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生成缩略图的php类，新建一个文件叫做 thumbnailimage.php，文件名最好不要用大写。
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- define ( 'MAX_IMG_SIZE', 100000 );
- // Supported image types
- define ( 'THUMB_JPEG', 'image/jpeg' );
- define ( 'THUMB_PNG', 'image/png' );
- define ( 'THUMB_GIF', 'image/gif' );
- // Interlacing modes
- define ( 'INTERLACE_OFF', 0 );
- define ( 'INTERLACE_ON', 1 );
- // Output modes
- define ( 'STDOUT', '' );
- // Empty constants
- define ( 'NO_LOGO', '' );
- define ( 'NO_LABEL', '' );
- // Logo and label positioning
- define ( 'POS_LEFT', 0 );
- define ( 'POS_RIGHT', 1 );
- define ( 'POS_CENTER', 2 );
- define ( 'POS_TOP', 3 );
- define ( 'POS_BOTTOM', 4 );
- // Error messages
- define ( 'E_001', 'File %s do not exist' );
- define ( 'E_002', 'Failed reading image data from %s' );
- define ( 'E_003', 'Cannot create the copy of %s' );
- define ( 'E_004', 'Cannot copy the logo image' );
- define ( 'E_005', 'Cannot create final image' );
- // ****************************************************************************
- // CLASS DEFINITION
- // ****************************************************************************
- class ThumbnailImage
- {
- // ****************************************************************************
- // PUBLIC PROPERTIES
- // ****************************************************************************
- var $src_file; // source image file
- var $dest_file; // destination image file
- var $dest_type; // destination image type
- var $interlace; // destination image interlacing mode
- var $jpeg_quality; // quality of resulting JPEG
- var $max_width; // maximal thumbnail width
- var $max_height; // maximal thumbnail height
- var $fit_to_max; // enlarge small images?
- var $logo; // array of logo parameters
- var $label; // array of label parameters
- // ****************************************************************************
- // CLASS CONSTRUCTOR
- // ****************************************************************************
- /*
- Description:
- Defines default values for properties.
- Prototype:
- void ThumbImg ( string src_file = '' )
- Parameters:
- src_file - source image filename
- */
- function ThumbnailImage ( $src_file = '' )
- {
- $this->src_file = $src_file;
- $this->dest_file = STDOUT;
- $this->dest_type = THUMB_JPEG;
- $this->interlace = INTERLACE_OFF;
- $this->jpeg_quality = -1;
- $this->max_width = 100;
- $this->max_height = 90;
- $this->fit_to_max = FALSE;
- $this->logo['file'] = NO_LOGO;
- $this->logo['vert_pos'] = POS_TOP;
- $this->logo['horz_pos'] = POS_LEFT;
- $this->label['text'] = NO_LABEL;
- $this->label['vert_pos'] = POS_BOTTOM;
- $this->label['horz_pos'] = POS_RIGHT;
- $this->label['font'] = '';
- $this->label['size'] = 20;
- $this->label['color'] = '#000000';
- $this->label['angle'] = 0;
- }
- // ****************************************************************************
- // PRIVATE METHODS
- // ****************************************************************************
- /*
- Description:
- Extracts decimal color components from hex color string.
- Prototype:
- array ParseColor ( string hex_color )
- Parameters:
- hex_color - color in '#rrggbb' format
- Return:
- Decimal values for red, green and blue color components.
- */
- function ParseColor ( $hex_color )
- {
- if ( strpos ( $hex_color, '#' ) === 0 )
- $hex_color = substr ( $hex_color, 1 );
- $r = hexdec ( substr ( $hex_color, 0, 2 ) );
- $g = hexdec ( substr ( $hex_color, 2, 2 ) );
- $b = hexdec ( substr ( $hex_color, 4, 2 ) );
- return array ( $r, $g, $b );
- }
- /*
- Description:
- Retrives image data as a string.
- Thanks to Luis Larrateguy for the idea of this function.
- Prototype:
- string GetImageStr ( string image_file )
- Parameters:
- image_file - filename of image
- Return:
- Image file contents string.
