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PHP创建缩略图造成图片质量低下的完美解决办法

时间：2021-07-01 10:21:17 帮助过：6人阅读

PHP创建缩略图造成图片质量低下的完美解决方法

    1. /**?
    2. [email protected]?
    3. [email protected]$img_name???图片路径?
    4. [email protected]$max_width??略图最大宽度?
    5. [email protected]$max_height?略图最大高度?
    6. [email protected]$suffix?略图后缀(如"img_x.jpg"代表小图,"img_m.jpg"代表中图,"img_l.jpg"代表大图)?
    7. [email protected]?
    8. */??
    9. function?thum($img_name,$max_width,$max_height,$suffix){??
    10. ????????$img_infos=getimagesize($img_name);??
    11. ????????$img_height=$img_infos[0];//图片高??
    12. ????????$img_width=$img_infos[1];//图片宽??
    13. ????????$img_extension='';//图片后缀名??
    14. ????????switch($img_infos[2]){??
    15. ????????????case?1:??
    16. ????????????????$img_extension='gif';??
    17. ????????????????break;??
    18. ????????????case?2:??
    19. ????????????????$img_extension='jpeg';??
    20. ????????????????break;??
    21. ?????????case?3:??
    22. ????????????????$img_extension='png';??
    23. ????????????????break;??
    24. ????????????default:??
    25. ????????????????$img_extension='jpeg';??
    26. ????????????????break;??
    27. ????????????}??
    28. ????????$new_img_size=get_thum_size($img_width,$img_height,$max_width,$max_height);//新的图片尺寸??
    29. ??????????
    30. ??????????
    31. ????????//print_r($new_img_size);??
    32. ????????//die('test');??
    33. ????????$img_func='';//函数名称??
    34. ????????$img_handle='';//图片句柄??
    35. ????????$thum_handle='';//略图图片句柄??
    36. ????????switch($img_extension){??
    37. ????????????case?'jpg':??
    38. ????????????????$img_handle=imagecreatefromjpeg($img_name);??
    39. ????????????????$img_func='imagejpeg';??
    40. ????????????????break;??
    41. ????????????case?'jpeg':??
    42. ????????????????$img_handle=imagecreatefromjpeg($img_name);??
    43. ????????????????$img_func='imagejpeg';??
    44. ???????????????break;??
    45. ????????????case?'png':??
    46. ????????????????$img_handle=imagecreatefrompng($img_name);??
    47. ????????????????$img_func='imagepng';??
    48. ????????????????break;??
    49. ????????????case?'gif':??
    50. ????????????????$img_handle=imagecreatefromgif($img_name);??
    51. ????????????????$img_func='imagegif';??
    52. ????????????????break;??
    53. ????????????default:??
    54. ????????????????$img_handle=imagecreatefromjpeg($img_name);??
    55. ????????????????$img_func='imagejpeg';?
    56. ????????????????break;??
    57. ????????????}??
    58. ????????/****/????
    59. ????????$quality=100;//图片质量??
    60. ????????if($img_func==='imagepng'?&&?(str_replace('.',?'',?PHP_VERSION)>=?512)){//针对php版本大于5.12参数变化后的处理情况??
    61. ????????????$quality=9;??
    62. ????????????}???
    63. ????????/****/??
    64. ????????$thum_handle=imagecreatetruecolor($new_img_size['height'],$new_img_size['width']);??
    65. ????????if(function_exists('imagecopyresampled')){??
    66. ????????????imagecopyresampled($thum_handle,$img_handle,?0,?0,?0,?0,$new_img_size['height'],$new_img_size['width'],$img_height,$img_width);??
    67. ????????????}else{??
    68. ????????????????imagecopyresized($thum_handle,$img_handle,?0,?0,?0,?0,$new_img_size['height'],$new_img_size['width'],$img_height,$img_width);??
    69. ????????????}??
    70. ????????call_user_func_array($img_func,array($thum_handle,get_thum_name($img_name,$suffix),$quality));??
    71. ????????imagedestroy($thum_handle);//清除句柄??
    72. ????????imagedestroy($img_handle);//清除句柄??
    73. ????}??
    74. ??
    75. /**?
    76. [email protected]_thum_size?获得缩略图的尺寸?
    77. [email protected]$width??图片宽?
    78. [email protected]$height?图片高?
    79. [email protected]$max_width?最大宽度?
    80. [email protected]$maxHeight?最大高度?
    81. [email protected]$size;?
    82. */??
    83. function?get_thum_size($width,$height,$max_width,$max_height){??
    84. ????$now_width=$width;//现在的宽度??
    85. ????$now_height=$height;//现在的高度??
    86. ????$size=

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