Fix 3118622, where tile-base jpeg decode does not handle the region

width correctly in Progressive JPEG when the h_samp_factor is different from one color
component to anothor.

To decode a region in a progressive JPEG, each time we decode
one iMCU row, the width of which equals to the region width.
However, for each color component the region width in DCT blocks depends on its h_samp_factor.
The change ensures we get a correct region width from our recorded MCU_column number.

Bug: 3118622
Change-Id: I6d3e30f946e0395c0719aee0c8e694824ab3d27f

1 files changed, 23 insertions, 10 deletions

diff --git a/jdcoefct.c b/jdcoefct.c
index 9e8040b..e6e9506 100644
--- a/jdcoefct.c
+++ b/jdcoefct.c
@@ -277,15 +277,24 @@ consume_data (j_decompress_ptr cinfo)
   unsigned int MCUs_per_row = cinfo->MCUs_per_row;
 #ifdef ANDROID_TILE_BASED_DECODE
   if (cinfo->tile_decode) {
+    int iMCU_width_To_MCU_width;
+    if (cinfo->comps_in_scan > 1) {
+      // Interleaved
+      iMCU_width_To_MCU_width = 1;
+    } else {
+      // Non-intervleaved
+      iMCU_width_To_MCU_width = cinfo->cur_comp_info[0]->h_samp_factor;
+    }
     MCUs_per_row = jmin(MCUs_per_row,
         (cinfo->coef->column_right_boundary - cinfo->coef->column_left_boundary)
-        * cinfo->entropy->index->MCU_sample_size * cinfo->max_h_samp_factor);
+        * cinfo->entropy->index->MCU_sample_size * iMCU_width_To_MCU_width);
   }
 #endif
 
   /* Loop to process one whole iMCU row */
   for (yoffset = coef->MCU_vert_offset; yoffset < coef->MCU_rows_per_iMCU_row;
        yoffset++) {
+   // configure huffman decoder
 #ifdef ANDROID_TILE_BASED_DECODE
     if (cinfo->tile_decode) {
       huffman_scan_header scan_header =
@@ -296,8 +305,10 @@ consume_data (j_decompress_ptr cinfo)
               [col_offset + yoffset * scan_header.MCUs_per_row]);
     }
 #endif
+
+    // zero all blocks
     for (MCU_col_num = coef->MCU_ctr; MCU_col_num < MCUs_per_row;
-	 MCU_col_num++) {
+          MCU_col_num++) {
       /* Construct list of pointers to DCT blocks belonging to this MCU */
       blkn = 0;			/* index of current DCT block within MCU */
       for (ci = 0; ci < cinfo->comps_in_scan; ci++) {
@@ -309,7 +320,7 @@ consume_data (j_decompress_ptr cinfo)
             coef->MCU_buffer[blkn++] = buffer_ptr++;
 #ifdef ANDROID_TILE_BASED_DECODE
             if (cinfo->tile_decode && cinfo->input_scan_number == 0) {
-              // need to do pre-zero ourself.
+              // need to do pre-zero ourselves.
               jzero_far((void FAR *) coef->MCU_buffer[blkn-1],
                         (size_t) (SIZEOF(JBLOCK)));
             }
@@ -317,12 +328,14 @@ consume_data (j_decompress_ptr cinfo)
           }
         }
       }
+
+
       /* Try to fetch the MCU. */
       if (! (*cinfo->entropy->decode_mcu) (cinfo, coef->MCU_buffer)) {
-	/* Suspension forced; update state counters and exit */
-	coef->MCU_vert_offset = yoffset;
-	coef->MCU_ctr = MCU_col_num;
-	return JPEG_SUSPENDED;
+        /* Suspension forced; update state counters and exit */
+        coef->MCU_vert_offset = yoffset;
+        coef->MCU_ctr = MCU_col_num;
+        return JPEG_SUSPENDED;
       }
     }
     /* Completed an MCU row, but perhaps not an iMCU row */
@@ -584,14 +597,14 @@ decompress_data (j_decompress_ptr cinfo, JSAMPIMAGE output_buf)
     int start_block = 0;
 #if ANDROID_TILE_BASED_DECODE
     if (cinfo->tile_decode) {
+      // width_in_blocks for a component depends on its h_samp_factor.
       width_in_blocks = jmin(width_in_blocks,
         (cinfo->coef->MCU_column_right_boundary -
          cinfo->coef->MCU_column_left_boundary) *
-         cinfo->max_h_samp_factor /
          compptr->h_samp_factor);
       start_block = coef->pub.MCU_columns_to_skip *
-        cinfo->max_h_samp_factor / compptr->h_samp_factor;
-    }
+         compptr->h_samp_factor;
+   }
 #endif
     /* Loop over all DCT blocks to be processed. */
     for (block_row = 0; block_row < block_rows; block_row++) {