Added saving support to TGA image handler.

Supports saving 24-bit and 32-bit (RGB with alpha).
Updated image unit test to verify the alpha channel of saved TGA images. Also removed a condition skipping a test which only was in place for TGA (formerly its saving handler would do nothing yet say saving was succesful).

See also #7661.



git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66485 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

tests/image/image.cpp

@@ -874,13 +874,14 @@ static
 void CompareImage(const wxImageHandler& handler, const wxImage& expected)
 {
     bool testAlpha = expected.HasAlpha();
-    if (testAlpha && type != wxBITMAP_TYPE_PNG)
+    wxBitmapType type = handler.GetType();
+    if (testAlpha
+        && !(type == wxBITMAP_TYPE_PNG || type == wxBITMAP_TYPE_TGA) )
     {
         // don't test images with alpha if this handler doesn't support alpha
         return;
     }
 
-    wxBitmapType type = handler.GetType();
     if (type == wxBITMAP_TYPE_JPEG /* skip lossy JPEG */
         || type == wxBITMAP_TYPE_TIF)
     {
@@ -901,14 +902,6 @@ void CompareImage(const wxImageHandler& handler, const wxImage& expected)
         return;
     }
 
-    if ( !memOut.GetSize() )
-    {
-        // A handler that does not support saving can return true during
-        // SaveFile, in that case the stream is empty.
-        return;
-    }
-
-
     wxMemoryInputStream memIn(memOut);
     CPPUNIT_ASSERT(memIn.IsOk());