/*
* Copyright 2002-2012 Drew Noakes
*
* 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.
*
* More information about this project is available at:
*
* http://drewnoakes.com/code/exif/
* http://code.google.com/p/metadata-extractor/
*/
package com.drew.metadata.exif;
import com.drew.lang.Rational;
import com.drew.lang.annotations.NotNull;
import com.drew.lang.annotations.Nullable;
import com.drew.metadata.TagDescriptor;
import java.io.UnsupportedEncodingException;
/**
* Provides human-readable string representations of tag values stored in a <code>ExifIFD0Directory</code>.
*
* @author Drew Noakes http://drewnoakes.com
*/
public class ExifIFD0Descriptor extends TagDescriptor<ExifIFD0Directory>
{
/**
* Dictates whether rational values will be represented in decimal format in instances
* where decimal notation is elegant (such as 1/2 -> 0.5, but not 1/3).
*/
private final boolean _allowDecimalRepresentationOfRationals = true;
public ExifIFD0Descriptor(@NotNull ExifIFD0Directory directory)
{
super(directory);
}
// Note for the potential addition of brightness presentation in eV:
// Brightness of taken subject. To calculate Exposure(Ev) from BrightnessValue(Bv),
// you must add SensitivityValue(Sv).
// Ev=BV+Sv Sv=log2(ISOSpeedRating/3.125)
// ISO100:Sv=5, ISO200:Sv=6, ISO400:Sv=7, ISO125:Sv=5.32.
/**
* Returns a descriptive value of the the specified tag for this image.
* Where possible, known values will be substituted here in place of the raw
* tokens actually kept in the Exif segment. If no substitution is
* available, the value provided by getString(int) will be returned.
* @param tagType the tag to find a description for
* @return a description of the image's value for the specified tag, or
* <code>null</code> if the tag hasn't been defined.
*/
@Nullable
public String getDescription(int tagType)
{
switch (tagType) {
case ExifIFD0Directory.TAG_RESOLUTION_UNIT:
return getResolutionDescription();
case ExifIFD0Directory.TAG_YCBCR_POSITIONING:
return getYCbCrPositioningDescription();
case ExifIFD0Directory.TAG_X_RESOLUTION:
return getXResolutionDescription();
case ExifIFD0Directory.TAG_Y_RESOLUTION:
return getYResolutionDescription();
case ExifIFD0Directory.TAG_REFERENCE_BLACK_WHITE:
return getReferenceBlackWhiteDescription();
case ExifIFD0Directory.TAG_ORIENTATION:
return getOrientationDescription();
case ExifIFD0Directory.TAG_WIN_AUTHOR:
return getWindowsAuthorDescription();
case ExifIFD0Directory.TAG_WIN_COMMENT:
return getWindowsCommentDescription();
case ExifIFD0Directory.TAG_WIN_KEYWORDS:
return getWindowsKeywordsDescription();
case ExifIFD0Directory.TAG_WIN_SUBJECT:
return getWindowsSubjectDescription();
case ExifIFD0Directory.TAG_WIN_TITLE:
return getWindowsTitleDescription();
default:
return super.getDescription(tagType);
}
}
@Nullable
public String getReferenceBlackWhiteDescription()
{
int[] ints = _directory.getIntArray(ExifIFD0Directory.TAG_REFERENCE_BLACK_WHITE);
if (ints==null)
return null;
int blackR = ints[0];
int whiteR = ints[1];
int blackG = ints[2];
int whiteG = ints[3];
int blackB = ints[4];
int whiteB = ints[5];
return "[" + blackR + "," + blackG + "," + blackB + "] " +
"[" + whiteR + "," + whiteG + "," + whiteB + "]";
}
@Nullable
public String getYResolutionDescription()
{
Rational value = _directory.getRational(ExifIFD0Directory.TAG_Y_RESOLUTION);
if (value==null)
return null;
final String unit = getResolutionDescription();
return value.toSimpleString(_allowDecimalRepresentationOfRationals) +
" dots per " +
(unit==null ? "unit" : unit.toLowerCase());
}
@Nullable
public String getXResolutionDescription()
{
Rational value = _directory.getRational(ExifIFD0Directory.TAG_X_RESOLUTION);
if (value==null)
return null;
final String unit = getResolutionDescription();
return value.toSimpleString(_allowDecimalRepresentationOfRationals) +
" dots per " +
(unit==null ? "unit" : unit.toLowerCase());
}
@Nullable
public String getYCbCrPositioningDescription()
{
Integer value = _directory.getInteger(ExifIFD0Directory.TAG_YCBCR_POSITIONING);
if (value==null)
return null;
switch (value) {
case 1: return "Center of pixel array";
case 2: return "Datum point";
default:
return String.valueOf(value);
}
}
@Nullable
public String getOrientationDescription()
{
Integer value = _directory.getInteger(ExifIFD0Directory.TAG_ORIENTATION);
if (value==null)
return null;
switch (value) {
case 1: return "Top, left side (Horizontal / normal)";
case 2: return "Top, right side (Mirror horizontal)";
case 3: return "Bottom, right side (Rotate 180)";
case 4: return "Bottom, left side (Mirror vertical)";
case 5: return "Left side, top (Mirror horizontal and rotate 270 CW)";
case 6: return "Right side, top (Rotate 90 CW)";
case 7: return "Right side, bottom (Mirror horizontal and rotate 90 CW)";
case 8: return "Left side, bottom (Rotate 270 CW)";
default:
return String.valueOf(value);
}
}
@Nullable
public String getResolutionDescription()
{
// '1' means no-unit, '2' means inch, '3' means centimeter. Default value is '2'(inch)
Integer value = _directory.getInteger(ExifIFD0Directory.TAG_RESOLUTION_UNIT);
if (value==null)
return null;
switch (value) {
case 1: return "(No unit)";
case 2: return "Inch";
case 3: return "cm";
default:
return "";
}
}
/** The Windows specific tags uses plain Unicode. */
@Nullable
private String getUnicodeDescription(int tag)
{
byte[] commentBytes = _directory.getByteArray(tag);
if (commentBytes==null)
return null;
try {
// Decode the unicode string and trim the unicode zero "\0" from the end.
return new String(commentBytes, "UTF-16LE").trim();
}
catch (UnsupportedEncodingException ex) {
return null;
}
}
@Nullable
public String getWindowsAuthorDescription()
{
return getUnicodeDescription(ExifIFD0Directory.TAG_WIN_AUTHOR);
}
@Nullable
public String getWindowsCommentDescription()
{
return getUnicodeDescription(ExifIFD0Directory.TAG_WIN_COMMENT);
}
@Nullable
public String getWindowsKeywordsDescription()
{
return getUnicodeDescription(ExifIFD0Directory.TAG_WIN_KEYWORDS);
}
@Nullable
public String getWindowsTitleDescription()
{
return getUnicodeDescription(ExifIFD0Directory.TAG_WIN_TITLE);
}
@Nullable
public String getWindowsSubjectDescription()
{
return getUnicodeDescription(ExifIFD0Directory.TAG_WIN_SUBJECT);
}
}