SizeUtils.java

package com.liyu.fakeweather.utils;

import android.content.Context;
import android.util.DisplayMetrics;
import android.view.WindowManager;

/**
 * Created by liyu on 2016/8/30.
 */
public class SizeUtils {

    private static int screenWidth = 0;

    /**
     * dp转px
     *
     * @param context 上下文
     * @param dpValue dp值
     * @return px值
     */
    public static int dp2px(Context context, float dpValue) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return (int) (dpValue * scale + 0.5f);
    }

    /**
     * px转dp
     *
     * @param context 上下文
     * @param pxValue px值
     * @return dp值
     */
    public static int px2dp(Context context, float pxValue) {
        final float scale = context.getResources().getDisplayMetrics().density;
        return (int) (pxValue / scale + 0.5f);
    }

    /**
     * sp转px
     *
     * @param context 上下文
     * @param spValue sp值
     * @return px值
     */
    public static int sp2px(Context context, float spValue) {
        final float fontScale = context.getResources().getDisplayMetrics().scaledDensity;
        return (int) (spValue * fontScale + 0.5f);
    }

    /**
     * px转sp
     *
     * @param context 上下文
     * @param pxValue px值
     * @return sp值
     */
    public static int px2sp(Context context, float pxValue) {
        final float fontScale = context.getResources().getDisplayMetrics().scaledDensity;
        return (int) (pxValue / fontScale + 0.5f);
    }

    public static int getScreenWidth(Context context) {
        if (screenWidth != 0)
            return screenWidth;
        WindowManager windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
        DisplayMetrics dm = new DisplayMetrics();// 创建了一张白纸
        windowManager.getDefaultDisplay().getMetrics(dm);// 给白纸设置宽高
        screenWidth = dm.widthPixels;
        return screenWidth;
    }

    public static int getScreenWidth(Context context, float padding) {
        if (screenWidth != 0)
            return screenWidth - sp2px(context, padding);
        WindowManager windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
        DisplayMetrics dm = new DisplayMetrics();// 创建了一张白纸
        windowManager.getDefaultDisplay().getMetrics(dm);// 给白纸设置宽高
        screenWidth = dm.widthPixels;
        return screenWidth - sp2px(context, padding);
    }

}