Android_ basis of Resolution

Common screen resolution corresponding to the size

Standard screen	Resolution	proportion	Widescreen	Resolution	proportion
QCIF	176X144	11:9
CIF	352X288	11:9
QVGA	320X240	4:3	WQVGA	400X240	5:3
HVGA	480X320	3:2
VGA	640X480	4:3	WVGA	800X480	5:3
qHD	960X540	16:9
HD/720P	1280X720	16:9
HD+	1600X900	16:9
FHD/1080P	1920X1080	16:9
FHD+	2160X1440	16:9
QHD	2560X1440	16:9

 

 basic concepts

Screen size : the length of the line focus of the screen, in inches (inch).

Resolution : The above table is a high resolution and number of pixels of the wide screen. Such as 320x240, i.e., 320 pixels tall and 240 pixels wide points.

Screen densities (actual physical dpi): dpi (dots per inch ), i.e., the number of pixels per inch. The screen size is 4, the resolution is 320x240, the screen density (√ (320. ² +240 ² )) / 4 = 100.

Density System ( System dpi): density, system default configuration fixed density.

The following information is the system density, mdpi (160) as the reference:

	ldpi	mdpi	hdpi	xhdpi	xxhdpi
System density	120	160	240	320	480
On behalf of resolution	240x320	320x480	480x800	720x1280	1080x1920
Reference ratio	0.75	1	1.5	2	3

 

Relationship between the various units: dp, px, sp

dp units commonly used in the layout, px i.e. pixels, sp commonly used in the font size. 

 dp and PX :

 dp px and conversion systems based on the density. In mdpi, 160 as a reference, as in the 320x480 1dp device, 1dp = 1px; 480x800 in the 1dp = 1.5px.

Property system configuration in the system density is ro.sf.lcd_density, codes obtained by the following

Log.d( TAG, "density="+getResources().getDisplayMetrics().density
            +";densityDpi="+getResources().getDisplayMetrics().densityDpi);

Phone (ro.sf.lcd_density = 240,480x960) execution of the results obtained

2019-09-29 10:27:52.432 5521-5521/com.flx.testfilestorage D/flx_storage: density=1.5;densityDpi=240

Therefore 1DP = Density PX or 1DP = ( densitydpi / 160. ) PX

 sp and PX :

 Android design principles font size to use sp, non-use font size dp. When the standard (default) font, 1sp = 1px.

Therefore, the standard (default) font case, sp px and transferred as dp, 1SP = Density px  or  1SP = ( densitydpi / 160. ) px.

The default setting of several selectable font size change value as follows (different mobile phone manufacturers may be revised, so that different phones may vary):

<item>0.85</item> 　　//小
<item>1.0</item>　　　//默认
<item>1.15</item>　　 //大
<item>1.30</item>　　 //最大