php调整图片大小的image resize函数详解
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2022-04-12 15:14:14
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我用过一些php实现的图片大小调整(image resize)函数,但是都不是很完美,有的图片在调整之后完全变形,还有的无缘无故多了一些线条,有的在颜色亮度上也差强人意。今天我重新找了下,又有了一些收获。
if(isset($_FILES['manager_photo']) && !empty($_FILES['manager_photo']['name'])) { $photo_name=$manager_name."-".$_FILES["manager_photo"]["name"]; $tmpname = $_FILES['manager_photo']['tmp_name']; $file_ext= substr($photo_name, strripos($photo_name, '.')); $dir = "./manager_photos/"; // finally resize @img_resize( $tmpname , 90 , $dir , $photo_name, 1); } function img_resize( $tmpname, $size, $save_dir, $save_name, $maxisheight = 0 ) { $save_dir .= ( substr($save_dir,-1) != "/") ? "/" : ""; $gis = getimagesize($tmpname); $type = $gis[2]; switch($type) { case "1": $imorig = imagecreatefromgif($tmpname); break; case "2": $imorig = imagecreatefromjpeg($tmpname);break; case "3": $imorig = imagecreatefrompng($tmpname); break; default: $imorig = imagecreatefromjpeg($tmpname); } $x = imagesx($imorig); $y = imagesy($imorig); $woh = (!$maxisheight)? $gis[0] : $gis[1] ; if($woh <= $size) { $aw = $x; $ah = $y; } else { if(!$maxisheight){ $aw = $size; $ah = $size * $y / $x; } else { $aw = $size * $x / $y; $ah = $size; } } $im = imagecreatetruecolor($aw,$ah); if (imagecopyresampled($im,$imorig , 0,0,0,0,$aw,$ah,$x,$y)) if (imagejpeg($im, $save_dir.$save_name)) return true; else return false; }//img_resize
用ImageMagick来实现
有人提到用ImageMagick来实现,它里面有很多选项,我们可以用很少的代码就能实现图片调整。值得研究下。
$image = new Imagick($src); $image->resizeImage($width,$height,Imagick::FILTER_LANCZOS,1); $image->cropImage($width_2, $height_2, $x, $y); $image->setCompression(Imagick::COMPRESSION_JPEG); $image->setImageCompressionQuality(82); $image->writeImage($dest); $image->destroy();
用php_class_upload实现
如果如上介绍不适合你,你不单能图片上传和图片调整,还可以切、割、加水印、旋转、翻转等等。
其他实现代码参考
此代码可以返回图片以及正确的名称,但是只能是黑色的?
function resize($originalImage){ list($width, $height) = getimagesize($originalImage); $newName=basename($originalImage); $imageResized = imagecreatetruecolor(128, 128); $imageTmp = imagecreatefromjpeg($originalImage); imagecopyresampled($imageResized, $imageTmp, 0, 0, 0, 0, 128, 128, $width, $height); imagejpeg($imageResized, "resizedImg/$newName",100); imageDestroy($imageResized); }
代码改善后,看看如下代码,可以设置颜色。
function resizeImage($file){ define ('MAX_WIDTH', 1500);//max image width define ('MAX_HEIGHT', 1500);//max image height define ('MAX_FILE_SIZE', 10485760); //iamge save path $path = 'storeResize/'; //size of the resize image $new_width = 128; $new_height = 128; //name of the new image $nameOfFile = 'resize_'.$new_width.'x'.$new_height.'_'.basename($file['name']); $image_type = $file['type']; $image_size = $file['size']; $image_error = $file['error']; $image_file = $file['tmp_name']; $image_name = $file['name']; $image_info = getimagesize($image_file); //check image type if ($image_info['mime'] == 'image/jpeg' or $image_info['mime'] == 'image/jpg'){ } else if ($image_info['mime'] == 'image/png'){ } else if ($image_info['mime'] == 'image/gif'){ } else{ //set error invalid file type } if ($image_error){ //set error image upload error } if ( $image_size > MAX_FILE_SIZE ){ //set error image size invalid } switch ($image_info['mime']) { case 'image/jpg': //This isn't a valid mime type so we should probably remove it case 'image/jpeg': $image = imagecreatefromjpeg ($image_file); break; case 'image/png': $image = imagecreatefrompng ($image_file); break; case 'image/gif': $image = imagecreatefromgif ($image_file); break; } if ($new_width == 0 && $new_height == 0) { $new_width = 100; $new_height = 100; } // ensure size limits can not be abused $new_width = min ($new_width, MAX_WIDTH); $new_height = min ($new_height, MAX_HEIGHT); //get original image h/w $width = imagesx ($image); $height = imagesy ($image); //$align = 'b'; $zoom_crop = 1; $origin_x = 0; $origin_y = 0; //TODO setting Memory // generate new w/h if not provided if ($new_width && !