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Fix loading of RLE bitmaps in wxBMPHandler

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- Fix handling of delta encoding that change vertical position
- Fix handling of end-of-line encodings that are given mid-line
- Removed unnecessary computation for linepos

Add regression tests for the bitmaps using RLE and loading which
previously didn't work correctly.

Closes https://github.com/wxWidgets/wxWidgets/pull/2590

Closes #19318.
This commit is contained in:
David Costanzo
2021-11-17 20:38:43 -08:00
committed by Vadim Zeitlin
parent 94f10eba4e
commit 0985996d01
10 changed files with 41 additions and 18 deletions
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42
src/common/imagbmp.cpp
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@@ -772,11 +772,15 @@ bool wxBMPHandler::DoLoadDib(wxImage * image, int width, int height,
if ( first == 0 )
{
// This is an escape sequence with special meaning.
if ( aByte == 0 )
{
// end of scanline marker
column = width;
row--;
// This is ignored if the end-of-line was
// implicitly assumed when column==width,
// in which case column is now 0.
if (column != 0)
column = width;
}
else if ( aByte == 1 )
{
@@ -787,18 +791,23 @@ bool wxBMPHandler::DoLoadDib(wxImage * image, int width, int height,
else if ( aByte == 2 )
{
// delta marker, move in image
// process column offset
aByte = stream.GetC();
if ( !stream.IsOk() )
return false;
column += aByte;
linepos = column * bpp / 4;
// process row offset
aByte = stream.GetC();
if ( !stream.IsOk() )
return false;
row += aByte; // upside down
row += aByte;
line = isUpsideDown ? height - 1 - row : row;
}
else
{
// absolute mode (pixels not runs)
int absolute = aByte;
wxUint8 nibble[2] ;
int readBytes = 0 ;
@@ -817,8 +826,6 @@ bool wxBMPHandler::DoLoadDib(wxImage * image, int width, int height,
ptr[poffset + 1] = cmap[nibble[k%2]].g;
ptr[poffset + 2] = cmap[nibble[k%2]].b;
column++;
if ( k % 2 )
linepos++;
}
if ( readBytes & 0x01 )
{
@@ -840,8 +847,6 @@ bool wxBMPHandler::DoLoadDib(wxImage * image, int width, int height,
ptr[poffset + 1] = cmap[nibble[l%2]].g;
ptr[poffset + 2] = cmap[nibble[l%2]].b;
column++;
if ( l % 2 )
linepos++;
}
}
}
@@ -874,8 +879,11 @@ bool wxBMPHandler::DoLoadDib(wxImage * image, int width, int height,
if ( aByte == 0 )
{
// end of scanline marker
column = width;
row--;
// This is ignored if the end-of-line was
// implicitly assumed when column==width,
// in which case column is now 0.
if (column != 0)
column = width;
}
else if ( aByte == 1 )
{
@@ -886,22 +894,26 @@ bool wxBMPHandler::DoLoadDib(wxImage * image, int width, int height,
else if ( aByte == 2 )
{
// delta marker, move in image
// process column offset
aByte = stream.GetC();
if ( !stream.IsOk() )
return false;
column += aByte;
linepos = column * bpp / 8;
// process row offset
aByte = stream.GetC();
if ( !stream.IsOk() )
return false;
row -= aByte;
row += aByte;
line = isUpsideDown ? height - 1 - row : row;
}
else
{
// absolute mode (pixels not runs)
int absolute = aByte;
for (int k = 0; k < absolute; k++)
{
linepos++;
aByte = stream.GetC();
if ( !stream.IsOk() )
return false;
@@ -920,13 +932,13 @@ bool wxBMPHandler::DoLoadDib(wxImage * image, int width, int height,
}
else
{
// encoded mode (repeat aByte first times)
for ( int l = 0; l < first && column < width; l++ )
{
ptr[poffset ] = cmap[aByte].r;
ptr[poffset + 1] = cmap[aByte].g;
ptr[poffset + 2] = cmap[aByte].b;
column++;
linepos++;
}
}
}
@@ -994,7 +1006,7 @@ bool wxBMPHandler::DoLoadDib(wxImage * image, int width, int height,
column++;
}
}
while ( (linepos < linesize) && (comp != 1) && (comp != 2) )
while ( (linepos < linesize) && (comp != BI_RLE8) && (comp != BI_RLE4) )
{
++linepos;
if ( !stream.ReadAll(&aByte, 1) )