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Optimize wxImage::Rotate90() by rotating alpha separately.

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Bringing the alpha rotation out in a separate loop results in an
approximatively 10% performance improvement.

Closes #12712.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66254 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
Vadim Zeitlin 2010-11-24 12:43:36 +00:00
parent a6bf0c9533
commit 89a1395ebc
1 changed files with 23 additions and 11 deletions
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34
src/common/image.cpp
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@ -1091,33 +1091,45 @@ wxImage wxImage::Rotate90( bool clockwise ) const
unsigned char *data = image.GetData();
const unsigned char *source_data = M_IMGDATA->m_data;
unsigned char *target_data;
unsigned char *alpha_data = image.GetAlpha();
const unsigned char *source_alpha = M_IMGDATA->m_alpha;
unsigned char *target_alpha = 0 ;
for (long j = 0; j < height; j++)
{
for (long i = 0; i < width; i++)
{
if (clockwise)
if ( clockwise )
{
target_data = data + (((i+1)*height) - j - 1)*3;
if (source_alpha)
target_alpha = alpha_data + (((i+1)*height) - j - 1);
}
else
{
target_data = data + ((height*(width-1)) + j - (i*height))*3;
if (source_alpha)
target_alpha = alpha_data + ((height*(width-1)) + j - (i*height));
}
memcpy( target_data, source_data, 3 );
source_data += 3;
}
}
if (source_alpha)
const unsigned char *source_alpha = M_IMGDATA->m_alpha;
if ( source_alpha )
{
unsigned char *alpha_data = image.GetAlpha();
unsigned char *target_alpha = 0 ;
for (long j = 0; j < height; j++)
{
for (long i = 0; i < width; i++)
{
memcpy( target_alpha, source_alpha, 1 );
source_alpha += 1;
if ( clockwise )
{
target_alpha = alpha_data + (((i+1)*height) - j - 1);
}
else
{
target_alpha = alpha_data + ((height*(width-1)) + j - (i*height));
}
*target_alpha = *source_alpha++;
}
}
}