$new_height) { $new_height = floor ($height * ($new_width / $width)); } else if ($new_height && !$new_width) { $new_width = floor ($width * ($new_height / $height)); } // scale down and add borders if ($zoom_crop == 3) { $final_height = $height * ($new_width / $width); if ($final_height > $new_height) { $new_width = $width * ($new_height / $height); } else { $new_height = $final_height; } } // create a new true color image $canvas = imagecreatetruecolor ($new_width, $new_height); imagealphablending ($canvas, false); if (strlen ($canvas_color) < 6) { $canvas_color = 'ffffff'; } $canvas_color_R = hexdec (substr ($canvas_color, 0, 2)); $canvas_color_G = hexdec (substr ($canvas_color, 2, 2)); $canvas_color_B = hexdec (substr ($canvas_color, 2, 2)); // Create a new transparent color for image $color = imagecolorallocatealpha ($canvas, $canvas_color_R, $canvas_color_G,$canvas_color_B, 127); // Completely fill the background of the new image with allocated color. imagefill ($canvas, 0, 0, $color); // scale down and add borders if ($zoom_crop == 2) { $final_height = $height * ($new_width / $width); if ($final_height > $new_height) { $origin_x = $new_width / 2; $new_width = $width * ($new_height / $height); $origin_x = round ($origin_x - ($new_width / 2)); } else { $origin_y = $new_height / 2; $new_height = $final_height; $origin_y = round ($origin_y - ($new_height / 2)); } } // Restore transparency blending imagesavealpha ($canvas, true); if ($zoom_crop > 0) { $src_x = $src_y = 0; $src_w = $width; $src_h = $height; $cmp_x = $width / $new_width; $cmp_y = $height / $new_height; // calculate x or y coordinate and width or height of source if ($cmp_x > $cmp_y) { $src_w = round ($width / $cmp_x * $cmp_y); $src_x = round (($width - ($width / $cmp_x * $cmp_y)) / 2); } else if ($cmp_y > $cmp_x) { $src_h = round ($height / $cmp_y * $cmp_x); $src_y = round (($height - ($height / $cmp_y * $cmp_x)) / 2); } // positional cropping! if ($align) { if (strpos ($align, 't') !== false) { $src_y = 0; } if (strpos ($align, 'b') !== false) { $src_y = $height - $src_h; } if (strpos ($align, 'l') !== false) { $src_x = 0; } if (strpos ($align, 'r') !== false) { $src_x = $width - $src_w; } } // positional cropping! imagecopyresampled ($canvas, $image, $origin_x, $origin_y, $src_x, $src_y, $new_width, $new_height, $src_w, $src_h); } else { imagecopyresampled ($canvas, $image, 0, 0, 0, 0, $new_width, $new_height, $width, $height); } //Straight from Wordpress core code. Reduces filesize by up to 70% for PNG's if ( (IMAGETYPE_PNG == $image_info[2] || IMAGETYPE_GIF == $image_info[2]) && function_exists('imageistruecolor') && !imageistruecolor( $image ) && imagecolortransparent( $image ) > 0 ){ imagetruecolortopalette( $canvas, false, imagecolorstotal( $image ) ); } $quality = 100; $nameOfFile = 'resize_'.$new_width.'x'.$new_height.'_'.basename($file['name']); if (preg_match('/^image\/(?:jpg|jpeg)$/i', $image_info['mime'])){ imagejpeg($canvas, $path.$nameOfFile, $quality); } else if (preg_match('/^image\/png$/i', $image_info['mime'])){ imagepng($canvas, $path.$nameOfFile, floor($quality * 0.09)); } else if (preg_match('/^image\/gif$/i', $image_info['mime'])){ imagegif($canvas, $path.$nameOfFile); } }
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