remove doubling "None" in effect selection

[goddisignz]

Remove the doubling "None" in the preferences -> equalizer -> effect list when "None" is already selected.
Fixes https://bugs.launchpad.net/mixxx/+bug/1824624.

[uklotzde]

Please prefer to use operator == if you don't need the ordering capabilities of compare()

[uklotzde]

Please follow our coding guidelines by placing the else on the same line

[goddisignz]

Just didn't see them beforehand. I will keep it in mind and re-commit.

[rrrapha]

I don't really like the string compare, wouldn't the following diff work as well?
(untested)

--- a/src/preferences/dialog/dlgprefeq.cpp
+++ b/src/preferences/dialog/dlgprefeq.cpp
@@ -231,7 +231,7 @@ void DlgPrefEQ::slotPopulateDeckEffectSelectors() {
         }
         //: Displayed when no effect is selected
         box->addItem(tr("None"), QVariant(QString("")));
-        if (selectedEffectId.isNull()) {
+        if (selectedEffectId.isEmpty()) {
             currentIndex = availableEQEffects.size(); // selects "None"
         }
         if (currentIndex < 0 && !selectedEffectName.isEmpty()) {
@@ -261,7 +261,7 @@ void DlgPrefEQ::slotPopulateDeckEffectSelectors() {
         }
         //: Displayed when no effect is selected
         box->addItem(tr("None"), QVariant(QString("")));
-        if (selectedEffectId.isNull()) {
+        if (selectedEffectId.isEmpty()) {
             currentIndex = availableQuickEffects.size(); // selects "None"
         }
         if (currentIndex < 0 && !selectedEffectName.isEmpty()) {

[goddisignz]

I will give it a shot, but the code would probably not work as expected. As far as I can tell the selectedEffectId will not be empty unless no entry of the was ever selected. Probably only after fresh install or something.

[rrrapha]

I think selectedEffectId is empty if 'None' is selected, no?

[goddisignz]

@rrrapha thanks for the hint, the isEmpty() does the job. I didn't recognize that the effectid is set to an empty string.

[rrrapha]

Cool, it looks good and works for me :)

[uklotzde]

LGTM. Thank you.