Various scale units in Android development

Px

Pixel (pixel), which represents a physical pixel point on the screen
It is not recommended to use the px drawing UI directly, because the px actual size displayed on different phones will be different for the UI drawn for units affected by pixel density

DP (used to define the size of the control)

Density-independent pixels. One of the virtual pixel units that Android recommends is to have the same effect on a device with a defined UI layout at a different pixel density.

Pixel density dpi = number of pixels per inch length = Screen portrait (landscape) Length/Number of screen portrait (landscape) pixels.

This density-independent pixel size is equivalent to dpi a physical pixel on the screen. So px = dp * (dpi / 160) .

The Android system defines four pixel densities:

name	abbreviation	DPI
low	ldpi	Approx. 120dpi
medium	mdpi	Approx. 160dpi
high	hdpi	Approx. 240dpi
extra-high	xhdpi	Approx. 320dpi
extra-extra-high	xxhdpi	Approx. 480dpi
extra-extra-extra-high	xxxdpi	Approx. 640dpi

Dip

dpThe early naming, and dp exactly the same.

SP (for defining font size)

Scale independent pixels (scale-independent pixel). spand dp very similar but the difference is that theAndroid system allows users to customize text size (small, normal, large, oversized, and so on), when the text size is "normal" when the 1 sp =1 dp , and when the text size is "large" or "super-large" When, 1 sp >1 dp .

Therefore sp , it is mainly used to define the font size, and when the user sets the magnification font, only the text in the SP is magnified .

Pt

Standard length unit, 1 pt =1/72 inch = 0.035 cm.

Inch

inches, 1 inches = 2.54 cm (approx.)

Various scale units in Android development