Develop Reference

How can I create a feathered brush with JavaFX?

So I'm trying to create a very basic photo editor program in Java, using JavaFX. I got a brush and eraser working pretty well so far the following way:
package application;
import java.io.File;
import javax.imageio.ImageIO;
import javafx.application.Platform;
import javafx.embed.swing.SwingFXUtils;
import javafx.fxml.FXML;
import javafx.geometry.Point2D;
import javafx.scene.canvas.*;
import javafx.scene.control.*;
import javafx.scene.image.Image;
import javafx.scene.paint.Color;
import javafx.scene.shape.*;
public class EditorController {
private boolean eraser = false;
#FXML
private Canvas canvas;
#FXML
private ColorPicker colorPicker;
#FXML
private TextField brushSize;
#FXML
private TextField selectedTool;
private Point2D last = null;
public void initialize() {
GraphicsContext gc = canvas.getGraphicsContext2D();
canvas.setOnMouseReleased(e -> {last = null;});
canvas.setOnMouseClicked(e -> {
if (!eraser) {
double size = Double.parseDouble(brushSize.getText());
float mouseX = (float) e.getX();
float mouseY = (float) e.getY();
gc.fillOval(mouseX-(size/2), mouseY-(size/2), size, size);
}
});
canvas.setOnMouseDragged(e -> {
System.out.println(eraser);
double size = Double.parseDouble(brushSize.getText());
gc.setLineCap(StrokeLineCap.ROUND);
gc.setLineWidth(size);
float mouseX = (float) e.getX();
float mouseY = (float) e.getY();
if (last != null && !eraser) {
gc.strokeLine(last.getX(), last.getY(), mouseX, mouseY);
} else if (eraser) {
gc.clearRect(mouseX, mouseY, size, size);
}
last = new Point2D(mouseX, mouseY);
});
}
public void onSave() {
try {
Image snapshot = canvas.snapshot(null, null);
ImageIO.write(SwingFXUtils.fromFXImage(snapshot, null), "png", new File("paint.png"));
} catch (Exception e) {
System.out.println("Failed to save image: " + e);
}
}
public void onLoad() {
// not implemented yet
}
// not implemented yet
public void onUndo() { }
public void onRedo() { }
public void onSmaller() { }
public void onBigger() { }
public void onResetView() { }
public void onFitView() { }
public void onFillView() { }
public void onNewLayer() { }
public void onDeleteLayer() { }
public void onDuplicateLayer() { }
public void onGroupLayers() { }
public void onMergeLayers() { }
public void onAddMask() { }
public void onBrush() { eraser = false; selectedTool.setText("Brush"); }
public void onEraser() { eraser = true; selectedTool.setText("Eraser"); }
public void onExit() {
Platform.exit();
}
}
Now I want to have a feather/hardness value for the brush (like in photoshop) where I can draw a softer-looking line, but I'm not sure how to achieve it with JavaFX? Are there any tools within it for things like this?
So with a visual example: the brush on the left would be a feathered brush, the one on the right isn't (and that's what I have currently)