- */
- function GetImageStr ( $image_file )
- {
- if ( function_exists ( 'file_get_contents' ) )
- {
- $str = @file_get_contents ( $image_file );
- if ( ! $str )
- {
- $err = sprintf( E_002, $image_file );
- trigger_error( $err, E_USER_ERROR );
- }
- return $str;
- }
- $f = fopen ( $image_file, 'rb' );
- if ( ! $f )
- {
- $err = sprintf( E_002, $image_file );
- trigger_error( $err, E_USER_ERROR );
- }
- $fsz = @filesize ( $image_file );
- if ( ! $fsz )
- $fsz = MAX_IMG_SIZE;
- $str = fread ( $f, $fsz );
- fclose ( $f );
- return $str;
- }
- /*
- Description:
- Loads image from file.
- Prototype:
- resource LoadImage ( string image_file, int &image_width, int &image_height )
- Parameters:
- image_file - filename of image
- image_width - width of loaded image
- image_height - height of loaded image
- Return:
- Image identifier representing the image obtained from the given file.
- */
- function LoadImage ( $image_file, &$image_width, &$image_height )
- {
- $image_width = 0;
- $image_height = 0;
- $image_data = $this->GetImageStr( $image_file );
- $image = imagecreatefromstring ( $image_data );
- if ( ! $image )
- {
- $err = sprintf( E_003, $image_file );
- trigger_error( $err, E_USER_ERROR );
- }
- $image_width = imagesx ( $image );
- $image_height = imagesy ( $image );
- return $image;
- }
- /*
- Description:
- Calculates thumbnail image sizes from source image width and height.
- Prototype:
- array GetThumbSize ( int src_width, int src_height )
- Parameters:
- src_width - width of source image
- src_height - height of source image
- Return:
- An array with 2 elements. Index 0 contains the width of thumbnail image
- and index 1 contains the height.
- */ 生成缩略图
- function GetThumbSize ( $src_width, $src_height )
- {
- $max_width = $this->max_width;
- $max_height = $this->max_height;
- $x_ratio = $max_width / $src_width;
- $y_ratio = $max_height / $src_height;
- $is_small = ( $src_width
- if ( ! $this->fit_to_max && $is_small )
- {
- $dest_width = $src_width;
- $dest_height = $src_height;
- }
- elseif ( $x_ratio * $src_height
- {
- $dest_width = $max_width;
- $dest_height = ceil ( $x_ratio * $src_height );
- }
- else
- {
- $dest_width = ceil ( $y_ratio * $src_width );
- $dest_height = $max_height;
- }
- return array ( $dest_width, $dest_height );
- }
- /*
- Description:
- Adds logo image to thumbnail.
- Prototype:
- void AddLogo ( int thumb_width, int thumb_height, resource &thumb_img )
- Parameters:
- thumb_width - width of thumbnail image
- thumb_height - height of thumbnail image
- thumb_img - thumbnail image identifier
- */
- function AddLogo ( $thumb_width, $thumb_height, &$thumb_img )
- {
- extract ( $this->logo );
- $logo_image = $this->LoadImage ( $file, $logo_width, $logo_height );
- if ( $vert_pos == POS_CENTER )
- $y_pos = ceil ( $thumb_height / 2 - $logo_height / 2 );
- elseif ($vert_pos == POS_BOTTOM)
- $y_pos = $thumb_height - $logo_height;
- else
- $y_pos = 0;
- if ( $horz_pos == POS_CENTER )
- $x_pos = ceil ( $thumb_width / 2 - $logo_width / 2 );
- elseif ( $horz_pos == POS_RIGHT )
- $x_pos = $thumb_width - $logo_width;
- else
- $x_pos = 0;
- if ( ! imagecopy ( $thumb_img, $logo_image, $x_pos, $y_pos, 0, 0,
- $logo_width, $logo_height ) )
- trigger_error( E_004, E_USER_ERROR );
- }
- /*
- Description:
- Adds label text to thumbnail.
