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php GD库生成高质量缩略图(示例)

程序员文章站 2024-02-07 11:49:52
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  1. $FILENAME="image.thumb";

  2. // 生成图片的宽度
  3. $RESIZEWIDTH=400;
  4. // 生成图片的高度
  5. $RESIZEHEIGHT=400;
  6. function ResizeImage($im,$maxwidth,$maxheight,$name){

  7. $width = imagesx($im);
  8. $height = imagesy($im);
  9. if(($maxwidth && $width > $maxwidth) || ($maxheight && $height > $maxheight)){
  10. if($maxwidth && $width > $maxwidth){
  11. $widthratio = $maxwidth/$width;
  12. $RESIZEWIDTH=true;
  13. }
  14. if($maxheight && $height > $maxheight){
  15. $heightratio = $maxheight/$height;
  16. $RESIZEHEIGHT=true;
  17. }
  18. if($RESIZEWIDTH && $RESIZEHEIGHT){
  19. if($widthratio $ratio = $widthratio;
  20. }else{
  21. $ratio = $heightratio;
  22. }
  23. }elseif($RESIZEWIDTH){
  24. $ratio = $widthratio;
  25. }elseif($RESIZEHEIGHT){
  26. $ratio = $heightratio;
  27. }
  28. $newwidth = $width * $ratio;
  29. $newheight = $height * $ratio;
  30. if(function_exists("imagecopyresampled")){
  31. $newim = imagecreatetruecolor($newwidth, $newheight);
  32. imagecopyresampled($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
  33. }else{
  34. $newim = imagecreate($newwidth, $newheight);
  35. imagecopyresized($newim, $im, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
  36. }
  37. ImageJpeg ($newim,$name . ".jpg");
  38. ImageDestroy ($newim);
  39. }else{
  40. ImageJpeg ($im,$name . ".jpg");
  41. }
  42. }
  43. if($_FILES['image']['size']){

  44. if($_FILES['image']['type'] == "image/pjpeg"){
  45. $im = imagecreatefromjpeg($_FILES['image']['tmp_name']);
  46. }elseif($_FILES['image']['type'] == "image/x-png"){
  47. $im = imagecreatefrompng($_FILES['image']['tmp_name']);
  48. }elseif($_FILES['image']['type'] == "image/gif"){
  49. $im = imagecreatefromgif($_FILES['image']['tmp_name']);
  50. }
  51. if($im){
  52. if(file_exists("$FILENAME.jpg")){
  53. unlink("$FILENAME.jpg");
  54. }
  55. ResizeImage($im,$RESIZEWIDTH,$RESIZEHEIGHT,$FILENAME);
  56. ImageDestroy ($im);
  57. }
  58. }
  59. ?>
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2,测试代码(demo.php)

  1. /**
  2. * PHP生成高质量缩略图
  3. * by bbs.it-home.org
  4. */
  5. include('ResizeImage.php');
  6. if(!empty($_POST)){
  7. echo($FILENAME.".jpg?cache=".rand(0,999999));
  8. }
  9. ?>
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