Android屏幕尺寸与度量单位(px,dp,sp)简介

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1.各度量单位的含义

• px:pixels(像素）。显示器是由一个一个的像素点组成的，例如在通用显示器中，每英寸包括72个像素点；
• dp:device independent pixels(设备独立像素），不同的设备有不同的显示效果，这个和设备硬件有关；Android中，使用dp可以对目标进行自动缩放，比较方便兼容不同尺寸的设备；详见下面介绍；
• dip:和dp是一样的，Android的早期版本使用了dip这个称呼，后来改成了dp；
• pt:point，这个是一个标准的长度单位，注意与px区分，1pt=1/72英寸，主要用于印刷行业
• sp:scaled pixels，主要用于字体的大小显示，个人理解，sp其实和dp差不多，唯一的区别在于sp可以随系统字体进行放大缩小，，当在设置中选中大字体模式后，使用sp标注的字体大小会自动缩放；
• in（英寸）：长度单位
• mm（毫米）：长度单位
• PPI：密度单位，表示每英寸包括多少个像素点，如显示器一般为72ppi

2.像素密度

Android设备主要包括以下几种屏幕:

屏幕	宽度	高度	尺寸	屏幕密度
QVGA	240	320	2.6-3.0	LOW
WQVGA	240	400	3.2-3.5	LOW
FWQVGA	240	432	3.5-3.8	LOW
HVGA	320	480	3.0-3.5	MEDIUM
WVGA	480	800	3.3-4.0	high
FWVGA	480	854	3.5-4.0	HIGH
wvga	480	800	4.8-5.5	MEDIUM
FWVGA	480	854	5.0-5.8	MEDIUM
VGA	480	640	2.8	286ppi

备注：目前Android默认的low=120;medium=160;high=240
设备信息有很多，具体的可以参考下面链接：
http://www.xyaz.cn/thread-71-1-1.html

3.px与dp的转换

转换公式为：
px=dp*density/160。denisty表示屏幕密度，即当density=160时，1dp = 1px = 1sp;

转载请注明原文地址：
http://www.cnblogs.com/yanyojun/p/6250383.html