- Prototype:
- void AddLabel ( int thumb_width, int thumb_height, resource &thumb_img )
- Parameters:
- thumb_width - width of thumbnail image
- thumb_height - height of thumbnail image
- thumb_img - thumbnail image identifier
- */
- function AddLabel ( $thumb_width, $thumb_height, &$thumb_img )
- {
- extract ( $this->label );
- list( $r, $g, $b ) = $this->ParseColor ( $color );
- $color_id = imagecolorallocate ( $thumb_img, $r, $g, $b );
- $text_box = imagettfbbox ( $size, $angle, $font, $text );
- $text_width = $text_box [ 2 ] - $text_box [ 0 ];
- $text_height = abs ( $text_box [ 1 ] - $text_box [ 7 ] );
- if ( $vert_pos == POS_TOP )
- $y_pos = 5 + $text_height;
- elseif ( $vert_pos == POS_CENTER )
- $y_pos = ceil( $thumb_height / 2 - $text_height / 2 );
- elseif ( $vert_pos == POS_BOTTOM )
- $y_pos = $thumb_height - $text_height;
- if ( $horz_pos == POS_LEFT )
- $x_pos = 5;
- elseif ( $horz_pos == POS_CENTER )
- $x_pos = ceil( $thumb_width / 2 - $text_width / 2 );
- elseif ( $horz_pos == POS_RIGHT )
- $x_pos = $thumb_width - $text_width -5;
- imagettftext ( $thumb_img, $size, $angle, $x_pos, $y_pos,
- $color_id, $font, $text );
- }
- /*
- Description:
- Output thumbnail image into the browser.
- Prototype:
- void OutputThumbImage ( resource dest_image )
- Parameters:
- dest_img - thumbnail image identifier
- */ 输出缩略图
- function OutputThumbImage ( $dest_image )
- {
- imageinterlace ( $dest_image, $this->interlace );
- header ( 'Content-type: ' . $this->dest_type );
- if ( $this->dest_type == THUMB_JPEG )
- imagejpeg ( $dest_image, '', $this->jpeg_quality );
- elseif ( $this->dest_type == THUMB_GIF )
- imagegif($dest_image);
- elseif ( $this->dest_type == THUMB_PNG )
- imagepng ( $dest_image );
- }
- /*
- Description:
- Save thumbnail image into the disc file.
- Prototype:
- void SaveThumbImage ( string image_file, resource dest_image )
- Parameters:
- image_file - destination file name
- dest_img - thumbnail image identifier
- */
- function SaveThumbImage ( $image_file, $dest_image )
- {
- imageinterlace ( $dest_image, $this->interlace );
- if ( $this->dest_type == THUMB_JPEG )
- imagejpeg ( $dest_image, $this->dest_file, $this->jpeg_quality );
- elseif ( $this->dest_type == THUMB_GIF )
- imagegif ( $dest_image, $this->dest_file );
- elseif ( $this->dest_type == THUMB_PNG )
- imagepng ( $dest_image, $this->dest_file );
- }
- // ****************************************************************************
- // PUBLIC METHODS
- // ****************************************************************************
- /*
- Description:
- Output thumbnail image into the browser or disc file according to the
- values of parameters.
- Prototype:
- void Output ( )
- */ 生成缩略图片
- function Output()
- {
- $src_image = $this->LoadImage($this->src_file, $src_width, $src_height);
- $dest_size = $this->GetThumbSize($src_width, $src_height);
- $dest_width=$dest_size[0];
- $dest_height=$dest_size[1];
- $dest_image=imagecreatetruecolor($dest_width, $dest_height);
- if (!$dest_image)
- trigger_error(E_005, E_USER_ERROR);
- imagecopyresampled( $dest_image, $src_image, 0, 0, 0, 0,
- $dest_width, $dest_height, $src_width, $src_height );
- if ($this->logo['file'] != NO_LOGO)
- $this->AddLogo($dest_width, $dest_height, $dest_image);
- if ($this->label['text'] != NO_LABEL)
- $this->AddLabel($dest_width, $dest_height, $dest_image);
- if ($this->dest_file == STDOUT)
- $this->OutputThumbImage ( $dest_image );
- else
- $this->SaveThumbImage ( $this->dest_file, $dest_image );
- imagedestroy ( $src_image );
- imagedestroy ( $dest_image );
- }
- } // End of class definition
- ?>
使用方法：
1、首先引用该php文件（不要告诉我不会)
2、调用代码
-
- $tis = new ThumbnailImage();
- $tis->src_file = "这里写源文件的路径"
- $tis->dest_type = THUMB_JPEG;//生成图片的类型是 jpg
- $tis->dest_file = '这里写目标文件的路径';
- $tis->max_width = 120;//自适应大小，但是最大宽度为120
- $tis->max_height = 4000; //自适应大小，但是最大高度为4000
- $tis->Output();
-
代码关键在于：
max_width 和max_height，
一般来说除非图片很有个性，否则缩略图生成的还是很不错的。
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