TurboJPEG: Add alpha offset array/method

Also, set the red/green/blue offsets for TJPF_GRAY to -1 rather than 0.
It was undefined behavior for an application to use those arrays/methods
with TJPF_GRAY anyhow, and this makes it easier for applications to
programmatically detect whether a given pixel format has red, green, and
blue components.

ChangeLog.md

@@ -110,6 +110,16 @@ TJBench, and they also provide a convenient way for first-time users of
 libjpeg-turbo to quickly develop a complete JPEG compression/decompression
 program.
 
+14. The TurboJPEG C API now includes a new convenience array
+(`tjAlphaOffset[]`) that contains the alpha component index for each pixel
+format (or -1 if the pixel format lacks an alpha component.)  The TurboJPEG
+Java API now includes a new method (`TJ.getAlphaOffset()`) that returns the
+same value.  In addition, the `tjRedOffset[]`, `tjGreenOffset[]`, and
+`tjBlueOffset[]` arrays-- and the corresponding `TJ.getRedOffset()`,
+`TJ.getGreenOffset()`, and `TJ.getBlueOffset()` methods-- now return -1 for
+`TJPF_GRAY`/`TJ.PF_GRAY` rather than 0.  This allows programs to easily
+determine whether a pixel format has red, green, blue, and alpha components.
+
 
 1.5.2
 =====

doc/html/group___turbo_j_p_e_g.html

@@ -347,6 +347,9 @@ Variables</h2></td></tr>
 <tr class="memitem:ga84e2e35d3f08025f976ec1ec53693dea"><td class="memItemLeft" align="right" valign="top">static const int&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="group___turbo_j_p_e_g.html#ga84e2e35d3f08025f976ec1ec53693dea">tjBlueOffset</a> [<a class="el" href="group___turbo_j_p_e_g.html#ga7010a4402f54a45ba822ad8675a4655e">TJ_NUMPF</a>]</td></tr>
 <tr class="memdesc:ga84e2e35d3f08025f976ec1ec53693dea"><td class="mdescLeft">&#160;</td><td class="mdescRight">Blue offset (in bytes) for a given pixel format.  <a href="#ga84e2e35d3f08025f976ec1ec53693dea">More...</a><br/></td></tr>
 <tr class="separator:ga84e2e35d3f08025f976ec1ec53693dea"><td class="memSeparator" colspan="2">&#160;</td></tr>
+<tr class="memitem:ga5af0ab065feefd526debf1e20c43e837"><td class="memItemLeft" align="right" valign="top">static const int&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="group___turbo_j_p_e_g.html#ga5af0ab065feefd526debf1e20c43e837">tjAlphaOffset</a> [<a class="el" href="group___turbo_j_p_e_g.html#ga7010a4402f54a45ba822ad8675a4655e">TJ_NUMPF</a>]</td></tr>
+<tr class="memdesc:ga5af0ab065feefd526debf1e20c43e837"><td class="mdescLeft">&#160;</td><td class="mdescRight">Alpha offset (in bytes) for a given pixel format.  <a href="#ga5af0ab065feefd526debf1e20c43e837">More...</a><br/></td></tr>
+<tr class="separator:ga5af0ab065feefd526debf1e20c43e837"><td class="memSeparator" colspan="2">&#160;</td></tr>
 <tr class="memitem:gad77cf8fe5b2bfd3cb3f53098146abb4c"><td class="memItemLeft" align="right" valign="top">static const int&#160;</td><td class="memItemRight" valign="bottom"><a class="el" href="group___turbo_j_p_e_g.html#gad77cf8fe5b2bfd3cb3f53098146abb4c">tjPixelSize</a> [<a class="el" href="group___turbo_j_p_e_g.html#ga7010a4402f54a45ba822ad8675a4655e">TJ_NUMPF</a>]</td></tr>
 <tr class="memdesc:gad77cf8fe5b2bfd3cb3f53098146abb4c"><td class="mdescLeft">&#160;</td><td class="mdescRight">Pixel size (in bytes) for a given pixel format.  <a href="#gad77cf8fe5b2bfd3cb3f53098146abb4c">More...</a><br/></td></tr>
 <tr class="separator:gad77cf8fe5b2bfd3cb3f53098146abb4c"><td class="memSeparator" colspan="2">&#160;</td></tr>
@@ -2581,6 +2584,29 @@ If you choose option 1, <code>dstSizes[i]</code> should be set to the size of yo
 </div>
 </div>
 <h2 class="groupheader">Variable Documentation</h2>
+<a class="anchor" id="ga5af0ab065feefd526debf1e20c43e837"></a>
+<div class="memitem">
+<div class="memproto">
+<table class="mlabels">
+  <tr>
+  <td class="mlabels-left">
+      <table class="memname">
+        <tr>
+          <td class="memname">const int tjAlphaOffset[<a class="el" href="group___turbo_j_p_e_g.html#ga7010a4402f54a45ba822ad8675a4655e">TJ_NUMPF</a>]</td>
+        </tr>
+      </table>
+  </td>
+  <td class="mlabels-right">
+<span class="mlabels"><span class="mlabel">static</span></span>  </td>
+  </tr>
+</table>
+</div><div class="memdoc">
+
+<p>Alpha offset (in bytes) for a given pixel format. </p>
+<p>This specifies the number of bytes that the Alpha component is offset from the start of the pixel. For instance, if a pixel of format TJ_BGRA is stored in <code>char pixel[]</code>, then the alpha component will be <code>pixel[tjAlphaOffset[TJ_BGRA]]</code>. This will be -1 if the pixel format does not have an alpha component. </p>
+
+</div>
+</div>
 <a class="anchor" id="ga84e2e35d3f08025f976ec1ec53693dea"></a>
 <div class="memitem">
 <div class="memproto">
@@ -2600,7 +2626,7 @@ If you choose option 1, <code>dstSizes[i]</code> should be set to the size of yo
 </div><div class="memdoc">
 
