放到baos中    int options = 100;    while (baos.toByteArray().length / 1024 > 100)    { // 循环判断如果压缩后图片是否大于100kb,大于继续压缩     baos.reset();// 重置baos即清空baos     image.compress(Bitmap.CompressFormat.JPEG, options, baos);// 这里压缩options%，把压缩后的数据存放到baos中     options -= 10;// 每次都减少10    }    ByteArrayInputStream isBm = new ByteArrayInputStream(baos.toByteArray());// 把压缩后的数据baos存放到ByteArrayInputStream中    Bitmap bitmap = BitmapFactory.decodeStream(isBm, null, null);// 把ByteArrayInputStream数据生成图片    if (baos != null)    {     try     {      baos.close();     } catch (IOException e)     {      // TODO Auto-generated catch block      e.printStackTrace();     }    }    if (isBm != null)    {     try     {      isBm.close();     } catch (IOException e)     {      // TODO Auto-generated catch block      e.printStackTrace();     }    }    if (image != null && !image.isRecycled())    {     image.recycle();     image = null;    }    return bitmap;   }   /**   * 图片按比例大小压缩方法(根据Bitmap图片压缩)   *   * @param image   * @return   */   public static Bitmap getImage(Bitmap image)   {    ByteArrayOutputStream baos = new ByteArrayOutputStream();    image.compress(Bitmap.CompressFormat.JPEG, 100, baos);    if (baos.toByteArray().length / 1024 > 1024)    {// 判断如果图片大于1M,进行压缩避免在生成图片（BitmapFactory.decodeStream）时溢出     baos.reset();// 重置baos即清空baos     image.compress(Bitmap.CompressFormat.JPEG, 50, baos);// 这里压缩50%，把压缩后的数据存放到baos中    }    ByteArrayInputStream isBm = new ByteArrayInputStream(baos.toByteArray());    BitmapFactory.Options newOpts = new BitmapFactory.Options();    // 开始读入图片，此时把options.inJustDecodeBounds 设回true了    newOpts.inJustDecodeBounds = true;    Bitmap bitmap = BitmapFactory.decodeStream(isBm, null, newOpts);    newOpts.inJustDecodeBounds = false;    int w = newOpts.outWidth;    int h = newOpts.outHeight;    // 现在主流手机比较多是800*480分辨率，所以高和宽我们设置为    float hh = 800f;// 这里设置高度为800f    float ww = 480f;// 这里设置宽度为480f    // 缩放比。由于是固定比例缩放，只用高或者宽其中一个数据进行计算即可    int be = 1;// be=1表示不缩放    if (w > h && w > ww)    {// 如果宽度大的话根据宽度固定大小缩放     be = (int) (newOpts.outWidth / ww);    } else if (w < h && h > hh)    {// 如果高度高的话根据宽度固定大小缩放     be = (int) (newOpts.outHeight / hh);    }    if (be <= 0)     be = 1;    newOpts.inSampleSize = be;// 设置缩放比例    // 重新读入图片，注意此时已经把options.inJustDecodeBounds 设回false了    isBm = new ByteArrayInputStream(baos.toByteArray());    bitmap = BitmapFactory.decodeStream(isBm, null, newOpts);    if (isBm != null)    {     try     {      isBm.close();     } catch (IOException e)     {      // TODO Auto-generated catch block      e.printStackTrace();     }    }    if (image != null && !image.isRecycled())    {     image.recycle();     image = null;    }    return compressImage(bitmap);// 压缩好比例大小后再进行质量压缩   }   /**   * 通过资源id转化成Bitmap 全屏显示   *   * @param context   * @param drawableId   * @param screenWidth   * @param screenHight   * @return   */   public static Bitmap ReadBitmapById(Context context, int drawableId,     int screenWidth, int screenHight)   {    BitmapFactory.Options options = new BitmapFactory.Options();    options.inPreferredConfig = Config.ARGB_8888;    options.inInputShareable = true;    options.inPurgeable = true;    InputStream stream = context.getResources().openRawResource(drawableId);    Bitmap bitmap = BitmapFactory.decodeStream(stream, null, options);    return getBitmap(bitmap, screenWidth, screenHight);   }  }