added wxImage::IsTransparent(x, y)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@33284 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -29,6 +29,7 @@ All (GUI):
 - Added wxTE_BESTWRAP (based on patch by Mart Raudsepp).
 - wxEVT_COMMAND_SPLITTER_SASH_POS_CHANGED is now only sent once at the end of
   splitter dragging and not after each CHANGING event (Jacobo Vilella Vilahur).
+- Added wxImage::IsTransparent()
 
 Unix:
 

docs/latex/wx/image.tex

@@ -270,7 +270,7 @@ Returns number of colours in the histogram.
 
 \membersection{wxImage::ConvertAlphaToMask}\label{wximageconvertalphatomask}
 
-\func{bool}{ConvertAlphaToMask}{\param{unsigned char}{ threshold = 128}}
+\func{bool}{ConvertAlphaToMask}{\param{unsigned char}{ threshold = $128$}}
 
 If the image has alpha channel, this method converts it to mask. All pixels
 with alpha value less than \arg{threshold} are replaced with mask colour
@@ -708,6 +708,15 @@ of a given handler class in an application session.}
 \helpref{wxImageHandler}{wximagehandler}
 
 
+\membersection{wxImage::IsTransparent}\label{wximageistransparent}
+
+\constfunc{IsTransparent}{\param{int }{x}, \param{int }{y}, \param{unsigned char threshold = $128$}}
+
+Returns \true if the given pixel is transparent, i.e. either has the mask
+colour if this image has a mask or if this image has alpha channel and alpha
+value of this pixel is strictly less than \arg{threshold}.
+
+
 \membersection{wxImage::LoadFile}\label{wximageloadfile}
 
 \func{bool}{LoadFile}{\param{const wxString\&}{ name}, \param{long}{ type = wxBITMAP\_TYPE\_ANY}, \param{int}{ index = -1}}