androdi ImageView.ScaleType

1  这里我们重点理解ImageView的属性android:scaleType，即ImageView.setScaleType(ImageView.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：
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 3 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
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 5 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)
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 7 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
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 9 FIT_CENTER / fitCenter  把图片按比例扩大/缩小到View的宽度，居中显示
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11 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
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13 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
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15 FIT_XY / fitXY  把图片不按比例扩大/缩小到View的大小显示
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17 MATRIX / matrix 用矩阵来绘制

ImageView.ScaleType CENTER Center the image in the view, but perform no scaling. ImageView.ScaleType CENTER_CROP Scale the image uniformly (maintain the image's aspect ratio) so that both dimensions (width and height) of the image will be equal to or larger than the corresponding dimension of the view (minus padding). ImageView.ScaleType CENTER_INSIDE Scale the image uniformly (maintain the image's aspect ratio) so that both dimensions (width and height) of the image will be equal to or less than the corresponding dimension of the view (minus padding). ImageView.ScaleType FIT_CENTER Scale the image using CENTER. ImageView.ScaleType FIT_END Scale the image using END. ImageView.ScaleType FIT_START Scale the image using START. ImageView.ScaleType FIT_XY Scale the image using FILL. ImageView.ScaleType MATRIX Scale using the image matrix when drawing.