超越PHP - Exceed PHP: imagecolortransparent

imagecolortransparent

(PHP 3, PHP 4 , PHP 5)

imagecolortransparent -- 将某个颜色定义为透明色

说明

int imagecolortransparent ( resource image [, int color])

imagecolortransparent() 将 image 图像中的透明色设定为 color。image 是 imagecreate() 返回的图像标识符，color 是 imagecolorallocate() 返回的颜色标识符。

注: 透明色是图像的一种属性，透明度不是颜色的属性。一旦设定了某个颜色为透明色，图像中之前画为该色的任何区域都成为透明的。

返回新透明色的标识符，如果省略 color 则返回当前透明色的标识符。

add a note User Contributed Notes
imagecolortransparent

07-Dec-2001 11:18

when a color is defined as transparent, anytime that color is used in
another function (before or after transparency definition) will be
transparent



ex:

$red = ImageColorAllocate ($im, 233, 14,
91);

$blue = ImageColorAllocate ($im, 0x20, 0x60,
0xaa);

imagefilledarc ($im, 100, 100, 80, 80, 0, 60, $blue,
IMG_ARC_PIE);//arc is transparent even though is not defined
yet

$trans=imagecolortransparent($im,$blue);//affects all occurances of
blue, before and after this line



ALSO:

ImageString ($im, 10,
5, 5,  "Transparent Text String", $blue);

---is equivalent
to----

ImageString ($im, 10, 5, 5,  "Transparent Text
String", $trans);

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