Simple drawing app.
It uses a radial gradient rendered to an image that is drawn on the canvas, but you could just draw the gradient directly onto the canvas. A gradient is a paint so you can set it directly as an argument to setFill on a graphics context.
The solution in my example probably won't exactly give you the solution you are looking for, but perhaps you could tweak it for what you need.
It was a quick app I put together for demo purposes, it could be structured better if a more functional drawing app was required.
The code which creates the "feathered brush" is based on a gradient:
private RadialGradient createSoftBrushGradient(Color primaryColor) {
return new RadialGradient(
0, 0,
.5, .5,
.5,
true,
CycleMethod.NO_CYCLE,
new Stop(0, primaryColor),
new Stop(1, Color.TRANSPARENT)
);
}
import javafx.application.Application;
import javafx.beans.property.*;
import javafx.event.EventHandler;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.SnapshotParameters;
import javafx.scene.canvas.*;
import javafx.scene.control.*;
import javafx.scene.image.Image;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.*;
import javafx.scene.paint.*;
import javafx.scene.shape.Circle;
import javafx.stage.Stage;
public class SprayPaint extends Application {
private final IntegerProperty brushDiameter = new SimpleIntegerProperty();
private final ObjectProperty<Image> brushImage = new SimpleObjectProperty<>();
private final ToggleGroup brushHardnessSelection = new ToggleGroup();
private final RadioButton hardBrushSelection = new RadioButton();
private final RadioButton softBrushSelection = new RadioButton();
private final Circle hardBrush = new Circle();
private final Circle softBrush = new Circle();
private final SnapshotParameters snapshotParams = new SnapshotParameters();
private final Canvas canvas = new Canvas(600, 450);
#Override
public void start(Stage stage) {
snapshotParams.setFill(Color.TRANSPARENT);
Pane controls = createControls();
StackPane canvasHolder = new StackPane(canvas);
canvasHolder.setStyle("-fx-border-color: gray;");
canvasHolder.setMaxSize(Pane.USE_PREF_SIZE, Pane.USE_PREF_SIZE);
VBox layout = new VBox(
10,
controls,
canvasHolder
);
layout.setPadding(new Insets(10));
stage.setScene(new Scene(layout));
stage.show();
enableDrawing(canvas);
}
private void enableDrawing(Canvas canvas) {
EventHandler<MouseEvent> drawHandler = event -> {
Image brush = snapshotBrushImage();
GraphicsContext gc = canvas.getGraphicsContext2D();
gc.drawImage(
brush,
event.getX() - brushDiameter.doubleValue() / 2,
event.getY() - brushDiameter.doubleValue() / 2
);
};
canvas.setOnMousePressed(drawHandler);
canvas.setOnMouseDragged(drawHandler);
}
private Image snapshotBrushImage() {
if (brushImage.get() == null) {
if (hardBrushSelection == brushHardnessSelection.getSelectedToggle()) {
brushImage.set(snapshot(hardBrush));
} else { // soft brush selected
brushImage.set(snapshot(softBrush));
}
}
return brushImage.get();
}
private Image snapshot(Circle brushNode) {
return brushNode.snapshot(snapshotParams, null);
}
private Pane createControls() {
hardBrush.radiusProperty().bind(
brushDiameter.divide(2.0)
);
softBrush.radiusProperty().bind(
brushDiameter.divide(2.0)
);
hardBrushSelection.getStyleClass().addAll("toggle-button", "left-pill");
hardBrushSelection.getStyleClass().remove( "radio-button");
StackPane hardBrushGraphic = new StackPane(hardBrush);
hardBrushGraphic.setMinSize(40, 40);
hardBrushSelection.setGraphic(hardBrushGraphic);
hardBrushSelection.setToggleGroup(brushHardnessSelection);
softBrushSelection.getStyleClass().addAll( "toggle-button", "right-pill");
softBrushSelection.getStyleClass().remove( "radio-button");
StackPane softBrushGraphic = new StackPane(softBrush);
softBrushGraphic.setMinSize(40, 40);
softBrushSelection.setGraphic(softBrushGraphic);
softBrushSelection.setToggleGroup(brushHardnessSelection);
hardBrushSelection.setSelected(true);
HBox brushSelectionPanel = new HBox(hardBrushSelection, softBrushSelection);
Slider brushDiameterSlider = new Slider(8, 40, 20);
brushDiameterSlider.setMajorTickUnit(4);
brushDiameterSlider.setMinorTickCount(0);
brushDiameterSlider.setShowTickMarks(true);
brushDiameter.setValue((int) Math.round(brushDiameterSlider.getValue()));
brushDiameterSlider.valueProperty().addListener((observable, oldValue, newValue) ->
brushDiameter.setValue((int) Math.round(newValue.doubleValue()))
);
Label diameterLabel = new Label();
diameterLabel.textProperty().bind(
brushDiameter.asString()
);
ColorPicker colorPicker = new ColorPicker();
hardBrush.fillProperty().bind(
colorPicker.valueProperty()
);
colorPicker.valueProperty().addListener((observable, oldColor, newColor) ->
softBrush.setFill(
createSoftBrushGradient(newColor)
)
);
colorPicker.setValue(Color.NAVY);
brushDiameter.addListener((observable, oldValue, newValue) ->
brushImage.set(null)
);
colorPicker.valueProperty().addListener((observable, oldValue, newValue) ->
brushImage.set(null)
);
brushHardnessSelection.selectedToggleProperty().addListener((observable, oldValue, newValue) ->
brushImage.set(null)
);
Button clear = new Button("Clear");
clear.setOnAction(e ->
canvas.getGraphicsContext2D().clearRect(
0, 0, canvas.getWidth(), canvas.getHeight()
)
);
HBox controlPanel = new HBox(
10,
colorPicker,
brushSelectionPanel,
new Label("Diameter: "),
brushDiameterSlider,
diameterLabel,
clear
);
controlPanel.setMinWidth(450);
controlPanel.setMinHeight(Pane.USE_PREF_SIZE);
return controlPanel;
}
private RadialGradient createSoftBrushGradient(Color primaryColor) {
return new RadialGradient(
0, 0,
.5, .5,
.5,
true,
CycleMethod.NO_CYCLE,
new Stop(0, primaryColor),
new Stop(1, Color.TRANSPARENT)
);
}
}

