Bitmap——用法

Bitmap13个的用法：

　　01.Drawable 的用法

Resources resources = mContext.getResources();
Drawable drawable = resources.getDrawable(R.drawable.a);
imageview.setBackground(drawable);

　　02.BitmapDrawable的用法Bitmap

Resources r = this.getContext().getResources();
Inputstream is = r.openRawResource(R.drawable.my_background_image);
BitmapDrawable  bmpDraw = new BitmapDrawable(is);
Bitmap bmp = bmpDraw.getBitmap();

　　03.Bitmap –>BitmapFactory.decodeResource

Bitmap bmp=BitmapFactory.decodeResource(r, R.drawable.icon);
Bitmap newb = Bitmap.createBitmap( 300, 300, Config.ARGB_8888 ); 

    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        Paint paint = new Paint(); //创建Paint对象
        //根据图片生成位图对象
        Bitmap bitmap = BitmapFactory.decodeResource(this.getResources(), R.drawable.hat);
        canvas.drawBitmap(bitmap, bitmapX, bitmapY, paint); // 绘制帽子
        if (bitmap.isRecycled()) { // 判断图片是否回收
            bitmap.recycle(); // 强制回收图片
        }
    }

　　04.Bitmap –>BitmapFactory.decodeStream

InputStream is = getResources().openRawResource(R.drawable.icon);  
Bitmap mBitmap = BitmapFactory.decodeStream(is);

　　05.Drawable → Bitmap

public static Bitmap drawableToBitmap(Drawable drawable) {
Bitmap bitmap = Bitmap
.createBitmap(
drawable.getIntrinsicWidth(),
drawable.getIntrinsicHeight(),
drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888:Bitmap.Config.RGB_565);
Canvas canvas = new Canvas(bitmap);
// canvas.setBitmap(bitmap);
drawable.setBounds(0, 0, drawable.getIntrinsicWidth(),
drawable.getIntrinsicHeight());
drawable.draw(canvas);
return bitmap;
}

　　06.从资源中获取Bitmap

Resources res=getResources();
Bitmap bmp=BitmapFactory.decodeResource(res, R.drawable.pic);

　　07.Bitmap → byte[]

private byte[] Bitmap2Bytes(Bitmap bm){
ByteArrayOutputStream baos = new ByteArrayOutputStream();
bm.compress(Bitmap.CompressFormat.PNG, 100, baos);
return baos.toByteArray();
}

　　08.byte[] → Bitmap

private Bitmap Bytes2Bimap(byte[] b){
　　if(b.length!=0){
　　　　return BitmapFactory.decodeByteArray(b, 0, b.length);
　　}
　　else {
　　　　return null;
　　}
}

　　09.保存bitmap

static boolean saveBitmap2file(Bitmap bmp,String filename){
　　CompressFormat format= Bitmap.CompressFormat.JPEG;
　　int quality = 100;
　　OutputStream stream = null;
　　try {
　　stream = new FileOutputStream("/sdcard/" + filename);
　　} catch (
　　　　FileNotFoundException e) {
　　　　// TODO Auto-generated catch blockGenerated by Foxit PDF Creator © Foxit Softwarehttp://www.foxitsoftware.com For evaluation only.
　　　　e.printStackTrace();
　　}
　　return bmp.compress(format, quality, stream);
}

　　10.将图片按自己的要求缩放

Bitmap bm = BitmapFactory.decodeStream(getResources()
.openRawResource(R.drawable.dog));
// 获得图片的宽高
int width = bm.getWidth();
int height = bm.getHeight();
// 设置想要的大小
int newWidth = 320;
int newHeight = 480;
// 计算缩放比例
float scaleWidth = ((float) newWidth) / width;
float scaleHeight = ((float) newHeight) / height;
// 取得想要缩放的matrix参数
Matrix matrix = new Matrix();
matrix.postScale(scaleWidth, scaleHeight);
// 得到新的图片
Bitmap newbm = Bitmap.createBitmap(bm, 0, 0, width, height, matrix,
true);
// 放在画布上
canvas.drawBitmap(newbm, 0, 0, paint);

　　11.File图片转Bitmap

Bitmap bt = BitmapFactory.decodeFile("/sdcard/myImage/" + "head.jpg");//图片地址

　　12.图片转Bitmap

public Bitmap drawableToBitamp(int drawableResource) {  //可以取raw里面的资源
        BitmapFactory.Options opt = new BitmapFactory.Options();
        opt.inPreferredConfig = Bitmap.Config.RGB_565;
        opt.inPurgeable = true;
        opt.inInputShareable = true;
        InputStream is = this.getResources().openRawResource(drawableResource);
        BitmapFactory.decodeStream(is, null, opt);
        return BitmapFactory.decodeStream(is, null, opt);
}

　　13.bitmap的用法小结

BitmapFactory.Options option = new BitmapFactory.Options();
option.inSampleSize = 2; //将图片设为原来宽高的1/2，防止内存溢出
Bitmap bm = BitmapFactory.decodeFile("",option);//文件流
URL url = new URL("");
InputStream is = url.openStream();
Bitmap bm = BitmapFactory.decodeStream(is);
android:scaleType：
android:scaleType//是控制图片如何resized/moved来匹对ImageView的size。ImageView.ScaleType /