我还没有找到一种机制来根据路径清除画布。但您可以手动执行以下操作:
带有路径的蒙版的蓝色矩形示例:
public class ManualBlendWithMask extends Application {
public static void main(String[] args) {
launch(args);
}
@Override
public void start(Stage primaryStage) {
Group root = new Group();
// create canvas
Canvas canvas = new Canvas(200, 200);
canvas.setTranslateX(100);
canvas.setTranslateY(100);
// create canvas with blue rectangle
GraphicsContext canvasGC = canvas.getGraphicsContext2D();
canvasGC.setFill(Color.BLUE);
canvasGC.fillRect(0, 0, canvas.getWidth(), canvas.getHeight());
// create mask
Canvas mask = new Canvas( canvas.getWidth(), canvas.getHeight());
GraphicsContext maskGC = mask.getGraphicsContext2D();
maskGC.setFill(Color.WHITE);
maskGC.fillRect(0, 0, mask.getWidth(), mask.getHeight());
// draw path
maskGC.setStroke(Color.BLACK);
maskGC.setLineWidth(20);
maskGC.beginPath();
maskGC.moveTo(0, 0);
maskGC.lineTo(400, 400);
maskGC.stroke();
// get image from canvas
WritableImage srcImage = new WritableImage((int) canvas.getWidth(), (int) canvas.getHeight());
srcImage = canvas.snapshot(null, srcImage);
// get image from mask
WritableImage srcMask = new WritableImage((int) mask.getWidth(), (int) mask.getHeight());
srcMask = mask.snapshot(null, srcMask);
PixelReader maskReader = srcMask.getPixelReader();
PixelReader imageReader = srcImage.getPixelReader();
int width = (int) srcMask.getWidth();
int height = (int) srcMask.getHeight();
// create dest image
WritableImage dest = new WritableImage(width, height);
PixelWriter writer = dest.getPixelWriter();
// blend image and mask
for (int x = 0; x < width; x++) {
for (int y = 0; y < height; y++) {
Color maskColor = maskReader.getColor(x, y);
Color imageColor = imageReader.getColor(x, y);
if (maskColor.equals(Color.WHITE)) {
writer.setColor(x, y, imageColor);
}
}
}
// clear canvas and fill it with the blended image
canvasGC = canvas.getGraphicsContext2D();
canvasGC.clearRect(0, 0, canvas.getWidth(), canvas.getHeight());
canvasGC.drawImage(dest, 0, 0);
// draw background with gradient
Rectangle rect = new Rectangle(400, 400);
rect.setFill(new LinearGradient(0, 0, 1, 1, true, CycleMethod.REFLECT, new Stop(0, Color.RED), new Stop(1, Color.YELLOW)));
// show nodes
root.getChildren().addAll(rect, canvas);
primaryStage.setScene(new Scene(root, 400, 400));
primaryStage.show();
}
}
当然,如果有人能想出一个使用 BlendModes 的例子会更好。