Line painting in painting program JavaFX

I created a simple paint program which allows the user to choose between 4 shapes(line,circle,rectangle,ellipse) , the user can change the width height and stroke width , he can save the design he makes , undo and redo , the user can also choose the stroke type (solid or dashed) ,I'm almost done with the program but I'm facing one problem , the line is getting displayed not in the way I want it to be displayed as the photo below :
So the line here is of width 32 and height 32 , my line is getting printed in a different way.Is it correct the way I'm printing my line ?
NOTE : I'm using the line shape in the code to make the code small.
import javafx.application.Application;
import javafx.collections.FXCollections;
import javafx.geometry.Insets;
import javafx.scene.Cursor;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.control.*;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.layout.BorderPane;
import javafx.scene.layout.VBox;
import javafx.scene.paint.Color;
import javafx.scene.shape.Line;
import javafx.stage.Stage;
public class paintLine extends Application {
#Override
public void start(Stage primaryStage) {
Image image1 = new
Image("C:\\Users\\Mhamd\\Desktop\\laol\\src\\resources\\Daco_70400.png",
100, 100, false, false);
ImageView view1 = new ImageView(image1);
view1.setFitHeight(40);
view1.setPreserveRatio(true);
ToggleButton linebtn = new ToggleButton();
linebtn.setGraphic(view1);
ToggleButton[] toolsArr = {linebtn};
ToggleGroup tools = new ToggleGroup();
for (ToggleButton tool : toolsArr) {
tool.setMinWidth(50);
tool.setToggleGroup(tools);
tool.setCursor(Cursor.HAND);
}
ColorPicker cpLine = new ColorPicker(Color.BLACK);
ColorPicker cpFill = new ColorPicker(Color.TRANSPARENT);
TextField textWidth = new TextField("32");
TextField textHeight = new TextField("32");
TextField contouring = new TextField("2");
Label line_color = new Label("Line Color");
Label fill_color = new Label("Fill Color");
Label line_width = new Label("3.0");
Label imgWidth = new Label("Width");
Label imgHeight = new Label("Height");
String week_days[] =
{"Solid", "Dotted"};
ChoiceBox choiceBox = new ChoiceBox(FXCollections
.observableArrayList(week_days));
VBox btns = new VBox(10);
btns.getChildren().addAll(linebtn, imgWidth, textWidth, imgHeight,
textHeight, line_color, cpLine,
fill_color, cpFill, line_width, contouring, choiceBox);
btns.setPadding(new Insets(5));
btns.setStyle("-fx-background-color: #999");
btns.setPrefWidth(100);
Canvas canvas = new Canvas(1080, 790);
GraphicsContext gc;
gc = canvas.getGraphicsContext2D();
gc.setLineWidth(1);
Line line = new Line();
canvas.setOnMouseClicked(e -> {
if (linebtn.isSelected()) {
// double widthSize =
Double.parseDouble(textWidth.getText());
// double heightSize =
Double.parseDouble(textHeight.getText());
double strokeWidth =
Double.parseDouble(contouring.getText());
// gc.setLineWidth(strokeWidth);
gc.setStroke(cpLine.getValue());
if (choiceBox.getSelectionModel().isSelected(0)) {
gc.setLineWidth(strokeWidth);
} else if (choiceBox.getSelectionModel().isSelected(1)) {
gc.setLineWidth(strokeWidth);
gc.setLineDashes(10);
}
gc.setFill(cpFill.getValue());
line.setStartX(e.getX());
line.setStartY(e.getY());
line.setEndX(e.getX() / 2);
line.setEndY(e.getY() / 2);
gc.strokeLine(line.getStartX(), line.getStartY(),
line.getEndX(), line.getEndY());
}
});
BorderPane pane = new BorderPane();
pane.setRight(btns);
pane.setCenter(canvas);
Scene scene = new Scene(pane, 1200, 800);
primaryStage.setTitle("Paint");
primaryStage.setScene(scene);
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}

