First, the concept:
1. Screen size: Refers to the diagonal length of the screen, in inches
2. Pixels: The smallest point that makes up the image, a relative size unit, the smaller the screen, the clearer the more
3. Screen pixel density (ppi) = total pixels/Screen size (inches)
4. Retina screen principle: When the phone is about 25-30 cm away from you, if the phone PPI reaches more than 300, your eyes will not be able to distinguish the pixel point
5.DPI: Graphic Design/printing technology Unit, the higher the value, indicates that the higher the printer accuracy
Dpi=ppi
Second, Android screen size normalization
1. Program development Unified use of virtual dimension units: Dp/dip (other than text), SP (text)
2.PX~DP Conversion:
LDPI:PX-->DP divided by 0.75.
Dp-->px Times 0.75.
MDPI:PX-->DP divided by 1.
DP-->PX Times 1.
HDPI:PX-->DP divided by 1.5.
DP-->PX times 1.5.
XHDPI:PX-->DP divided by 2.
DP-->PX Times 2.
XXHDPI:PX-->DP divided by 3.
DP-->PX Times 3.
XXXHDPI:PX-->DP divided by 4.
DP-->PX Times 4.
3. Principle of baseline spacing:
(1) Component minimum spacing is 8DP or 10DP, layout/text minimum interval recommended 4DP
(2) Component size recommendations can be divisible by 4
(3) The component size is recommended to be even (the singular is prone to aliasing)
4.48 Touch Law: 48DP is about 9mm physical size, is a user finger can be accurate and comfortable touch the smallest size
5. Common Component Dimensions:
Status bar: 24DP
Action Bar: 44/48DP
Side navigation: 286/304DP
Suspension Operation Button: 56DP
Action Bar +TAB:36+33DP/44+40DP
Bottom bar: 44/48DP
6.Android Common font size/line spacing/color:
Mobile-Side UI Design dimension specification