Android 图片操作，Image实战

平时有很多时候会涉及到图片的操作，如获取缩略图，裁剪图片，旋转图片，获取尺寸，改变大学，drawable与bitmap相互转换等问题。本文给打击总结一些常用的操作，比较基础但是实用。

一，drawable与bitmap相互转换

drawable资源转换为bitmap对象

/**
* 将已有的drawable资源转换为bitmap对象
*/
public static Bitmap drawableToBitamp(Drawable drawable)
{
BitmapDrawable bd = (BitmapDrawable) drawable;
Bitmap bitmap = bd.getBitmap();
return bitmap;
}

或者

/**
* 将已有的drawable资源转换为bitmap对象,方式二
*/
public static Bitmap drawable2Bitamp(Drawable drawable)
{
int w = drawable.getIntrinsicWidth();
int h = drawable.getIntrinsicHeight();
//System.out.println("Drawable转Bitmap");
Bitmap.Config config =
drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888
: Bitmap.Config.RGB_565;
Bitmap bitmap = Bitmap.createBitmap(w,h,config);
//注意，下面三行代码要用到，否在在View或者surfaceview里的canvas.drawBitmap会看不到图
Canvas canvas = new Canvas(bitmap);
drawable.setBounds(0, 0, w, h);
drawable.draw(canvas);
return bitmap;
}

Bitmap转化为drawable

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

二，缩放图片到指定的大小

//图片缩放到指定的宽高
public static Bitmap zoomBitmap(Bitmap bitmap, int width, int height) {
int w = bitmap.getWidth();
int h = bitmap.getHeight();
Matrix matrix = new Matrix();
float scaleWidth = ((float) width / w);
float scaleHeight = ((float) height / h);
matrix.postScale(scaleWidth, scaleHeight);
Bitmap newbmp = Bitmap.createBitmap(bitmap, 0, 0, w, h, matrix, true);
return newbmp;
}

三，保存bitmap到本地

//将bitmap保存到sdcard中
public static File saveBitmapToSDCard(Bitmap photoBitmap,String path,String photoName){
if (FileUtils.isSDCardAvailable()) {
File dir = new File(path);
if (!dir.exists()){
dir.mkdirs();
}
File photoFile = new File(path , photoName + ".jpg");
FileOutputStream fileOutputStream = null;
try {
fileOutputStream = new FileOutputStream(photoFile);
if (photoBitmap != null) {
if (photoBitmap.compress(Bitmap.CompressFormat.JPEG, 100, fileOutputStream)) {
fileOutputStream.flush();
//fileOutputStream.close();
return photoFile;
}
}
} catch (FileNotFoundException e) {
photoFile.delete();
e.printStackTrace();
} catch (Exception e) {
photoFile.delete();
e.printStackTrace();
} finally{
try {
if (fileOutputStream!=null)
fileOutputStream.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
return null;
}

四，把bitmap转换成String

/**
* 把bitmap转换成String
*/
public static String bitmapToString(String filePath) {
Bitmap bm = getSmallBitmap(filePath);
ByteArrayOutputStream baos = new ByteArrayOutputStream();
bm.compress(Bitmap.CompressFormat.JPEG, 40, baos);
byte[] b = baos.toByteArray();
return Base64.encodeToString(b, Base64.DEFAULT);
}

五，计算图片的缩放值

/**
* 计算图片的缩放值
* @return
*/
public static int calculateInSampleSize(BitmapFactory.Options options,
int reqWidth, int reqHeight) {
final int height = options.outHeight;
final int width = options.outWidth;
int inSampleSize = 1;
if (height > reqHeight || width > reqWidth) {
// Calculate ratios of height and width to requested height andwidth
final int heightRatio = Math.round((float) height / (float) reqHeight);
final int widthRatio = Math.round((float) width / (float) reqWidth);
// Choose the smallest ratio as inSampleSize value, this will guarantee
// a final image with both dimensions larger than or equal to the requested height and width.
inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
}
return inSampleSize;
}

六，根据路径获得图片并返回压缩的bitmap

/**
* 根据路径获得图片并压缩，返回bitmap用于显示
*/
public static Bitmap getSmallBitmap(String filePath) {
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(filePath, options);
// Calculate inSampleSize
options.inSampleSize = calculateInSampleSize(options, 480, 800);
// Decode bitmap with inSampleSize set
options.inJustDecodeBounds = false;
return BitmapFactory.decodeFile(filePath, options);
}

七，判断照片角度

/**
* 判断照片角度
* @param path
* @return
*/
public static int readPictureDegree(String path) {
int degree = 0;
try {
ExifInterface exifInterface = new ExifInterface(path);
int orientation = exifInterface.getAttributeInt(
ExifInterface.TAG_ORIENTATION,
ExifInterface.ORIENTATION_NORMAL);
switch (orientation) {
case ExifInterface.ORIENTATION_ROTATE_90:
degree = 90;
break;
case ExifInterface.ORIENTATION_ROTATE_180:
degree = 180;
break;
case ExifInterface.ORIENTATION_ROTATE_270:
degree = 270;
break;
}
} catch (IOException e) {
e.printStackTrace();
}
return degree;
}

八，旋转照片

/**
* 旋转照片
* @param bitmap
* @param degress
* @return
*/
public static Bitmap rotateBitmap(Bitmap bitmap,int degress) {
if (bitmap != null) {
Matrix m = new Matrix();
m.postRotate(degress);
bitmap = Bitmap.createBitmap(bitmap, 0, 0, bitmap.getWidth(),
bitmap.getHeight(), m, true);
return bitmap;
}
return bitmap;
}

九，处理手机相片的角度旋转

/**
* 压缩图片，处理某些手机拍照角度旋转的问题
*/
public static String compressImage(String filePath, String targetPath, int quality)  {
Bitmap bm = getSmallBitmap(filePath);
int degree = readPictureDegree(filePath);
if(degree!=0){//旋转照片角度
bm=rotateBitmap(bm,degree);
}
File outputFile=new File(targetPath);
try {
if (!outputFile.exists()) {
outputFile.getParentFile().mkdirs();
outputFile.createNewFile();
}else{
outputFile.delete();
}
FileOutputStream out = new FileOutputStream(outputFile);
bm.compress(Bitmap.CompressFormat.JPEG, quality, out);
}catch (Exception e){
LogUtils.debug(TAG,"compressImage error"+e.toString());
}
return outputFile.getPath();
}

未完待续，欢迎交流，杜乾，Dusan，Q 291902259。