imagepalettetotruecolor

    (PHP 5 >= 5.5.0, PHP 7, PHP 8)

    imagepalettetotruecolor — Converts a palette based image to true color

    说明

    imagepalettetotruecolor(GdImage $image): bool

    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 GdImage 对象。

    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.

    更新日志

    版本 说明
    8.0.0 image 现在需要 GdImage 实例；之前需要有效的 gd resource。

    示例

    示例 #1 Converts any image object 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);
    ?>

    以上示例会输出：

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

    参见

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    用户贡献的备注 3 notes

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    1
    Polda18
    10 years ago
    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);
    up
    0
    walf - iftfy
    7 years ago
    here the working version of walf's solution

    <?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
    $transparent = imagecolorallocatealpha($dst, 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;
    }
    }
    ?>
    up
    -2
    walf
    10 years ago
    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;
    }
    }
    ?>
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