qdial.3qt

Linux下的基于X11的图形开发环境。

'\" t
.TH QDial 3qt "9 December 2002" "Trolltech AS" \" -*- nroff -*-
.\" Copyright 1992-2001 Trolltech AS.  All rights reserved.  See the
.\" license file included in the distribution for a complete license
.\" statement.
.\"
.ad l
.nh
.SH NAME
QDial \- Rounded range control (like a speedometer or potentiometer)
.SH SYNOPSIS
\fC#include <qdial.h>\fR
.PP
Inherits QWidget and QRangeControl.
.PP
.SS "Public Members"
.in +1c
.ti -1c
.BI "\fBQDial\fR ( QWidget * parent = 0, const char * name = 0, WFlags f = 0 )"
.br
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.BI "\fBQDial\fR ( int minValue, int maxValue, int pageStep, int value, QWidget * parent = 0, const char * name = 0 )"
.br
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.BI "\fB~QDial\fR ()"
.br
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.BI "bool \fBtracking\fR () const"
.br
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.BI "bool \fBwrapping\fR () const"
.br
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.BI "int \fBnotchSize\fR () const"
.br
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.BI "virtual void \fBsetNotchTarget\fR ( double )"
.br
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.BI "double \fBnotchTarget\fR () const"
.br
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.BI "bool \fBnotchesVisible\fR () const"
.br
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.BI "int \fBminValue\fR () const"
.br
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.BI "int \fBmaxValue\fR () const"
.br
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.BI "void \fBsetMinValue\fR ( int )"
.br
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.BI "void \fBsetMaxValue\fR ( int )"
.br
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.BI "int \fBlineStep\fR () const"
.br
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.BI "int \fBpageStep\fR () const"
.br
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.BI "void \fBsetLineStep\fR ( int )"
.br
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.BI "void \fBsetPageStep\fR ( int )"
.br
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.BI "int \fBvalue\fR () const"
.br
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.SS "Public Slots"
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.BI "virtual void \fBsetValue\fR ( int )"
.br
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.BI "void \fBaddLine\fR ()"
.br
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.BI "void \fBsubtractLine\fR ()"
.br
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.BI "void \fBaddPage\fR ()"
.br
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.BI "void \fBsubtractPage\fR ()"
.br
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.BI "virtual void \fBsetNotchesVisible\fR ( bool b )"
.br
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.BI "virtual void \fBsetWrapping\fR ( bool on )"
.br
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.BI "virtual void \fBsetTracking\fR ( bool enable )"
.br
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.SS "Signals"
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.BI "void \fBvalueChanged\fR ( int value )"
.br
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.BI "void \fBdialPressed\fR ()"
.br
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.BI "void \fBdialMoved\fR ( int value )"
.br
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.BI "void \fBdialReleased\fR ()"
.br
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.SS "Properties"
.in +1c
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.BI "int \fBlineStep\fR - the current line step"
.br
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.BI "int \fBmaxValue\fR - the current maximum value"
.br
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.BI "int \fBminValue\fR - the current minimum value"
.br
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.BI "int \fBnotchSize\fR - the current notch size  \fI(read " "only" ")\fR"
.br
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.BI "double \fBnotchTarget\fR - the target number of pixels between notches"
.br
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.BI "bool \fBnotchesVisible\fR - whether the notches are shown"
.br
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.BI "int \fBpageStep\fR - the current page step"
.br
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.BI "bool \fBtracking\fR - whether tracking is enabled"
.br
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.BI "int \fBvalue\fR - the current dial value"
.br
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.BI "bool \fBwrapping\fR - whether wrapping is enabled"
.br
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.SS "Protected Members"
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.BI "virtual void \fBvalueChange\fR ()"
.br
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.BI "virtual void \fBrangeChange\fR ()"
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.BI "virtual void \fBrepaintScreen\fR ( const QRect * cr = 0 )"
.br
.in -1c
.SH DESCRIPTION
The QDial class provides a rounded range control (like a speedometer or potentiometer).
.PP
QDial is used when the user needs to control a value within a program-definable range, and the range either wraps around (typically, 0..359 degrees) or the dialog layout needs a square widget.
.PP
Both API- and UI-wise, the dial is very similar to a slider. Indeed, when wrapping() is FALSE (the default) there is no real difference between a slider and a dial. They have the same signals, slots and member functions, all of which do the same things. Which one you use depends only on your taste and on the application.
