Android實現對圖片的縮放、剪切、旋轉、存儲

一、問題描述

在開發中，當我們需要的有一張大圖片同時還需要一些小圖片時，我們只需要通過代碼對此圖片進行不同比例的縮放即可，這樣大大節約資源，減小了安裝包的尺寸 。除縮放外，我們還經常對圖片進行其他操作如裁剪、旋轉、存儲等。

這樣我們可以編寫對於圖片進行處理的通用組件，方便開發。下面就分享一下對圖片進行處理的組件BitmapUtil，案例界面：

二、技術點描述

1、通過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);

該方法可實現位圖的縮放、裁剪、旋轉操作

參數說明：

Bitmap s：要處理的原始位圖

int x ,y：起始位置坐標

int w：要截的圖的寬度

int h：要截的圖的寬度

Matrix m 矩陣，主要是用於平面的縮放、平移、旋轉

boolean f：是否保證等比

返回值：返回處理後的Bitmap

三、BitmapUtil組件

可實現對圖片進行按比例縮放、圖片按比例裁剪、圓形圖片處理等方法，實現功能如下：

1、readBitmapById（）方法

/**
     * 通過資源id轉化成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，實現按指定寬高縮放圖片

執行效果如圖：

/**
* 縮放圖片
     * @param bm 要縮放圖片
     * @param newWidth 寬度
     * @param newHeight 高度
     * @return處理後的圖片
     */
    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();//銷毀原圖片
            bm = null;
        }
        return newbm;
    }

3、imageCrop()方法

執行效果如圖：

/**
     * 按照一定的寬高比例裁剪圖片
     * @param bitmap 要裁剪的圖片
     * @param num1 長邊的比例
     * @param num2 短邊的比例
     * @param isRecycled是否回收原圖片
     * @return 裁剪後的圖片
     */
    public static Bitmap  imageCrop(Bitmap bitmap, int num1, int num2, boolean isRecycled){
        if (bitmap == null){
            return null;
        }
        int w = bitmap.getWidth(); // 得到圖片的寬，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();//回收原圖片
            bitmap = null;
        }
        return bmp;
    }

4、toRoundCorner()實現將圖片轉圓角

執行效果如圖：

/**
     *圖片轉圓角 
     * @param bitmap需要轉的bitmap
     * @param pixels轉圓角的弧度
     * @return 轉圓角的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（）方法將圖像裁剪成圓形

執行效果如圖：

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，實現旋轉圖片

執行效果如圖：

/**
     * 旋轉圖片
     * @param angle 旋轉角度
     * @param bitmap 要處理的Bitmap
     * @return 處理後的Bitmap
     */
    public static Bitmap rotaingImageView(int angle, Bitmap bitmap)
    {
        // 旋轉圖片 動作
        Matrix matrix = new Matrix();
        matrix.postRotate(angle);
        // 創建新的圖片
        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()實現將保存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;
    }