Added documentation for "fl_can_do_alpha_blending()"

git-svn-id: file:///fltk/svn/fltk/branches/branch-1.1@5434 ea41ed52-d2ee-0310-a9c1-e6b18d33e121

documentation/drawing.html

@@ -865,13 +865,19 @@ color.
 The <TT>draw()</TT> method draws the image using the colors in the
 file, and masks off any transparent colors automatically.
 
-<P>The <TT>Fl_RGB_Image</TT> class encapsulates a full-color (or
+<P>The <TT>Fl_RGB_Image</TT> class encapsulates a full-color 
-grayscale) image with 1 to 4 color components. Images with an
+(or grayscale) image with 1 to 4 color components. Images with 
-even number of components are assumed to contain an alpha
+an even number of components are assumed to contain an 
-channel that is used for transparency. The transparency provided
+alpha channel that is used for transparency. The transparency 
-by the <TT>draw()</TT> method is either a 24-bit blend against
+provided by the <TT>draw()</TT> method is either a 24-bit 
-the existing window contents or a "screen door" transparency
+blend against the existing window contents or a "screen door" 
-mask, depending on the platform and screen color depth.
+transparency mask, depending on the platform and screen color depth. 
+
+<H4><A NAME=fl_can_do_alpha_blending>char fl_can_do_alpha_blending()</A></H4>
+
+<P><TT>fl_can_do_alpha_blending()</TT> will return 1, if your
+platform supports true alpha blending for RGBA images, or 0, 
+if FLTK will use screen door transparency.
 
 <P>FLTK also provides several image classes based on the three
 standard image types for common file formats:

documentation/functions.html

@@ -27,6 +27,7 @@ A</A>.
         <LI><A HREF="drawing.html#fl_begin_points"><TT>fl_begin_points</TT></A></LI>
         <LI><A HREF="drawing.html#fl_begin_polygon"><TT>fl_begin_polygon</TT></A></LI>
         <LI><A HREF="osissues.html#WIN32.gdi"><TT>fl_brush</TT></A> (WIN32)</LI>
+        <LI><A HREF="drawing.html#fl_can_do_alpha_blending"><TT>fl_can_do_alpha_blending</TT></A></LI>
         <LI><A HREF="#fl_casealphasort"><TT>fl_casealphasort</TT></A></LI>
         <LI><A HREF="#fl_casenumericsort"><TT>fl_casenumericsort</TT></A></LI>
         <LI><A HREF="#fl_choice2"><TT>fl_choice</TT></A></LI>
@@ -99,11 +100,11 @@ A</A>.
         <LI><A HREF="drawing.html#fl_measure"><TT>fl_measure</TT></A></LI>
         <LI><A HREF="drawing.html#fl_measure_pixmap"><TT>fl_measure_pixmap</TT></A></LI>
         <LI><A HREF="#fl_message"><TT>fl_message</TT></A></LI>
+        <LI><A HREF="#fl_message_font"><TT>fl_message_font</TT></A></LI>
       </UL>
     </TD>
     <TD width=30%>
       <UL>
-        <LI><A HREF="#fl_message_font"><TT>fl_message_font</TT></A></LI>
         <LI><A HREF="#fl_message_icon"><TT>fl_message_icon</TT></A></LI>
         <LI><A HREF="drawing.html#fl_scale"><TT>fl_mult_matrix</TT></A></LI>
         <LI><A HREF="drawing.html#fl_not_clipped"><TT>fl_not_clipped</TT></A></LI>
@@ -314,12 +315,13 @@ A</A>.
 
 	<LI>Image Functions
 	<UL>
+		<LI><A HREF="drawing.html#fl_can_do_alpha_blending"><TT>fl_can_do_alpha_blending</TT></A></LI>
 		<LI><A HREF="#fl_register_images"><TT>fl_register_images</TT></A></LI>
-        	<LI><A HREF="drawing.html#fl_draw_image"><TT>fl_draw_image</TT></A></LI>
+		<LI><A HREF="drawing.html#fl_draw_image"><TT>fl_draw_image</TT></A></LI>
-        	<LI><A HREF="drawing.html#fl_draw_image"><TT>fl_draw_image_mono</TT></A></LI>
+		<LI><A HREF="drawing.html#fl_draw_image"><TT>fl_draw_image_mono</TT></A></LI>
-        	<LI><A HREF="drawing.html#fl_draw_pixmap"><TT>fl_draw_pixmap</TT></A></LI>
+		<LI><A HREF="drawing.html#fl_draw_pixmap"><TT>fl_draw_pixmap</TT></A></LI>
-        <LI><A HREF="drawing.html#fl_measure_pixmap"><TT>fl_measure_pixmap</TT></A></LI>
+		<LI><A HREF="drawing.html#fl_measure_pixmap"><TT>fl_measure_pixmap</TT></A></LI>
-        <LI><A HREF="drawing.html#fl_read_image"><TT>fl_read_image</TT></A></LI>
+		<LI><A HREF="drawing.html#fl_read_image"><TT>fl_read_image</TT></A></LI>
 	</UL>
 	</LI>