X-Git-Url: https://git.saurik.com/wxWidgets.git/blobdiff_plain/9a83f860948059b0273b5cc6d9e43fadad3ebfca..bc9666c99939f6f1a6fc11fd10fa2db3deb747ae:/src/common/imagbmp.cpp

diff --git a/src/common/imagbmp.cpp b/src/common/imagbmp.cpp
index bf232cd51a..41edf784b4 100644
--- a/src/common/imagbmp.cpp
+++ b/src/common/imagbmp.cpp
@@ -599,7 +599,7 @@ bool wxBMPHandler::DoLoadDib(wxImage * image, int width, int height,
     {
         if ( comp == BI_BITFIELDS )
         {
-            int bit = 0;
+            int bit;
             stream.Read(dbuf, 4 * 3);
             rmask = wxINT32_SWAP_ON_BE(dbuf[0]);
             gmask = wxINT32_SWAP_ON_BE(dbuf[1]);
@@ -661,8 +661,10 @@ bool wxBMPHandler::DoLoadDib(wxImage * image, int width, int height,
     {
         // NOTE: seeking a positive amount in wxFromCurrent mode allows us to
         //       load even non-seekable streams (see wxInputStream::SeekI docs)!
-        if (stream.SeekI(bmpOffset, wxFromCurrent) == wxInvalidOffset)
-            return false;
+        const wxFileOffset pos = stream.TellI();
+        if (pos != wxInvalidOffset && bmpOffset > pos)
+            if (stream.SeekI(bmpOffset - pos, wxFromCurrent) == wxInvalidOffset)
+                return false;
         //else: icon, just carry on
     }
 
@@ -682,6 +684,14 @@ bool wxBMPHandler::DoLoadDib(wxImage * image, int width, int height,
 
     int linesize = ((width * bpp + 31) / 32) * 4;
 
+    // flag indicating if we have any not fully transparent alpha values: this
+    // is used to account for the bitmaps which use 32bpp format (normally
+    // meaning that they have alpha channel) but have only zeroes in it so that
+    // without this hack they appear fully transparent -- and as this is
+    // unlikely intentional, we consider that they don't have alpha at all in
+    // this case (see #10915)
+    bool hasValidAlpha = false;
+
     /* BMPs are stored upside down */
     for ( int line = (height - 1); line >= 0; line-- )
     {
@@ -776,7 +786,7 @@ bool wxBMPHandler::DoLoadDib(wxImage * image, int width, int height,
                     {
                         for (int nibble = 0; nibble < 2 && column < width; nibble++)
                         {
-                            int index = ((aByte & (0xF0 >> nibble * 4)) >> (!nibble * 4));
+                            int index = ((aByte & (0xF0 >> (nibble * 4))) >> (!nibble * 4));
                             if ( index >= 16 )
                                 index = 15;
                             ptr[poffset] = cmap[index].r;
@@ -865,15 +875,15 @@ bool wxBMPHandler::DoLoadDib(wxImage * image, int width, int height,
                 stream.Read(&aWord, 2);
                 aWord = wxUINT16_SWAP_ON_BE(aWord);
                 linepos += 2;
-                /* use the masks and calculated amonut of shift
+                /* Use the masks and calculated amount of shift
                    to retrieve the color data out of the word.  Then
                    shift it left by (8 - number of bits) such that
                    the image has the proper dynamic range */
-                temp = (unsigned char)((aWord & rmask) >> rshift << (8-rbits));
+                temp = (unsigned char)(((aWord & rmask) >> rshift) << (8-rbits));
                 ptr[poffset] = temp;
-                temp = (unsigned char)((aWord & gmask) >> gshift << (8-gbits));
+                temp = (unsigned char)(((aWord & gmask) >> gshift) << (8-gbits));
                 ptr[poffset + 1] = temp;
-                temp = (unsigned char)((aWord & bmask) >> bshift << (8-bbits));
+                temp = (unsigned char)(((aWord & bmask) >> bshift) << (8-bbits));
                 ptr[poffset + 2] = temp;
                 column++;
             }
@@ -893,6 +903,9 @@ bool wxBMPHandler::DoLoadDib(wxImage * image, int width, int height,
                 {
                     temp = (unsigned char)((aDword & amask) >> ashift);
                     alpha[line * width + column] = temp;
+
+                    if ( temp != wxALPHA_TRANSPARENT )
+                        hasValidAlpha = true;
                 }
                 column++;
             }
@@ -908,6 +921,13 @@ bool wxBMPHandler::DoLoadDib(wxImage * image, int width, int height,
 
     image->SetMask(false);
 
