BitmapHelper

提供一些获取本地缩略图，获取网络图片。dp与px的相互转换等方法。

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.ProtocolException;
import java.net.URL;
import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Matrix;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.graphics.PorterDuff;
import android.graphics.PorterDuffXfermode;
import android.graphics.Rect;
import android.graphics.RectF;
import android.graphics.Bitmap.Config;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.NinePatchDrawable;
import android.util.Base64;

public class BitmapHelper {

    private static BitmapHelper util;
    private static Context context = App.getInstance();

    public static BitmapHelper getInstance() {

        if (util == null) {
            util = new BitmapHelper();

        }
        return util;

    }

    private BitmapHelper() {
        super();
    }

    /**
     * 将bitmap转为base64
     * 
     * @param bitmap
     * @param imgFormat
     * @return
     */
    @SuppressLint("NewApi")
    public String bitmapToBase64(Bitmap bitmap, String imgFormat) {

        if (null == bitmap) {

            return null;
        }
        ByteArrayOutputStream out = null;
        try {
            out = new ByteArrayOutputStream();
            Bitmap.CompressFormat compressFormat = Bitmap.CompressFormat.JPEG;
            if (imgFormat.equalsIgnoreCase("png"))
                compressFormat = Bitmap.CompressFormat.PNG;
            bitmap.compress(compressFormat, 85, out);
            out.flush();
            out.close();
            byte[] imgBytes = out.toByteArray();
            return Base64.encodeToString(imgBytes, Base64.DEFAULT);
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                out.flush();
                out.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return null;
    }

    /**
     * 将图片转为base64
     * 
     * @param imgPath
     * @param imgFormat
     * @return
     */
    @SuppressLint("NewApi")
    public String urlToBase64(String imgPath, String imgFormat) {
        Bitmap bitmap = null;
        if (imgPath != null && imgPath.length() > 0) {
            bitmap = readBitmap(imgPath);
        }
        return bitmapToBase64(bitmap, imgFormat);

    }

    private Bitmap readBitmap(String imgPath) {
        try {
            return BitmapFactory.decodeFile(imgPath);
        } catch (Exception e) {
            return null;
        }
    }

    /**
     * 得到圆角的bitmap
     * 
     * @param bitmap
     * @param corner
     *            以长或宽的比例为半径，2表示二分之中的一个。8表示八分之中的一个
     * @return
     */
    public Bitmap getRoundedCornerBitmap(Bitmap bitmap, int corner) {
        int width = bitmap.getWidth();
        int height = bitmap.getHeight();
        float roundPx;
        float left, top, right, bottom, dst_left, dst_top, dst_right, dst_bottom;
        if (width <= height) {
            roundPx = width / corner;
            top = 0;
            bottom = width;
            left = 0;
            right = width;
            height = width;
            dst_left = 0;
            dst_top = 0;
            dst_right = width;
            dst_bottom = width;
        } else {
            roundPx = height / corner;
            float clip = (width - height) / corner;
            left = clip;
            right = width - clip;
            top = 0;
            bottom = height;
            width = height;
            dst_left = 0;
            dst_top = 0;
            dst_right = height;
            dst_bottom = height;
        }
        Bitmap output = Bitmap.createBitmap(width, height, Config.ARGB_8888);
        Canvas canvas = new Canvas(output);
        final int color = 0xff424242;
        final Paint paint = new Paint();
        final Rect src = http://www.mamicode.com/new Rect((int) left, (int) top, (int) right,
                (int) bottom);
        final Rect dst = new Rect((int) dst_left, (int) dst_top,
                (int) dst_right, (int) dst_bottom);
        final RectF rectF = new RectF(dst);
        paint.setAntiAlias(true);
        canvas.drawARGB(0, 0, 0, 0);
        paint.setColor(color);
        canvas.drawRoundRect(rectF, roundPx, roundPx, paint);
        paint.setXfermode(new PorterDuffXfermode(
                android.graphics.PorterDuff.Mode.SRC_IN));
        canvas.drawBitmap(bitmap, src, dst, paint);
        return output;
    }

    /**
     * 设置Bitmap圆角
     * 
     * @param image
     *            传入的Bitmap
     * @param outerRadiusRat
     *            圆角半径
     * @return 返回处理后的Bitmap
     */
    public Bitmap getRoundedBitmap(Bitmap image, int outerRadiusRat) {
        int x = image.getWidth();
        int y = image.getHeight();
        // 依据源文件新建一个darwable对象
        Drawable imageDrawable = new BitmapDrawable(image);

        // 新建一个新的输出图片
        Bitmap output = Bitmap.createBitmap(x, y, Bitmap.Config.ARGB_8888);
        Canvas canvas = new Canvas(output);

        // 新建一个矩形
        RectF outerRect = new RectF(0, 0, x, y);

        // 产生一个红色的圆角矩形
        Paint paint = new Paint(Paint.ANTI_ALIAS_FLAG);
        paint.setColor(Color.RED);
        canvas.drawRoundRect(outerRect, outerRadiusRat, outerRadiusRat, paint);

        // 将源图片绘制到这个圆角矩形上
        // 具体解释见http://lipeng88213.iteye.com/blog/1189452
        paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC_IN));
        imageDrawable.setBounds(0, 0, x, y);
        canvas.saveLayer(outerRect, paint, Canvas.ALL_SAVE_FLAG);
        imageDrawable.draw(canvas);
        canvas.restore();

        return output;
    }

    /**
     * 图片压缩
     * 
     * @param image
     * @return
     */
    public Bitmap getCompressBitmap(Bitmap image, int minSize) {
        ByteArrayOutputStream baos = new ByteArrayOutputStream();
        image.compress(Bitmap.CompressFormat.JPEG, 100, baos);
        int options = 100;
        while (baos.toByteArray().length / 1024 > minSize) {
            options -= 10;
            baos.reset();
            image.compress(Bitmap.CompressFormat.JPEG, options, baos);
        }
        ByteArrayInputStream isBm = new ByteArrayInputStream(baos.toByteArray());
        Bitmap bitmap = BitmapFactory.decodeStream(isBm, null, null);
        return bitmap;
    }

    /**
     * 得到本地缩略图
     * 
     * @param srcPath
     * @return
     */
    public Bitmap getCompressBitmapByLocal(String srcPath, int ww, int hh) {
        BitmapFactory.Options newOpts = new BitmapFactory.Options();
        newOpts.inJustDecodeBounds = true;
        Bitmap bitmap = BitmapFactory.decodeFile(srcPath, newOpts);
        newOpts.inJustDecodeBounds = false;
        int w = newOpts.outWidth;
        int h = newOpts.outHeight;

        int be = 1;
        if (w > h && w > ww) {
            be = (int) (newOpts.outWidth / ww);
        } else if (w < h && h > hh) {
            be = (int) (newOpts.outHeight / hh);
        }
        if (be <= 0)
            be = 1;
        newOpts.inSampleSize = be;
        bitmap = BitmapFactory.decodeFile(srcPath, newOpts);
        return getCompressBitmap(bitmap, 100);
    }

    /**
     * 放大缩小图片
     * 
     * @param bitmap
     * @param w
     * @param h
     * @return
     */
    public Bitmap getZoomBitmap(Bitmap bitmap, int w, int h) {
        Bitmap newbmp = null;
        if (bitmap != null) {
            int width = bitmap.getWidth();
            int height = bitmap.getHeight();
            Matrix matrix = new Matrix();
            float scaleWidht = ((float) w / width);
            float scaleHeight = ((float) h / height);
            matrix.postScale(scaleWidht, scaleHeight);
            newbmp = Bitmap.createBitmap(bitmap, 0, 0, width, height, matrix,
                    true);
        }
        return newbmp;
    }

    /**
     * 得到网络图片
     * 
     * @param imgUrl
     * @return
     */
    public Bitmap getHttpBitmap(String imgUrl) {

        Bitmap bitmap = null;
        if (!PhoneHelper.getInstance().isNetworkConnected()) {

            return null;
        }

        InputStream is = getHttpPicInputStream(imgUrl);
        if (is != null) {

            bitmap = BitmapFactory.decodeStream(is);

            try {
                is.close();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }

        }

        return bitmap;

    }

    /**
     * 得到网络图片的输入流
     * 
     * @param url
     * @return
     */
    public InputStream getHttpPicInputStream(String url) {
        InputStream is = null;
        URL url1 = null;
        try {
            url1 = new URL(url);
            HttpURLConnection conn = (HttpURLConnection) url1.openConnection();
            conn.setDoInput(true);
            conn.setConnectTimeout(30000);
            conn.setRequestMethod("GET");
            conn.connect();

            if (conn.getResponseCode() == HttpURLConnection.HTTP_OK) {
                is = conn.getInputStream();
            }
        } catch (MalformedURLException e) {
            e.printStackTrace();
        } catch (ProtocolException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        }

        return is;
    }

    /**
     * Bitmap转化为drawable
     * 
     * @param bitmap
     * @return
     */
    public Drawable bitmap2Drawable(Bitmap bitmap) {
        return new BitmapDrawable(bitmap);
    }

    /**
     * Drawable 转 bitmap
     * 
     * @param drawable
     * @return
     */
    public Bitmap drawable2Bitmap(Drawable drawable) {
        if (drawable instanceof BitmapDrawable) {
            return ((BitmapDrawable) drawable).getBitmap();
        } else if (drawable instanceof NinePatchDrawable) {
            Bitmap bitmap = Bitmap
                    .createBitmap(
                            drawable.getIntrinsicWidth(),
                            drawable.getIntrinsicHeight(),
                            drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888
                                    : Bitmap.Config.RGB_565);
            Canvas canvas = new Canvas(bitmap);
            drawable.setBounds(0, 0, drawable.getIntrinsicWidth(),
                    drawable.getIntrinsicHeight());
            drawable.draw(canvas);
            return bitmap;
        } else {
            return null;
        }
    }

