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add support for reading alpha channel from BMP images (#9741)

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git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@54942 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
Vadim Zeitlin
2008-08-03 00:23:38 +00:00
parent 59e601677a
commit 55a35cb0c1
1 changed files with 32 additions and 5 deletions
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37
src/common/imagbmp.cpp
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@@ -479,9 +479,9 @@ bool wxBMPHandler::DoLoadDib(wxImage * image, int width, int height,
wxFileOffset bmpOffset, wxInputStream& stream,
bool verbose, bool IsBmp, bool hasPalette)
{
wxInt32 aDword, rmask = 0, gmask = 0, bmask = 0;
int rshift = 0, gshift = 0, bshift = 0;
int rbits = 0, gbits = 0, bbits = 0;
wxInt32 aDword, rmask = 0, gmask = 0, bmask = 0, amask = 0;
int rshift = 0, gshift = 0, bshift = 0, ashift = 0;
int rbits = 0, gbits = 0, bbits = 0, abits = 0;
wxInt32 dbuf[4];
wxInt8 bbuf[4];
wxUint8 aByte;
@@ -513,11 +513,29 @@ bool wxBMPHandler::DoLoadDib(wxImage * image, int width, int height,
{
if ( verbose )
wxLogError( _("BMP: Couldn't allocate memory.") );
if ( cmap )
delete[] cmap;
delete[] cmap;
return false;
}
unsigned char *alpha;
if ( bpp == 32 )
{
// tell the image to allocate an alpha buffer
image->SetAlpha();
alpha = image->GetAlpha();
if ( !alpha )
{
if ( verbose )
wxLogError(_("BMP: Couldn't allocate memory."));
delete[] cmap;
return false;
}
}
else // no alpha
{
alpha = NULL;
}
// Reading the palette, if it exists:
if ( bpp < 16 && ncolors != 0 )
{
@@ -602,9 +620,13 @@ bool wxBMPHandler::DoLoadDib(wxImage * image, int width, int height,
rmask = 0x00FF0000;
gmask = 0x0000FF00;
bmask = 0x000000FF;
amask = 0xFF000000;
ashift = 24;
rshift = 16;
gshift = 8;
bshift = 0;
abits = 8;
rbits = 8;
gbits = 8;
bbits = 8;
@@ -840,6 +862,11 @@ bool wxBMPHandler::DoLoadDib(wxImage * image, int width, int height,
ptr[poffset + 1] = temp;
temp = (unsigned char)((aDword & bmask) >> bshift);
ptr[poffset + 2] = temp;
if ( alpha )
{
temp = (unsigned char)((aDword & amask) >> ashift);
alpha[line * width + column] = temp;
}
column++;
}
}