 <p>Blue offset (in bytes) for a given pixel format. </p>
-<p>This specifies the number of bytes that the Blue component is offset from the start of the pixel. For instance, if a pixel of format TJ_BGRX is stored in <code>char pixel[]</code>, then the blue component will be <code>pixel[tjBlueOffset[TJ_BGRX]]</code>. </p>
+<p>This specifies the number of bytes that the Blue component is offset from the start of the pixel. For instance, if a pixel of format TJ_BGRX is stored in <code>char pixel[]</code>, then the blue component will be <code>pixel[tjBlueOffset[TJ_BGRX]]</code>. This will be -1 if the pixel format does not have a blue component. </p>
 
 </div>
 </div>
@@ -2623,7 +2649,7 @@ If you choose option 1, <code>dstSizes[i]</code> should be set to the size of yo
 </div><div class="memdoc">
 
 <p>Green offset (in bytes) for a given pixel format. </p>
-<p>This specifies the number of bytes that the green component is offset from the start of the pixel. For instance, if a pixel of format TJ_BGRX is stored in <code>char pixel[]</code>, then the green component will be <code>pixel[tjGreenOffset[TJ_BGRX]]</code>. </p>
+<p>This specifies the number of bytes that the green component is offset from the start of the pixel. For instance, if a pixel of format TJ_BGRX is stored in <code>char pixel[]</code>, then the green component will be <code>pixel[tjGreenOffset[TJ_BGRX]]</code>. This will be -1 if the pixel format does not have a green component. </p>
 
 </div>
 </div>
@@ -2728,7 +2754,7 @@ If you choose option 1, <code>dstSizes[i]</code> should be set to the size of yo
 </div><div class="memdoc">
 
 <p>Red offset (in bytes) for a given pixel format. </p>
-<p>This specifies the number of bytes that the red component is offset from the start of the pixel. For instance, if a pixel of format TJ_BGRX is stored in <code>char pixel[]</code>, then the red component will be <code>pixel[tjRedOffset[TJ_BGRX]]</code>. </p>
+<p>This specifies the number of bytes that the red component is offset from the start of the pixel. For instance, if a pixel of format TJ_BGRX is stored in <code>char pixel[]</code>, then the red component will be <code>pixel[tjRedOffset[TJ_BGRX]]</code>. This will be -1 if the pixel format does not have a red component. </p>
 
 </div>
 </div>

doc/html/search/all_74.js

@@ -6,6 +6,7 @@ var searchData=
   ['tj_5fnumsamp',['TJ_NUMSAMP',['../group___turbo_j_p_e_g.html#ga5ef3d169162ce77ce348e292a0b7477c',1,'turbojpeg.h']]],
   ['tj_5fnumxop',['TJ_NUMXOP',['../group___turbo_j_p_e_g.html#ga0f6dbd18adf38b7d46ac547f0f4d562c',1,'turbojpeg.h']]],
   ['tjalloc',['tjAlloc',['../group___turbo_j_p_e_g.html#ga5c9234bda6d993cdaffdd89bf81a00ff',1,'turbojpeg.h']]],
+  ['tjalphaoffset',['tjAlphaOffset',['../group___turbo_j_p_e_g.html#ga5af0ab065feefd526debf1e20c43e837',1,'turbojpeg.h']]],
   ['tjblueoffset',['tjBlueOffset',['../group___turbo_j_p_e_g.html#ga84e2e35d3f08025f976ec1ec53693dea',1,'turbojpeg.h']]],
   ['tjbufsize',['tjBufSize',['../group___turbo_j_p_e_g.html#gaccc5bca7f12fcdcc302e6e1c6d4b311b',1,'turbojpeg.h']]],
   ['tjbufsizeyuv2',['tjBufSizeYUV2',['../group___turbo_j_p_e_g.html#gaf451664a62c1f6c7cc5a6401f32908c9',1,'turbojpeg.h']]],

doc/html/search/variables_74.js

@@ -1,5 +1,6 @@
 var searchData=
 [
+  ['tjalphaoffset',['tjAlphaOffset',['../group___turbo_j_p_e_g.html#ga5af0ab065feefd526debf1e20c43e837',1,'turbojpeg.h']]],
   ['tjblueoffset',['tjBlueOffset',['../group___turbo_j_p_e_g.html#ga84e2e35d3f08025f976ec1ec53693dea',1,'turbojpeg.h']]],
   ['tjgreenoffset',['tjGreenOffset',['../group___turbo_j_p_e_g.html#ga82d6e35da441112a411da41923c0ba2f',1,'turbojpeg.h']]],
   ['tjmcuheight',['tjMCUHeight',['../group___turbo_j_p_e_g.html#gabd247bb9fecb393eca57366feb8327bf',1,'turbojpeg.h']]],

java/TJUnitTest.java

@@ -64,10 +64,6 @@ public class TJUnitTest {
     "RGBA", "BGRA", "ABGR", "ARGB", "CMYK"
   };
 
