move Home JTree - Java Swing

Java examples for Swing:JTree

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Description

move Home JTree

Demo Code

/*//from   w  ww.ja va 2s  . c o m
 * Copyright 2003-2011 JetBrains s.r.o.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
//package com.java2s;

import javax.swing.JTree;

import javax.swing.tree.TreePath;
import java.awt.Rectangle;

public class Main {
    public static void moveHome(JTree tree) {
        showRowCentred(tree, 0);
    }

    private static void showRowCentred(JTree tree, int row) {
        showRowCentred(tree, row, true);
    }

    public static void showRowCentred(JTree tree, int row,
            boolean centerHorizontally) {
        int visible = getVisibleRowCount(tree);
        int top = visible > 0 ? row - (visible - 1) / 2 : row;
        int bottom = visible > 0 ? top + visible - 1 : row;
        showAndSelect(tree, top, bottom, row, centerHorizontally);
    }

    private static int getVisibleRowCount(JTree tree) {
        Rectangle visible = tree.getVisibleRect();
        int count = 0;
        for (int i = 0; i < tree.getRowCount(); i++) {
            Rectangle bounds = tree.getRowBounds(i);
            if (visible.y <= bounds.y
                    && visible.y + visible.height >= bounds.y
                            + bounds.height) {
                count++;
            }
        }
        return count;
    }

    private static void showAndSelect(JTree tree, int top, int bottom,
            int row, boolean centerHorizontally) {
        int size = tree.getRowCount();
        if (size == 0) {
            tree.clearSelection();
            return;
        }
        if (top < 0) {
            top = 0;
        }
        if (bottom >= size) {
            bottom = size - 1;
        }
        Rectangle topBounds = tree.getRowBounds(top);
        Rectangle bottomBounds = tree.getRowBounds(bottom);
        Rectangle bounds;
        if (topBounds == null) {
            bounds = bottomBounds;
        } else if (bottomBounds == null) {
            bounds = topBounds;
        } else {
            bounds = topBounds.union(bottomBounds);
        }
        if (bounds != null) {
            TreePath path = tree.getPathForRow(row);
            if (path != null && path.getParentPath() != null) {
                Rectangle parentBounds = tree.getPathBounds(path
                        .getParentPath());
                if (parentBounds != null) {
                    bounds.x = parentBounds.x;
                }
            }
            if (!centerHorizontally) {
                bounds.x = 0;
                bounds.width = tree.getWidth();
            } else {
                bounds.width = Math.min(bounds.width,
                        tree.getVisibleRect().width);
            }
            tree.scrollRectToVisible(bounds);
        }
        tree.setSelectionRow(row);
    }
}

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