The EffectParameter class describes one parameter of an effect. 更多...
The EffectParameter class describes one parameter of an 效果。
You fetch the parameters of an Effect with Effect.parameters() .
QList<Phonon.EffectParameter> parameters = effect->parameters();
foreach(Phonon.EffectParameter parameter, parameters) {
// Do something with parameter
}
To describe itself, an effect parameter gives a name () and possibly description () (depending on the backend used). These are suited to present the effect parameter to the user of a Phonon application.
Note that effects are created by the backend, and that their name and descriptions may vary.
The value of an effect parameter is stored in a QVariant , of which type () is usually int or double .
The value is retrieved with Effect.parameterValue() and set with setParameterValue() - both of which takes the EffectParameter as argument. Note that not all effect parameters support setting of their value.
You get the values a parameter can take with possibleValues (); an empty list is returned if the values are continuous.
A parameter may also specify default (), minimum(), and maximum() values. Values are returned as QVariant s. If the parameter does not have the requested value, an QVariant.Invalid invalid QVariant is returned from these functions.
EffectWidget 提供 a widget with which one can control the parameters of an Effect .
Phonon.EffectWidget *effectWidget = new Phonon.EffectWidget(effect);
Only for backend developers:
Flags to set the return values of isToggleControl(), isLogarithmicControl (), isIntegerControl(), isBoundedBelow() and isBoundedAbove(). The values of the flags correspond to the values used for LADSPA effects.
| 常量 | 值 | 描述 |
|---|---|---|
| Phonon.EffectParameter.ToggledHint | 0x04 | If this hint is set it means that the control has only two states: zero and non-zero (see isToggleControl()). |
| Phonon.EffectParameter.LogarithmicHint | 0x10 | LADSPA's SAMPLE_RATE hint needs to be translated by the backend to normal bounds, as the backend knows the sample rate - and the frontend doesn't (see isLogarithmicControl ()). |
| Phonon.EffectParameter.IntegerHint | 0x20 | See isIntegerControl(). |
The Hints type is a typedef for QFlags <Hint>. It stores an OR combination of Hint values.
构造副本为 other effect parameter.
The default value.
The parameter may come with a description (LADSPA doesn't have a field for this, so don't expect many effects to provide a description).
The description can be used for a tooltip or WhatsThis help.
Returns A text describing the parameter.
Returns whether the parameter should be displayed using a logarithmic scale. This is particularly useful for frequencies and gains.
The maximum value to be used for the control to edit the 参数。
If the returned QVariant 是无效的 the value is not bounded from above.
The minimum value to be used for the control to edit the 参数。
If the returned QVariant 是无效的 the value is not bounded from below.
The name of the parameter. Can be used as the label.
Returns A label for the parameter.
The possible values to be used for the control to edit the 参数。
if the value of this parameter is to be picked from predefined values this returns the list (otherwise it returns an empty QVariantList ).
Returns the parameter type.
Common types are QVariant.Int , QVariant.Double , QVariant.Bool and QVariant.String 。当 QVariant.String is returned you get the possible values from possibleValues.