android 中 dp和px转换

DisplayUtils代码：

public class DisplayUtil {

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

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

Android Framework也提供了相应的工具类供我们使用的。TypedValue 中的 applyDimension() 方法：

/**
     * 
     * @param unit The unit to convert from.
     * @param value The value to apply the unit to.
     * @param metrics Current display metrics to use in the conversion -- 
     *                supplies display density and scaling information.
     */
    public static float applyDimension(int unit, float value,
                                       DisplayMetrics metrics)
    {
        switch (unit) {
        case COMPLEX_UNIT_PX:
            return value;
        case COMPLEX_UNIT_DIP:
            return value * metrics.density;
        case COMPLEX_UNIT_SP:
            return value * metrics.scaledDensity;
        case COMPLEX_UNIT_PT:
            return value * metrics.xdpi * (1.0f/72);
        case COMPLEX_UNIT_IN:
            return value * metrics.xdpi;
        case COMPLEX_UNIT_MM:
            return value * metrics.xdpi * (1.0f/25.4f);
        }
        return 0;
    }

　使用方法：

        //获取10dp
        int dp= (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,10,getResources().getDisplayMetrics());
        //获取10px
        int px= (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_PX,10,getResources().getDisplayMetrics());
        //获取10sp
        int sp= (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP,10,getResources().getDisplayMetrics());