java - Scroll bars / scrollpane disappearing upon image upload and zoom in JavaFX

Question

This is a JavaFX application. There is an imageView nested inside a Scroll Pane, and before an image loads/displays, the scroll bars are visible. However, when the user uploads the image or clicks/zooms in on the image, the scroll bars disappear. This leaves only a portion of the image visible.

I'm a very new developer so I might be using the wrong methods to resize the image. I also might be calling the method on the wrong object (in this case, the imageView itself is acted upon, not the image object painted on it).

Here is the zoom method I built:

// a method that allows user to zoom in and out on the image
    @FXML
    private void zoomImage(MouseEvent event) {
        if (imageDisplay != null) {
            if (imageDisplay.getScaleX() == 1.0 & imageDisplay.getScaleY() 
== 1.0) {
                imageDisplay.setScaleX(3.0);
                imageDisplay.setScaleY(3.0);
            } else {
                imageDisplay.setScaleX(1.0);
                imageDisplay.setScaleY(1.0);
            }
        } else {
            return;
        }
    }

(Here is the FXML for the imageView and Scroll Pane, both of which are in a VBox)

<ScrollPane>
    <content>
         <ImageView fx:id="imageDisplay" fitHeight="300.0" fitWidth="650.0" 
onDragDropped="#handleImageDrop" onDragOver="#handleImageDrag" 
onMouseClicked="#zoomImage" pickOnBounds="true" preserveRatio="true" />
    </content>
</ScrollPane>

I expect the scroll bars to remain visible after the image is uploaded and zoomed in.

标签： javajavafxscenebuilder

Answer 1

hbarPolicy="ALWAYS" vbarPolicy="ALWAYS">您可以通过添加默认值或未指定设置来将滚动条设置为从 fxml 始终可见，AS_NEEDED这就是它们可能不会显示的原因

前任。

<ScrollPane hbarPolicy="ALWAYS" vbarPolicy="ALWAYS">
    <content>
        <ImageView fx:id="imageDisplay" fitHeight="300.0" fitWidth="650.0"
                   onDragDropped="#handleImageDrop" onDragOver="#handleImageDrag"
                   onMouseClicked="#zoomImage" pickOnBounds="true" preserveRatio="true" />
    </content>
</ScrollPane>

或者，您可以使用代码例如

scrollPane.setVbarPolicy(ScrollPane.ScrollBarPolicy.ALWAYS);