cvs: gd /playground/text_on_transparent_background text_aa_alpha.c

pajoye		Sat Mar 17 18:46:10 2007 UTC

  Added files:                 
    /gd/playground/text_on_transparent_background	text_aa_alpha.c 
  Log:
  - example of antialiased text using alpha and not blending ops
  
  

http://cvs.php.net/viewvc.cgi/gd/playground/text_on_transparent_background/text_aa_alpha.c?view=markup&rev=1.1
Index: gd/playground/text_on_transparent_background/text_aa_alpha.c
+++ gd/playground/text_on_transparent_background/text_aa_alpha.c
#include <gd.h>
#include <stdio.h>
#include <math.h>

int main()
{
	gdImagePtr im, tmp_im;
	int error = 0;
	char *fontname = "/var/lib/defoma/fontconfig.d/B/Bitstream-Vera-Sans.ttf";
	char *string = "AA using alpha";
	int linespacing	= 1.05;
	int charmap    	= gdFTEX_Unicode;
	int resolution		= 96;
	int color_text 	= 0xFFFFFF;
	int pt_size 		= 50;
	double angle 		= -45 * M_PI / 180;
	int pos_x = 0, pos_y = 40;
	FILE *fp;
	gdFTStringExtra extra;

	/* Optional but it makes the code clearer and forward compatible */
	extra.flags = gdFTEX_CHARMAP|gdFTEX_RESOLUTION;
	extra.charmap = gdFTEX_Unicode;
	extra.hdpi = resolution;
	extra.vdpi = resolution;

	im = gdImageCreateTrueColor(400,400);

	/* We want to presereve the alpha information, don't blend */
	gdImageAlphaBlending(im, 0);

	/* let fill it with zero opacity (gdMaxAlphaMax) */
	gdImageFilledRectangle(im, 0,0, 399,399, gdImageColorAllocateAlpha(im, 0,0,0, gdAlphaMax));
	gdImageStringFTEx(im, NULL, color_text, fontname, pt_size, angle, pos_x, pos_y, string, &extra);

	/* Save the alpha channel in the image, that disallows the usage
		of a background/transparent color. See PNG specs for the details.
	 */
 	gdImageSaveAlpha(im, 1);
	fp = fopen("1.png", "wb");
 	gdImagePng(im,fp);
	fclose(fp);

 	/* Destroy images */
 	gdImageDestroy(im);
	return error;
}