In javaFX to resize a canvas there is no such method to do that, the only solution is to extends from Canvas.
class ResizableCanvas extends Canvas {
public ResizableCanvas() {
// Redraw canvas when size changes.
widthProperty().addListener(evt -> draw());
heightProperty().addListener(evt -> draw());
}
private void draw() {
double width = getWidth();
double height = getHeight();
GraphicsContext gc = getGraphicsContext2D();
gc.clearRect(0, 0, width, height);
}
@Override
public boolean isResizable() {
return true;
}
}
is extends from Canvas is the only solution to make canvas Resizable ? because this solution work only if we don't want to use FXML, if we declare in fxml a canvas how can we make it resizable?
this is my code :
package sample;
import javafx.application.Application;
import javafx.fxml.FXMLLoader;
import javafx.scene.Scene;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.layout.AnchorPane;
import javafx.scene.paint.Color;
import javafx.stage.Stage;
public class Main extends Application {
Controller controller;
@Override
public void start(Stage primaryStage) throws Exception{
FXMLLoader loader = new FXMLLoader(getClass().getResource("sample.fxml"));
AnchorPane root = loader.load(); // controller initialized
controller = loader.getController();
GraphicsContext gc = controller.canvas.getGraphicsContext2D();
gc.setFill(Color.AQUA);
gc.fillRect(0, 0, root.getPrefWidth(), root.getPrefHeight());
primaryStage.setTitle("Hello World");
primaryStage.setScene(new Scene(controller.Pane, controller.Pane.getPrefWidth(), controller.Pane.getPrefHeight()));
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}
There's a guide that I think that you may find useful for setting up a resizable canvas:
JavaFx tip - resizable canvas
Piece of code from the guide:
/**
* Tip 1: A canvas resizing itself to the size of
* the parent pane.
*/
public class Tip1ResizableCanvas extends Application {
class ResizableCanvas extends Canvas {
public ResizableCanvas() {
// Redraw canvas when size changes.
widthProperty().addListener(evt -> draw());
heightProperty().addListener(evt -> draw());
}
private void draw() {
double width = getWidth();
double height = getHeight();
GraphicsContext gc = getGraphicsContext2D();
gc.clearRect(0, 0, width, height);
gc.setStroke(Color.RED);
gc.strokeLine(0, 0, width, height);
gc.strokeLine(0, height, width, 0);
}
@Override
public boolean isResizable() {
return true;
}
@Override
public double prefWidth(double height) {
return getWidth();
}
@Override
public double prefHeight(double width) {
return getHeight();
}
}
Of all the answers given, none of them actually worked for me in terms of making the canvas automatically resize with its parent. I decided to take a crack at this and this is what I came up with:
import javafx.scene.canvas.Canvas;
public class ResizableCanvas extends Canvas {
@Override
public boolean isResizable() {
return true;
}
@Override
public double maxHeight(double width) {
return Double.POSITIVE_INFINITY;
}
@Override
public double maxWidth(double height) {
return Double.POSITIVE_INFINITY;
}
@Override
public double minWidth(double height) {
return 1D;
}
@Override
public double minHeight(double width) {
return 1D;
}
@Override
public void resize(double width, double height) {
this.setWidth(width);
this.setHeight(height);
}
}
This was the only one that actually made the canvas truly resizable.
My reasons for going with this approach is as follows:
width
and height
in the constructor which would also mean that the canvas cannot be used in FXML
.width
and height
properties thus making the canvas the only child in it's parent, by taking up all the space.With this canvas, I do not need to bind to its parent width/height properties to make the canvas resize. It just resizes with whatever size the parent chooses. In addition, anyone using the canvas can just bind to its width/height properties and manage their own drawing when these properties change.
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