Android Bitmap用法总结

Bitmap用法总结
1、Drawable → Bitmap

Java代码  

 1、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;
 }

2、从资源中获取Bitmap

 "font-size: medium;">Resources res=getResources();
 Bitmap bmp=BitmapFactory.decodeResource(res, R.drawable.pic);

3、Bitmap → byte[]

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

4、byte[] → Bitmap

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

5、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 block
 Generated by Foxit PDF Creator © Foxit Software
 http://www.foxitsoftware.com For evaluation only.
 e.printStackTrace();
 }
 return bmp.compress(format, quality, stream);
 }

6、将图片按自己的要求缩放

 // 图片源
 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);

相关知识链接：http://www.eoeandroid.com/thread-3162-1-1.html
7、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 /
 android:scaleType值的意义区别：
 CENTER /center 按图片的原来size居中显示，当图片长/宽超过View的长/宽，则截取图片的居中部分
 显示
 CENTER_CROP / centerCrop 按比例扩大图片的size居中显示，使得图片长(宽)等于或大于View的长
 (宽)
 CENTER_INSIDE / centerInside 将图片的内容完整居中显示，通过按比例缩小或原来的size使得图片
 长/宽等于或小于View的长/宽
 Generated by Foxit PDF Creator © Foxit Software
 http://www.foxitsoftware.com For evaluation only.
 FIT_CENTER / fitCenter 把图片按比例扩大/缩小到View的宽度，居中显示
 FIT_END / fitEnd 把图片按比例扩大/缩小到View的宽度，显示在View的下部分位置
 FIT_START / fitStart 把图片按比例扩大/缩小到View的宽度，显示在View的上部分位置
 FIT_XY / fitXY 把图片 不按比例 扩大/缩小到View的大小显示
 MATRIX / matrix 用矩阵来绘制，动态缩小放大图片来显示。

8. 放大缩小图片

 public static Bitmap zoomBitmap(Bitmap bitmap,int w,int h){
 int width = bitmap.getWidth();
 int height = bitmap.getHeight();
 Matrix matrix = new Matrix();
 float scaleWidht = ((float)w / width);
 float scaleHeight = ((float)h / height);
 matrix.postScale(scaleWidht, scaleHeight);
 Bitmap newbmp = Bitmap.createBitmap(bitmap, 0, 0, width, height, matrix,
 true);
 return newbmp;
 }

9. 将Drawable转化为Bitmap

 public static Bitmap drawableToBitmap(Drawable drawable){
 int width = drawable.getIntrinsicWidth();
 int height = drawable.getIntrinsicHeight();
 Bitmap bitmap = Bitmap.createBitmap(width, height,
 drawable.getOpacity() != PixelFormat.OPAQUE ? Bitmap.Config.ARGB_8888
 : Bitmap.Config.RGB_565);
 Canvas canvas = new Canvas(bitmap);
 drawable.setBounds(0,0,width,height);
 drawable.draw(canvas);
 return bitmap;
 Generated by Foxit PDF Creator © Foxit Software
 http://www.foxitsoftware.com For evaluation only.
 }

10. 获得圆角图片的方法

 public static Bitmap getRoundedCornerBitmap(Bitmap bitmap,float roundPx){
 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);
 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);
 return output;
 }

11. 获得带倒影的图片方法

 public static Bitmap createReflectionImageWithOrigin(Bitmap bitmap){
 final int reflectionGap =4;
 int width = bitmap.getWidth();
 int height = bitmap.getHeight();
 Matrix matrix = new Matrix();
 matrix.preScale(1, -1);
 Bitmap reflectionImage = Bitmap.createBitmap(bitmap,
 0, height/2, width, height/2, matrix,false);
 Bitmap bitmapWithReflection = Bitmap.createBitmap(width, (height + height/2),
 Config.ARGB_8888);
 Canvas canvas = new Canvas(bitmapWithReflection);
 canvas.drawBitmap(bitmap, 0,0,null);
 Paint deafalutPaint = new Paint();
 Generated by Foxit PDF Creator © Foxit Software
 http://www.foxitsoftware.com For evaluation only.
 canvas.drawRect(0, height,width,height + reflectionGap,
 deafalutPaint);
 canvas.drawBitmap(reflectionImage, 0, height + reflectionGap,null);
 Paint paint = new Paint();
 LinearGradient shader = new LinearGradient(0,
 bitmap.getHeight(), 0, bitmapWithReflection.getHeight()
 + reflectionGap, 0x70ffffff,0x00ffffff, TileMode.CLAMP);
 paint.setShader(shader);
 // Set the Transfer mode to be porter duff and destination in
 paint.setXfermode(new PorterDuffXfermode(Mode.DST_IN));
 // Draw a rectangle using the paint with our linear gradient
 canvas.drawRect(0, height, width, bitmapWithReflection.getHeight()
 + reflectionGap, paint);
 return bitmapWithReflection;
 }
 }<