+    // check if we had any valid alpha values in this bitmap
+    if ( alpha && !hasValidAlpha )
+    {
+        // we didn't, so finally discard the alpha channel completely
+        image->ClearAlpha();
+    }
+
     const wxStreamError err = stream.GetLastError();
     return err == wxSTREAM_NO_ERROR || err == wxSTREAM_EOF;
 }
@@ -1318,7 +1338,7 @@ bool wxICOHandler::DoLoadFile(wxImage *image, wxInputStream& stream,
 
     stream.Read(&IconDir, sizeof(IconDir));
     wxUint16 nIcons = wxUINT16_SWAP_ON_BE(IconDir.idCount);
-    
+
     // nType is 1 for Icons, 2 for Cursors:
     wxUint16 nType = wxUINT16_SWAP_ON_BE(IconDir.idType);
 
@@ -1331,11 +1351,11 @@ bool wxICOHandler::DoLoadFile(wxImage *image, wxInputStream& stream,
 
     // remember how many bytes we read from the stream:
     wxFileOffset alreadySeeked = sizeof(IconDir);
-    
+
     for (unsigned int i = 0; i < nIcons; i++ )
     {
         alreadySeeked += stream.Read(pCurrentEntry, sizeof(ICONDIRENTRY)).LastRead();
-        
+
         // bHeight and bColorCount are wxUint8
         if ( pCurrentEntry->bWidth >= wMax )
         {
@@ -1349,7 +1369,7 @@ bool wxICOHandler::DoLoadFile(wxImage *image, wxInputStream& stream,
                 colmax = pCurrentEntry->bColorCount;
             }
         }
-        
+
         pCurrentEntry++;
     }
 
@@ -1369,13 +1389,13 @@ bool wxICOHandler::DoLoadFile(wxImage *image, wxInputStream& stream,
     {
         // seek to selected icon:
         pCurrentEntry = pIconDirEntry + iSel;
-        
+
         // NOTE: seeking a positive amount in wxFromCurrent mode allows us to
         //       load even non-seekable streams (see wxInputStream::SeekI docs)!
         wxFileOffset offset = wxUINT32_SWAP_ON_BE(pCurrentEntry->dwImageOffset) - alreadySeeked;
         if (offset != 0 && stream.SeekI(offset, wxFromCurrent) == wxInvalidOffset)
             return false;
-        
+
         bResult = LoadDib(image, stream, true, IsBmp);
         bool bIsCursorType = (this->GetType() == wxBITMAP_TYPE_CUR) || (this->GetType() == wxBITMAP_TYPE_ANI);
         if ( bResult && bIsCursorType && nType == 2 )
@@ -1385,9 +1405,9 @@ bool wxICOHandler::DoLoadFile(wxImage *image, wxInputStream& stream,
             image->SetOption(wxIMAGE_OPTION_CUR_HOTSPOT_Y, wxUINT16_SWAP_ON_BE(pCurrentEntry->wBitCount));
         }
     }
-    
+
     delete [] pIconDirEntry;
-    
+
     return bResult;
 }
 
@@ -1398,7 +1418,7 @@ int wxICOHandler::DoGetImageCount(wxInputStream& stream)
     if (stream.Read(&IconDir, sizeof(IconDir)).LastRead() != sizeof(IconDir))
              // it's ok to modify the stream position here
         return 0;
-    
+
     return (int)wxUINT16_SWAP_ON_BE(IconDir.idCount);
 }