Moving marker in a Grid Pane - javafx

Question

I have created a Grid Pane with a number of rows. A marker should only be moveable on 1 row. When moving the mouse it should move sideways only, left or right. When you click on the marker it should be locked, no more movement. It should be highlighted with a different color.
How can I achive this?
If you know any tutorials or examples please add, thanks.
Message Output:
Executing
C:\Users\s22380\Desktop\temp\JavaFXApplication9\dist\run269988000\JavaFXApplication9.jar
using platform C:\Program Files\Java\jdk1.8.0_92\jre/bin/java
Exception in Application constructor
java.lang.reflect.InvocationTargetException at
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498) at
com.sun.javafx.application.LauncherImpl.launchApplicationWithArgs(LauncherImpl.java:389)
at
com.sun.javafx.application.LauncherImpl.launchApplication(LauncherImpl.java:328)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498) at
sun.launcher.LauncherHelper$FXHelper.main(LauncherHelper.java:767)
Caused by: java.lang.RuntimeException: Unable to construct Application
instance: class javafxapplication9.JavaFXApplication9 at
com.sun.javafx.application.LauncherImpl.launchApplication1(LauncherImpl.java:907)
at
com.sun.javafx.application.LauncherImpl.lambda$launchApplication$155(LauncherImpl.java:182)
at java.lang.Thread.run(Thread.java:745) Caused by:
java.lang.reflect.InvocationTargetException at
sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
at
sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
at
sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
at
com.sun.javafx.application.LauncherImpl.lambda$launchApplication1$161(LauncherImpl.java:819)
at
com.sun.javafx.application.PlatformImpl.lambda$runAndWait$175(PlatformImpl.java:326)
at
com.sun.javafx.application.PlatformImpl.lambda$null$173(PlatformImpl.java:295)
at java.security.AccessController.doPrivileged(Native Method) at
com.sun.javafx.application.PlatformImpl.lambda$runLater$174(PlatformImpl.java:294)
at
com.sun.glass.ui.InvokeLaterDispatcher$Future.run(InvokeLaterDispatcher.java:95)
at com.sun.glass.ui.win.WinApplication._runLoop(Native Method) at
com.sun.glass.ui.win.WinApplication.lambda$null$148(WinApplication.java:191)
... 1 more Caused by: java.lang.NullPointerException at
sample.Controller.(Controller.java:33) at
javafxapplication9.JavaFXApplication9.(JavaFXApplication9.java:19)
... 13 more Exception running application
javafxapplication9.JavaFXApplication9 Java Result: 1 Deleting
directory
C:\Users\s22380\Desktop\temp\JavaFXApplication9\dist\run269988000
jfxsa-run: BUILD SUCCESSFUL (total time: 1 second)

