Well I managed to work around it by placing the applyCss() call on the Cell
itself, rather than the Shape node that I was styling. I'm still not sure
if I'm doing something wrong, if this is just how it's done and the
applyCss() call is the correct thing to do for this case, or if this should
be considered a bug.
Scott
On Tue, Feb 21, 2023 at 7:37 PM Scott Palmer <swpal...@gmail.com> wrote:
> I agree, this seems like it could be the same issue. Could you give me a
> little more context as to how this code works? I'm not implementing my own
> skin (maybe I should, I've never tried that before). Is this something I
> can trigger without a custom skin?
>
> Regards,
>
> Scott.
>
> On Tue, Feb 21, 2023 at 12:01 PM John Hendrikx <john.hendr...@gmail.com>
> wrote:
>
>> I've run into something similar, maybe even the same issue.
>>
>> My issue was that modifying the list of cell children (in a Skin for
>> ListView) caused a 1 frame white flicker (my application is black, so it
>> was annoying) because no CSS was applied yet to those newly added
>> children. This occured when the ListView first only had a few children and
>> wasn't completely filled, and then switching to a list which required more
>> cells to be created. I couldn't find a "correct" place to modify the list
>> of children that would avoid the flicker (layoutChildren/computePrefWidth
>> are places I tried).
>>
>> In the end I did this, and added a comment to remind me why the hack was
>> there:
>>
>> /*
>> * A pre-layout pulse listener is added to the current Scene to
>> manage the
>> * cells before the CSS pass occurs (this could also be done with an
>> AnimationTimer).
>> *
>> * If cells are not managed before the CSS pass, new cells will be
>> rendered for
>> * one frame without CSS applied. This results in a visual artifact
>> (a white flash
>> * for example if the background is supposed to be dark, while white
>> is the default
>> * color without any CSS applied).
>> */
>> private final Runnable pulseListener = () -> {
>> int lines = vertical ? visibleColumns.get() : visibleRows.get();
>> int firstIndex = (int)(scrollPosition.get()) * lines;
>>
>> content.manageCells(firstIndex);
>> };
>>
>> Now, the reason I think this may be same issue is that you're also doing
>> a modification of the children list during layout: setting the graphic is
>> sort of equivalent to label.getChildren().add(graphic)
>>
>> --John
>> On 20/02/2023 20:58, Scott Palmer wrote:
>>
>> I'm seeing an odd issue with using CSS to colour a Shape when I have it
>> as a child of a TextFlow.
>>
>> My use case is a "rich" text Cell in a tree or list. I want to have the
>> text portion in multiple colours and so instead of using the graphic and
>> text parts of a typical Cell, I'm using only the Graphic and setting it to
>> a TextFlow to get the text colours. This means that I lose the ability to
>> set a graphic independen to the text, and so the graphic is also added to
>> the TextFlow.
>>
>> To style the graphics, which are made of simple shapes, I'm using CSS.
>> It makes it easy to adapt the colours for when a cell is selected etc.
>> What I've noticed is that as the cell selection moves around the Shape
>> component of the TextFlow flickers, as if it is drawn first using default
>> colours and then the CSS is applied afterward. I tried working around this
>> by explicitly calling applyCss() on the Shape from the Cell's update
>> method, but it did not help. If I explicitly set the Stroke and Fill via
>> the Shape API the flickering does not occur. If I use CSS, but set the
>> Shape as the Cell's graphic and resort to only having plain text, there is
>> no flickering.
>>
>> A test program that demonstrates this is below.
>>
>> Bug or known limitation?
