问题
I design an very simple application just to calculate Height and Width of display screen. I am using HDMI display that running on full-HD 1920x1080. But when I am calculating display size I am just getting half-HD resolution i.e. 720x1080. I am using WindowManager/DisplayMetrics for calculating window size.
any one have any idea about why it responding half of display device resolution.
回答1:
Maybe even though the device uses 1920x1080 display output, to the screen by hardware, it is just scaled up from 720x1080 (or maybe is it rather 1280x720?).
Is the built-in screen of the device exactly the same resolution as the smaller one, that is reported to be the "half" resolution?
So I think the Android device handles a canvas (display buffer) of the smaller resolution, then just rescales the image (possibly by the display hardware) to use the higher resolution ofr outputting the image to the external screen.
This is however just a guess, as you didn't provide too many details, like what device, what code you use, etc.
EDIT prior to Android 4.0, Motorola provided an API for handling dual screen operations, the Motorola Dual Screen API. Sadly, support in ICS has been dropped. Biggest mistake ever, IMHO.
来源：https://stackoverflow.com/questions/13525870/hdmi-screen-resolution-issue-while-displaying-android-content