Answer 1

How about this: Main.java
package sample;
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.stage.Stage;
public class Main extends Application
{
Controller controller = new Controller(10,10);
#Override
public void start(Stage primaryStage) throws Exception{
FXMLLoader loader = new FXMLLoader(getClass().getResource("sample.fxml"));
loader.setController(this.controller);
Parent root = (Parent)loader.load();
this.controller.InitUi();
primaryStage.setTitle("Hello World");
primaryStage.setScene(new Scene(root, 300, 275));
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
This is basically the sample code when you say new JavaFX project in IntelliJ. I changed it to explicitly set the controller. But that is just personal preference.
The xaml for that
<?import javafx.scene.layout.*?>
<GridPane fx:id="mainGrid" alignment="center" gridLinesVisible="true" hgap="10" vgap="10" xmlns="http://javafx.com/javafx/8" xmlns:fx="http://javafx.com/fxml/1">
<children>
</children>
</GridPane>
Again. Basically the default stuff.
I also added a style sheet to define the different lock for the not movable state.
redStyle.css
.button {
-fx-text-fill: #006464;
-fx-background-color: #DFB951;
-fx-border-radius: 20;
-fx-background-radius: 20;
-fx-padding: 5;
}
Now for the controller.
It will do a few things:
Listen to the mouse events of the object I want to push around. If the delata is big enough I will move it => if the mouse is moved fast enough
When the button is pressed I will switch out the style sheet to get the different look. Right now this style works on all buttons in the scene. It could be changed to work only on a specific one.
package sample;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.fxml.FXML;
import javafx.scene.control.Button;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.ColumnConstraints;
import javafx.scene.layout.GridPane;
import javafx.scene.layout.RowConstraints;
import javafx.scene.shape.Rectangle;
public class Controller
{
#FXML
private GridPane mainGrid;
#FXML
private Button movable;
private final int sizeX;
private final int sizeY;
private final double minMoveDistanc = 3;
private boolean canMove = true;
private Double lastX = null;
private Double lastY = null;
private String redButtonStyle = Controller.class.getResource("redStyle.css").toExternalForm();
public Controller(int sizeX, int sizeY)
{
this.sizeX = sizeX;
this.sizeY = sizeY;
}
public void InitUi()
{
if (this.mainGrid != null)
{
final int numCols = sizeX;
final int numRows = sizeY;
for (int i = 0; i < numCols; i++)
{
ColumnConstraints colConst = new ColumnConstraints();
this.mainGrid.getColumnConstraints().add(colConst);
}
for (int i = 0; i < numRows; i++)
{
RowConstraints rowConst = new RowConstraints();
this.mainGrid.getRowConstraints().add(rowConst);
}
// add rectangle to keep grid in size
for (int i = 0; i < numCols; i++)
{
for (int j = 0; j < numRows; j++)
{
Rectangle rect = new Rectangle();
rect.setWidth(50);
rect.setHeight(50);
this.mainGrid.add(rect,i,j);
}
}
// ad movable object (Button)
this.movable = new Button("Hallo");
this.movable.setPrefWidth(50);
this.movable.setPrefHeight(50);
this.movable.setOnAction(new EventHandler<ActionEvent>()
{
#Override
public void handle(ActionEvent actionEvent)
{
canMove = ! canMove;
movable.setText(canMove? "move" : "stop");
if (canMove)
{
movable.getScene().getStylesheets().remove(redButtonStyle);
}
else
{
movable.getScene().getStylesheets().add(redButtonStyle);
}
}
});
this.mainGrid.add(this.movable,5,5);
}
if (this.movable != null)
{
this.movable.setOnMouseEntered(new EventHandler<MouseEvent>()
{
#Override
public void handle(MouseEvent mouseEvent)
{
lastX = null;
lastY = null;
}
});
this.movable.setOnMouseExited(new EventHandler<MouseEvent>()
{
#Override
public void handle(MouseEvent mouseEvent)
{
lastX = null;
lastY = null;
}
});
this.movable.setOnMouseMoved(new EventHandler<MouseEvent>()
{
#Override
public void handle(MouseEvent mouseEvent)
{
if (!canMove)
{ return; }
double x = mouseEvent.getSceneX();
double y = mouseEvent.getSceneY();
if (lastX == null)
{
lastX = x;
lastY = y;
return;
}
// calculate delta
double deltaX = x - lastX;
double deltaY = y - lastY;
// remember new position
lastX = x;
lastY = y;
boolean moved = false;
// x movement
if (Math.abs(deltaX) > minMoveDistanc)
{
moved = true;
int currentColumn = GridPane.getColumnIndex(movable);
if (deltaX < 0)
{
GridPane.setColumnIndex(movable, Math.max(currentColumn -1 ,0));
}
else
{
GridPane.setColumnIndex(movable, Math.min(currentColumn + 1 ,sizeX-1));
}
}
// y movement
if (Math.abs(deltaY) > minMoveDistanc)
{
moved = true;
int currentRow = GridPane.getRowIndex(movable);
if (deltaY < 0)
{
GridPane.setRowIndex(movable, Math.max(currentRow - 1 ,0));
}
else
{
GridPane.setRowIndex(movable, Math.min(currentRow + 1 ,sizeY-1));
}
}
if (moved)
{
lastX = null;
lastY = null;
}
}
});
}
}
}