CODEWITHSUNDEEP
javajavafxscrollpane
Dims
Dims

Reputation: 51229

Is it possible to scroll ScrollPane programmatically to given position?

Is it possible to scroll ScrollPane programmatically to given position?

ScrollPane#vvalue and ScrollPane#hvalue are useless, because they vary from 0 to 1. Are there any absolute properties or I should code them myself?

Upvotes: 1

Views: 3140

Answers (4)

FLUXparticle
FLUXparticle

Reputation: 1203

@trilogy asked for a code answer to this question... And here it is:

static void scrollToPosition(ScrollPane scrollPane, double topLeftX, double topLeftY) {
    Bounds contentBounds = scrollPane.getContent().getBoundsInLocal();
    Bounds viewportBounds = scrollPane.getViewportBounds();
        
    double hValue = topLeftX / (contentBounds.getWidth() - viewportBounds.getWidth());
    double vValue = topLeftY / (contentBounds.getHeight() - viewportBounds.getHeight());

    scrollPane.setHvalue(hValue);
    scrollPane.setVvalue(vValue);
}

Upvotes: 0

TBF
TBF

Reputation: 102

Use setHvalue and setVvalue to position your scrollPane.

Values can be calculated with respect to Nodes

For eg:

double nodeX = dummyNode.getBoundsInParent().getMaxX(); double nodeY = dummyNode.getBoundsInParent().getMaxY(); double scrollPaneWidth = dummyScrollPane.getContent().getBoundsInLocal().getWidth() double scrollPaneHeight = dummyScrollPane.getContent().getBoundsInLocal().getHeight() dummyScrollPane.setVvalue(nodeY/height); dummyScrollPane.setHvalue(nodeX/width);

Upvotes: 0

fabian
fabian

Reputation: 82491

Those properties are not useless, you just need to know how to use them correctly. (There are no methods allowing you to specify absolute values directly.)

Assuming the ScrollBar is visible, you know the following equation

topLeft / (contentSize - viewportSize) = scrollValue / scrollMax

This can be reformulated as

scrollValue = (topLeft * scrollMax) / (contentSize - viewportSize)
            = topLeft / (contentSize - viewportSize)

hvalue = topLeftX / (contentWidth - viewportWidth)
vvalue = topLeftY / (contentHeight - viewportHeight)

Where topLeftX and topLeftY are the x and y coordiantes of the pixel in the top left corner of the viewport. Use the viewportBounds to determine the size of the viewport.

Upvotes: 4

Politic Revolutionnaire
Politic Revolutionnaire

Reputation: 927

If you mean move the scroll pane a given number of pixels then get the image size and calculate how much you need to move with hvalue or vvalue.

int pixelsH = 45; int change = pixelsH/scrollpane.getWidth(); scrollpane.setHvalue(scrollpane.getHValue() + change);

Same concept for vertical change.

Upvotes: 1

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