added support for alpha channel to wxColour to/from string conversion functions (slightly modified patch 1750112)

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@47361 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/latex/wx/colour.tex

@@ -118,17 +118,21 @@ Returns the blue intensity.
 Converts this colour to a \helpref{wxString}{wxstring} 
 using the given {\it flags}.
 
-The supported flags are {\bf wxC2S\_NAME}, to obtain the colour
+The supported flags are \textbf{wxC2S\_NAME}, to obtain the colour name (e.g.
-name (e.g. wxColour(255,0,0) -> \texttt{``red"}), {\bf wxC2S\_CSS\_SYNTAX}, to obtain
+wxColour(255,0,0) -> \texttt{``red"}), \textbf{wxC2S\_CSS\_SYNTAX}, to obtain
-the colour in the \texttt{``rgb(r,g,b)"} syntax
+the colour in the \texttt{``rgb(r,g,b)"} or \texttt{``rgba(r,g,b,a)"} syntax
-(e.g. wxColour(255,0,0) -> \texttt{``rgb(255,0,0)"}), and {\bf wxC2S\_HTML\_SYNTAX}, to obtain
+(e.g. wxColour(255,0,0,85) -> \texttt{``rgba(255,0,0,0.333)"}), and 
-the colour as  \texttt{``\#"} followed by 6 hexadecimal digits
+\textbf{wxC2S\_HTML\_SYNTAX}, to obtain the colour as  \texttt{``\#"} followed
-(e.g. wxColour(255,0,0) -> \texttt{``\#FF0000"}).
+by 6 hexadecimal digits (e.g. wxColour(255,0,0) -> \texttt{``\#FF0000"}).
 
-This function never fails and always returns a non-empty string.
+This function never fails and always returns a non-empty string but asserts if
+the colour has alpha channel (i.e. is non opaque) but
+\textbf{wxC2S\_CSS\_SYNTAX} (which is the only one supporting alpha) is not
+specified in flags.
 
 \newsince{2.7.0}
 
+
 \membersection{wxColour::GetPixel}\label{wxcolourgetpixel}
 
 \constfunc{long}{GetPixel}{\void}
@@ -170,7 +174,11 @@ Returns the red intensity.
 
 Sets the RGB intensity values using the given values (first overload), extracting them from the packed long (second overload), using the given string (third overloard).
 
-When using third form, Set() accepts: colour names (those listed in \helpref{wxTheColourDatabase}{wxcolourdatabase}), the CSS-like \texttt{``RGB(r,g,b)"} syntax (case insensitive) and the HTML-like syntax (i.e. \texttt{``\#"} followed by 6 hexadecimal digits for red, green, blue components).
+When using third form, Set() accepts: colour names (those listed in 
+\helpref{wxTheColourDatabase}{wxcolourdatabase}), the CSS-like 
+\texttt{``rgb(r,g,b)"} or \texttt{``rgba(r,g,b,a)"} syntax (case insensitive) 
+and the HTML-like syntax (i.e. \texttt{``\#"} followed by 6 hexadecimal digits 
+for red, green, blue components).
 
 Returns \true if the conversion was successful, \false otherwise.
 

src/common/colourcmn.cpp

@@ -39,19 +39,34 @@ bool wxColourBase::FromString(const wxString& str)
     if ( str.empty() )
         return false;       // invalid or empty string
 
-    if ( wxStrncmp(str, wxT("RGB"), 3) == 0 ||
+    if ( wxStrnicmp(str, wxT("RGB"), 3) == 0 )
-         wxStrncmp(str, wxT("rgb"), 3) == 0 )
     {
         // CSS-like RGB specification
-        // according to http://www.w3.org/TR/REC-CSS2/syndata.html#color-units
+        // according to http://www.w3.org/TR/css3-color/#colorunits
         // values outside 0-255 range are allowed but should be clipped
-        int red, green, blue;
+        int red, green, blue,
-        if (wxSscanf(str.wx_str() + 3, wxT("(%d, %d, %d)"), &red, &green, &blue) != 3)
+            alpha = wxALPHA_OPAQUE;
-            return false;
+        if ( str.length() > 3 && (str[3] == wxT('a') || str[3] == wxT('A')) )
+        {
+            float a;
+            // TODO: use locale-independent function
+            if ( wxSscanf(str.wx_str() + 4, wxT("( %d , %d , %d , %f )"),
+                                                &red, &green, &blue, &a) != 4 )
+                return false;
 
-        Set((unsigned char)wxClip(red,0,255),
+            alpha = wxRound(a * 255);
-            (unsigned char)wxClip(green,0,255),
+        }
-            (unsigned char)wxClip(blue,0,255));
+        else // no 'a' following "rgb"
+        {
+            if ( wxSscanf(str.wx_str() + 3, wxT("( %d , %d , %d )"),
+                                                &red, &green, &blue) != 3 )
+                return false;
+        }
+
+        Set((unsigned char)wxClip(red, 0, 255),
+            (unsigned char)wxClip(green, 0, 255),
+            (unsigned char)wxClip(blue, 0, 255),
+            (unsigned char)wxClip(alpha, 0, 255));
     }
     else if ( str[0] == wxT('#') && wxStrlen(str) == 7 )
     {
@@ -88,23 +103,46 @@ wxString wxColourBase::GetAsString(long flags) const
 {
     wxString colName;
 
-    if (flags & wxC2S_NAME)
+    const bool isOpaque = Alpha() == wxALPHA_OPAQUE;
-        colName = wxTheColourDatabase->FindName((const wxColour &)(*this)).MakeLower();
 
-    if ( colName.empty() && (flags & wxC2S_CSS_SYNTAX) )
+    // we can't use the name format if the colour is not opaque as the alpha
+    // information would be lost
+    if ( (flags & wxC2S_NAME) && isOpaque )
     {
-        // no name for this colour; return it in CSS syntax
+        colName = wxTheColourDatabase->FindName(
-        colName.Printf(wxT("rgb(%d, %d, %d)"),
+                    wx_static_cast(const wxColour &, *this)).MakeLower();
-                       Red(), Green(), Blue());
-    }
-    else if ( colName.empty() && (flags & wxC2S_HTML_SYNTAX) )
-    {
-        // no name for this colour; return it in HTML syntax
-        colName.Printf(wxT("#%02X%02X%02X"),
-                       Red(), Green(), Blue());
     }
 
-    // this function always returns a non-empty string
+    if ( colName.empty() )
+    {
+        const int red = Red(),
+                  blue = Blue(),
+                  green = Green();
+
+        if ( flags & wxC2S_CSS_SYNTAX )
+        {
+            // no name for this colour; return it in CSS syntax
+            if ( isOpaque )
+            {
+                colName.Printf(wxT("rgb(%d, %d, %d)"), red, green, blue);
+            }
+            else // use rgba() form
+            {
+                // TODO: use locale-independent function
+                colName.Printf(wxT("rgba(%d, %d, %d, %.3f)"),
+                               red, green, blue, Alpha() / 255.);
+            }
+        }
+        else if ( flags & wxC2S_HTML_SYNTAX )
+        {
+            wxASSERT_MSG( isOpaque, "alpha is lost in HTML syntax" );
+
+            // no name for this colour; return it in HTML syntax
+            colName.Printf(wxT("#%02X%02X%02X"), red, green, blue);
+        }
+    }
+
+    // this function should alway returns a non-empty string
     wxASSERT_MSG(!colName.empty(),
                  wxT("Invalid wxColour -> wxString conversion flags"));