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Android图像处理
相机的拍摄照片尺寸通常都很大，需要预先处理，然后才能在ImageView视图上显示。主流Android手机都带有800万像素的照相机组件。大尺寸的图片很容易耗尽应用的内存。因此，加载图片前，需要编写代码缩小图片。图片使用完毕，也需要编写代码清理删除它。
/**
* 图像处理
* @author mw
*
*/
public class PictureUtils {
/**
* 将图片缩放到设备默认的显示尺寸 onStart()调用
* @param a
* @param path
* @return
*/
public static BitmapDrawable getScaledDrawable(Activity a,String path){
Display display = a.getWindowManager().getDefaultDisplay();
float destWidth = display.getWidth();
float destHeight = display.getHeight();
BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(path,options);
float srcWidth = options.outWidth;
float srcHeight = options.outHeight;
int inSampleSize = 1;
if (srcWidth > destWidth || srcHeight > destHeight) {
if (srcWidth > srcHeight) {
inSampleSize = Math.round(srcWidth/ destWidth);
}else{
inSampleSize = Math.round(srcHeight / destHeight);
}
}
options = new BitmapFactory.Options();
options.inSampleSize = inSampleSize;
Bitmap bitmap = BitmapFactory.decodeFile(path,options);
return new BitmapDrawable(a.getResources(),bitmap);
}
/**
* 缷载图片 onStop()调用
* @param imageView
*/
public static void cleanImageView(ImageView imageView){
if ( !(imageView.getDrawable() instanceof BitmapDrawable)) {
return;
}
BitmapDrawable b = (BitmapDrawable)imageView.getDrawable();
//释放bitmap占用的原始存储空间，避免可能的内存耗尽问题
b.getBitmap().recycle();
imageView.setImageDrawable(null);
}
} //以下示例：加载图片---压缩图片---缩放图片---处理圆角
/**
* 根据传入的宽和高，计算出合适的inSampleSize值
* @param options
* @param reqWidth
* @param reqHeight
* @return
*/
public static int calculateInSampleSize(BitmapFactory.Options options,
int reqWidth, int reqHeight) {
// 源图片的高度和宽度
final int height = options.outHeight;
final int width = options.outWidth;
int inSampleSize = 1;
if (height > reqHeight || width > reqWidth) {
// 计算出实际宽高和目标宽高的比率
if (width > height) {
inSampleSize = Math.round((float) width / (float) reqWidth);
}else {
//round 返回最接近参数，意思也就是四舍五入math.round(-8.1)=-8 math.round(8.9)=9
inSampleSize = Math.round((float) height / (float) reqHeight);
}
// 选择宽和高中最小的比率作为inSampleSize的值，这样可以保证最终图片的宽和高
// 一定都会大于等于目标的宽和高。
//inSampleSize = heightRatio < widthRatio ? heightRatio : widthRatio;
}
return inSampleSize;
}
/**
* 压缩好的bitmap
* @param pathName
* @param reqWidth
* @param reqHeight
* @return
*/
public static Bitmap decodeSampledBitmapFromResource(String pathName,
int reqWidth, int reqHeight) {
// 第一次解析将inJustDecodeBounds设置为true，来获取图片大小
final BitmapFactory.Options options = new BitmapFactory.Options();
options.inJustDecodeBounds = true;
BitmapFactory.decodeFile(pathName,options);
// 调用上面定义的方法计算inSampleSize值
options.inSampleSize = calculateInSampleSize(options, reqWidth,reqHeight);
// 使用获取到的inSampleSize值再次解析图片
options.inJustDecodeBounds = false;
//options.inSampleSize = 5;
return BitmapFactory.decodeFile(pathName,options);
}
/**
* 处理圆角的图标
* @param background
* @param src
* @param r 弧度
* @param x
* @param y
* @return
*/
public static Bitmap mergerIcon(Bitmap background,Bitmap src,int r,int x,int y){
Bitmap output = Bitmap.createBitmap(background.getWidth(), background.getHeight(), Config.ARGB_8888);
Canvas canvas = new Canvas(output);
final int color = 0xff000000;
final Paint paint = new Paint();
final Rect rect = new Rect(0, 0, background.getWidth(), background.getHeight());
final RectF rectF = new RectF(rect);
final float roundPx = r;
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(background, rect, rect, paint);
// canvas.drawBitmap(src, rect, rect, paint);
canvas.drawBitmap(src, x, y, paint);
canvas.save();
return output;
}
/**缩放图片*/
public static Bitmap resizeImage(Bitmap src, int destW, int destH){
if(src == null)return null;
int srcW = src.getWidth();
int srcH = src.getHeight();
float scaleWidth = 1;
float scaleHeight = 1;
if(srcW == destW&&srcH == destH){
return src;
}
//计算出这次要缩小的比例
scaleWidth=(float)destW/(float)srcW;
scaleHeight=(float)destH/(float)srcH;
//产生resize后的Bitmap对象
Matrix matrix=new Matrix();
matrix.postScale(scaleWidth, scaleHeight);
Bitmap resizeBmp=Bitmap.createBitmap(src, 0, 0, srcW, srcH, matrix, true);
return resizeBmp;
} //示例使用
//获取图片路径
File fileDir = new File(SdcardUtil.getSdcardCollInfo() + str + "/" + pathList.get(0));
//处理图片
Bitmap bitmap = BitmapUtils.decodeSampledBitmapFromResource(fileDir.getPath(),200,700);
Bitmap background = BitmapFactory.decodeResource(mContext.getResources(), R.drawable.intdex_page_cll_point);
//缩放图片
Bitmap map = BitmapUtils.resizeImage(bitmap, background.getWidth(), background.getWidth());
//处理圆角
image_Bitemap.setImageBitmap(BitmapUtils.mergerIcon(background, map, 7,0,0));