-  private static final int[] alphaOffset = {
-    -1, -1, -1, -1, -1, -1, -1, 3, 3, 0, 0, -1
-  };
-
   private static final int[] _3byteFormats = {
     TJ.PF_RGB, TJ.PF_BGR
   };
@@ -146,7 +142,7 @@ public class TJUnitTest {
     int roffset = TJ.getRedOffset(pf);
     int goffset = TJ.getGreenOffset(pf);
     int boffset = TJ.getBlueOffset(pf);
-    int aoffset = alphaOffset[pf];
+    int aoffset = TJ.getAlphaOffset(pf);
     int ps = TJ.getPixelSize(pf);
     int index, row, col, halfway = 16;
 
@@ -215,7 +211,7 @@ public class TJUnitTest {
     int rshift = TJ.getRedOffset(pf) * 8;
     int gshift = TJ.getGreenOffset(pf) * 8;
     int bshift = TJ.getBlueOffset(pf) * 8;
-    int ashift = alphaOffset[pf] * 8;
+    int ashift = TJ.getAlphaOffset(pf) * 8;
     int index, row, col, halfway = 16;
 
     Arrays.fill(buf, 0);
@@ -298,7 +294,7 @@ public class TJUnitTest {
     int roffset = TJ.getRedOffset(pf);
     int goffset = TJ.getGreenOffset(pf);
     int boffset = TJ.getBlueOffset(pf);
-    int aoffset = alphaOffset[pf];
+    int aoffset = TJ.getAlphaOffset(pf);
     int ps = TJ.getPixelSize(pf);
     int index, row, col, retval = 1;
     int halfway = 16 * sf.getNum() / sf.getDenom();
@@ -306,6 +302,9 @@ public class TJUnitTest {
 
     try {
 
+      if (pf == TJ.PF_GRAY)
+        roffset = goffset = boffset = 0;
+
       if (pf == TJ.PF_CMYK) {
         for (row = 0; row < h; row++) {
           for (col = 0; col < w; col++) {
@@ -422,7 +421,7 @@ public class TJUnitTest {
     int rshift = TJ.getRedOffset(pf) * 8;
     int gshift = TJ.getGreenOffset(pf) * 8;
     int bshift = TJ.getBlueOffset(pf) * 8;
-    int ashift = alphaOffset[pf] * 8;
+    int ashift = TJ.getAlphaOffset(pf) * 8;
     int index, row, col, retval = 1;
     int halfway = 16 * sf.getNum() / sf.getDenom();
     int blockSize = 8 * sf.getNum() / sf.getDenom();

java/doc/constant-values.html

@@ -7,8 +7,12 @@
 </head>
 <body>
 <script type="text/javascript"><!--
-    if (location.href.indexOf('is-external=true') == -1) {
+    try {
-        parent.document.title="Constant Field Values";
+        if (location.href.indexOf('is-external=true') == -1) {
+            parent.document.title="Constant Field Values";
+        }
+    }
+    catch(err) {
     }
 //-->
 </script>

java/doc/deprecated-list.html

@@ -7,8 +7,12 @@
 </head>
 <body>
 <script type="text/javascript"><!--
-    if (location.href.indexOf('is-external=true') == -1) {
+    try {
-        parent.document.title="Deprecated List";
+        if (location.href.indexOf('is-external=true') == -1) {
+            parent.document.title="Deprecated List";
+        }
+    }
+    catch(err) {
     }
 //-->
 </script>

java/doc/help-doc.html

@@ -7,8 +7,12 @@
 </head>
 <body>
 <script type="text/javascript"><!--
-    if (location.href.indexOf('is-external=true') == -1) {
+    try {
-        parent.document.title="API Help";
+        if (location.href.indexOf('is-external=true') == -1) {
+            parent.document.title="API Help";
+        }
+    }
+    catch(err) {
     }
 //-->
 </script>

