Question

我正在使用这个问题的函数 PHP - Create Thumbnail & maintaining aspect ratio

代码如下，

        define('THUMBNAIL_IMAGE_MAX_WIDTH', 150);
        define('THUMBNAIL_IMAGE_MAX_HEIGHT', 150);
        function generate_image_thumbnail($source_image_path, $thumbnail_image_path)
        {
                list($source_image_width, $source_image_height, $source_image_type) = getimagesize($source_image_path);
                switch ($source_image_type) {
                        case IMAGETYPE_GIF:
                                $source_gd_image = imagecreatefromgif($source_image_path);
                                break;
                        case IMAGETYPE_JPEG:
                                $source_gd_image = imagecreatefromjpeg($source_image_path);
                                break;
                        case IMAGETYPE_PNG:
                                $source_gd_image = imagecreatefrompng($source_image_path);
                                break;
                }
                if ($source_gd_image === false) {
                        return false;
                }
                $source_aspect_ratio = $source_image_width / $source_image_height;
                $thumbnail_aspect_ratio = THUMBNAIL_IMAGE_MAX_WIDTH / THUMBNAIL_IMAGE_MAX_HEIGHT;
                if ($source_image_width <= THUMBNAIL_IMAGE_MAX_WIDTH && $source_image_height <= THUMBNAIL_IMAGE_MAX_HEIGHT) {
                        $thumbnail_image_width = $source_image_width;
                        $thumbnail_image_height = $source_image_height;
                } elseif ($thumbnail_aspect_ratio > $source_aspect_ratio) {
                        $thumbnail_image_width = (int) (THUMBNAIL_IMAGE_MAX_HEIGHT * $source_aspect_ratio);
                        $thumbnail_image_height = THUMBNAIL_IMAGE_MAX_HEIGHT;
                } else {
                        $thumbnail_image_width = THUMBNAIL_IMAGE_MAX_WIDTH;
                        $thumbnail_image_height = (int) (THUMBNAIL_IMAGE_MAX_WIDTH / $source_aspect_ratio);
                }
                $thumbnail_gd_image = imagecreatetruecolor($thumbnail_image_width, $thumbnail_image_height);
                imagecopyresampled($thumbnail_gd_image, $source_gd_image, 0, 0, 0, 0, $thumbnail_image_width, $thumbnail_image_height, $source_image_width, $source_image_height);

                $img_disp = imagecreatetruecolor(THUMBNAIL_IMAGE_MAX_WIDTH,THUMBNAIL_IMAGE_MAX_HEIGHT);
                $backcolor = imagecolorallocate($img_disp,0,0,0);
                imagefill($img_disp,0,0,$backcolor);

                        imagecopy($img_disp, $thumbnail_gd_image, (imagesx($img_disp)/2)-(imagesx($thumbnail_gd_image)/2), (imagesy($img_disp)/2)-(imagesy($thumbnail_gd_image)/2), 0, 0, imagesx($thumbnail_gd_image), imagesy($thumbnail_gd_image));

                imagejpeg($img_disp, $thumbnail_image_path, 90);
                imagedestroy($source_gd_image);
                imagedestroy($thumbnail_gd_image);
                imagedestroy($img_disp);
                return true;
        }

效果很好，会创建像这样的缩略图

example image

我注意到该功能会用黑色填充未使用的部分

imagefill（$ img_disp，0,0，$背景色）;

我怎样才能删除黑色部分？我不需要固定宽度或高度。

Answer 1

也许最简单的方法是保持宽高比。

// RESIZE AN IMAGE PROPORTIONALLY AND CROP TO THE CENTER


function resize_and_crop($original_image_url, $thumb_image_url, $thumb_w, $thumb_h, $quality=75)
{
    // ACQUIRE THE ORIGINAL IMAGE: http://php.net/manual/en/function.imagecreatefromjpeg.php
    $original = imagecreatefromjpeg($original_image_url);
    if (!$original) return FALSE;

    // GET ORIGINAL IMAGE DIMENSIONS
    list($original_w, $original_h) = getimagesize($original_image_url);

    // RESIZE IMAGE AND PRESERVE PROPORTIONS
    $thumb_w_resize = $thumb_w;
    $thumb_h_resize = $thumb_h;
    if ($original_w > $original_h)
    {
        $thumb_h_ratio  = $thumb_h / $original_h;
        $thumb_w_resize = (int)round($original_w * $thumb_h_ratio);
    }
    else
    {
        $thumb_w_ratio  = $thumb_w / $original_w;
        $thumb_h_resize = (int)round($original_h * $thumb_w_ratio);
    }
    if ($thumb_w_resize < $thumb_w)
    {
        $thumb_h_ratio  = $thumb_w / $thumb_w_resize;
        $thumb_h_resize = (int)round($thumb_h * $thumb_h_ratio);
        $thumb_w_resize = $thumb_w;
    }

    // CREATE THE PROPORTIONAL IMAGE RESOURCE
    $thumb = imagecreatetruecolor($thumb_w_resize, $thumb_h_resize);
    if (!imagecopyresampled($thumb, $original, 0,0,0,0, $thumb_w_resize, $thumb_h_resize, $original_w, $original_h)) return FALSE;

    // ACTIVATE THIS TO STORE THE INTERMEDIATE IMAGE
    // imagejpeg($thumb, 'thumbs/temp_' . $thumb_w_resize . 'x' . $thumb_h_resize . '.jpg', 100);

    // CREATE THE CENTERED CROPPED IMAGE TO THE SPECIFIED DIMENSIONS
    $final = imagecreatetruecolor($thumb_w, $thumb_h);

    $thumb_w_offset = 0;
    $thumb_h_offset = 0;
    if ($thumb_w < $thumb_w_resize)
    {
        $thumb_w_offset = (int)round(($thumb_w_resize - $thumb_w) / 2);
    }
    else
    {
        $thumb_h_offset = (int)round(($thumb_h_resize - $thumb_h) / 2);
    }

    if (!imagecopy($final, $thumb, 0,0, $thumb_w_offset, $thumb_h_offset, $thumb_w_resize, $thumb_h_resize)) return FALSE;

    // STORE THE FINAL IMAGE - WILL OVERWRITE $thumb_image_url
    if (!imagejpeg($final, $thumb_image_url, $quality)) return FALSE;
    return TRUE;
}


// USE CASE
echo '<a target="_blank" href="images/image_600x374.jpg">Original 600x374</a><br/>';

resize_and_crop('images/image_600x374.jpg', 'thumbs/temp_100x100.jpg', 100, 100);
echo '<a target="_blank" href="thumbs/temp_100x100.jpg">100x100</a><br/>';

resize_and_crop('images/image_600x374.jpg', 'thumbs/temp_200x100.jpg', 200, 100);
echo '<a target="_blank" href="thumbs/temp_200x100.jpg">200x100</a><br/>';

resize_and_crop('images/image_600x374.jpg', 'thumbs/temp_200x300.jpg', 200, 300);
echo '<a target="_blank" href="thumbs/temp_200x300.jpg">200x300</a><br/>';

PHP - 创建缩略图维持宽高比＆amp;删除空白部分？

1 个答案: