PHP压缩图片

1. function scale_dimensions_within_limits($w,$h,$max_w,$max_h){
2. // $w is the width of the current rectangle
3. // $h is the height of the current rectangle
4. // $max_w is the maximum width that an image can be sized
5. // $max_h is the maximum height that an image can be sized
7. // **** Here's where the magic is starts ****
8. // Switch the concept of horiz/vertical/square to long/short side
9. $short_side_len = ($w $long_side_len = ($w > $h ? $w : $h);
10. // Set a variable to the variable name of the output variable
11. $ssvar = ($w > $h ? 'h':'w');
12. $lsvar = ($w > $h ? 'w':'h');
13. $maxLSvar = "max_".$lsvar;
14. $maxSSvar = "max_".$ssvar;
16. // Do the first pass on the long side
17. $ratio = $$maxLSvar/$long_side_len;
18. $newSS = round($short_side_len * $ratio);
19. $newLS = round($long_side_len * $ratio);
21. // *** Note - the only coditional block!
22. // If short side is still out of limit, limit the short side and adjust
23. if($newSS > $$maxSSvar){
24. $ratio = $$maxSSvar/$newSS;
25. $newLS = round($ratio*$newLS);
26. $newSS = $$maxSSvar;
27. }
29. // **** Here's where the magic ends ****
30. // Re-couple the h/w (or w/h) with the long/shortside counterparts
31. // $$ means it's a variable variable (dynamic assignment)
32. $$ssvar = $newSS;
33. $$lsvar = $newLS;
35. // Prep the return array
36. $dimensions['w'] = $w; // this is derived from either $ssvar or $lsvar
37. $dimensions['h'] = $h; return $dimensions;
38. }

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