I am building a picker replacement that uses a dialog to display a list of
buttons. (the iOS picker of only 3 lines is a joke)
The picker is a Dialog component with an associated button. When the
button is pressed, the dialog is shown. I would like to scroll to the last
selected item (even better would be to put it in the middle of the dialog).
when the button is clicked, my code does:
protected void onButton() {
cnt.removeAll();
for (T t : vData) {
Button b = new Button(t.toString());
b.setAlignment(LEFT);
b.addActionListener(e -> { onClick(t); });
cnt.add(b);
if (t == selectedObject)
cmpLastVisible = b;
}
if (cmpLastVisible != null)
cnt.scrollComponentToVisible(cmpLastVisible);
this.show();
}
however I believe it is too early to scrollComponent since the dialog is
not shown and is not layed out.
1: How can I scroll to component?
2: How can I scroll the component to the middle of the screen?
Here is the whole dialog:
package com.howudodat.pts.ui;
import java.util.ArrayList;
import com.codename1.ui.Button;
import com.codename1.ui.Component;
import com.codename1.ui.Container;
import com.codename1.ui.Dialog;
import com.codename1.ui.FontImage;
import com.codename1.ui.Label;
import com.codename1.ui.layouts.BorderLayout;
import com.codename1.ui.layouts.BoxLayout;
import com.codename1.ui.plaf.UIManager;
public class DlgPicker<T> extends Dialog {
// was the dialog canceled?
public boolean Cancelled = false;
// the data and container for the list
protected ArrayList<T>vData = null;
protected Container cnt = new Container();
// last selected objects
protected T selectedObject = null;
protected Component cmpLastVisible = null;
// this is the field that can be placed into the parent container
protected Button btnField = new Button();
// title bar for the dialog with a cancel button
protected Label lblTitle = new Label();
Button cmdClose = new
Button("",FontImage.createMaterial(FontImage.MATERIAL_CLEAR,
UIManager.getInstance().getComponentStyle("Command")));
/**
* constructor - Create a new DlgPicker with no parameters
*/
public DlgPicker() {
initManualComponents();
}
/**
* constructor - Create a new DlgPicker
* @param sTitle - title of the dialog
*/
public DlgPicker(String sTitle) {
lblTitle.setText(sTitle);
initManualComponents();
}
/**
* constructor - Create a new DlgPicker
* @param sTitle - title of the dialog
* @param vData - data for the list
*/
public DlgPicker(String sTitle, ArrayList<T> vData) {
this.vData = vData;
lblTitle.setText(sTitle);
initManualComponents();
}
/**
* create the base gui Note: the list is created when showing the dialog
*/
protected void initManualComponents() {
this.setLayout(new BorderLayout());
lblTitle.setAlignment(CENTER);
cmdClose.addActionListener(e->onClose());
btnField.addActionListener(e->onButton());
Container title = new Container();
title.setLayout(new BorderLayout());
title.add(BorderLayout.CENTER, lblTitle);
title.add(BorderLayout.EAST, cmdClose);
cnt.setLayout(new BoxLayout(BoxLayout.Y_AXIS));
cnt.setScrollableY(true);
this.add(BorderLayout.NORTH, title);
this.add(BorderLayout.CENTER, cnt);
}
/**
* retrieve the component to place in the parent (this is a button)
* @return Component
*/
public Component getComponent() {
return btnField;
}
/**
* set the title of the dialog
*/
public void setTitle(String sTitle) {
lblTitle.setText(sTitle);
}
/**
* set the data for the list
* @param vData
*/
public void setData(ArrayList<T>vData) {
this.vData = vData;
}
/**
* called when the button is clicked. This is where we load the data
and display the dialog
*/
protected void onButton() {
cnt.removeAll();
for (T t : vData) {
Button b = new Button(t.toString());
b.setAlignment(LEFT);
b.addActionListener(e -> { onClick(t); });
cnt.add(b);
if (t == selectedObject)
cmpLastVisible = b;
}
if (cmpLastVisible != null)
cnt.scrollComponentToVisible(cmpLastVisible);
this.show();
}
/**
* called when a list item is clicked. we save the object and set the
button text
* @param t
*/
protected void onClick(T t) {
selectedObject = t;
btnField.setText(t.toString());
this.dispose();
}
/**
* closed by clicking the cancel button
*/
protected void onClose() {
Cancelled = true;
dispose();
}
public void setSelectedObject(T t) {
selectedObject = t;
}
public T getSelectedObject() {
return selectedObject;
}
}
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