qt:wiring_up_signals_and_slots
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qt:wiring_up_signals_and_slots [2011/03/31 12:48] – [Wiring up signals and slots] mithat | qt:wiring_up_signals_and_slots [2011/03/31 15:02] – mithat | ||
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====== Wiring up signals and slots ====== | ====== Wiring up signals and slots ====== | ||
+ | |||
+ | ===== Creating signal→slot connections ===== | ||
Qt uses a signals and slots system to process events. If you use Qt Creator for development, | Qt uses a signals and slots system to process events. If you use Qt Creator for development, | ||
- | * Create an "event handler" | + | * [[#Create an "event handler" |
- | * Do it " | + | * [[#Do it " |
- | * Do it in the *.ui file | + | * [[#Do it in the *.ui file]] |
- | * Do it in the constructor | + | * [[#Do it in the constructor |
- | If you use Qt Designer with some other IDE for development, | + | If you use Qt Designer with some other IDE for development, |
- | ===== Create an "event handler" | + | ==== Create an "event handler" |
// | // | ||
Line 25: | Line 27: | ||
void on_button_quit_clicked();</ | void on_button_quit_clicked();</ | ||
- | ==== Behind the scenes ==== | + | === Behind the scenes === |
How does the build system know that that '' | How does the build system know that that '' | ||
+ | == Question == | ||
+ | If the above is true, then it should be possible to create event handlers just by writing code. Two tests are indicated: | ||
+ | * Write the handlers manually in Qt Creator. | ||
+ | * Write the handlers manually in a project managed by something other than Qt Creator. | ||
- | ===== Do it visually | + | ==== Do it "visually" |
// | // | ||
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- From the dialog that appears, select the desired signal from the left column and the desired slot from the right and click OK. | - From the dialog that appears, select the desired signal from the left column and the desired slot from the right and click OK. | ||
- | If you don't see a slot that you expect, try clicking on the "Show slots inherited from ..." checkbox. IMHO, this should be checked by default, but isn' | + | If you don't see a slot that you expect, try clicking on the "Show slots inherited from ..." checkbox. IMHO, this should be checked by default, but it isn' |
When you set signal/slot connections this way, you will see arrows connecting widgets indicating signal/slot relationships. | When you set signal/slot connections this way, you will see arrows connecting widgets indicating signal/slot relationships. | ||
- | ==== Special cases ==== | + | === Special cases === |
There are a couple special cases that are worth mentioning. | There are a couple special cases that are worth mentioning. | ||
- | === Connecting to the window | + | == Connecting to the window == |
If you want to connect a signal to the slot of a window, just drag onto the window rather than onto another widget. You will know you are connecting to the main window because the slot end of the connector will turn into an electrical earth ground symbol {{: | If you want to connect a signal to the slot of a window, just drag onto the window rather than onto another widget. You will know you are connecting to the main window because the slot end of the connector will turn into an electrical earth ground symbol {{: | ||
- | === Connecting a widget to itself | + | == Connecting a widget to itself == |
You can also connect widgets to themselves. If you do this, you can set up all sorts of hilarity. Sometimes you can even do useful things. | You can also connect widgets to themselves. If you do this, you can set up all sorts of hilarity. Sometimes you can even do useful things. | ||
- | ==== Editing signals and slots ==== | ||
+ | === Editing signals and slots === | ||
You can edit existing signal/slot connections made in Edit Signal/ | You can edit existing signal/slot connections made in Edit Signal/ | ||
You can add new relationships and delete existing ones using the **+** and **–** icons. The **–** icon seems a bit temperamental, | You can add new relationships and delete existing ones using the **+** and **–** icons. The **–** icon seems a bit temperamental, | ||
- | ==== Behind the scenes | + | === Behind the scenes === |
Connections made this way are stored in a form's ''//< | Connections made this way are stored in a form's ''//< | ||
< | < | ||
Line 85: | Line 90: | ||
Note: If you are using Qt Creator to develop your project, the Qt gods discourage you from manually editing '' | Note: If you are using Qt Creator to develop your project, the Qt gods discourage you from manually editing '' | ||
- | ===== Do it in the *.ui file ===== | + | ==== Do it in the *.ui file ==== |
// | // | ||
- | If your project uses '' | + | If your project uses '' |
- | + | <code xml> | |
- | ===== Do it in the constructor | + | < |
+ | < | ||
+ | < | ||
+ | < | ||
+ | < | ||
+ | < | ||
+ | </ | ||
+ | </ | ||
+ | </ | ||
+ | ==== Do it in the constructor ==== | ||
// | // | ||
Line 100: | Line 114: | ||
widget.setupUi(this); | widget.setupUi(this); | ||
- | connect(widget.button_quit, | + | connect(widget.button_quit, |
- | | + | |
}</ | }</ | ||
+ | |||
+ | ===== Runtime signal→slot connection modifications ===== | ||
+ | I don't know. But it should be possible. |
qt/wiring_up_signals_and_slots.txt · Last modified: 2011/04/03 13:14 by mithat