![[Go to CFHT Home Page]](/images/cfht-icon.gif){kind=icon}
Man Pages 
Back to Software Index 
Manpage Top Level
Sensor is derived from Resource and has an initial reference count of 1. Sensors ought never be deleted directly. Instead, an application should call Unref(sensor) on any sensor which it created or referenced. This should be done after the final use of the sensor. InterViews Plus will take care of deletion when the reference count has reached zero.
Several sensors are predefined as variables for use by all interactors:
| Sensor Type | Description |
| allEvents | |
| updownEvents | |
| onoffEvents | |
| noEvents |
Class HierarchySensor->Resource
ConstructorsSensor()Creates a new sensor.
Initially, this sensor will not catch any events. Sensor is a Resource
with an initial reference count of 1.
Sensor(const Sensor&)Creates a copy
of the given sensor.
Sensor(const Sensor*)Creates a sensor that points to
the same data as the passed sensor.
Public Operationsvoid Catch(EventType)Expresses
interest in a particular type of event. Valid event types (from <ivplus/event.h>)
are: Event TypeDescription MotionEventDownEventUpEventKeyEventEnterEventLeaveEventFocusInEventFocusOutEvent
Two other event types,
DeleteWindowEventand
CheckpointEventhave been added for window manager interaction. These are
caught by all
sensors, but are usually handled by a special window handler.
void CatchButton(EventType, int)Expresses interest in a particular type
of button event for a specific mouse button. The mouse button is passed
as an int using the mouse button types LEFTMOUSE, MIDDLEMOUSE and RIGHTMOUSE.
virtual boolean Caught(const Event&)Returns whether or not the sensor is
catching the given event.
void Ignore(EventType)Removes interest in a particular
event type.
void IgnoreButton(EventType, int)Removes interest in a particular
type of button event for a specific mouse button. The mouse button is passed
as an int using the mouse button types LEFTMOUSE, MIDDLEMOUSE and RIGHTMOUSE.
static void init()Initializes the predefined sensors: allEvents, updownEvents,
onoffEvents, noEvents. This is called by world at application startup and
is not for use by applications in general.
virtual Sensor& operator=(const
Sensor&)Overloaded operator = for copying Sensors.
Protected Operationsint
ButtonFlag(unsigned long b) constReturns the flag needed to indicate interest
in the indicated button. b is the button field retrieved from an X event.
Used by Catch() and Ignore() to determine appropriate flag to set the
internal variables up and down.
int ButtonIndex(unsigned long b) constReturns
the button index of the indicated button field retrieved from an X event.
Used by Catch() and Ignore() to index into the internal variables up
and down.
boolean ButtonIsSet(unsigned long a[], unsigned long b) constReturns
whether or not interest has been expressed in the type of event represented
by a (up or down) for the indicated button. b is the button field retrieved
from an X event.
void ClearButton(unsigned long a[], unsigned long b) {Removes
interest in the type of event represented by a (up or down) for the button
indicated by b. a is one of the internal variables up or down. b is the
button field retrieved from an X event.
void ClearMouseButtons(unsigned
long a[])Removes interest in the type of event indicated by a (up or down)
for all buttons.
boolean MouseButtons(unsigned long a[]) constReturns whether
interest in the type of event represented by a (up or down) is set for
mouse buttons.
void SetButton(unsigned long a[], unsigned long b)Expresses
interest in the type of event represented by a (up or down) for the button
indicated by b. a is one of the internal variables up or down. b is the
button field retrieved from an X event.
void SetMouseButtons(unsigned long
a[])Expresses interest in the type of event indicated by a (up or down)
for all buttons.
X ResourcesNone.
Examples
// Sensor Example
#include <ivplus/event.h>
#include <ivplus/frame.h>
#include <ivplus/message.h>
#include <ivplus/sensor.h>
#include <ivplus/world.h>
#include <iostream.h>
// MySample has 2 sensors, Interactor is asked to listen to sensor1 whenever
// a down event is encountered. Interactor is asked to listen to sensor2
// whenever up event is encountered. This is an illustration using a sensor.
class MySample : public Message {
public:
MySample(const char* text)
: Message(text)
{
Init();
}
void MySample::Handle(Event& e);
void MySample::Sensor1On() { Listen(sensor1);};
void MySample::Sensor2On() { Listen(sensor2);};
private:
void Init();
Sensor *sensor1, *sensor2;
};
void MySample::Init()
{
// Create a sensor that listens to enter, leave, up and down events.
sensor1 = new Sensor();
sensor1->Catch(EnterEvent);
sensor1->Catch(LeaveEvent);
sensor1->Catch(DownEvent);
sensor1->Catch(UpEvent);
// By default, make sensor1 active.
Sensor1On();
// Create a sensor that listen only to down events for the right
// mouse button.
sensor2 = new Sensor();
sensor2->CatchButton(DownEvent, RIGHTMOUSE);
};
void MySample::Handle(Event& e)
{
if (e.eventType == DownEvent && e.target == this)
{
// Listen to sensor1.
Sensor1On();
cout << " Encountered Down Event" << endl;
}
if (e.eventType == UpEvent && e.target == this)
{
// Listen to sensor2.
Sensor2On();
cout << " Encountered Up Event" << endl;
}
if (e.eventType == EnterEvent)
cout << " Encountered Enter Event" << endl;
if (e.eventType == LeaveEvent)
cout << " Encountered Leave Event" << endl;
};
int main(int argc, char **argv)
{
// Create the world to get the connection with the display.
World* world = new World("MyApp", argc, argv);
MySample* sample = new MySample("Use mouse button3 down event for Sensor1\n
Use mouse button3 up event for Sensor2");
// Map the window.
world->InsertApplication(new Frame(sample, 1, BevelOut));
// Enter the event loop.
world->Run();
return 0;
}
sensor.h