android TypedValue.applyDimension()代码转换dp,sp

/**
     * Converts an unpacked complex data value holding a dimension to its final floating 
     * point value. The two parameters <var>unit</var> and <var>value</var>
     * are as in {@link #TYPE_DIMENSION}.
     *  
     * @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.
     * 
     * @return The complex floating point value multiplied by the appropriate 
     * metrics depending on its unit. 
     */
    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;
    }

然..

/**
	 * 根据手机的分辨率从 dp 的单位 转成为 px(像素)
	 */
	public static int dip2px(Context context, float dpValue) {
		final float scale = context.getResources().getDisplayMetrics().density;
		return (int) (dpValue * scale + 0.5f);
	}

	/**
	 * 根据手机的分辨率从 px(像素) 的单位 转成为 dp
	 */
	public static int px2dip(Context context, float pxValue) {
		final float scale = context.getResources().getDisplayMetrics().density;
		return (int) (pxValue / scale + 0.5f);
	}

由以上代码分析可知:

第一个参数为 单位，第二个参数为值(第一个参数设置的单位指定的值)，返回值 都是像素

(2)也可以把单位设置成COMPLEX_UNIT_PX,验证返回值都是像素