.PP
The dial initially emits valueChanged() signals continuously while the slider is being moved; you can make it emit the signal less often by calling setTracking(FALSE). dialMoved() is emitted continuously even when tracking() is FALSE.
.PP
The slider also emits dialPressed() and dialReleased() signals when the mouse button is pressed and released. But note that the dial's value can change without these signals being emitted; the keyboard and wheel can be used to change the value.
.PP
Unlike the slider, QDial attempts to draw a "nice" number of notches rather than one per lineStep(). If possible, the number of notches drawn is one per lineStep(), but if there aren't enough pixels to draw every one, QDial will draw every second, third etc., notch. notchSize() returns the number of units per notch, hopefully a multiple of lineStep(); setNotchTarget() sets the target distance between neighbouring notches in pixels. The default is 3.75 pixels.
.PP
Like the slider, the dial makes the QRangeControl functions setValue(), addLine(), subtractLine(), addPage() and subtractPage() available as slots.
.PP
The dial's keyboard interface is fairly simple: The left/up and right/down arrow keys move by lineStep(), page up and page down by pageStep() and Home and End to minValue() and maxValue().
.PP
.ce 1
.B "[Image Omitted]"
.PP

.ce 1
.B "[Image Omitted]"
.PP
See also QScrollBar, QSpinBox, GUI Design Handbook: Slider, and Basic Widgets.
.SH MEMBER FUNCTION DOCUMENTATION
.SH "QDial::QDial ( QWidget * parent = 0, const char * name = 0, WFlags f = 0 )"
Constructs a dial called \fIname\fR with parent \fIparent\fR. \fIf\fR is propagated to the QWidget constructor. It has the default range of a QRangeControl.
.SH "QDial::QDial ( int minValue, int maxValue, int pageStep, int value, QWidget * parent = 0, const char * name = 0 )"
Constructs a dial called \fIname\fR with parent \fIparent\fR. The dial's value can never be smaller than \fIminValue\fR or greater than \fImaxValue\fR. Its page step size is \fIpageStep\fR, and its initial value is \fIvalue\fR.
.PP
\fIvalue\fR is forced to be within the legal range.
.SH "QDial::~QDial ()"
Destroys the dial.
.SH "void QDial::addLine ()\fC [slot]\fR"
Increments the dial's value() by one lineStep().
.SH "void QDial::addPage ()\fC [slot]\fR"
Increments the dial's value() by one pageStep() of steps.
.SH "void QDial::dialMoved ( int value )\fC [signal]\fR"
This signal is emitted whenever the dial \fIvalue\fR changes. The frequency of this signal is \fInot\fR influenced by setTracking().
.PP
See also valueChanged().
.SH "void QDial::dialPressed ()\fC [signal]\fR"
This signal is emitted when the user begins mouse interaction with the dial.
.PP
See also dialReleased().
.SH "void QDial::dialReleased ()\fC [signal]\fR"
This signal is emitted when the user ends mouse interaction with the dial.
.PP
See also dialPressed().
.SH "int QDial::lineStep () const"
Returns the current line step. See the "lineStep" property for details.
.SH "int QDial::maxValue () const"
Returns the current maximum value. See the "maxValue" property for details.
.SH "int QDial::minValue () const"
Returns the current minimum value. See the "minValue" property for details.
.SH "int QDial::notchSize () const"
Returns the current notch size. See the "notchSize" property for details.
.SH "double QDial::notchTarget () const"
Returns the target number of pixels between notches. See the "notchTarget" property for details.
.SH "bool QDial::notchesVisible () const"
Returns TRUE if the notches are shown; otherwise returns FALSE. See the "notchesVisible" property for details.
.SH "int QDial::pageStep () const"
Returns the current page step. See the "pageStep" property for details.
.SH "void QDial::rangeChange ()\fC [virtual protected]\fR"
Reimplemented to ensure tick-marks are consistent with the new range.
.PP
Reimplemented from QRangeControl.
.SH "void QDial::repaintScreen ( const QRect * cr = 0 )\fC [virtual protected]\fR"
Paints the dial using clip region \fIcr\fR.
.SH "void QDial::setLineStep ( int )"
Sets the current line step. See the "lineStep" property for details.
.SH "void QDial::setMaxValue ( int )"
Sets the current maximum value. See the "maxValue" property for details.
.SH "void QDial::setMinValue ( int )"
Sets the current minimum value. See the "minValue" property for details.
