[trunk] Handle cmap where direct use is specified (issue235_cmapsubbox.jp2)

I doubt the old code ever work. The new code copy the old codestream bytes into the new components (instead of copying the pointer).
Technically the issue235.jp2 file should be handled since I.5.3.5 specifies that:
...
If the JP2 Header box does not contain a Component Mapping box, the components shall be mapped directly to channels,
such that component i is mapped to channel i.
...
Update issue 235

src/lib/openjp2/jp2.c

@@ -798,20 +798,27 @@ static OPJ_BOOL opj_jp2_check_color(opj_image_t *image, opj_jp2_color_t *color,
 		/* verify that no component is targeted more than once */
 		for (i = 0; i < nr_channels; i++) {
       OPJ_UINT16 pcol = cmap[i].pcol;
+      assert(cmap[i].mtyp == 0 || cmap[i].mtyp == 1);
 			if (pcol >= nr_channels) {
 				opj_event_msg(p_manager, EVT_ERROR, "Invalid component/palette index for direct mapping %d.\n", pcol);
 				is_sane = OPJ_FALSE;
 			}
-			else if (pcol_usage[pcol]) {
+			else if (pcol_usage[pcol] && cmap[i].mtyp == 1) {
 				opj_event_msg(p_manager, EVT_ERROR, "Component %d is mapped twice.\n", pcol);
 				is_sane = OPJ_FALSE;
 			}
+      else if (cmap[i].mtyp == 0 && cmap[i].pcol != 0) {
+        /* I.5.3.5 PCOL: If the value of the MTYP field for this channel is 0, then
+         * the value of this field shall be 0. */
+				opj_event_msg(p_manager, EVT_ERROR, "Direct use at #%d however pcol=%d.\n", i, pcol);
+				is_sane = OPJ_FALSE;
+      }
 			else
 				pcol_usage[pcol] = OPJ_TRUE;
 		}
 		/* verify that all components are targeted at least once */
 		for (i = 0; i < nr_channels; i++) {
-			if (!pcol_usage[i]) {
+			if (!pcol_usage[i] && cmap[i].mtyp != 0) {
 				opj_event_msg(p_manager, EVT_ERROR, "Component %d doesn't have a mapping.\n", i);
 				is_sane = OPJ_FALSE;
 			}
@@ -850,40 +857,52 @@ void opj_jp2_apply_pclr(opj_image_t *image, opj_jp2_color_t *color)
 	for(i = 0; i < nr_channels; ++i) {
 		pcol = cmap[i].pcol; cmp = cmap[i].cmp;
 
-		new_comps[pcol] = old_comps[cmp];
-
 		/* Direct use */
     if(cmap[i].mtyp == 0){
-			old_comps[cmp].data = NULL; continue;
+      assert( pcol == 0 );
+      new_comps[i] = old_comps[cmp];
+    } else {
+      assert( i == pcol );
+      new_comps[pcol] = old_comps[cmp];
     }
 
 		/* Palette mapping: */
-		new_comps[pcol].data = (OPJ_INT32*)
+		new_comps[i].data = (OPJ_INT32*)
 				opj_malloc(old_comps[cmp].w * old_comps[cmp].h * sizeof(OPJ_INT32));
-		new_comps[pcol].prec = channel_size[i];
+		new_comps[i].prec = channel_size[i];
-		new_comps[pcol].sgnd = channel_sign[i];
+		new_comps[i].sgnd = channel_sign[i];
 	}
 
 	top_k = color->jp2_pclr->nr_entries - 1;
 
 	for(i = 0; i < nr_channels; ++i) {
-		/* Direct use: */
-		if(cmap[i].mtyp == 0) continue;
-
 		/* Palette mapping: */
 		cmp = cmap[i].cmp; pcol = cmap[i].pcol;
 		src = old_comps[cmp].data;
-		dst = new_comps[pcol].data;
+    assert( src );
 		max = new_comps[pcol].w * new_comps[pcol].h;
 
-		for(j = 0; j < max; ++j)
+		/* Direct use: */
-		{
+    if(cmap[i].mtyp == 0) {
+      assert( cmp == 0 );
+      dst = new_comps[i].data;
+      assert( dst );
+      for(j = 0; j < max; ++j) {
+        dst[j] = src[j];
+      }
+    }
+    else {
+      assert( i == pcol );
+      dst = new_comps[pcol].data;
+      assert( dst );
+      for(j = 0; j < max; ++j) {
         /* The index */
         if((k = src[j]) < 0) k = 0; else if(k > top_k) k = top_k;
 
         /* The colour */
         dst[j] = entries[k * nr_channels + pcol];
         }
+    }
 	}
 
 	max = image->numcomps;