imagepalettetotruecolor

(PHP 5 >= 5.5.0, PHP 7)

imagepalettetotruecolor — Converts a palette based image to true color

说明

bool imagepalettetotruecolor ( resource $src )

Converts a palette based image, created by functions like imagecreate() to a true color image, like imagecreatetruecolor() .

参数

image: 由图象创建函数(例如 imagecreatetruecolor() )返回的图象资源。

返回值

Returns TRUE if the convertion was complete, or if the source image already is a true color image, otherwise FALSE is returned.

范例

Example #1 Converts any image resource to true color

  <?php
 // Backwards compatiblity
 if(! function_exists ( 'imagepalettetotruecolor' ))
{
    function  imagepalettetotruecolor (& $src )
    {
        if( imageistruecolor ( $src ))
        {
            return( true );
        }

         $dst  =  imagecreatetruecolor ( imagesx ( $src ),  imagesy ( $src ));

         imagecopy ( $dst ,  $src ,  0 ,  0 ,  0 ,  0 ,  imagesx ( $src ),  imagesy ( $src ));
         imagedestroy ( $src );

         $src  =  $dst ;

        return( true );
    }
}

 // Helper closure
 $typeof  = function() use( $im )
{
    echo  'typeof($im) = '  . ( imageistruecolor ( $im ) ?  'true color'  :  'palette' ),  PHP_EOL ;
};

 // Create a palette based image
 $im  =  imagecreate ( 100 ,  100 );
 $typeof ();

 // Convert it to true color
 imagepalettetotruecolor ( $im );
 $typeof ();

 // Free the memory
 imagedestroy ( $im );
 ?>

以上例程会输出：

typeof($im) = palette
typeof($im) = true color

参见

imagecreatetruecolor() - 新建一个真彩色图像
imageistruecolor() - 检查图像是否为真彩色图像

用户评论:

[#1] Polda18 [2014-04-30 14:44:20]

PHP ver 5.4.24 does not support this function (it has not been defined). To get rid of this, you must copy image resource to new image created by function imagecreatetruecolor();

Example with image loaded from GIF file:

$image  = imagecreatefromgif("path/to/gif/file.gif");  //create an image from GIF
$width  = imagesx($image);                             //get width of source image
$height = imagesy($image);                             //get height of source image
$image2 = imagecreatetruecolor($width,$height);        //create new image of true colors with given width and height
imagecopy($image2,$image,0,0,0,0,$width,$height);      //copy source image to new one

header("Content-Type: image/jpeg");                    //set header for JPG image
imagejpg($image2);                                     //render JPg image into browser

imagedestroy($image);                                  //free up memory
imagedestroy($image2);

[#2] walf [2014-03-21 06:20:15]

The backwards compatibility example does not preserve transparency. You must first wipe out the default black background on the new image:

<?php // Backwards compatiblity if (!function_exists('imagepalettetotruecolor')) { function imagepalettetotruecolor(&$src) { if (imageistruecolor($src)) { return true; } $dst = imagecreatetruecolor(imagesx($src), imagesy($src)); imagealphablending($dst, false);//prevent blending with default black $transparent = imagecolorallocatealpha($new_image, 255, 255, 255, 127);//change the RGB values if you need, but leave alpha at 127 imagefilledrectangle($dst, 0, 0, $imagesx($src), imagesy($src), $transparent);//simpler than flood fill imagealphablending($dst, true);//restore default blending imagecopy($dst, $src, 0, 0, 0, 0, imagesx($src), imagesy($src)); imagedestroy($src); $src = $dst; return true; } } ?>