Question

我需要修复此调整大小类，以便具有透明背景的图像在上传和调整大小时保留其透明背景。这个类将透明背景转换为看起来不太好的所有黑色。

Class resize
    {
        // *** Class variables
        private $image;
        private $width;
        private $height;
        private $imageResized;

        function __construct($fileName)
        {
            // *** Open up the file
            $this->image = $this->openImage($fileName);

            // *** Get width and height
            $this->width  = imagesx($this->image);
            $this->height = imagesy($this->image);
        }

        ## --------------------------------------------------------

        private function openImage($file)
        {
            // *** Get extension
            $extension = strtolower(strrchr($file, '.'));

            switch($extension)
            {
                case '.jpg':
                case '.jpeg':
                    $img = @imagecreatefromjpeg($file);
                    break;
                case '.gif':
                    $img = @imagecreatefromgif($file);
                    break;
                case '.png':
                    $img = @imagecreatefrompng($file);
                    break;
                default:
                    $img = false;
                    break;
            }
            return $img;
        }

        ## --------------------------------------------------------

        public function resizeImage($newWidth, $newHeight, $option="auto")
        {
            // *** Get optimal width and height - based on $option
            $optionArray = $this->getDimensions($newWidth, $newHeight, $option);

            $optimalWidth  = $optionArray['optimalWidth'];
            $optimalHeight = $optionArray['optimalHeight'];


            // *** Resample - create image canvas of x, y size
            $this->imageResized = imagecreatetruecolor($optimalWidth, $optimalHeight);
            imagecopyresampled($this->imageResized, $this->image, 0, 0, 0, 0, $optimalWidth, $optimalHeight, $this->width, $this->height);


            // *** if option is 'crop', then crop too
            if ($option == 'crop') {
                $this->crop($optimalWidth, $optimalHeight, $newWidth, $newHeight);
            }
        }

        ## --------------------------------------------------------

        private function getDimensions($newWidth, $newHeight, $option)
        {

           switch ($option)
            {
                case 'exact':
                    $optimalWidth = $newWidth;
                    $optimalHeight= $newHeight;
                    break;
                case 'portrait':
                    $optimalWidth = $this->getSizeByFixedHeight($newHeight);
                    $optimalHeight= $newHeight;
                    break;
                case 'landscape':
                    $optimalWidth = $newWidth;
                    $optimalHeight= $this->getSizeByFixedWidth($newWidth);
                    break;
                case 'auto':
                    $optionArray = $this->getSizeByAuto($newWidth, $newHeight);
                    $optimalWidth = $optionArray['optimalWidth'];
                    $optimalHeight = $optionArray['optimalHeight'];
                    break;
                case 'crop':
                    $optionArray = $this->getOptimalCrop($newWidth, $newHeight);
                    $optimalWidth = $optionArray['optimalWidth'];
                    $optimalHeight = $optionArray['optimalHeight'];
                    break;
            }
            return array('optimalWidth' => $optimalWidth, 'optimalHeight' => $optimalHeight);
        }

        ## --------------------------------------------------------

        private function getSizeByFixedHeight($newHeight)
        {
            $ratio = $this->width / $this->height;
            $newWidth = $newHeight * $ratio;
            return $newWidth;
        }

        private function getSizeByFixedWidth($newWidth)
        {
            $ratio = $this->height / $this->width;
            $newHeight = $newWidth * $ratio;
            return $newHeight;
        }

        private function getSizeByAuto($newWidth, $newHeight)
        {
            if ($this->height < $this->width)
            // *** Image to be resized is wider (landscape)
            {
                $optimalWidth = $newWidth;
                $optimalHeight= $this->getSizeByFixedWidth($newWidth);
            }
            elseif ($this->height > $this->width)
            // *** Image to be resized is taller (portrait)
            {
                $optimalWidth = $this->getSizeByFixedHeight($newHeight);
                $optimalHeight= $newHeight;
            }
            else
            // *** Image to be resizerd is a square
            {
                if ($newHeight < $newWidth) {
                    $optimalWidth = $newWidth;
                    $optimalHeight= $this->getSizeByFixedWidth($newWidth);
                } else if ($newHeight > $newWidth) {
                    $optimalWidth = $this->getSizeByFixedHeight($newHeight);
                    $optimalHeight= $newHeight;
                } else {
                    // *** Sqaure being resized to a square
                    $optimalWidth = $newWidth;
                    $optimalHeight= $newHeight;
                }
            }

            return array('optimalWidth' => $optimalWidth, 'optimalHeight' => $optimalHeight);
        }

