imagecopyresampled左侧位置图像

Question

代码工作正常。

肖像图像正好是中心。

但是当需要图像移动左侧位置时：

我改变了这段代码。

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_WIDTH);
$backcolor = imagecolorallocate($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;
}

generate_image_thumbnail('original_image.jpg', 'thumb_image.jpg'); //call the function

来自PHP - Create Thumbnail & maintaining aspect ratio

的代码

Answer 1

imagecopy函数指定图像的 x 和 y 坐标。将 x 坐标设置为0以使其最左对齐：

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_WIDTH);
$backcolor = imagecolorallocate($img_disp,0,0,0);
imagefill($img_disp,0,0,$backcolor);

    imagecopy($img_disp, $thumbnail_gd_image, 0 /* changed this to 0 */, (imagesy($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;
}

generate_image_thumbnail('original_image.jpg', 'thumb_image.jpg'); //call the function