Android实现对图片的缩放、剪切、旋转、存储

一、问题描述

　　在开发中，当我们需要的有一张大图片同时还需要一些小图片时，我们只需要通过代码对此图片进行不同比例的缩放即可，这样大大节约资源，减小了安装包的尺寸 。除缩放外，我们还经常对图片进行其他操作如裁剪、旋转、存储等。

　　这样我们可以编写对于图片进行处理的通用组件，方便开发。下面就分享一下对图片进行处理的组件BitmapUtil，案例界面：

二、技术点描述

　　1、通过BitmapFactory取得Bitmap

Bitmap bm=BitmapFactory.decodeStream(InputStream is );

　　2、Bimap的createBitmap()方法

Bitmap newbm = Bitmap.createBitmap( Bitmap s, int x, int y, int w, int h, Matrix m, boolean f);

　　该方法可实现位图的缩放、裁剪、旋转操作

　　参数说明：

Bitmap s：要处理的原始位图

int x ,y：起始位置坐标

int w：要截的图的宽度

int h：要截的图的宽度

Matrix m 矩阵，主要是用于平面的缩放、平移、旋转

boolean f：是否保证等比

返回值：返回处理后的Bitmap

三、BitmapUtil组件

　　可实现对图片进行按比例缩放、图片按比例裁剪、圆形图片处理等方法，实现功能如下：

1、readBitmapById（）方法

/**     * 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);    }

2、scaleImage()方法，实现按指定宽高缩放图片

　　执行效果如图：

/*** 缩放图片     * @param bm 要缩放图片     * @param newWidth 宽度     * @param newHeight 高度     * @return处理后的图片     */    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();//销毁原图片            bm = null;        }        return newbm;    }

3、imageCrop()方法

 执行效果如图：

/**     * 按照一定的宽高比例裁剪图片     * @param bitmap 要裁剪的图片     * @param num1 长边的比例     * @param num2 短边的比例     * @param isRecycled是否回收原图片     * @return 裁剪后的图片     */    public static Bitmap  imageCrop(Bitmap bitmap, int num1, int num2, boolean isRecycled){        if (bitmap == null){            return null;        }        int w = bitmap.getWidth(); // 得到图片的宽，高        int h = bitmap.getHeight();        int retX, retY;        int nw, nh;        if (w > h){            if (h > w * num2 / num1){                nw = w;                nh = w * num2 / num1;                retX = 0;                retY = (h - nh) / 2;            } else{                nw = h * num1 / num2;                nh = h;                retX = (w - nw) / 2;                retY = 0;            }        } else{            if (w > h * num2 / num1){                nh = h;                nw = h * num2 / num1;                retY = 0;                retX = (w - nw) / 2;            } else{                nh = w * num1 / num2;                nw = w;                retY = (h - nh) / 2;                retX = 0;}        }        Bitmap bmp = Bitmap.createBitmap(bitmap, retX, retY, nw, nh, null,false);        if (isRecycled && bitmap != null && !bitmap.equals(bmp)&& !bitmap.isRecycled()){            bitmap.recycle();//回收原图片            bitmap = null;        }        return bmp;    }

4、toRoundCorner()实现将图片转圆角

 　　执行效果如图：

 

/**     *图片转圆角      * @param bitmap需要转的bitmap     * @param pixels转圆角的弧度     * @return 转圆角的bitmap     */    public static Bitmap toRoundCorner(Bitmap bitmap, int pixels)    {        Bitmap output = Bitmap.createBitmap(bitmap.getWidth(),                bitmap.getHeight(), Config.ARGB_8888);        Canvas canvas = new Canvas(output);        final int color = 0xff424242;        final Paint paint = new Paint();        final Rect rect = new Rect(0, 0, bitmap.getWidth(), bitmap.getHeight());        final RectF rectF = new RectF(rect);        final float roundPx = pixels;        paint.setAntiAlias(true);        canvas.drawARGB(0, 0, 0, 0);        paint.setColor(color);        canvas.drawRoundRect(rectF, roundPx, roundPx, paint);        paint.setXfermode(new PorterDuffXfermode(Mode.SRC_IN));        canvas.drawBitmap(bitmap, rect, rect, paint);        if (bitmap != null && !bitmap.isRecycled())        {            bitmap.recycle();        }        return output;    }

5、toRoundBitmap（）方法将图像裁剪成圆形

 　　执行效果如图：

public static Bitmap toRoundBitmap(Bitmap bitmap){if (bitmap == null){            return null;        }        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 / 2;            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 / 2;            float clip = (width - height) / 2;            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 = 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(Mode.SRC_IN));        canvas.drawBitmap(bitmap, src, dst, paint);        if (bitmap != null && !bitmap.isRecycled()){            bitmap.recycle();            bitmap = null;        }        return output;    }

6、rotaingImageView()方法，实现旋转图片

 执行效果如图：

/**     * 旋转图片     * @param angle 旋转角度     * @param bitmap 要处理的Bitmap     * @return 处理后的Bitmap     */    public static Bitmap rotaingImageView(int angle, Bitmap bitmap)    {        // 旋转图片 动作        Matrix matrix = new Matrix();        matrix.postRotate(angle);        // 创建新的图片        Bitmap resizedBitmap = Bitmap.createBitmap(bitmap, 0, 0,                bitmap.getWidth(), bitmap.getHeight(), matrix, true);        if (resizedBitmap != bitmap && bitmap != null && !bitmap.isRecycled()){            bitmap.recycle();            bitmap = null;        }        return resizedBitmap;        }

7、saveBmpToSd()实现将保存Bitmap到sdcard

        public static boolean saveBmpToSd(String dir, Bitmap bm, String filename,            int quantity, boolean recyle) {        boolean ret = true;        if (bm == null) {            return false;}        File dirPath = new File(dir);        if (!exists(dir)) {            dirPath.mkdirs();        }        if (!dir.endsWith(File.separator)) {            dir += File.separator;        }        File file = new File(dir + filename);        OutputStream outStream = null;        try {            file.createNewFile();            outStream = new FileOutputStream(file);            bm.compress(Bitmap.CompressFormat.JPEG, quantity, outStream);        } catch (Exception e) {            e.printStackTrace();            ret = false;        } finally {            try {                if (outStream != null) outStream.close();            } catch (IOException e) {                e.printStackTrace();            }            if (recyle && !bm.isRecycled()) {                bm.recycle();                bm = null;            }        }        return ret;    }