OverlayLayouter.java

/**
 * Copyright (c) 2014 - 2017 Frank Appel
 * All rights reserved. This program and the accompanying materials
 * are made available under the terms of the Eclipse Public License v1.0
 * which accompanies this distribution, and is available at
 * http://www.eclipse.org/legal/epl-v10.html
 *
 * Contributors:
 *   Frank Appel - initial API and implementation
 */
package com.codeaffine.eclipse.swt.widget.scrollable;

import static com.codeaffine.eclipse.swt.widget.scrollable.FlatScrollBarTree.MAX_EXPANSION;

import org.eclipse.swt.graphics.Point;
import org.eclipse.swt.graphics.Rectangle;
import org.eclipse.swt.widgets.Label;

import com.codeaffine.eclipse.swt.widget.scrollable.context.AdaptionContext;
import com.codeaffine.eclipse.swt.widget.scrollbar.FlatScrollBar;

class OverlayLayouter {

  static final int CORNER_COVERAGE = 2;

  private final FlatScrollBar horizontal;
  private final FlatScrollBar vertical;
  private final Label cornerOverlay;

  OverlayLayouter( FlatScrollBar horizontal, FlatScrollBar vertical, Label cornerOverlay  ) {
    this.cornerOverlay = cornerOverlay;
    this.horizontal = horizontal;
    this.vertical = vertical;
  }

  void layout( AdaptionContext<?> context ) {
    layoutVertical( context );
    layoutHorizontal( context );
    layoutCornerOverlay( context );
  }

  private void layoutVertical( AdaptionContext<?> context ) {
    if( context.isVerticalBarVisible() ) {
      int x = context.getVisibleArea().width - barBreadth( context ) - borderOffset( context );
      int height = computeVerticalHeight( context );
      vertical.setBounds( x, 0, barBreadth( context ), height );
      vertical.setVisible( true );
    } else {
      vertical.setVisible( false );
      vertical.setBounds( 0, 0, 0, 0 );
    }
  }

  private static int computeVerticalHeight( AdaptionContext<?> context ) {
    Rectangle visibleArea = context.getVisibleArea();
    int baseHeight = context.isHorizontalBarVisible() ? visibleArea.height - MAX_EXPANSION  : visibleArea.height;
    return baseHeight - borderOffset( context );
  }

  private void layoutHorizontal( AdaptionContext<?> context ) {
    if( context.isHorizontalBarVisible() ) {
      int y = context.getVisibleArea().height - barBreadth( context ) - borderOffset( context );
      int width = computeHorizontalWidth( context );
      horizontal.setBounds( 0, y, width, barBreadth( context ) );
      horizontal.setVisible( true );
    } else {
      horizontal.setVisible( false );
      horizontal.setBounds( 0, 0, 0, 0 );
    }
  }

  private static int computeHorizontalWidth( AdaptionContext<?> context ) {
    Rectangle visibleArea = context.getVisibleArea();
    int baseWidth = context.isVerticalBarVisible() ? visibleArea.width - MAX_EXPANSION : visibleArea.width;
    return baseWidth - borderOffset( context ) ;
  }

  private void layoutCornerOverlay( AdaptionContext<?> context ) {
    cornerOverlay.setBounds( calculateCornerOverlayBounds( horizontal, vertical, context ) );
  }

  static Rectangle calculateCornerOverlayBounds(
    FlatScrollBar horizontal, FlatScrollBar vertical, AdaptionContext<?> context )
  {
    Point hSize = horizontal.getSize();
    Point vSize = vertical.getSize();
    int borderWidth = context.getBorderWidth();
    int width = vSize.x + context.getOffset() + borderWidth + CORNER_COVERAGE;
    int height = hSize.y + borderWidth + CORNER_COVERAGE;
    return new Rectangle( hSize.x, vSize.y, width, height );
  }

  private static int borderOffset( AdaptionContext<?> context ) {
    return context.getBorderWidth() * 2;
  }

  private static int barBreadth( AdaptionContext<?> context ) {
    return context.get( Demeanor.class ).getBarBreadth();
  }
}