标签：屏幕物理尺寸 分辨率 android 屏幕密度 dip
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通过程序去了解硬件情况是一件十分有意思的事情。很早我就研究在WM6.5上获得屏幕物理尺寸，但一直没有成功。后来又想要在Android上有所突破，不过在今天之前得到的尺寸都不准确。虽然很多人认为没必要这么较真，因为貌似很多情况下用不到。不过我就当这是一件很有挑战性的事，一定要做到。对，就是这么任性。
源码中android.view包下的Display类提供了很多方法供程序员获得显示相关的信息，通过此类让我们开启了解设备屏幕之旅吧。
public void getSize(Point outSize) {
synchronized (this) {
updateDisplayInfoLocked();
mDisplayInfo.getAppMetrics(mTempMetrics, mDisplayAdjustments);
outSize.x = mTempMetrics.widthPixels;
outSize.y = mTempMetrics.heightPixels;
}
}参数是一个返回参数，用以返回分辨率的Point，这个Point也比较简单，我们只需要关注x和y这两个成员就可以了。 private void getDisplayInfomation() {
Point point = new Point();
getWindowManager().getDefaultDisplay().getSize(point);
Log.d(TAG,"the screen size is "+point.toString());
}结果如下：D/MainActivity﹕ the screen size is Point(800, 1280)
public void getRealSize(Point outSize) {
synchronized (this) {
updateDisplayInfoLocked();
outSize.x = mDisplayInfo.logicalWidth;
outSize.y = mDisplayInfo.logicalHeight;
}
}android:theme="@android:style/Theme.Black.NoTitleBar.Fullscreen" android:theme="@android:style/Theme.NoTitleBar.Fullscreen"结果还是相同的。
private void getDisplayInfomation() {
Point point = new Point();
getWindowManager().getDefaultDisplay().getSize(point);
Log.d(TAG,"the screen size is "+point.toString());
getWindowManager().getDefaultDisplay().getRealSize(point);
Log.d(TAG,"the screen real size is "+point.toString());
}D/MainActivity﹕ the screen size is Point(800, 1202) D/MainActivity﹕ the screen real size is Point(800, 1280)
DENSITY_LOW = 120 DENSITY_MEDIUM = 160 //默认值 DENSITY_TV = 213 //TV专用 DENSITY_HIGH = 240 DENSITY_XHIGH = 320 DENSITY_400 = 400 DENSITY_XXHIGH = 480 DENSITY_XXXHIGH = 640
private void getDensity() {
DisplayMetrics displayMetrics = getResources().getDisplayMetrics();
Log.d(TAG,"Density is "+displayMetrics.density+" densityDpi is "+displayMetrics.densityDpi+" height: "+displayMetrics.heightPixels+
" width: "+displayMetrics.widthPixels);
}the screen size is Point(1600, 2438) the screen real size is Point(1600, 2560) Density is 2.0 densityDpi is 320 height: 2438 width: 1600
private void getScreenSizeOfDevice() {
DisplayMetrics dm = getResources().getDisplayMetrics();
int width=dm.widthPixels;
int height=dm.heightPixels;
double x = Math.pow(width,2);
double y = Math.pow(height,2);
double diagonal = Math.sqrt(x+y);
int dens=dm.densityDpi;
double screenInches = diagonal/(double)dens;
Log.d(TAG,"The screenInches "+screenInches);
}Log如下：
01-13 16:35:03.026 16601-16601/com.linc.listviewanimation D/MainActivity﹕ the screen size is Point(1600, 2438) 01-13 16:35:03.026 16601-16601/com.linc.listviewanimation D/MainActivity﹕ the screen real size is Point(1600, 2560) 01-13 16:35:03.026 16601-16601/com.linc.listviewanimation D/MainActivity﹕ Density is 2.0 densityDpi is 320 height: 2438 width: 1600 xdpi 338.666 ydpi 338.666 01-13 16:35:03.026 16601-16601/com.linc.listviewanimation D/MainActivity﹕ The screenInches 9.112922229586951如Log所见，使用heightPixels得出的值是2483而不是正确的2560.从而使结果9.11反倒跟真实屏幕尺寸很接近。下面用正确的height再算一遍。
01-13 16:39:05.476 17249-17249/com.linc.listviewanimation D/MainActivity﹕ the screen size is Point(1600, 2560) 01-13 16:39:05.476 17249-17249/com.linc.listviewanimation D/MainActivity﹕ the screen real size is Point(1600, 2560) 01-13 16:39:05.476 17249-17249/com.linc.listviewanimation D/MainActivity﹕ Density is 2.0 densityDpi is 320 height: 2560 width: 1600 xdpi 338.666 ydpi 338.666 01-13 16:39:05.476 17249-17249/com.linc.listviewanimation D/MainActivity﹕ The screenInches 9.433981132056605结果是9.43英寸，而真实值是8.91.如果再换一个设备，那么值差的更多。说明上面的计算是错误的。
//The exact physical pixels per inch of the screen in the X/Y dimension.屏幕X/Y轴上真正的物理PPI。
private void getScreenSizeOfDevice2() {
Point point = new Point();
getWindowManager().getDefaultDisplay().getRealSize(point);
DisplayMetrics dm = getResources().getDisplayMetrics();
double x = Math.pow(point.x/ dm.xdpi, 2);
double y = Math.pow(point.y / dm.ydpi, 2);
double screenInches = Math.sqrt(x + y);
Log.d(TAG, "Screen inches : " + screenInches);
}Log is as follows:01-13 16:58:50.142 17249-17249/com.linc.listviewanimation D/MainActivity﹕ Screen inches : 8.914015757534717
//pixel = dip*density;
private int convertDpToPixel(int dp) {
DisplayMetrics displayMetrics = mContext.getResources().getDisplayMetrics();
return (int)(dp*displayMetrics.density);
}
private int convertPixelToDp(int pixel) {
DisplayMetrics displayMetrics = mContext.getResources().getDisplayMetrics();
return (int)(pixel/displayMetrics.density);
} 参考：
http://stackoverflow.com/questions/19155559/how-to-get-android-device-screen-size
标签：屏幕物理尺寸 分辨率 android 屏幕密度 dip
原文地址：http://blog.csdn.net/lincyang/article/details/42679589