Focusing on just drawing a line interactively, you need to at least do the following:
Record the initial point at which the mouse was pressed and then
Render the line when you know where the mouse was released:
private double startX;
private double startY;
…
canvas.setOnMousePressed(e -> {
startX = e.getX();
startY = e.getY();
});
canvas.setOnMouseReleased(e -> {
gc.strokeLine(startX, startY, e.getX(), e.getY());
});
This works as shown above, but the problem then becomes how to draw the line while dragging—without damaging previous work. One solution is to add each new line to a List<Line> and render the accumulated lines with each update:
private final List<Line> lines = new ArrayList<>();
…
canvas.setOnMouseReleased(e -> {
lines.add(new Line(startX, startY, e.getX(), e.getY()));
});
canvas.setOnMouseDragged(e -> {
if (lineButton.isSelected()) {
…
gc.clearRect(0, 0, canvas.getWidth(), canvas.getHeight());
lines.forEach(l -> {
gc.strokeLine(l.getStartX(), l.getStartY(), l.getEndX(), l.getEndY());
});
gc.strokeLine(startX, startY, e.getX(), e.getY());
}
});
A more general solution, which illustrates undo() and redo(), is offered here.

How to write custom text on JavaFX 2.2 cursor?

I want a cursor that displays the coordinates of the place the mouse is pointing to, besides the pointer itself (it should look like a crosshair with little numbers is bottom right corner, that change when the mouse is moving). How to achive such effect efficiently? I tried to use the tooltip mechanism, but then the text lags behind the cursor a lot...

You could attach a label, and change the text inside the mouse moved event everytime that the mouse coordinates changes.

You can create a Text object with the current coordinates, snapshot it to an Image, and then create a WritableImage from that and any other cursor decoration you need. Then wrap the WritableImage in an ImageCursor:
import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.scene.Cursor;
import javafx.scene.ImageCursor;
import javafx.scene.Scene;
import javafx.scene.image.Image;
import javafx.scene.image.WritableImage;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.text.Text;
import javafx.stage.Stage;
public class MouseCoordinateCursor extends Application {
#Override
public void start(Stage primaryStage) {
Pane root = new Pane();
root.setOnMouseExited(new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent event) {
root.setCursor(Cursor.DEFAULT);
}
});
root.setOnMouseMoved(new EventHandler<MouseEvent>() {
final int padding = 9 ;
final int offset = 6 ;
#Override
public void handle(MouseEvent e) {
Text text = new Text(String.format("[%.1f,%.1f]", e.getX(), e.getY()));
Image textImage = text.snapshot(null, null);
int width = (int)textImage.getWidth();
int height = (int)textImage.getHeight();
WritableImage cursorImage = new WritableImage(width + offset, height + offset);
cursorImage.getPixelWriter().setPixels(offset, offset, width, height, textImage.getPixelReader(), 0, 0);
for (int i = 0; i < padding; i++) {
cursorImage.getPixelWriter().setColor(i, padding/2, Color.BLACK);
cursorImage.getPixelWriter().setColor(padding/2, i, Color.BLACK);
}
root.setCursor(new ImageCursor(cursorImage));
}
});
primaryStage.setScene(new Scene(root, 600, 600));
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}

Implementing drawing areas in tabs in JavaFX

I would want to add a drawing area to my tabs in JavaFX. I am new to the field, and tried adding a Canvas to each tab I create. However, this does not seem to be working. Relevant code included.
#FXML
void fileNewTabHandler(ActionEvent event) {
++indexTab;
Tab tab = new Tab("Untitled " + indexTab);
Canvas canvas = new Canvas(500, 285);
GraphicsContext gc = canvas.getGraphicsContext2D();
gc.setFill(Color.BLUE);
gc.fillRect(250, 856, 50, 60);
tab.setContent(canvas);
tabPane.getTabs().add(tab);
}
Here tabPane and indexTab are defined and work as long as I do not use the canvas. Where am I going wrong. Should I use a different method to implement what I want to?

Quick Sample
There is no real trick to this, you just set the canvas as the content of the tab.
import javafx.application.Application;
import javafx.scene.*;
import javafx.scene.canvas.*;
import javafx.scene.control.*;
import javafx.scene.layout.*;
import javafx.scene.paint.Color;
import javafx.stage.Stage;
import java.util.Random;
public class TabbedCanvas extends Application {
private int tabId = 0;
private double W = 200, H = 150;
private Random random = new Random(42);
#Override
public void start(Stage stage) {
TabPane tabPane = new TabPane();
Button newTabButton = new Button("New Tab");
newTabButton.setOnAction(
event -> addTab(tabPane)
);
newTabButton.fire();
ToolBar toolBar = new ToolBar(newTabButton);
toolBar.setMinHeight(ToolBar.USE_PREF_SIZE);
VBox layout = new VBox(toolBar, tabPane);
VBox.setVgrow(tabPane, Priority.ALWAYS);
stage.setScene(new Scene(layout));
stage.show();
}
private void addTab(TabPane tabPane) {
Tab tab = new Tab("Tab: " + tabId++);
tab.setContent(createTabContent());
tabPane.getTabs().add(tab);
tabPane.getSelectionModel().select(tab);
}
private Node createTabContent() {
Canvas canvas = new Canvas(W, H);
GraphicsContext gc = canvas.getGraphicsContext2D();
gc.setFill(randomColor());
gc.fillRect(0, 0, W, H);
return canvas;
}
private Color randomColor() {
return Color.rgb(
random.nextInt(256),
random.nextInt(256),
random.nextInt(256)
);
}
public static void main(String[] args) {
launch(args);
}
}

