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;}

作者：杰瑞教育
出处：http://www.cnblogs.com/jerehedu/
本文版权归烟台杰瑞教育科技有限公司和博客园共有，欢迎转载，但未经作者同意必须保留此段声明，且在文章页面明显位置给出原文连接，否则保留追究法律责任的权利。

转载于:https://www.cnblogs.com/Im-Victor/p/10102194.html