Aitch的部落格

今天改寫了之前寫得縮圖程式，之前寫的縮圖程式會將小於特定寬度的圖片重新取樣成特定尺寸，這樣的做法會導致小圖片的失真，所以我改寫了這個過程，將小於特定尺寸的圖片透過補色，變成一張符合特定尺寸的圖：

public function resizeImg($img, $width = 300, $height = 300, $newFilename = '', $maxImgWidth = 800, $maxImgHeight=800, $bgColor=null) {
        
        $bgColor = $bgColor === null || !is_array($bgColor) ? array('r'=>255, 'g'=>255, 'b'=>255) : $bgColor;

        switch (strtolower($img['type'])) {
            case 'image/jpg':
            case 'image/jpeg':
            case 'image/pjpeg':
                $image = imagecreatefromjpeg($img['tmp_name']);
                break;
            case 'image/png':
                $image = imagecreatefrompng($img['tmp_name']);
                break;
            case 'image/gif':
                $image = imagecreatefromgif($img['tmp_name']);
                break;
            default:
                throw new Exception('Unsupported type: ' . $img['type']);
        }

        // Target dimensions
        $max_width = $width;
        $max_height = $height;

        // Get current dimensions
        $old_width = imagesx($image);
        $old_height = imagesy($image);

        // Calculate the scaling we need to do to fit the image inside our frame
        $scale = min($max_width / $old_width, $max_height / $old_height);

        $new_width = ceil($scale * $old_width);
        $new_height = ceil($scale * $old_height);
            
        // Create new empty image
        $new = imagecreatetruecolor($new_width, $new_height);

        // Get the new dimensions
        if($old_width >= $maxImgWidth){
            imagecopyresampled($new, $image, 0, 0, 0, 0, $new_width, $new_height, $old_width, $old_height);
        }else{
            $new_width = $maxImgWidth;
            $new_height = ($maxImgHeight >= $old_height ? $maxImgHeight : $old_height);
            $new = imagecreatetruecolor($new_width, $new_height);
            $backgroundColor = imagecolorallocate($new, $bgColor['r'], $bgColor['g'], $bgColor['b']);
            imagefill($new, 0, 0, $backgroundColor);
            $centerX = (($new_width - $old_width)   / 2);
            $centerY = (($new_height - $old_height) / 2);
            $centerY = $centerY + $old_height >= $new_height ? 0 : $centerY;
            imagecopy($new, $image, $centerX, $centerY, 0, 0, $old_width, $old_height);
        }
        

        switch (strtolower($img['type'])) {
            case 'image/jpg':
            case 'image/jpeg':
            case 'image/pjpeg':
                $optImg = imagejpeg($new, $newFilename, 100);
                break;
            case 'image/png':
                $optImg = imagepng($new, $newFilename, 0, PNG_ALL_FILTERS);
                break;
            case 'image/gif':
                $optImg = imagegif($new, $newFilename);
                break;
        }

        imagedestroy($image);
        imagedestroy($new);
    }