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Fix bitmap transparency in Cairo GAL. 

Cairo ARGB32 format needs alpha pre-multiplied with color.
This commit is contained in:
Alex Shvartzkop 2023-07-02 08:36:30 +03:00
parent 0d7b4bbb09
commit f286015bc7
1 changed files with 20 additions and 10 deletions
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30
common/gal/cairo/cairo_gal.cpp
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@ -2,7 +2,7 @@
* This program source code file is part of KICAD, a free EDA CAD application.
*
* Copyright (C) 2012 Torsten Hueter, torstenhtr <at> gmx.de
* Copyright (C) 2012-2021 Kicad Developers, see AUTHORS.txt for contributors.
* Copyright (C) 2012-2023 Kicad Developers, see AUTHORS.txt for contributors.
* Copyright (C) 2017-2018 CERN
*
* @author Maciej Suminski <maciej.suminski@cern.ch>
@ -538,17 +538,27 @@ void CAIRO_GAL_BASE::DrawBitmap( const BITMAP_BASE& aBitmap, double alphaBlend )
{
for( int col = 0; col < w; col++ )
{
// Build the RGB24 pixel:
uint32_t pixel = bm_pix_buffer.GetRed( col, row ) << 16;
pixel += bm_pix_buffer.GetGreen( col, row ) << 8;
pixel += bm_pix_buffer.GetBlue( col, row );
unsigned char r = bm_pix_buffer.GetRed( col, row );
unsigned char g = bm_pix_buffer.GetGreen( col, row );
unsigned char b = bm_pix_buffer.GetBlue( col, row );
unsigned char a = wxALPHA_OPAQUE;
if( bm_pix_buffer.HasAlpha() )
pixel += bm_pix_buffer.GetAlpha( col, row ) << 24;
else if( bm_pix_buffer.HasMask() && pixel == mask_color )
pixel += ( wxALPHA_TRANSPARENT << 24 );
else
pixel += ( wxALPHA_OPAQUE << 24 );
{
a = bm_pix_buffer.GetAlpha( col, row );
// ARGB32 format needs pre-multiplied alpha
r = int32_t( r ) * a / 0xFF;
g = int32_t( g ) * a / 0xFF;
b = int32_t( b ) * a / 0xFF;
}
else if( bm_pix_buffer.HasMask() && ( r << 16 | g << 8 | b ) == mask_color )
{
a = wxALPHA_TRANSPARENT;
}
// Build the ARGB24 pixel:
uint32_t pixel = a << 24 | r << 16 | g << 8 | b;
// Write the pixel to the cairo image buffer:
uint32_t* pix_ptr = (uint32_t*) pix_buffer;