java/doc/index-all.html

@@ -7,8 +7,12 @@
 </head>
 <body>
 <script type="text/javascript"><!--
-    if (location.href.indexOf('is-external=true') == -1) {
+    try {
-        parent.document.title="Index";
+        if (location.href.indexOf('is-external=true') == -1) {
+            parent.document.title="Index";
+        }
+    }
+    catch(err) {
     }
 //-->
 </script>
@@ -349,6 +353,11 @@
 </a>
 <h2 class="title">G</h2>
 <dl>
+<dt><span class="strong"><a href="./org/libjpegturbo/turbojpeg/TJ.html#getAlphaOffset(int)">getAlphaOffset(int)</a></span> - Static method in class org.libjpegturbo.turbojpeg.<a href="./org/libjpegturbo/turbojpeg/TJ.html" title="class in org.libjpegturbo.turbojpeg">TJ</a></dt>
+<dd>
+<div class="block">For the given pixel format, returns the number of bytes that the alpha
+ component is offset from the start of the pixel.</div>
+</dd>
 <dt><span class="strong"><a href="./org/libjpegturbo/turbojpeg/TJ.html#getBlueOffset(int)">getBlueOffset(int)</a></span> - Static method in class org.libjpegturbo.turbojpeg.<a href="./org/libjpegturbo/turbojpeg/TJ.html" title="class in org.libjpegturbo.turbojpeg">TJ</a></dt>
 <dd>
 <div class="block">For the given pixel format, returns the number of bytes that the blue

java/doc/index.html

@@ -4,11 +4,12 @@
 <head>
 <title>Generated Documentation (Untitled)</title>
 <script type="text/javascript">
-    targetPage = "" + window.location.search;
+    tmpTargetPage = "" + window.location.search;
-    if (targetPage != "" && targetPage != "undefined")
+    if (tmpTargetPage != "" && tmpTargetPage != "undefined")
-        targetPage = targetPage.substring(1);
+        tmpTargetPage = tmpTargetPage.substring(1);
-    if (targetPage.indexOf(":") != -1 || (targetPage != "" && !validURL(targetPage)))
+    if (tmpTargetPage.indexOf(":") != -1 || (tmpTargetPage != "" && !validURL(tmpTargetPage)))
-        targetPage = "undefined";
+        tmpTargetPage = "undefined";
+    targetPage = tmpTargetPage;
     function validURL(url) {
         try {
             url = decodeURIComponent(url);