.SH "void QDial::setNotchTarget ( double )\fC [virtual]\fR"
Sets the target number of pixels between notches. See the "notchTarget" property for details.
.SH "void QDial::setNotchesVisible ( bool b )\fC [virtual slot]\fR"
Sets whether the notches are shown to \fIb\fR. See the "notchesVisible" property for details.
.SH "void QDial::setPageStep ( int )"
Sets the current page step. See the "pageStep" property for details.
.SH "void QDial::setTracking ( bool enable )\fC [virtual slot]\fR"
Sets whether tracking is enabled to \fIenable\fR. See the "tracking" property for details.
.SH "void QDial::setValue ( int )\fC [virtual slot]\fR"
Sets the current dial value. See the "value" property for details.
.SH "void QDial::setWrapping ( bool on )\fC [virtual slot]\fR"
Sets whether wrapping is enabled to \fIon\fR. See the "wrapping" property for details.
.SH "void QDial::subtractLine ()\fC [slot]\fR"
Decrements the dial's value() by one lineStep().
.SH "void QDial::subtractPage ()\fC [slot]\fR"
Decrements the dial's value() by one pageStep() of steps.
.SH "bool QDial::tracking () const"
Returns TRUE if tracking is enabled; otherwise returns FALSE. See the "tracking" property for details.
.SH "int QDial::value () const"
Returns the current dial value. See the "value" property for details.
.SH "void QDial::valueChange ()\fC [virtual protected]\fR"
Reimplemented to ensure the display is correct and to emit the valueChanged(int) signal when appropriate.
.PP
Reimplemented from QRangeControl.
.SH "void QDial::valueChanged ( int value )\fC [signal]\fR"
This signal is emitted whenever the dial's \fIvalue\fR changes. The frequency of this signal is influenced by setTracking().
.SH "bool QDial::wrapping () const"
Returns TRUE if wrapping is enabled; otherwise returns FALSE. See the "wrapping" property for details.
.SS "Property Documentation"
.SH "int lineStep"
This property holds the current line step.
.PP
setLineStep() calls the virtual stepChange() function if the new line step is different from the previous setting.
.PP
See also QRangeControl::setSteps(), pageStep, and setRange().
.PP
Set this property's value with setLineStep() and get this property's value with lineStep().
.SH "int maxValue"
This property holds the current maximum value.
.PP
When setting this property, the QDial::minValue is adjusted if necessary to ensure that the range remains valid.
.PP
See also setRange().
.PP
Set this property's value with setMaxValue() and get this property's value with maxValue().
.SH "int minValue"
This property holds the current minimum value.
.PP
When setting this property, the QDial::maxValue is adjusted if necessary to ensure that the range remains valid.
.PP
See also setRange().
.PP
Set this property's value with setMinValue() and get this property's value with minValue().
.SH "int notchSize"
This property holds the current notch size.
.PP
The notch size is in range control units, not pixels, and if possible it is a multiple of lineStep() that results in an on-screen notch size near notchTarget().
.PP
See also notchTarget and lineStep.
.PP
Get this property's value with notchSize().
.SH "double notchTarget"
This property holds the target number of pixels between notches.
.PP
The notch target is the number of pixels QDial attempts to put between each notch.
.PP
The actual size may differ from the target size.
.PP
Set this property's value with setNotchTarget() and get this property's value with notchTarget().
.SH "bool notchesVisible"
This property holds whether the notches are shown.
.PP
If TRUE, the notches are shown. If FALSE (the default) notches are not shown.
.PP
Set this property's value with setNotchesVisible() and get this property's value with notchesVisible().
.SH "int pageStep"
This property holds the current page step.
.PP
setPageStep() calls the virtual stepChange() function if the new page step is different from the previous setting.
.PP
See also stepChange().
.PP
Set this property's value with setPageStep() and get this property's value with pageStep().
.SH "bool tracking"
This property holds whether tracking is enabled.
.PP
If TRUE (the default), tracking is enabled. This means that the arrow can be moved using the mouse; otherwise the arrow cannot be moved with the mouse.
.PP
Set this property's value with setTracking() and get this property's value with tracking().
.SH "int value"
This property holds the current dial value.
.PP
This is guaranteed to be within the range QDial::minValue..QDial::maxValue.
.PP
See also minValue and maxValue.
.PP
Set this property's value with setValue() and get this property's value with value().
.SH "bool wrapping"
This property holds whether wrapping is enabled.
.PP
If TRUE, wrapping is enabled. This means that the arrow can be turned around 360