ColoredRangeManager.java

/*
Copyright 2011-2016 Google Inc. All Rights Reserved.

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.google.security.zynamics.zylib.gui.JHexPanel;

import java.util.ArrayList;
import java.util.Collections;

public class ColoredRangeManager {
  private final ArrayList<ColoredRange> ranges = new ArrayList<ColoredRange>();

  public void addRange(final ColoredRange range) {
    ranges.add(range);

    Collections.sort(ranges);
  }

  public void clear() {
    ranges.clear();
  }

  public ColoredRange findRange(final long offset) {
    for (final ColoredRange range : ranges) {
      if (range.getStart() >= offset) {
        return range;
      }
    }

    return null;
  }

  public ColoredRange findRangeWith(final long offset) {
    for (final ColoredRange range : ranges) {
      if (range.containsOffset(offset)) {
        return range;
      }
    }

    return null;
  }

  public void removeRange(final long offset, final int size) {
    // Try to find the range that contains the offset
    ColoredRange range = findRangeWith(offset);

    // If there is no such range, at least find the range right
    // before the offset.
    if (range == null) {
      range = findRange(offset);
    }

    // If there is no such range then there is nothing to remove.
    if (range == null) {
      return;
    }

    // TODO: The <= is a hack; used to be just ==; Check this again
    if (offset <= range.getStart()) {
      // The offset starts exactly at the range. That means
      // we start decolorizing at the beginning of the range.

      if (range.getSize() == size) {
        // If the sizes are equal the entire range is decolorized and we're done.

        ranges.remove(range);
      } else if (range.getSize() < size) {
        // If the range is smaller the entire range is decolorized and the
        // remaining bytes are decolorized in the next step.

        ranges.remove(range);
        removeRange(range.getStart() + range.getSize(), size - range.getSize());
      } else
      // if (range.getSize() > size)
      {
        // If the range is larger than the decolorizing area, ditch the
        // range and add a new range that contains the area that stays colorized.

        ranges.remove(range);
        addRange(new ColoredRange(offset + size, range.getSize() - size, range.getColor(),
            range.getBackgroundColor()));
      }
    } else
    // if (offset > range.getStart())
    {
      // We start to decolorize somewhere in the middle of the range.

      if ((offset + size) == (range.getStart() + range.getSize())) {
        // If the last offset of the range and the decolorizing area is equal,
        // then the latter part of the range is ditched. Get rid of the range
        // and create a new range that represents the first part of the area.

        ranges.remove(range);

        final long newStart = range.getStart();
        final int newSize = range.getSize() - size;
        // int newSize = (int)(offset - range.getStart());
        addRange(new ColoredRange(newStart, newSize, range.getColor(), range.getBackgroundColor()));
      } else if ((offset + size) < (range.getStart() + range.getSize())) {
        // Some part is cut out of the middle of the range. Get rid of the old range
        // and create two new ranges for the first part and last part of the old range.

        ranges.remove(range);

        final long newStartFirst = range.getStart();
        final int newSizeFirst = (int) (offset - range.getStart());

        addRange(new ColoredRange(newStartFirst, newSizeFirst, range.getColor(),
            range.getBackgroundColor()));

        final long newStartLast = offset + size;
        final int newSizeLast = (int) ((range.getStart() + range.getSize()) - offset - size);

        addRange(new ColoredRange(newStartLast, newSizeLast, range.getColor(),
            range.getBackgroundColor()));
      } else
      // if (offset + size > range.getStart() + range.getSize())
      {
        // More than the current range must be decolorized. That means the entire range
        // except for the start is ditched.

        ranges.remove(range);

        final long newStart = range.getStart();
        final int newSize = (int) (offset - range.getStart());

        addRange(new ColoredRange(newStart, newSize, range.getColor(), range.getBackgroundColor()));
        removeRange(range.getStart() + range.getSize(),
            size - (int) ((range.getStart() + range.getSize()) - offset));
      }
    }
  }
}