Hi all,

I am trying to populate a QTableWidget with 50 lines and 50 columns with the following code:
Qt Code: 
  1. {
  2.         SKGTRACEIN(10, "test-Filltable");
  3.         ui.kTable->clear();
  4.         ui.kTable->setRowCount(50);
  5.         ui.kTable->setColumnCount(50);
  6.         for (int i=0; i<49; ++i) {
  7.                 for (int j=0; j<49; ++j) {
  8.                         SKGTRACEIN(10, "test-setItem");
  10.                         ui.kTable->setItem(i, j, item);
  11.                 }
  12.         }
  13. }
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The macro SKGTRACEIN allows to measure the time consumed by the code in of the scope.

The first call of the code returns following traces:
Qt Code: 
  1. ##    >test-Filltable
  2. ##      >test-setItem
  3. ##      <test-setItem TIME=0.100014 ms
  4. ##      >test-setItem
  5. ##      <test-setItem TIME=0.0169843 ms
  6. ##      >test-setItem
  7. ##      <test-setItem TIME=0.0140117 ms
  8. ##      >test-setItem
  9. ##      <test-setItem TIME=0.0148984 ms
  10. ##      >test-setItem
  11. ##      <test-setItem TIME=0.0140293 ms
  12. ...
  13. ...
  14. ##      >test-setItem
  15. ##      <test-setItem TIME=0.0139316 ms
  16. ##      >test-setItem
  17. ##      <test-setItem TIME=0.0148886 ms
  18. ##      >test-setItem
  19. ##      <test-setItem TIME=0.0138925 ms
  20. ##      >test-setItem
  21. ##      <test-setItem TIME=0.0150938 ms
  22. ##      >test-setItem
  23. ##      <test-setItem TIME=0.0150508 ms
  24. ##    <test-Filltable TIME=431.761 ms
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As you can see, performances are very good. Table is done in around 431ms.

The second call of this same code returns following traces:
Qt Code: 
  1. ##    >test-Filltable
  2. ##      >test-setItem
  3. ##      <test-setItem TIME=27.6061 ms
  4. ##      >test-setItem
  5. ##      <test-setItem TIME=13.549 ms
  6. ##      >test-setItem
  7. ##      <test-setItem TIME=14.058 ms
  8. ##      >test-setItem
  9. ##      <test-setItem TIME=14.132 ms
  10. ##      >test-setItem
  11. ##      <test-setItem TIME=13.943 ms
  12. ...
  13. ...
  14. ##      <test-setItem TIME=77.392 ms
  15. ##      >test-setItem
  16. ##      <test-setItem TIME=133.818 ms
  17. ##      >test-setItem
  18. ##      <test-setItem TIME=89.083 ms
  19. ##      >test-setItem
  20. ##      <test-setItem TIME=60.1529 ms
  21. ##      >test-setItem
  22. ##      <test-setItem TIME=61.99 ms
  23. ##    <test-Filltable TIME=109696 ms
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Now, performances are very bad (+25000%) and it seems to be due to setItem.

Why ? What is the solution to have good performances each time ?

Thank you in advance for your help.