java/doc/org/libjpegturbo/turbojpeg/TJ.html

@@ -7,8 +7,12 @@
 </head>
 <body>
 <script type="text/javascript"><!--
-    if (location.href.indexOf('is-external=true') == -1) {
+    try {
-        parent.document.title="TJ";
+        if (location.href.indexOf('is-external=true') == -1) {
+            parent.document.title="TJ";
+        }
+    }
+    catch(err) {
     }
 //-->
 </script>
@@ -417,53 +421,60 @@ extends java.lang.Object</pre>
 </tr>
 <tr class="rowColor">
 <td class="colFirst"><code>static int</code></td>
+<td class="colLast"><code><strong><a href="../../../org/libjpegturbo/turbojpeg/TJ.html#getAlphaOffset(int)">getAlphaOffset</a></strong>(int&nbsp;pixelFormat)</code>
+<div class="block">For the given pixel format, returns the number of bytes that the alpha
+ component is offset from the start of the pixel.</div>
+</td>
+</tr>
+<tr class="altColor">
+<td class="colFirst"><code>static int</code></td>
 <td class="colLast"><code><strong><a href="../../../org/libjpegturbo/turbojpeg/TJ.html#getBlueOffset(int)">getBlueOffset</a></strong>(int&nbsp;pixelFormat)</code>
 <div class="block">For the given pixel format, returns the number of bytes that the blue
  component is offset from the start of the pixel.</div>
 </td>
 </tr>
-<tr class="altColor">
+<tr class="rowColor">
 <td class="colFirst"><code>static int</code></td>
 <td class="colLast"><code><strong><a href="../../../org/libjpegturbo/turbojpeg/TJ.html#getGreenOffset(int)">getGreenOffset</a></strong>(int&nbsp;pixelFormat)</code>
 <div class="block">For the given pixel format, returns the number of bytes that the green
  component is offset from the start of the pixel.</div>
 </td>
 </tr>
-<tr class="rowColor">
+<tr class="altColor">
 <td class="colFirst"><code>static int</code></td>
 <td class="colLast"><code><strong><a href="../../../org/libjpegturbo/turbojpeg/TJ.html#getMCUHeight(int)">getMCUHeight</a></strong>(int&nbsp;subsamp)</code>
 <div class="block">Returns the MCU block height for the given level of chrominance
  subsampling.</div>
 </td>
 </tr>
-<tr class="altColor">
+<tr class="rowColor">
 <td class="colFirst"><code>static int</code></td>
 <td class="colLast"><code><strong><a href="../../../org/libjpegturbo/turbojpeg/TJ.html#getMCUWidth(int)">getMCUWidth</a></strong>(int&nbsp;subsamp)</code>
 <div class="block">Returns the MCU block width for the given level of chrominance
  subsampling.</div>
 </td>
 </tr>
-<tr class="rowColor">
+<tr class="altColor">
 <td class="colFirst"><code>static int</code></td>
 <td class="colLast"><code><strong><a href="../../../org/libjpegturbo/turbojpeg/TJ.html#getPixelSize(int)">getPixelSize</a></strong>(int&nbsp;pixelFormat)</code>
 <div class="block">Returns the pixel size (in bytes) for the given pixel format.</div>
 </td>
 </tr>
-<tr class="altColor">
+<tr class="rowColor">
 <td class="colFirst"><code>static int</code></td>
 <td class="colLast"><code><strong><a href="../../../org/libjpegturbo/turbojpeg/TJ.html#getRedOffset(int)">getRedOffset</a></strong>(int&nbsp;pixelFormat)</code>
 <div class="block">For the given pixel format, returns the number of bytes that the red
  component is offset from the start of the pixel.</div>
 </td>
 </tr>
-<tr class="rowColor">
+<tr class="altColor">
 <td class="colFirst"><code>static <a href="../../../org/libjpegturbo/turbojpeg/TJScalingFactor.html" title="class in org.libjpegturbo.turbojpeg">TJScalingFactor</a>[]</code></td>
 <td class="colLast"><code><strong><a href="../../../org/libjpegturbo/turbojpeg/TJ.html#getScalingFactors()">getScalingFactors</a></strong>()</code>
 <div class="block">Returns a list of fractional scaling factors that the JPEG decompressor in
  this implementation of TurboJPEG supports.</div>
 </td>
 </tr>
-<tr class="altColor">
+<tr class="rowColor">
 <td class="colFirst"><code>static int</code></td>
 <td class="colLast"><code><strong><a href="../../../org/libjpegturbo/turbojpeg/TJ.html#planeHeight(int,%20int,%20int)">planeHeight</a></strong>(int&nbsp;componentID,
            int&nbsp;height,
@@ -471,7 +482,7 @@ extends java.lang.Object</pre>
 <div class="block">Returns the plane height of a YUV image plane with the given parameters.</div>
 </td>
 </tr>
-<tr class="rowColor">
+<tr class="altColor">
 <td class="colFirst"><code>static int</code></td>
 <td class="colLast"><code><strong><a href="../../../org/libjpegturbo/turbojpeg/TJ.html#planeSizeYUV(int,%20int,%20int,%20int,%20int)">planeSizeYUV</a></strong>(int&nbsp;componentID,
             int&nbsp;width,
@@ -482,7 +493,7 @@ extends java.lang.Object</pre>
  plane with the given parameters.</div>
 </td>
 </tr>
-<tr class="altColor">
+<tr class="rowColor">
 <td class="colFirst"><code>static int</code></td>
 <td class="colLast"><code><strong><a href="../../../org/libjpegturbo/turbojpeg/TJ.html#planeWidth(int,%20int,%20int)">planeWidth</a></strong>(int&nbsp;componentID,
           int&nbsp;width,
@@ -1137,7 +1148,8 @@ public static final&nbsp;int FLAG_FORCESSE3</pre>
  then the red component will be
  <code>pixel[TJ.getRedOffset(TJ.PF_BGRX)]</code>.</div>
 <dl><dt><span class="strong">Parameters:</span></dt><dd><code>pixelFormat</code> - the pixel format (one of <code>PF_*</code>)</dd>
-<dt><span class="strong">Returns:</span></dt><dd>the red offset for the given pixel format.</dd></dl>
+<dt><span class="strong">Returns:</span></dt><dd>the red offset for the given pixel format, or -1 if the pixel
+ format does not have a red component.</dd></dl>
 </li>
 </ul>
 <a name="getGreenOffset(int)">
@@ -1153,7 +1165,8 @@ public static final&nbsp;int FLAG_FORCESSE3</pre>
  then the green component will be
  <code>pixel[TJ.getGreenOffset(TJ.PF_BGRX)]</code>.</div>
 <dl><dt><span class="strong">Parameters:</span></dt><dd><code>pixelFormat</code> - the pixel format (one of <code>PF_*</code>)</dd>
-<dt><span class="strong">Returns:</span></dt><dd>the green offset for the given pixel format.</dd></dl>
+<dt><span class="strong">Returns:</span></dt><dd>the green offset for the given pixel format, or -1 if the pixel
+ format does not have a green component.</dd></dl>
 </li>
 </ul>
 <a name="getBlueOffset(int)">
@@ -1169,7 +1182,25 @@ public static final&nbsp;int FLAG_FORCESSE3</pre>
  then the blue component will be
  <code>pixel[TJ.getBlueOffset(TJ.PF_BGRX)]</code>.</div>
 <dl><dt><span class="strong">Parameters:</span></dt><dd><code>pixelFormat</code> - the pixel format (one of <code>PF_*</code>)</dd>
-<dt><span class="strong">Returns:</span></dt><dd>the blue offset for the given pixel format.</dd></dl>
+<dt><span class="strong">Returns:</span></dt><dd>the blue offset for the given pixel format, or -1 if the pixel
+ format does not have a blue component.</dd></dl>
+</li>
+</ul>
+<a name="getAlphaOffset(int)">
+<!--   -->
+</a>
+<ul class="blockList">
+<li class="blockList">
+<h4>getAlphaOffset</h4>
+<pre>public static&nbsp;int&nbsp;getAlphaOffset(int&nbsp;pixelFormat)</pre>
+<div class="block">For the given pixel format, returns the number of bytes that the alpha
+ component is offset from the start of the pixel.  For instance, if a pixel
+ of format <code>TJ.PF_BGRA</code> is stored in <code>char pixel[]</code>,
+ then the alpha component will be
+ <code>pixel[TJ.getAlphaOffset(TJ.PF_BGRA)]</code>.</div>
+<dl><dt><span class="strong">Parameters:</span></dt><dd><code>pixelFormat</code> - the pixel format (one of <code>PF_*</code>)</dd>
+<dt><span class="strong">Returns:</span></dt><dd>the alpha offset for the given pixel format, or -1 if the pixel
+ format does not have a alpha component.</dd></dl>
 </li>
 </ul>
 <a name="bufSize(int, int, int)">

