标签：php transparency png gd

我有2个源图像,我想：

>对每个图像进行圆形裁剪,使圆的外部透明
>将所有图像合并/复制回目标透明图像.

我试过many examples,但似乎无法保持最终图像的透明度.

我正在努力实现这样的目标：

这是我得到的输出的一个例子：

这是我的circle_crop函数：

    function create_circle( $img_path ) {
    // Attribution: by NerdsOfTech

    // Step 1 - Start with image as layer 1 (canvas).
    if (! $img1 = $this->imageCreateFromAny( $img_path )) {
        return FALSE;
    }

    $x=imagesx($img1);
    $y=imagesy($img1);


    // Step 2 - Create a blank image.
    $img2 = imagecreatetruecolor($x, $y);

    $bg = imagecolorallocate($img2, 255,0,255, 127); // wierdo pink background
    // $bg = imagecolorallocate($img2, 0, 0, 0, 127 ); // white background

    imagefill($img2, 0, 0, $bg);
    imagecolortransparent($img2, $bg);

    // Step 3 - Create the ellipse OR circle mask.
    $e = imagecolorallocate($img2, 255, 255, 255); // black mask color

    // Draw a ellipse mask
    imagefilledellipse ($img2, ($x/2), ($y/2), $x, $y, $e);

    // OR
    // Draw a circle mask
    // $r = $x <= $y ? $x : $y; // use smallest side as radius & center shape
    // imagefilledellipse ($img2, ($x/2), ($y/2), $r, $r, $e);

    // Step 4 - Make shape color transparent
    imagecolortransparent($img2, $e);

    // Step 5 - Merge the mask into canvas with 100 percent opacity
    imagecopymerge($img1, $img2, 0, 0, 0, 0, $x, $y, 100);

    // Step 6 - Make outside border color around circle transparent
    imagecolortransparent($img1, $bg);

    /* Clean up memory */
    imagedestroy($img2);

    return $img1;
}

这是我在图像URL数组中传递的代码,并通过调用circle_crop函数来循环,以返回裁剪后的图像并将其合并到目标图像上.

function generate_collage( $img_name_path_array, $effect = 'POLAROID' ) {
    $base_img_width = 800;
    $base_img_height = 650;

    if (empty($img_name_path_array)) {
        error_log('Image name_path_array is blank?'.PHP_EOL);
        return FALSE;
    }
    $effect = strtoupper($effect);

    /* Create canvas */
    $collage_img = imagecreatetruecolor($base_img_width, $base_img_height);
    imagealphablending($collage_img, false);
    imagesavealpha($collage_img,true);
    /* Create alpha channel for transparent layer */
    $trans_col=imagecolorallocatealpha($collage_img,255,255,255, 127);
    /* Create overlapping transparent layer */
    imagefilledrectangle($collage_img,0,0,$base_img_width,$base_img_height,$trans_col);

    /* Continue to keep layers transparent */
    imagealphablending($collage_img,true);

    $size_reduction = .80;
    $start_size = 100;


    foreach ($img_name_path_array as $image_array ) {
        $img_text = $image_array[0];
        $img_path = $image_array[1];
        if (! empty($img_path)) {
            switch ($effect) {
                /* Add other collage image effects here */
                case 'POLAROID' : {
                    $temp_img = $this->create_polaroid($img_path, $img_text, TRUE);
                    break;
                }
                case 'CIRCLES' : {
                    // $temp_img = $this->circle_crop($img_path);
                    $temp_img = $this->create_circle($img_path);
                    break;
                }
                default : {
                    /* Default to polaroid for now */
                    $temp_img = $this->create_polaroid($img_path, $img_text, TRUE);
                    break;
                }
            }

            if ($temp_img) {
                /* Get original height and width paramaters */
                $source_w = imagesx($temp_img);
                $source_h = imagesy($temp_img);

                /* Randomise X and Y coordinates */
                $random_x_pos = rand(0, (int) ($base_img_width * .66));
                $random_y_pos = rand(0, (int) ($base_img_height * .3));

                /* Randomise image size */
                $start_size = ($start_size * $size_reduction);
                $random_img_size_ratio = $start_size / 100;