>>
>> Scott
>> ------------------------------------
>> package bugs;
>>
>> import javafx.application.Application;
>> import javafx.geometry.Insets;
>> import javafx.scene.Node;
>> import javafx.scene.Scene;
>> import javafx.scene.control.CheckBox;
>> import javafx.scene.control.ContentDisplay;
>> import javafx.scene.control.Label;
>> import javafx.scene.control.ListCell;
>> import javafx.scene.control.ListView;
>> import javafx.scene.control.Tab;
>> import javafx.scene.control.TabPane;
>> import javafx.scene.layout.HBox;
>> import javafx.scene.layout.VBox;
>> import javafx.scene.paint.Color;
>> import javafx.scene.shape.Circle;
>> import javafx.scene.shape.Rectangle;
>> import javafx.scene.shape.Shape;
>> import javafx.scene.text.Text;
>> import javafx.scene.text.TextFlow;
>> import javafx.stage.Stage;
>>
>>
>> public class CSSFlickerInTextFlow extends Application {
>>
>> public static void main(String[] args) {
>> launch(args);
>> }
>>
>> private CheckBox onlyCssCB;
>>
>> @Override
>> public void start(Stage stage) throws Exception {
>> ListView<String> list1 = new ListView<>();
>> ListView<String> list2 = new ListView<>();
>> var items1 = list1.getItems();
>> var items2 = list2.getItems();
>> for (int i = 1; i < 23; i++) {
>> var x = "Item #"+i;
>> items1.add(x);
>> items2.add(x);
>> }
>> list1.setCellFactory(t -> new MyCell1());
>> list2.setCellFactory(t -> new MyCell2());
>>
>> onlyCssCB = new CheckBox("Use only CSS (shapes will flicker in
>> TextFlow)");
>> HBox buttons = new HBox(8, onlyCssCB);
>> buttons.setPadding(new Insets(4));
>>
>> Tab custom = new Tab("Everything in Graphic", list1);
>> Tab withoutColoredText = new Tab("Graphic + Text", list2);
>> TabPane tabs = new TabPane(custom, withoutColoredText);
>>
>> VBox root = new VBox(
>> new Label("""
>> Focus in list, cursor up and down, pay
>> attention to the circle.
>> Try the same with the box checked - circle
>> flickers.
>> Doesn't happen when not using the TextFlow.
>> """),
>> buttons, tabs);
>> root.setPadding(new Insets(4));
>> var scene = new Scene(root);
>> stage.setScene(scene);
>> stage.setTitle("Flickering with CSS in TextFlow");
>> stage.show();
>> }
>>
>> private Shape makeGraphic() {
>> Shape graphic = new Circle(6);
>> if (!onlyCssCB.isSelected()) {
>> graphic.setFill(Color.SALMON); // CSS overrides these but
>> causes flickering if not the same
>> graphic.setStroke(Color.BLACK);
>> }
>> graphic.setStyle("-fx-fill: salmon; -fx-stroke: black;");
>> return graphic;
>> }
>>
>> class MyCell1 extends ListCell<String> {
>>
>> @Override
>> protected void updateItem(String item, boolean empty) {
>> super.updateItem(item, empty);
>> setContentDisplay(ContentDisplay.GRAPHIC_ONLY);
>> setText(null);
>> if (!empty && item != null) {
>> TextFlow flow = new TextFlow();
>> Shape graphic = makeGraphic();
>> graphic.setTranslateY(2);
>> var nodeList = flow.getChildren();
>> Text name = new Text(item + " : ");
>> name.setStyle("-fx-fill: -fx-text-background-color;");
>> Text extra = new Text("with Color");
>> extra.setStyle("-fx-fill:ladder(-fx-background, white
>> 49%, salmon 50%);");
>> nodeList.add(graphic);
>> nodeList.add(new Rectangle(4,0)); // gap
>> nodeList.add(name);
>> nodeList.add(extra);
>> setGraphic(flow);
>> } else {
>> setGraphic(null);
>> }
>> }
>> }
>>
>> class MyCell2 extends ListCell<String> {
>> @Override
>> protected void updateItem(String item, boolean empty) {
>> super.updateItem(item, empty);
>> if (!empty && item != null) {
>> setGraphic(makeGraphic());
>> setText(item);
>> } else {
>> setText(null);
>> setGraphic(null);
>> }
>> }
>> }
>> }
>>
>>