java/doc/org/libjpegturbo/turbojpeg/TJCompressor.html

@@ -7,8 +7,12 @@
 </head>
 <body>
 <script type="text/javascript"><!--
-    if (location.href.indexOf('is-external=true') == -1) {
+    try {
-        parent.document.title="TJCompressor";
+        if (location.href.indexOf('is-external=true') == -1) {
+            parent.document.title="TJCompressor";
+        }
+    }
+    catch(err) {
     }
 //-->
 </script>

java/doc/org/libjpegturbo/turbojpeg/TJCustomFilter.html

@@ -7,8 +7,12 @@
 </head>
 <body>
 <script type="text/javascript"><!--
-    if (location.href.indexOf('is-external=true') == -1) {
+    try {
-        parent.document.title="TJCustomFilter";
+        if (location.href.indexOf('is-external=true') == -1) {
+            parent.document.title="TJCustomFilter";
+        }
+    }
+    catch(err) {
     }
 //-->
 </script>

java/doc/org/libjpegturbo/turbojpeg/TJDecompressor.html

@@ -7,8 +7,12 @@
 </head>
 <body>
 <script type="text/javascript"><!--
-    if (location.href.indexOf('is-external=true') == -1) {
+    try {
-        parent.document.title="TJDecompressor";
+        if (location.href.indexOf('is-external=true') == -1) {
+            parent.document.title="TJDecompressor";
+        }
+    }
+    catch(err) {
     }
 //-->
 </script>

java/doc/org/libjpegturbo/turbojpeg/TJException.html

@@ -7,8 +7,12 @@
 </head>
 <body>
 <script type="text/javascript"><!--
-    if (location.href.indexOf('is-external=true') == -1) {
+    try {
-        parent.document.title="TJException";
+        if (location.href.indexOf('is-external=true') == -1) {
+            parent.document.title="TJException";
+        }
+    }
+    catch(err) {
     }
 //-->
 </script>

java/doc/org/libjpegturbo/turbojpeg/TJScalingFactor.html

@@ -7,8 +7,12 @@
 </head>
 <body>
 <script type="text/javascript"><!--
-    if (location.href.indexOf('is-external=true') == -1) {
+    try {
-        parent.document.title="TJScalingFactor";
+        if (location.href.indexOf('is-external=true') == -1) {
+            parent.document.title="TJScalingFactor";
+        }
+    }
+    catch(err) {
     }
 //-->
 </script>

java/doc/org/libjpegturbo/turbojpeg/TJTransform.html

@@ -7,8 +7,12 @@
 </head>
 <body>
 <script type="text/javascript"><!--
-    if (location.href.indexOf('is-external=true') == -1) {
+    try {
-        parent.document.title="TJTransform";
+        if (location.href.indexOf('is-external=true') == -1) {
+            parent.document.title="TJTransform";
+        }
+    }
+    catch(err) {
     }
 //-->
 </script>

java/doc/org/libjpegturbo/turbojpeg/TJTransformer.html

@@ -7,8 +7,12 @@
 </head>
 <body>
 <script type="text/javascript"><!--
-    if (location.href.indexOf('is-external=true') == -1) {
+    try {
-        parent.document.title="TJTransformer";
+        if (location.href.indexOf('is-external=true') == -1) {
+            parent.document.title="TJTransformer";
+        }
+    }
+    catch(err) {
     }
 //-->
 </script>

java/doc/org/libjpegturbo/turbojpeg/YUVImage.html

@@ -7,8 +7,12 @@
 </head>
 <body>
 <script type="text/javascript"><!--
-    if (location.href.indexOf('is-external=true') == -1) {
+    try {
-        parent.document.title="YUVImage";
+        if (location.href.indexOf('is-external=true') == -1) {
+            parent.document.title="YUVImage";
+        }
+    }
+    catch(err) {
     }
 //-->
 </script>

java/doc/org/libjpegturbo/turbojpeg/package-summary.html

@@ -7,8 +7,12 @@
 </head>
 <body>
 <script type="text/javascript"><!--
-    if (location.href.indexOf('is-external=true') == -1) {
+    try {
-        parent.document.title="org.libjpegturbo.turbojpeg";
+        if (location.href.indexOf('is-external=true') == -1) {
+            parent.document.title="org.libjpegturbo.turbojpeg";
+        }
+    }
+    catch(err) {
     }
 //-->
 </script>

