文件名称：android Bitmap用法总结
文件大小：48KB
文件格式：DOC
更新时间：2014-02-16 04:02:41
android Bitmap用法总结
android Bitmap用法总结 Bitmap用法总结 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 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。 //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; } //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. } //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; } //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; } }