"Go" Android Phone resolution basics (DPI,DIP calculation)

1. Terminology and concepts

Terms	Description	Note
Screen size	Refers to the actual physical size of the phone, such as the usual 2.8-inch, 3.2-inch, 3.5-inch, 3.7-inch	Motorola milestone phone is 3.7 inches
Aspect Ratio (width/height ratio)	Refers to the actual physical dimensions of the width-to-height ratio, divided into long and nolong	Milestone is 16:9, belongs to Long
Resolution (resolution)	The same as the computer resolution concept, refers to the phone screen vertical, horizontal direction of the number of pixels	Milestone is 854*480.
DPI (dot per inch)	Pixels per inch, such as 120dpi,160dpi, assume that the screen physical size of the QVGA (320*240) Resolution is (2 inches * 1.5 inches), dpi=160	Can reflect the sharpness of the screen, which is used to scale the UI
Density (Density)	The pixel concentration in the screen, Resolution/screen size can reflect the cell phone density,
Density-independent Pixel (DIP)	Refers to the logical density unit, the corresponding formula for dip and specific pixel values is dip/pixel=dpi value/160, which is PX = DP * (dpi/160)

2. DPI value calculation

For example: Calculate WVGA (800*480) resolution, 3.7-inch density dpi,1 shown

Figure 1

Diagonal pixel represents the pixel value (=) of the diagonal, dpi=933/3.7=252

3. Classification of mobile phone screen

3.1 According to the cell phone screen density (DPI) or screen size is divided into the following 3 classes, 2 shows

Figure 2

3.2 The corresponding relationship between screen classification and pixel density of mobile phones is shown in table 1:

	Low density (+), ldpi	Medium density (), mdpi	High Density (hdpi),
Small screen	QVGA (240x320)
Normal screen	WQVGA400 (240x400) WQVGA432 (240x432)	HVGA (320x480)	WVGA800 (480x800) WVGA854 (480x854)
Large screen		wvga800* (480x800) wvga854* (480x854)

Table 1

3.3 Mobile phone size distribution (http://developer.android.com/resources/dashboard/screens.html) 3, is mainly based on the resolution of 800*480 and 854*480 mobile phone users mostly

Figure 3

From the above screen size distribution, in fact, the phone just consider 3-4.5-inch density of 1 and 1.5 of mobile phones

4 UI Design

From a development perspective, the application will provide 3 sets of UI layout files based on the 3-class Android phone screen, but the corresponding interface icons also need to provide 3 sets, as shown in table 2

Icon Type	Standard Asset Sizes (in Pixels), for generalized screen densities
	Low density screen (ldpi)	Medium density screen (MDPI)	High density screen (hdpi)
Launcher	X × px	x px	x px
Menu	X × px	x px	x px
Status Bar	x px	x + px	x px
Tab	x px	x + px	x px
Dialog	x px	x + px	x px
List View	x px	x + px	x px

Table 2

5 How do I adapt to the screen size?

1) Interface layout aspect

It is necessary to prepare 5 sets of layouts according to the size of the physical size, layout (put some common layout XML files, such as the top and bottom layouts in the interface, will not change with the screen size, like the title bar of the WinDOS window), Layout-small ( Screen size less than 3 inches in layout), layout-normal (screen size less than 4.5 inches or so), Layout-large (4 inches-7 inches), Layout-xlarge (7-10 inches)

2) Picture Resources

5 sets of picture resources need to be prepared according to the DPI value, drawable,drawalbe-ldpi,drawable-mdpi,drawable-hdpi,drawable-xhdpi

Android has an automatic matching mechanism to select the corresponding layout and picture resources

from:http://blog.csdn.net/moruite/article/details/6028547

"Go" Android Phone resolution basics (DPI,DIP calculation)