java/doc/org/libjpegturbo/turbojpeg/package-tree.html

@@ -7,8 +7,12 @@
 </head>
 <body>
 <script type="text/javascript"><!--
-    if (location.href.indexOf('is-external=true') == -1) {
+    try {
-        parent.document.title="org.libjpegturbo.turbojpeg Class Hierarchy";
+        if (location.href.indexOf('is-external=true') == -1) {
+            parent.document.title="org.libjpegturbo.turbojpeg Class Hierarchy";
+        }
+    }
+    catch(err) {
     }
 //-->
 </script>

java/doc/overview-tree.html

@@ -7,8 +7,12 @@
 </head>
 <body>
 <script type="text/javascript"><!--
-    if (location.href.indexOf('is-external=true') == -1) {
+    try {
-        parent.document.title="Class Hierarchy";
+        if (location.href.indexOf('is-external=true') == -1) {
+            parent.document.title="Class Hierarchy";
+        }
+    }
+    catch(err) {
     }
 //-->
 </script>

java/doc/serialized-form.html

@@ -7,8 +7,12 @@
 </head>
 <body>
 <script type="text/javascript"><!--
-    if (location.href.indexOf('is-external=true') == -1) {
+    try {
-        parent.document.title="Serialized Form";
+        if (location.href.indexOf('is-external=true') == -1) {
+            parent.document.title="Serialized Form";
+        }
+    }
+    catch(err) {
     }
 //-->
 </script>

java/org/libjpegturbo/turbojpeg/TJ.java

@@ -235,7 +235,8 @@ public final class TJ {
    *
    * @param pixelFormat the pixel format (one of <code>PF_*</code>)
    *
-   * @return the red offset for the given pixel format.
+   * @return the red offset for the given pixel format, or -1 if the pixel
+   * format does not have a red component.
    */
   public static int getRedOffset(int pixelFormat) {
     checkPixelFormat(pixelFormat);
@@ -243,7 +244,7 @@ public final class TJ {
   }
 
   private static final int[] redOffset = {
-    0, 2, 0, 2, 3, 1, 0, 0, 2, 3, 1, -1
+    0, 2, 0, 2, 3, 1, -1, 0, 2, 3, 1, -1
   };
 
 
@@ -256,7 +257,8 @@ public final class TJ {
    *
    * @param pixelFormat the pixel format (one of <code>PF_*</code>)
    *
-   * @return the green offset for the given pixel format.
+   * @return the green offset for the given pixel format, or -1 if the pixel
+   * format does not have a green component.
    */
   public static int getGreenOffset(int pixelFormat) {
     checkPixelFormat(pixelFormat);
@@ -264,7 +266,7 @@ public final class TJ {
   }
 
   private static final int[] greenOffset = {
-    1, 1, 1, 1, 2, 2, 0, 1, 1, 2, 2, -1
+    1, 1, 1, 1, 2, 2, -1, 1, 1, 2, 2, -1
   };
 
 
@@ -277,7 +279,8 @@ public final class TJ {
    *
    * @param pixelFormat the pixel format (one of <code>PF_*</code>)
    *
-   * @return the blue offset for the given pixel format.
+   * @return the blue offset for the given pixel format, or -1 if the pixel
+   * format does not have a blue component.
    */
   public static int getBlueOffset(int pixelFormat) {
     checkPixelFormat(pixelFormat);
@@ -285,7 +288,29 @@ public final class TJ {
   }
 
   private static final int[] blueOffset = {
-    2, 0, 2, 0, 1, 3, 0, 2, 0, 1, 3, -1
+    2, 0, 2, 0, 1, 3, -1, 2, 0, 1, 3, -1
+  };
+
+
+  /**
+   * For the given pixel format, returns the number of bytes that the alpha
+   * component is offset from the start of the pixel.  For instance, if a pixel
+   * of format <code>TJ.PF_BGRA</code> is stored in <code>char pixel[]</code>,
+   * then the alpha component will be
+   * <code>pixel[TJ.getAlphaOffset(TJ.PF_BGRA)]</code>.
+   *
+   * @param pixelFormat the pixel format (one of <code>PF_*</code>)
+   *
+   * @return the alpha offset for the given pixel format, or -1 if the pixel
+   * format does not have a alpha component.
+   */
+  public static int getAlphaOffset(int pixelFormat) {
+    checkPixelFormat(pixelFormat);
+    return alphaOffset[pixelFormat];
+  }
+
+  private static final int[] alphaOffset = {
+    -1, -1, -1, -1, -1, -1, -1, 3, 3, 0, 0, -1
   };
 
 

tjunittest.c

@@ -84,8 +84,6 @@ const char *pixFormatStr[TJ_NUMPF]=
 	"RGBA", "BGRA", "ABGR", "ARGB", "CMYK"
 };
 
