ImageView.ScaleType 属性值

ImageView.ScaleType属性值：

CENTER Center the p_w_picpath in the view, but perform no scaling.

 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 Scale the p_w_picpath uniformly (maintain the p_w_picpath's aspect ratio) so that both dimensions (width and height) of the p_w_picpath will be equal to or larger than the corresponding dimension of the view (minus padding).

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 Scale the p_w_picpath uniformly (maintain the p_w_picpath's aspect ratio) so that both dimensions (width and height) of the p_w_picpath will be equal to or less than the corresponding dimension of the view (minus padding).

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

FIT_CENTER Scale the p_w_picpath using CENTER.

 把图片按比例扩大/缩小到View的宽度，居中显示

FIT_END Scale the p_w_picpath using END.

 把图片按比例扩大/缩小到View的宽度，底部显示

FIT_START Scale the p_w_picpath using START.

 把图片按比例扩大/缩小到View的宽度，顶部显示

FIT_XY Scale the p_w_picpath using FILL.

 不按比例缩放图片，目标是把图片塞满整个View。

MATRIX Scale using the p_w_picpath matrix when drawing.

   当绘画的时候使用，使用矩阵。

Bitmap常用：

http://www.cnblogs.com/fighter/archive/2012/02/20/android-bitmap-drawable.html