JavaFX - Clickable line on canvas

I have this JavaFX application that lets you plot locations on a map and connect them.
I do this by drawing a map as a background image on a canvas and then drawing circles and lines on it. I have made the circles clickable by using the contains() method in the Circle class, but how can I make the lines clickable?
edit: Look at this example where I just draw a line and set an event handler:
Canvas canvas = new Canvas();
GraphicsContext gc = canvas.getGraphicsContext2D();
gc.setLineWidth(5);
gc.strokeLine(100, 100, 200, 200);
canvas.setOnMouseClicked(event -> {
double x = event.getX(), y = event.getY();
});
My question is simply this: how do I finish the event handler so that it detects if the click is inside the line I just drew?

You should create a canvas and add the nodes (Circle, Line, etc) to it. Then you add mouse listeners to the nodes.
Example:
import java.util.ArrayList;
import java.util.List;
import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.scene.Group;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.scene.shape.Line;
import javafx.stage.Stage;
public class DragNodes extends Application {
public static List<Circle> circles = new ArrayList<Circle>();
public static void main(String[] args) {
launch(args);
}
#Override
public void start(Stage primaryStage) {
Group root = new Group();
Canvas canvas = new Canvas(300, 300);
GraphicsContext gc = canvas.getGraphicsContext2D();
drawShapes(gc);
Circle circle1 = new Circle(50);
circle1.setStroke(Color.GREEN);
circle1.setFill(Color.GREEN.deriveColor(1, 1, 1, 0.7));
circle1.relocate(100, 100);
Circle circle2 = new Circle(50);
circle2.setStroke(Color.BLUE);
circle2.setFill(Color.BLUE.deriveColor(1, 1, 1, 0.7));
circle2.relocate(200, 200);
Line line = new Line(circle1.getLayoutX(), circle1.getLayoutY(), circle2.getLayoutX(), circle2.getLayoutY());
line.setStrokeWidth(20);
Pane overlay = new Pane();
overlay.getChildren().addAll(circle1, circle2, line);
MouseGestures mg = new MouseGestures();
mg.makeDraggable(circle1);
mg.makeDraggable(circle2);
mg.makeDraggable(line);
root.getChildren().addAll(canvas, overlay);
primaryStage.setScene(new Scene(root, 800, 600));
primaryStage.show();
}
private void drawShapes(GraphicsContext gc) {
gc.setStroke(Color.RED);
gc.strokeRoundRect(10, 10, 230, 230, 10, 10);
}
public static class MouseGestures {
double orgSceneX, orgSceneY;
double orgTranslateX, orgTranslateY;
public void makeDraggable(Node node) {
node.setOnMousePressed(circleOnMousePressedEventHandler);
node.setOnMouseDragged(circleOnMouseDraggedEventHandler);
}
EventHandler<MouseEvent> circleOnMousePressedEventHandler = new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent t) {
orgSceneX = t.getSceneX();
orgSceneY = t.getSceneY();
if (t.getSource() instanceof Circle) {
Circle p = ((Circle) (t.getSource()));
orgTranslateX = p.getCenterX();
orgTranslateY = p.getCenterY();
} else {
Node p = ((Node) (t.getSource()));
orgTranslateX = p.getTranslateX();
orgTranslateY = p.getTranslateY();
}
}
};
EventHandler<MouseEvent> circleOnMouseDraggedEventHandler = new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent t) {
double offsetX = t.getSceneX() - orgSceneX;
double offsetY = t.getSceneY() - orgSceneY;
double newTranslateX = orgTranslateX + offsetX;
double newTranslateY = orgTranslateY + offsetY;
if (t.getSource() instanceof Circle) {
Circle p = ((Circle) (t.getSource()));
p.setCenterX(newTranslateX);
p.setCenterY(newTranslateY);
} else {
Node p = ((Node) (t.getSource()));
p.setTranslateX(newTranslateX);
p.setTranslateY(newTranslateY);
}
}
};
}
}