GWT 可调整大小的面板 [英] GWT resizable panel

问题描述

有没有办法在 GWT 中有一个可调整大小"的面板.

Is there any way to have a 'Resizable' panel in GWT.

通过调整大小我的意思是如果你在面板的边缘拖动它可以相应地调整大小.

By resizable I mean that if you you drag on the edge of Panel it can be resized accordingly.

推荐答案

自己想出来的，举个例子:

Figured it out myself, here is an example:

public class DraggablePanel extends VerticalPanel {
    private boolean isBeingDragged = false;
    private boolean isBeingMoved = false;
    private Element movingPanelElement;

    public void setMovingPanelElement(Element movingPanelElement) {
        this.movingPanelElement = movingPanelElement;
    }

    public DraggablePanel() {
        super();
        DOM.sinkEvents(getElement(), Event.ONMOUSEDOWN | Event.ONMOUSEMOVE
                | Event.ONMOUSEUP | Event.ONMOUSEOVER);
    }

    @Override
    public void onBrowserEvent(Event event) {
        final int eventType = DOM.eventGetType(event);
        if (Event.ONMOUSEOVER == eventType) {
            if (isCursorResize(event)) {
                getElement().getStyle().setProperty("cursor", "s-resize");
            } else if (isCursorMove(event)) {
                getElement().getStyle().setProperty("cursor", "move");
            } else {
                getElement().getStyle().setProperty("cursor", "default");
            }
        }
        if (Event.ONMOUSEDOWN == eventType) {
            if (isCursorResize(event)) {
                if (!isBeingDragged) {
                    isBeingDragged = true;
                    DOM.setCapture(getElement());
                }
            } else if (isCursorMove(event)) {
                DOM.setCapture(getElement());
                isBeingMoved = true;
            }
        } else if (Event.ONMOUSEMOVE == eventType) {
            if (!isCursorResize(event) && !isCursorMove(event)) {
                getElement().getStyle().setProperty("cursor", "default");
            }
            if (isBeingDragged) {
                int currentY = event.getClientY();
                int originalY = getElement().getAbsoluteTop();
                if (currentY > originalY) {
                    Integer height = currentY - originalY;
                    this.setHeight(height + "px");
                }
            } else if (isBeingMoved) {
                RootPanel.get().setWidgetPosition(this,
                        event.getClientX(), event.getClientY());
            }
        } else if (Event.ONMOUSEUP == eventType) {
            if (isBeingMoved) {
                isBeingMoved = false;
                DOM.releaseCapture(getElement());
            }
            if (isBeingDragged) {
                isBeingDragged = false;
                DOM.releaseCapture(getElement());
            }
        }
    }

    protected boolean isCursorResize(Event event) {
        int cursor = event.getClientY();
        int initial = getAbsoluteTop();
        int height = getOffsetHeight();
        return initial + height - 20 < cursor && cursor <= initial + height;
    }

    protected boolean isCursorMove(Event event) {
        int cursor = event.getClientY();
        int initial = movingPanelElement.getAbsoluteTop();
        int height = movingPanelElement.getOffsetHeight();
        return initial <= cursor && cursor <= initial + height;
    }
}

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