    /**
     * 将bitmap存为本地图片
     * @param bitmap
     * @param path
     * @return
     */
    public boolean saveBitmapForSdCard(Bitmap bitmap, String path) {
        File f = new File(path);
        File parent = new File(f.getParent());
        FileOutputStream out = null;
        if (!parent.exists()) {
            parent.mkdirs();
        }
        try {
            f.createNewFile();
            out = new FileOutputStream(f);
            bitmap.compress(Bitmap.CompressFormat.JPEG, 80, out);
            out.flush();
            out.close();

            return true;
        } catch (IOException e) {
            e.printStackTrace();
            return false;
        } finally {
            try {
                out.flush();
                out.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }

    /**
     * dp转px
     * 
     * @param context
     * @param dpValue
     * @return
     */
    public int dp2Px(float dpValue) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return (int) (dpValue * scale + 0.5f);
    }

    /**
     * px转dp
     */
    public int px2Dp(float pxValue) {
        final float scale = context.getResources().getDisplayMetrics().density;

        return (int) (pxValue / scale + 0.5f);
    }

    /**
     * 依据网络状态获取本地图片缩略图
     * 
     * @param picPath
     * @return
     */
    public Bitmap getBitmapByNetWork(String picPath) {
        int networkType = PhoneHelper.getInstance().getNetType();

        Bitmap tagBm = null;
        ByteArrayOutputStream decodeBitmap = null;
        int size = 100;
        switch (networkType) {
        case 1:
            size = 150;
            break;
        case 2:
            size = 80;
            break;
        case 3:
        case 4:
            size = 100;
            break;

        default:
            return null;

        }
        decodeBitmap = getBitmapByteArray(picPath, size);

        if (decodeBitmap != null) {
            byte[] array = decodeBitmap.toByteArray();
            try {
                tagBm = BitmapFactory.decodeByteArray(array, 0, array.length);
            } catch (OutOfMemoryError oError) {
                oError.printStackTrace();
            } catch (Exception e) {
            }

        }

        return tagBm;

    }

    /**
     * 将本地图片转为输出流
     * @param path
     * @param size
     * @return
     */
    public ByteArrayOutputStream getBitmapByteArray(String path, int size) {

        BitmapFactory.Options opts = new BitmapFactory.Options();
        opts.inJustDecodeBounds = true;// 设置成了true,不占用内存，仅仅获取bitmap宽高
        BitmapFactory.decodeFile(path, opts);
        opts.inSampleSize = computeSampleSize(opts, -1, 1024 * 800);

        opts.inJustDecodeBounds = false;// 这里一定要将其设置回false，由于之前我们将其设置成了true
        opts.inPurgeable = true;
        opts.inInputShareable = true;
        opts.inDither = false;
        opts.inPurgeable = true;
        opts.inPreferredConfig = Bitmap.Config.RGB_565;
        opts.inTempStorage = new byte[100 * 1024];
        FileInputStream is = null;
        Bitmap bmp = null;

        ByteArrayOutputStream baos = null;
        try {
            is = new FileInputStream(path);
            bmp = BitmapFactory.decodeFileDescriptor(is.getFD(), null, opts);

            baos = new ByteArrayOutputStream();

            bmp.compress(Bitmap.CompressFormat.JPEG, 100, baos);
            int options = 100;
            while (baos.toByteArray().length / 1024 > size && options > 4) { // 循环推断假设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
                bmp.compress(Bitmap.CompressFormat.JPEG, options, baos);// 这里压缩options%。把压缩后的数据存放到baos中
                options -= 2;// 每次都降低10
            }
            bmp.recycle();
            return baos;
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (OutOfMemoryError oError) {
            oError.printStackTrace();
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            try {
                if (is != null) {
                    is.close();
                }
                if (baos != null) {
                    baos.close();
                }

            } catch (IOException e) {
                e.printStackTrace();
            }
            System.gc();
        }
        return baos;
    }

    /**
     * 为了得到恰当的inSampleSize，Android提供了一种动态计算的方法
     * @param options
     * @param minSideLength
     * @param maxNumOfPixels
     * @return
     */
    private int computeSampleSize(BitmapFactory.Options options,
            int minSideLength, int maxNumOfPixels) {
        int initialSize = computeInitialSampleSize(options, minSideLength,
                maxNumOfPixels);

        int roundedSize;
        if (initialSize <= 8) {
            roundedSize = 1;
            while (roundedSize < initialSize) {
                roundedSize <<= 1;
            }
        } else {
            roundedSize = (initialSize + 7) / 8 * 8;
        }

        return roundedSize;
    }

    private int computeInitialSampleSize(BitmapFactory.Options options,
            int minSideLength, int maxNumOfPixels) {
        double w = options.outWidth;
        double h = options.outHeight;

        int lowerBound = (maxNumOfPixels == -1) ? 1 : (int) Math.ceil(Math
                .sqrt(w * h / maxNumOfPixels));
        int upperBound = (minSideLength == -1) ? 128 : (int) Math.min(
                Math.floor(w / minSideLength), Math.floor(h / minSideLength));

        if (upperBound < lowerBound) {
            return lowerBound;
        }

        if ((maxNumOfPixels == -1) && (minSideLength == -1)) {
            return 1;
        } else if (minSideLength == -1) {
            return lowerBound;
        } else {
            return upperBound;
        }
    }

}