[移动开发]Android DisplayMetrics介绍

0.前言

Android 官方文档解释：

A structure describing general information about a display, such as its size, density, and font scaling.
To access the DisplayMetrics members(描述显示信息的结构，诸如屏幕大小、屏幕密度和字体缩放)

获取DisplayMetrics使用下面代码

 context.getResources().getDisplayMetrics();

1.获取DisplayMetrics对象

//获取DisplayMetrics方法一
WindowManager windowManager = (WindowManager) getSystemService(WINDOW_SERVICE);
DisplayMetrics metrics1 = new DisplayMetrics();
windowManager.getDefaultDisplay().getMetrics(metrics1);
LUtil.d(TAG, ">>>>>>> metrics1 = " + metrics1);

//获取DisplayMetrics方法二
DisplayMetrics metrics2 = new DisplayMetrics();
getWindowManager().getDefaultDisplay().getMetrics(metrics2);
LUtil.d(TAG, ">>>>>>> metrics2 = " + metrics2);

//获取DisplayMetrics方法三
DisplayMetrics metrics3 = this.getResources().getDisplayMetrics();
LUtil.d(TAG, ">>>>>>> metrics3 = " + metrics3);

2.获取屏幕大小、屏幕密度、字体缩放因子

DisplayMetrics displayMetrics = this.getResources().getDisplayMetrics();
//1.获取设备屏幕密度
float density = displayMetrics.density;
//2.获取设备的dpi(表示每英寸的点数)
int dpi = displayMetrics.densityDpi;
//3.字体缩放因子scaledDensity
float scaledDensity = displayMetrics.scaledDensity;

输出结果参考：

D: >>>>>>> metrics1 = DisplayMetrics{density=3.0, width=1080, height=2159, scaledDensity=3.0, xdpi=428.625, ydpi=428.553, densityDpi=480, noncompatWidthPixels=1080, noncompatHeightPixels=2159, noncompatDensity=3.0, noncompatDensityDpi=480, noncompatXdpi=428.625, noncompatYdpi=428.553}
D: >>>>>>> metrics2 = DisplayMetrics{density=3.0, width=1080, height=2159, scaledDensity=3.0, xdpi=428.625, ydpi=428.553, densityDpi=480, noncompatWidthPixels=1080, noncompatHeightPixels=2159, noncompatDensity=3.0, noncompatDensityDpi=480, noncompatXdpi=428.625, noncompatYdpi=428.553}
D: >>>>>>> metrics3 = DisplayMetrics{density=3.0, width=1080, height=2159, scaledDensity=3.4499998, xdpi=428.625, ydpi=428.553, densityDpi=480, noncompatWidthPixels=1080, noncompatHeightPixels=2159, noncompatDensity=3.0, noncompatDensityDpi=480, noncompatXdpi=428.625, noncompatYdpi=428.553}

3.使用DisplayMetrics在dp和px间转换

//dp -> px
public static int dip2px(Context context, float dpValue) {
    final float scale = context.getResources().getDisplayMetrics().density;
    return (int) (dpValue * scale + 0.5f);
}

//px -> dp
public static int px2dip(Context context, float pxValue) {
    final float scale = context.getResources().getDisplayMetrics().density;
    return (int) (pxValue / scale + 0.5f);
}

4.扩展

• 【Android文档】https://developer.android.com/reference/android/util/DisplayMetrics
• 【Android文档】https://developer.android.google.cn/training/multiscreen/screendensities?hl=zh-cn