讀取本地資源的圖片，根據資源文件獲取Bitmap，等比例壓縮圖片

/**
	 * 讀取本地資源的圖片
	 * 
	 * @param context
	 * @param resId
	 * @return
	 */
	public static Bitmap ReadBitmapById(Context context, int resId) {
		BitmapFactory.Options opt = new BitmapFactory.Options();
		opt.inPreferredConfig = Bitmap.Config.RGB_565;
		opt.inPurgeable = true;
		opt.inInputShareable = true;
		// 獲取資源圖片
		InputStream is = context.getResources().openRawResource(resId);
		return BitmapFactory.decodeStream(is, null, opt);
	}

	/***
	 * 根據資源文件獲取Bitmap
	 * 
	 * @param context
	 * @param drawableId
	 * @return
	 */
	public static Bitmap ReadBitmapById(Context context, int drawableId,int screenWidth, int screenHight) {
		BitmapFactory.Options options = new BitmapFactory.Options();
		options.inPreferredConfig = Config.ARGB_8888;
		options.inInputShareable = true;
		options.inPurgeable = true;
		
		InputStream stream = context.getResources().openRawResource(drawableId);
		Bitmap bitmap = BitmapFactory.decodeStream(stream, null, options);
		return getBitmap(bitmap, screenWidth, screenHight);
	}

	/***
	 * 等比例壓縮圖片
	 * 
	 * @param bitmap
	 * @param screenWidth
	 * @param screenHight
	 * @return
	 */
	public static Bitmap getBitmap(Bitmap bitmap, int screenWidth,int screenHight) {
		int w = bitmap.getWidth();
		int h = bitmap.getHeight();
		Log.e("jj", "圖片寬度" + w + ",screenWidth=" + screenWidth);
		Matrix matrix = new Matrix();
		float scale = (float) screenWidth / w;
		float scale2 = (float) screenHight / h;

		// scale = scale < scale2 ? scale : scale2;

		// 保證圖片不變形.
		matrix.postScale(scale, scale);
		// w,h是原圖的屬性.
		return Bitmap.createBitmap(bitmap, 0, 0, w, h, matrix, true);
	}