(40分快速结贴) 如何在运行时得知union的具体类型

影子传说_Hades 2010-05-17 12:54:09

程序得到了一个union的数据指针



CMColor *ps_color = &((*alpha_display_info)->ps_color);

CMColor 具体类型如下：



/* Apple colour space data structures */



/* RGB Color Value

   A color value expressed in the RGB color space is composed of red, green,

   and blue component values. Each color component is expressed as a numeric

   value within the range of 0 to 65535.

*/

typedef struct

{

  guint16       red;

  guint16       green;

  guint16       blue;

}CMRGBColor;



/*  HSV Color Value

    A color value expressed in the HSV color space is composed of hue,

    saturation, and value component values. Each color component is

    expressed as a numeric value within the range of 0 to 65535 inclusive.

    The hue value represents a fraction of a circle in which red is

    positioned at 0.

*/



typedef struct

{

  guint16       hue;

  guint16       saturation;

  guint16       value;

}CMHSVColor;



/* CMYK Color Value

  A color value expressed in the CMYK color space is composed of cyan, magenta,

  yellow, and black component values. Each color component is expressed as a

  numeric value within the range of 0 to 65535 inclusive, with 0 representing

  100% ink (e.g. pure cyan = 0, 65535, 65535, 65535).

*/



typedef struct

{

  guint16       cyan;

  guint16       magenta;

  guint16       yellow;

  guint16       black;

}CMCMYKColor;



/* L*a*b* Color Value

   The first three values in the color data are, respectively, the colors

   lightness, a chrominance, and b chrominance components. The lightness

   component is a 16bit value ranging from 0 to 10000. The chrominance

   components are each 16bit values ranging from 12800 to 12700. Gray

   values are represented by chrominance components of 0 (e.g. pure white

   is defined as 10000, 0, 0).

*/

typedef struct

{

  guint16       L;

  gint16        a;

  gint16        b;

} CMLabColor;



/* Gray Color Value

  A color value expressed in the Gray color space is composed of a single component,

  gray, represented as a numeric value within the range of 0 to 10000.

*/

typedef struct

{

  guint16       gray;

} CMGrayColor ;



/* The color union is defined by the CMColor type definition.

*/

typedef union

{

   CMRGBColor        rgb;

   CMHSVColor        hsv;

   CMLabColor        Lab;

   CMCMYKColor       cmyk;

   CMGrayColor       gray;

} CMColor;

但是我下面的方法肯定是错误的，因为打印的所有内容均有值，有没有什么办法判断union具体是哪个类型



// CMColor

static int print_cmcolor_to_pro_file(SaveFileDes saveFileDes,

		CMColor *ps_color_p, char* openMod) {

	if (!ps_color_p) {

		return 0;

	}

	FILE *stream;

	char* linefeedp = saveFileDes.linefeedp;

	int ret = 1;

	stream = fopen(saveFileDes.fileName, openMod);

	if (stream == NULL) {

		fprintf(stderr, "Cannot open output file.\r\n");

		return ret;

	}

	CMColor ps_color = *ps_color_p;

	CMRGBColor rgb = ps_color.rgb;

	CMHSVColor hsv = ps_color.hsv;

	CMLabColor Lab = ps_color.Lab;

	CMCMYKColor cmyk = ps_color.cmyk;

	CMGrayColor gray = ps_color.gray;

	if (rgb.red) {

		//

		fprintf(stream, "CMColor.CMRGBColor.red = %d %s", rgb.red, linefeedp);

		printf("CMColor.CMRGBColor.red =%d %s", rgb.red, linefeedp);

		//

		fprintf(stream, "CMColor.CMRGBColor.green = %d %s", rgb.green,

				linefeedp);

		printf("CMColor.CMRGBColor.green =%d %s", rgb.green, linefeedp);

		//

		fprintf(stream, "CMColor.CMRGBColor.blue = %d %s", rgb.blue, linefeedp);

		printf("CMColor.CMRGBColor.blue =%d %s", rgb.blue, linefeedp);

	}

	if (hsv.hue) {

		//hue

		fprintf(stream, "CMColor.CMHSVColor.hue = %d %s", hsv.hue, linefeedp);

		printf("CMColor.CMHSVColor.hue =%d %s", hsv.hue, linefeedp);

		//saturation

		fprintf(stream, "CMColor.CMHSVColor.saturation = %d %s",

				hsv.saturation, linefeedp);

		printf("CMColor.CMHSVColor.saturation =%d %s", hsv.saturation,

				linefeedp);

		//value

		fprintf(stream, "CMColor.CMHSVColor.value = %d %s", hsv.value,

				linefeedp);

		printf("CMColor.CMHSVColor.value =%d %s", hsv.value, linefeedp);

	}

	if (Lab.L) {

		//L

		fprintf(stream, "CMColor.CMLabColor.L = %d %s", Lab.L, linefeedp);

		printf("CMColor.CMLabColor.L =%d %s", Lab.L, linefeedp);

		//a

		fprintf(stream, "CMColor.CMLabColor.a = %d %s", Lab.a, linefeedp);

		printf("CMColor.CMLabColor.a =%d %s", Lab.a, linefeedp);

		//b

		fprintf(stream, "CMColor.CMLabColor.b = %d %s", Lab.b, linefeedp);

		printf("CMColor.CMLabColor.b =%d %s", Lab.b, linefeedp);

	}

	if (cmyk.cyan) {

		//cyan

		fprintf(stream, "CMColor.CMCMYKColor.cyan = %d %s", cmyk.cyan,

				linefeedp);

		printf("CMColor.CMCMYKColor.cyan =%d %s", cmyk.cyan, linefeedp);

		//magenta

		fprintf(stream, "CMColor.CMCMYKColor.magenta = %d %s", cmyk.magenta,

				linefeedp);

		printf("CMColor.CMCMYKColor.magenta =%d %s", cmyk.magenta, linefeedp);

		//yellow

		fprintf(stream, "CMColor.CMCMYKColor.yellow = %d %s", cmyk.yellow,

				linefeedp);

		printf("CMColor.CMCMYKColor.yellow =%d %s", cmyk.yellow, linefeedp);

		//black

		fprintf(stream, "CMColor.CMCMYKColor.black = %d %s", cmyk.black,

				linefeedp);

		printf("CMColor.CMCMYKColor.black =%d %s", cmyk.black, linefeedp);

	}

	if (gray.gray) {

		//L

		fprintf(stream, "CMColor.CMGrayColor.gray= %d %s", gray.gray, linefeedp);

		printf("CMColor.CMGrayColor.gray =%d %s", gray.gray, linefeedp);

	}

	ret = fclose(stream);

	return ret;

}