Java Reference
In-Depth Information
Otherwise,themousecoordinatesaresavedin dragX and dragY variablestorecord
theoriginofthedragoperation,andthe dragging Booleanvariableisassigned true
operation begins.
During a drag operation, the mouse motion listener's void
mouseDragged(MouseEvent me) method is invoked. Its first task is to test
dragging toseeifthemousecursorwasovertheshape.Ifthisvariablecontainsfalse,
or was not on the round rectangle, and then starting to drag the mouse cursor, would
If dragging contains true, mouseDragged() next calculates a new upper-left
between the current mouse coordinates and the coordinates saved in dragX and
dragY . It then passes the new origin along with the current size and arc radius to the
round rectangle via a setRoundRect() method call.
Continuing, a call to repaint() causes the round rectangle to be repainted at the
newlocation,andapairofassignmentstatementsupdate dragX and dragY tothecur-
rentmousecoordinatessothatthenextcallto mouseDragged() calculatesthenew
round rectangle origin relative to the origin that was just calculated.
When the mouse button is released, the mouse listener's void
mouseReleased(MouseEvent me) method is called. This method assigns
false to dragging so that the shape isn't dragged when a drag operation is subse-
quently started but the mouse cursor isn't over the shape when that operation begins.
Compile this source code ( javac ) and run the application
( java DragRect ). Figure7-26 showstheresultingGUIwithadragoperationinpro-
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