如何在调整图像大小时填充白色背景

Question

当前背景为黑色。如何将颜色更改为白色？

    #assuming the mime type is correct
    switch ($imgtype) {
        case 'image/jpeg':
            $source = imagecreatefromjpeg($source_image);
            break;
        case 'image/gif':
            $source = imagecreatefromgif($source_image);
            break;
        case 'image/png':
            $source = imagecreatefrompng($source_image);
            break;
        default:
            die('Invalid image type.');
    }

    #Figure out the dimensions of the image and the dimensions of the desired thumbnail
    $src_w = imagesx($source);
    $src_h = imagesy($source);


    #Do some math to figure out which way we'll need to crop the image
    #to get it proportional to the new size, then crop or adjust as needed

    $width  = $info[0];
    $height = $info[1];

    $x_ratio = $tn_w / $src_w;
    $y_ratio = $tn_h / $src_h;

    if (($x_ratio * $height) < $tn_w) {
        $new_h = ceil($x_ratio * $height);
        $new_w  = $tn_w;
    } else {
        $new_w  = ceil($y_ratio * $width);
        $new_h = $tn_h;
    }  
        $x_mid  = $new_w / 2;
        $y_mid  = $new_h / 2;   

    $newpic = imagecreatetruecolor(round($new_w), round($new_h));
    imagecopyresampled($newpic, $source, 0, 0, 0, 0, $new_w, $new_h, $src_w, $src_h);
    $final = imagecreatetruecolor($tn_w, $tn_h);
    imagecopyresampled($final, $newpic, 0, 0, ($x_mid - ($tn_w / 2)), ($y_mid - ($tn_h / 2)), $tn_w, $tn_h, $tn_w, $tn_h);


    #if we need to add a watermark
    if ($wmsource) {
        #find out what type of image the watermark is
        $info    = getimagesize($wmsource);
        $imgtype = image_type_to_mime_type($info[2]);

        #assuming the mime type is correct
        switch ($imgtype) {
            case 'image/jpeg':
                $watermark = imagecreatefromjpeg($wmsource);
                break;
            case 'image/gif':
                $watermark = imagecreatefromgif($wmsource);
                break;
            case 'image/png':
                $watermark = imagecreatefrompng($wmsource);
                break;
            default:
                die('Invalid watermark type.');
        }

        #if we're adding a watermark, figure out the size of the watermark
        #and then place the watermark image on the bottom right of the image
        $wm_w = imagesx($watermark);
        $wm_h = imagesy($watermark);
        imagecopy($final, $watermark, $tn_w - $wm_w, $tn_h - $wm_h, 0, 0, $tn_w, $tn_h);

    }
    if (imagejpeg($final, $destination, $quality)) {
        return true;
    }
    return false;
}

黑与黑白色

Answer 1

$final = imagecreatetruecolor($tn_w, $tn_h);
$backgroundColor = imagecolorallocate($final, 255, 255, 255);
imagefill($final, 0, 0, $backgroundColor);
//imagecopyresampled($final, $newpic, 0, 0, ($x_mid - ($tn_w / 2)), ($y_mid - ($tn_h / 2)), $tn_w, $tn_h, $tn_w, $tn_h);
imagecopy($final, $newpic, (($tn_w - $new_w)/ 2), (($tn_h - $new_h) / 2), 0, 0, $new_w, $new_h);

这是您的整个脚本（使用纵向、横向和方形 jpg 进行测试）：

<?php
function resize($source_image, $destination, $tn_w, $tn_h, $quality = 100, $wmsource = false)
{
    $info = getimagesize($source_image);
    $imgtype = image_type_to_mime_type($info[2]);

    #assuming the mime type is correct
    switch ($imgtype) {
        case 'image/jpeg':
            $source = imagecreatefromjpeg($source_image);
            break;
        case 'image/gif':
            $source = imagecreatefromgif($source_image);
            break;
        case 'image/png':
            $source = imagecreatefrompng($source_image);
            break;
        default:
            die('Invalid image type.');
    }

    #Figure out the dimensions of the image and the dimensions of the desired thumbnail
    $src_w = imagesx($source);
    $src_h = imagesy($source);


    #Do some math to figure out which way we'll need to crop the image
    #to get it proportional to the new size, then crop or adjust as needed

    $x_ratio = $tn_w / $src_w;
    $y_ratio = $tn_h / $src_h;

    if (($src_w <= $tn_w) && ($src_h <= $tn_h)) {
        $new_w = $src_w;
        $new_h = $src_h;
    } elseif (($x_ratio * $src_h) < $tn_h) {
        $new_h = ceil($x_ratio * $src_h);
        $new_w = $tn_w;
    } else {
        $new_w = ceil($y_ratio * $src_w);
        $new_h = $tn_h;
    }

    $newpic = imagecreatetruecolor(round($new_w), round($new_h));
    imagecopyresampled($newpic, $source, 0, 0, 0, 0, $new_w, $new_h, $src_w, $src_h);
    $final = imagecreatetruecolor($tn_w, $tn_h);
    $backgroundColor = imagecolorallocate($final, 255, 255, 255);
    imagefill($final, 0, 0, $backgroundColor);
    //imagecopyresampled($final, $newpic, 0, 0, ($x_mid - ($tn_w / 2)), ($y_mid - ($tn_h / 2)), $tn_w, $tn_h, $tn_w, $tn_h);
    imagecopy($final, $newpic, (($tn_w - $new_w)/ 2), (($tn_h - $new_h) / 2), 0, 0, $new_w, $new_h);

    #if we need to add a watermark
    if ($wmsource) {
        #find out what type of image the watermark is
        $info    = getimagesize($wmsource);
        $imgtype = image_type_to_mime_type($info[2]);

        #assuming the mime type is correct
        switch ($imgtype) {
            case 'image/jpeg':
                $watermark = imagecreatefromjpeg($wmsource);
                break;
            case 'image/gif':
                $watermark = imagecreatefromgif($wmsource);
                break;
            case 'image/png':
                $watermark = imagecreatefrompng($wmsource);
                break;
            default:
                die('Invalid watermark type.');
        }

        #if we're adding a watermark, figure out the size of the watermark
        #and then place the watermark image on the bottom right of the image
        $wm_w = imagesx($watermark);
        $wm_h = imagesy($watermark);
        imagecopy($final, $watermark, $tn_w - $wm_w, $tn_h - $wm_h, 0, 0, $tn_w, $tn_h);

    }
    if (imagejpeg($final, $destination, $quality)) {
        return true;
    }
    return false;
}

resize('teszt2.jpg', 'out.jpg', 100, 100);
?>
<img src="out.jpg">

Answer 2

这对我有用。尽管从逻辑上看它应该用 $bgcolor 填充整个图像，但它只填充重新采样图像“后面”的部分。

imagecopyresampled($resized_image, $original_image, $xoffset, $yoffset, 0, 0, $new_width, $new_height, $orig_width, $orig_height);
$bgcolor = imagecolorallocate($resized_image, $red, $green, $blue);
imagefill($resized_image, 0, 0, $bgcolor);