                /* Add generated image to base collage image */
                imagecopyresampled($collage_img, $temp_img, $random_x_pos, $random_y_pos, 0, 0, ($base_img_width * $random_img_size_ratio), ($base_img_height * $random_img_size_ratio), $source_w, $source_h);

                imagecolortransparent($collage_img, $trans_col);
                /* Keep transparent when saving */
                imagesavealpha($collage_img,true);

                /* Memory clean up */
                imagedestroy($temp_img);

                // break;
            }
        }
    }


    /* Now display PNG to browser */
    $this->show_png_from_image_object($collage_img);
}

这是我的显示功能：

function show_png_from_image_object( $img_obj ) {
    header ( 'Content-Type: image/png' );

    /* Display PNG with max compression */
    imagepng ( $img_obj, NULL,  9, PNG_ALL_FILTERS);
    imagedestroy ( $img_obj );
}

我把头发拉了2天,所以任何指针都会非常感激.

谢谢你,杰森.

解决方法:

我编写了以下类来处理所有必需的图像处理：

class Img
{
    public $img;

    public $transparent;

    public $width;

    public $height;

    public function __construct($img = null)
    {
        if (!empty($img)) {
            $this->img = imagecreatefrompng($img);
            $this->width = imagesx($this->img);
            $this->height = imagesy($this->img);
            $this->setTransparentColour();
        }
    }

    public function create($width, $height, $transparent)
    {
        $this->img = imagecreatetruecolor($width, $height);
        $this->width = $width;
        $this->height =$height;

        $this->setTransparentColour();

        if (true === $transparent) {
            imagefill($this->img, 0, 0, $this->transparent);
        }
    }

    public function setTransparentColour($red = 255, $green = 0, $blue = 255)
    {
        $this->transparent = imagecolorallocate($this->img, $red, $green, $blue);
        imagecolortransparent($this->img, $this->transparent);
    }

    public function circleCrop()
    {
        $mask = imagecreatetruecolor($this->width, $this->height);
        $black = imagecolorallocate($mask, 0, 0, 0);
        $magenta = imagecolorallocate($mask, 255, 0, 255);

        imagefill($mask, 0, 0, $magenta);

        imagefilledellipse(
            $mask,
            ($this->width / 2),
            ($this->height / 2),
            $this->width,
            $this->height,
            $black
        );

        imagecolortransparent($mask, $black);

        imagecopymerge($this->img, $mask, 0, 0, 0, 0, $this->width, $this->height, 100);

        imagedestroy($mask);
    }

    public function merge(Img $in, $dst_x = 0, $dst_y = 0)
    {
        imagecopymerge(
            $this->img,
            $in->img,
            $dst_x,
            $dst_y,
            0,
            0,
            $in->width,
            $in->height,
            100
        );
    }

    public function render()
    {
        header('Content-type: image/png');
        imagepng($this->img);
    }
}

如上所述,该类仅适用于PNG文件,但如果需要,您应该能够轻松地修改它.

示例类用法：

// create a transparent base image that we will merge the cropped images into.
$img = new Img();
$img->create(400, 400, true);

// first image; crop and merge with base.
$img2 = new Img('./crop_1.png');
$img2->circleCrop();
$img->merge($img2, 50, 50);

// second image; crop and merge with base.
$img3 = new Img('./crop_2.png');
$img3->circleCrop();
$img->merge($img3, 25, 200);

$img->render();

这将导致下面的图像(当然,嵌入此处时无法看到透明度,因此请尝试单独打开图像)：

我使用了这两个源图像：

标签：php,transparency,png,gd
来源： https://codeday.me/bug/20191009/1876328.html

本站声明： 1. iCode9 技术分享网（下文简称本站）提供的所有内容，仅供技术学习、探讨和分享；
2. 关于本站的所有留言、评论、转载及引用，纯属内容发起人的个人观点，与本站观点和立场无关；
3. 关于本站的所有言论和文字，纯属内容发起人的个人观点，与本站观点和立场无关；
4. 本站文章均是网友提供，不完全保证技术分享内容的完整性、准确性、时效性、风险性和版权归属；如您发现该文章侵犯了您的权益，可联系我们第一时间进行删除；
5. 本站为非盈利性的个人网站，所有内容不会用来进行牟利，也不会利用任何形式的广告来间接获益，纯粹是为了广大技术爱好者提供技术内容和技术思想的分享性交流网站。