|
Home · All Classes · Main Classes · Grouped Classes · Modules · Functions | |
The Q3RangeControl class provides an integer value within a range. More...
#include <Q3RangeControl>
This class is part of the Qt 3 support library. It is provided to keep old source code working. We strongly advise against using it in new code. See Porting to Qt 4 for more information.
The Q3RangeControl class provides an integer value within a range.
Although originally designed for the QScrollBar widget, the Q3RangeControl can also be used in conjunction with other widgets such as QSlider and QSpinBox. Here are the five main concepts in the class:
Unity (1) may be viewed as a third step size. setValue() lets you set the current value to any integer in the allowed range, not just minValue() + n * lineStep() for integer values of n. Some widgets may allow the user to set any value at all; others may just provide multiples of lineStep() or pageStep().
Q3RangeControl provides three virtual functions that are well suited for updating the on-screen representation of range controls and emitting signals: valueChange(), rangeChange() and stepChange().
Q3RangeControl also provides a function called bound() which lets you force arbitrary integers to be within the allowed range of the range control.
We recommend that all widgets that inherit Q3RangeControl provide at least a signal called valueChanged(); many widgets will want to provide addStep(), addPage(), substractStep() and substractPage() as slots.
Note that you must use multiple inheritance if you plan to implement a widget using Q3RangeControl because Q3RangeControl is not derived from QWidget.
Constructs a range control with a minimum value of 0, maximum value of 99, line step of 1, page step of 10 and initial value 0.
Constructs a range control whose value can never be smaller than minValue or greater than maxValue, whose line step size is lineStep and page step size is pageStep and whose value is initially value (which is guaranteed to be in range using bound()).
Destroys the range control
Equivalent to setValue(value() + lineStep()).
If the value is changed, then valueChange() is called.
See also subtractLine(), addPage(), and setValue().
Equivalent to setValue(value() + pageStep()).
If the value is changed, then valueChange() is called.
See also subtractPage(), addLine(), and setValue().
Forces the value v to be within the range from minValue() to maxValue() inclusive, and returns the result.
This function is provided so that you can easily force other numbers than value() into the allowed range. You do not need to call it in order to use Q3RangeControl itself.
See also setValue(), value(), minValue(), and maxValue().
Sets the range control value directly without calling valueChange().
Forces the new value to be within the legal range.
You will rarely have to call this function. However, if you want to change the range control's value inside the overloaded method valueChange(), setValue() would call the function valueChange() again. To avoid this recursion you must use directSetValue() instead.
See also setValue().
Returns the line step.
See also setSteps() and pageStep().
Returns the maximum value of the range.
See also setMaxValue(), setRange(), and minValue().
Returns the minimum value of the range.
See also setMinValue(), setRange(), and maxValue().
Returns the page step.
See also setSteps() and lineStep().
Converts logical_val to a pixel position. minValue() maps to 0, maxValue() maps to span and other values are distributed evenly in-between.
This function can handle the entire integer range without overflow, providing span is <= 4096.
Calling this method is useful when actually drawing a range control such as a QScrollBar on-screen.
See also valueFromPosition().
Returns the previous value of the range control. "Previous value" means the value before the last change occurred. Setting a new range may affect the value, too, because the value is forced to be inside the specified range. When the range control is initially created, this is the same as value().
prevValue() can be outside the current legal range if a call to setRange() causes the current value to change. For example, if the range was [0, 1000] and the current value is 500, setRange(0, 400) makes value() return 400 and prevValue() return 500.
See also value() and setRange().
This virtual function is called whenever the range control's range changes. You can reimplement it if you want to be notified when the range changes. The default implementation does nothing.
Note that this method is called after the range has changed.
See also setRange(), valueChange(), and stepChange().
Sets the minimum value of the range to maxVal.
If necessary, the minValue() is adjusted so that the range remains valid.
See also maxValue() and setMinValue().
Sets the minimum value of the range to minVal.
If necessary, the maxValue() is adjusted so that the range remains valid.
See also minValue() and setMaxValue().
Sets the range control's minimum value to minValue and its maximum value to maxValue.
Calls the virtual rangeChange() function if one or both of the new minimum and maximum values are different from the previous setting. Calls the virtual valueChange() function if the current value is adjusted because it was outside the new range.
If maxValue is smaller than minValue, minValue becomes the only legal value.
See also minValue() and maxValue().
Sets the range's line step to lineStep and page step to pageStep.
Calls the virtual stepChange() function if the new line step or page step are different from the previous settings.
See also lineStep(), pageStep(), and setRange().
Sets the range control's value to value and forces it to be within the legal range.
Calls the virtual valueChange() function if the new value is different from the previous value. The old value can still be retrieved using prevValue().
See also value().
This virtual function is called whenever the range control's line or page step settings change. You can reimplement it if you want to be notified when the step changes. The default implementation does nothing.
Note that this method is called after a step setting has changed.
See also setSteps(), rangeChange(), and valueChange().
Equivalent to setValue(value() - lineStep()).
If the value is changed, then valueChange() is called.
See also addLine(), subtractPage(), and setValue().
Equivalent to setValue(value() - pageStep()).
If the value is changed, then valueChange() is called.
See also addPage(), subtractLine(), and setValue().
Returns the current range control value. This is guaranteed to be within the range [minValue(), maxValue()].
See also setValue() and prevValue().
This virtual function is called whenever the range control value changes. You can reimplement it if you want to be notified when the value changes. The default implementation does nothing.
Note that this method is called after the value has changed. The previous value can be retrieved using prevValue().
See also setValue(), addPage(), subtractPage(), addLine(), subtractLine(), rangeChange(), and stepChange().
Converts the pixel position pos to a value. 0 maps to minValue(), span maps to maxValue() and other values are distributed evenly in-between.
This function can handle the entire integer range without overflow.
Calling this method is useful if you actually implemented a range control widget such as QScrollBar and want to handle mouse press events. This function then maps screen coordinates to the logical values.
See also positionFromValue().
| Copyright © 2005 Trolltech | Trademarks | Qt 4.1.0 |