        ## --------------------------------------------------------

        private function getOptimalCrop($newWidth, $newHeight)
        {

            $heightRatio = $this->height / $newHeight;
            $widthRatio  = $this->width /  $newWidth;

            if ($heightRatio < $widthRatio) {
                $optimalRatio = $heightRatio;
            } else {
                $optimalRatio = $widthRatio;
            }

            $optimalHeight = $this->height / $optimalRatio;
            $optimalWidth  = $this->width  / $optimalRatio;

            return array('optimalWidth' => $optimalWidth, 'optimalHeight' => $optimalHeight);
        }

        ## --------------------------------------------------------

        private function crop($optimalWidth, $optimalHeight, $newWidth, $newHeight)
        {
            // *** Find center - this will be used for the crop
            $cropStartX = ( $optimalWidth / 2) - ( $newWidth /2 );
            $cropStartY = ( $optimalHeight/ 2) - ( $newHeight/2 );

            $crop = $this->imageResized;
            //imagedestroy($this->imageResized);

            // *** Now crop from center to exact requested size
            $this->imageResized = imagecreatetruecolor($newWidth , $newHeight);
            imagecopyresampled($this->imageResized, $crop , 0, 0, $cropStartX, $cropStartY, $newWidth, $newHeight , $newWidth, $newHeight);
        }

        ## --------------------------------------------------------

        public function saveImage($savePath, $imageQuality="100")
        {
            // *** Get extension
            $extension = strrchr($savePath, '.');
            $extension = strtolower($extension);

            switch($extension)
            {
                case '.jpg':
                case '.jpeg':
                    if (imagetypes() & IMG_JPG) {
                        imagejpeg($this->imageResized, $savePath, $imageQuality);
                    }
                    break;

                case '.gif':
                    if (imagetypes() & IMG_GIF) {
                        imagegif($this->imageResized, $savePath);
                    }
                    break;

                case '.png':
                    // *** Scale quality from 0-100 to 0-9
                    $scaleQuality = round(($imageQuality/100) * 9);

                    // *** Invert quality setting as 0 is best, not 9
                    $invertScaleQuality = 9 - $scaleQuality;

                    if (imagetypes() & IMG_PNG) {
                         imagepng($this->imageResized, $savePath, $invertScaleQuality);
                    }
                    break;

                // ... etc

                default:
                    // *** No extension - No save.
                    break;
            }

            imagedestroy($this->imageResized);
        }


        ## --------------------------------------------------------

    }

Answer 1

经过一番搜索，我找到了修复程序。添加此代码

public function resizeImage($newWidth, $newHeight, $option="auto") {
            // *** Get optimal width and height - based on $option
            $optionArray = $this->getDimensions($newWidth, $newHeight, $option);

            $optimalWidth  = $optionArray['optimalWidth'];
            $optimalHeight = $optionArray['optimalHeight'];


            // *** Resample - create image canvas of x, y size
            $this->imageResized = imagecreatetruecolor($optimalWidth, $optimalHeight);



    imagealphablending($this->imageResized, false);
    imagesavealpha($this->imageResized, true);
    $bg = imagecolorallocatealpha($this->imageResized, 0, 0, 0, 127);
    imagefilledrectangle($this->imageResized, 0, 0, $optimalWidth, $optimalHeight, $bg);
    imagecolortransparent($this->imageResized, $bg);


    imagecopyresampled($this->imageResized, $this->image, 0, 0, 0, 0, $optimalWidth,        $optimalHeight, $this->width, $this->height);


            // *** if option is 'crop', then crop too
            if ($option == 'crop') {
                $this->crop($optimalWidth, $optimalHeight, $newWidth, $newHeight);
            }
        }

Answer 2

创建画布时我会保留透明度，如下所示：

    private function openImage($file,$sizeX, $sizeY)
    {
        // *** Get extension
        $extension = strtolower(strrchr($file, '.'));

        switch($extension)
        {
            case '.jpg':
            case '.jpeg':
                $img = @imagecreatefromjpeg($file);
                break;
            case '.gif':
                $img = @imagecreatefromgif($file);
                break;
            case '.png':
                $img = @imagecreatefrompng($file);
                break;
            default:
                $img = false;
                break;
        }

        //create canvas:            

        $img = imagecreatetruecolor($sizeX,$sizeY);


        // preserve transparency`

        if($extension == "gif" or $extension == "png"){

           imagecolortransparent($img, imagecolorallocatealpha($img, 0, 0, 0, 127));
           imagealphablending($img, false);
           imagesavealpha($img, true);
        }

        return $img;
    }

然后，您的画布已激活透明度。但只有扩展可以支持它。但是，您应该设置像参数一样传递大小。

使用php resize-class.php调整大小时，使透明背景保持透明

2 个答案: