Merge pull request #386 from Libvisual/fix-bmp-palette-loading

Fix BMP palette loading.

libvisual/libvisual/lv_video.cpp

@@ -392,6 +392,10 @@ namespace LV {
           }
       }
 
+      // Videos must have the same palette.
+      if (m_impl->palette != video->m_impl->palette)
+          return false;
+
       return true;
   }
 

libvisual/libvisual/private/lv_video_bmp.cpp

@@ -31,9 +31,12 @@
 #include <istream>
 #include <cstring>
 
-#define BI_RGB  0
-#define BI_RLE8 1
-#define BI_RLE4 2
+/* BMP compression methods */
+#define BI_RGB       0
+#define BI_RLE8      1
+#define BI_RLE4      2
+#define BI_BITFIELDS 3
+
 
 namespace LV {
 
@@ -286,6 +289,8 @@ namespace LV {
       fp.read (reinterpret_cast<char*> (&bf_bits), 4);
       bf_bits = VISUAL_ENDIAN_LEI32 (bf_bits);
 
+      auto dib_header_pos = fp.tellg ();
+
       /* Read the info structure size */
       fp.read (reinterpret_cast<char*> (&bi_size), 4);
       bi_size = VISUAL_ENDIAN_LEI32 (bi_size);
@@ -341,13 +346,19 @@ namespace LV {
           return nullptr;
       }
 
-      if (bi_compression > 3) {
+      if (bi_compression >= BI_BITFIELDS) {
           visual_log (VISUAL_LOG_ERROR, "Bitmap uses an invalid or unsupported compression scheme");
           fp.seekg (saved_stream_pos);
           return nullptr;
       }
 
       /* Load the palette */
+
+      /* Skip past DIB header to color table */
+      /* BI_BITFIELDS and BI_ALPHABITFIELDS are unsupported, so there are
+         no bitmasks after the DIB header. */
+      fp.seekg (dib_header_pos + std::streampos {bi_size}, std::ios::beg);
+
       if (bi_bitcount < 24) {
           if (bi_clrused == 0) {
               /* When the colors used variable is zero, use the
@@ -385,6 +396,8 @@ namespace LV {
       if (palette)
           video->set_palette (*palette);
 
+      /* Read and decode image data */
+
       /* Set to the beginning of image data, note that MickeySoft likes stuff upside down .. */
       fp.seekg (bf_bits, std::ios::beg);