android中Bitmap用法(显示,保存,缩放,旋转)实例分析

Resources res=getResources();
//使用BitmapDrawable获取位图
//使用BitmapDrawable (InputStream is)构造一个BitmapDrawable；
//使用BitmapDrawable类的getBitmap()获取得到位图；
// 读取InputStream并得到位图
InputStream is=res.openRawResource(R.drawable.testImg); 
BitmapDrawable bmpDraw=new BitmapDrawable(is);
Bitmap bmp=bmpDraw.getBitmap();

File fImage = new File("/sdcard/testBitmap/testImg.png");  
fImage.createNewFile();
FileOutputStream iStream = new FileOutputStream(fImage); 
bmp.compress(CompressFormat.PNG, 100, iStream); 
iStream.close();
fImage.close();
iStream =null;
fImage =null;
//写到输出流里，就保存到文件了。

//图片的链接地址  
String imgURLStr = "http://tx.bdimg.com/sys/portrait/item/990e6271796a7a6c170c.jpg";  
URL imgURL = new URL(imgURLStr);  
URLConnection conn = imgURL.openConnection();  
conn.connect();  
InputStream is = conn.getInputStream();  
BufferedInputStream bis = new BufferedInputStream(is);
//下载图片
Bitmap bmp = BitmapFactory.decodeStream(bis);
//关闭Stream
bis.close();  
is.close(); 
imgURL =null;

// 转换为BitmapDrawable对象
BitmapDrawable bmpDraw=new BitmapDrawable(bmp);
// 显示位图
ImageView iv2 = (ImageView)findViewById(R.id.ImageView02);
iv2.setImageDrawable(bmpDraw);

Matrix matrix=new Matrix();
matrix.postScale(0.2f, 0.2f);
Bitmap dstbmp=Bitmap.createBitmap(bmp,0,0,bmp.getWidth(),bmp.getHeight(),matrix,true);
canvas.drawBitmap(dstbmp, 10, 10, null); 

Matrix matrix=new Matrix();
matrix.postRotate(45);
Bitmap dstbmp=Bitmap.createBitmap(bmp,0,0,bmp.getWidth(), bmp.getHeight(),matrix,true);
canvas.drawBitmap(dstbmp, 10, 10, null);