-const int alphaOffset[TJ_NUMPF] = {-1, -1, -1, -1, -1, -1, -1, 3, 3, 0, 0, -1};
-
 const int _3byteFormats[]={TJPF_RGB, TJPF_BGR};
 const int _4byteFormats[]={TJPF_RGBX, TJPF_BGRX, TJPF_XBGR, TJPF_XRGB,
 	TJPF_CMYK};
@@ -196,12 +194,14 @@ int checkBuf(unsigned char *buf, int w, int h, int pf, int subsamp,
 	int roffset=tjRedOffset[pf];
 	int goffset=tjGreenOffset[pf];
 	int boffset=tjBlueOffset[pf];
-	int aoffset=alphaOffset[pf];
+	int aoffset=tjAlphaOffset[pf];
 	int ps=tjPixelSize[pf];
 	int index, row, col, retval=1;
 	int halfway=16*sf.num/sf.denom;
 	int blocksize=8*sf.num/sf.denom;
 
+	if(pf==TJPF_GRAY) roffset=goffset=boffset=0;
+
 	if(pf==TJPF_CMYK)
 	{
 		for(row=0; row<h; row++)
@@ -738,7 +738,7 @@ int cmpBitmap(unsigned char *buf, int width, int pitch, int height, int pf,
 	int roffset=tjRedOffset[pf];
 	int goffset=tjGreenOffset[pf];
 	int boffset=tjBlueOffset[pf];
-	int aoffset=alphaOffset[pf];
+	int aoffset=tjAlphaOffset[pf];
 	int ps=tjPixelSize[pf];
 	int i, j;
 

turbojpeg.h

@@ -256,33 +256,54 @@ enum TJPF
   TJPF_UNKNOWN = -1
 };
 
-
 /**
  * Red offset (in bytes) for a given pixel format.  This specifies the number
  * of bytes that the red component is offset from the start of the pixel.  For
  * instance, if a pixel of format TJ_BGRX is stored in <tt>char pixel[]</tt>,
- * then the red component will be <tt>pixel[tjRedOffset[TJ_BGRX]]</tt>.
+ * then the red component will be <tt>pixel[tjRedOffset[TJ_BGRX]]</tt>.  This
+ * will be -1 if the pixel format does not have a red component.
  */
-static const int tjRedOffset[TJ_NUMPF] = {0, 2, 0, 2, 3, 1, 0, 0, 2, 3, 1, -1};
+static const int tjRedOffset[TJ_NUMPF] = {
+  0, 2, 0, 2, 3, 1, -1, 0, 2, 3, 1, -1
+};
 /**
  * Green offset (in bytes) for a given pixel format.  This specifies the number
  * of bytes that the green component is offset from the start of the pixel.
  * For instance, if a pixel of format TJ_BGRX is stored in
  * <tt>char pixel[]</tt>, then the green component will be
- * <tt>pixel[tjGreenOffset[TJ_BGRX]]</tt>.
+ * <tt>pixel[tjGreenOffset[TJ_BGRX]]</tt>.  This will be -1 if the pixel format
+ * does not have a green component.
  */
-static const int tjGreenOffset[TJ_NUMPF] = {1, 1, 1, 1, 2, 2, 0, 1, 1, 2, 2, -1};
+static const int tjGreenOffset[TJ_NUMPF] = {
+  1, 1, 1, 1, 2, 2, -1, 1, 1, 2, 2, -1
+};
 /**
  * Blue offset (in bytes) for a given pixel format.  This specifies the number
  * of bytes that the Blue component is offset from the start of the pixel.  For
  * instance, if a pixel of format TJ_BGRX is stored in <tt>char pixel[]</tt>,
- * then the blue component will be <tt>pixel[tjBlueOffset[TJ_BGRX]]</tt>.
+ * then the blue component will be <tt>pixel[tjBlueOffset[TJ_BGRX]]</tt>.  This
+ * will be -1 if the pixel format does not have a blue component.
  */
-static const int tjBlueOffset[TJ_NUMPF] = {2, 0, 2, 0, 1, 3, 0, 2, 0, 1, 3, -1};
+static const int tjBlueOffset[TJ_NUMPF] = {
+  2, 0, 2, 0, 1, 3, -1, 2, 0, 1, 3, -1
+};
 /**
- * Pixel size (in bytes) for a given pixel format.
+ * Alpha offset (in bytes) for a given pixel format.  This specifies the number
+ * of bytes that the Alpha component is offset from the start of the pixel.
+ * For instance, if a pixel of format TJ_BGRA is stored in
+ * <tt>char pixel[]</tt>, then the alpha component will be
+ * <tt>pixel[tjAlphaOffset[TJ_BGRA]]</tt>.  This will be -1 if the pixel format
+ * does not have an alpha component.
  */
-static const int tjPixelSize[TJ_NUMPF] = {3, 3, 4, 4, 4, 4, 1, 4, 4, 4, 4, 4};
+static const int tjAlphaOffset[TJ_NUMPF] = {
+  -1, -1, -1, -1, -1, -1, -1, 3, 3, 0, 0, -1
+};
+/**
+ * Pixel size (in bytes) for a given pixel format
+ */
+static const int tjPixelSize[TJ_NUMPF] = {
+  3, 3, 4, 4, 4, 4, 1, 4, 4, 4, 4, 4
+};
 
 
 /**