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Changed behaviour of wxImageResizeQuality parameter in wxImage.Scale and wxImage.Rescale.

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Made the following changes:

* Formerly specifying to resize using wxIMAGE_QUALITY_BICUBIC or wxIMAGE_QUALITY_BILINEAR could result in the ResampleBox method being used. Now always resize with the method that the user actually specified.

* Added wxIMAGE_QUALITY_BOX_AVERAGE to explicitly allow resizing with the ResampleBox method.

* Previously wxIMAGE_QUALITY_HIGH was equal to wxIMAGE_QUALITY_BICUBIC. It has been changed to use wxIMAGE_QUALITY_BOX_AVERAGE when reducing the size of an image and wxIMAGE_QUALITY_BICUBIC in all other cases.

Closes #12845.



git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@67203 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775
This commit is contained in:
Dimitri Schoolwerth
2011-03-15 16:42:34 +00:00
parent 41774f1b20
commit fdb7d5bbc2
3 changed files with 38 additions and 18 deletions
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3
include/wx/image.h
View File

@@ -62,12 +62,13 @@ enum wxImageResizeQuality
wxIMAGE_QUALITY_NEAREST = 0,
wxIMAGE_QUALITY_BILINEAR = 1,
wxIMAGE_QUALITY_BICUBIC = 2,
wxIMAGE_QUALITY_BOX_AVERAGE = 3,
// default quality is low (but fast)
wxIMAGE_QUALITY_NORMAL = wxIMAGE_QUALITY_NEAREST,
// highest (but best) quality
wxIMAGE_QUALITY_HIGH = wxIMAGE_QUALITY_BICUBIC
wxIMAGE_QUALITY_HIGH
};
// alpha channel values: fully transparent, default threshold separating

18
interface/wx/image.h
View File

@@ -39,10 +39,24 @@ enum wxImageResizeQuality
/// Highest quality but slowest execution time.
wxIMAGE_QUALITY_BICUBIC,
/// Default image resizing algorithm used by wxImage::Scale().
/**
Use surrounding pixels to calculate an average that will be used for
new pixels. This method is typically used when reducing the size of
an image.
wxIMAGE_QUALITY_BOX_AVERAGE,
/**
Default image resizing algorithm used by wxImage::Scale(). Currently
the same as wxIMAGE_QUALITY_NEAREST.
*/
wxIMAGE_QUALITY_NORMAL,
/// Best image resizing algorithm, currently same as wxIMAGE_QUALITY_BICUBIC.
/**
Best image resizing algorithm. Since version 2.9.2 this results in
wxIMAGE_QUALITY_BOX_AVERAGE being used when reducing the size of the
image (meaning that both the new width and height will be smaller than
the original size). Otherwise wxIMAGE_QUALITY_BICUBIC is used.
*/
wxIMAGE_QUALITY_HIGH
};

35
src/common/image.cpp
View File

@@ -442,23 +442,16 @@ wxImage::Scale( int width, int height, wxImageResizeQuality quality ) const
if ( old_width == width && old_height == height )
return *this;
// resample the image using either the nearest neighbourhood, bilinear or
// bicubic method as specified
if (quality == wxIMAGE_QUALITY_HIGH)
{
quality = (width < old_width && height < old_height)
? wxIMAGE_QUALITY_BOX_AVERAGE
: wxIMAGE_QUALITY_BICUBIC;
}
// Resample the image using the method as specified.
switch ( quality )
{
case wxIMAGE_QUALITY_BICUBIC:
case wxIMAGE_QUALITY_BILINEAR:
// both of these algorithms should be used for up-sampling the
// image only, when down-sampling always use box averaging for best
// results
if ( width < old_width && height < old_height )
image = ResampleBox(width, height);
else if ( quality == wxIMAGE_QUALITY_BILINEAR )
image = ResampleBilinear(width, height);
else if ( quality == wxIMAGE_QUALITY_BICUBIC )
image = ResampleBicubic(width, height);
break;
case wxIMAGE_QUALITY_NEAREST:
if ( old_width % width == 0 && old_width >= width &&
old_height % height == 0 && old_height >= height )
@@ -468,6 +461,18 @@ wxImage::Scale( int width, int height, wxImageResizeQuality quality ) const
image = ResampleNearest(width, height);
break;
case wxIMAGE_QUALITY_BILINEAR:
image = ResampleBilinear(width, height);
break;
case wxIMAGE_QUALITY_BICUBIC:
image = ResampleBicubic(width, height);
break;
case wxIMAGE_QUALITY_BOX_AVERAGE:
image = ResampleBox(width, height);
break;
}
// If the original image has a mask, apply the mask to the new image