ruby-****@sourc*****
ruby-****@sourc*****
2013年 3月 27日 (水) 22:56:42 JST
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REMOTE_ADDR = 70.49.48.128
REMOTE_HOST =
URL = http://ruby-gnome2.sourceforge.jp/hiki.cgi?tut-gtk2-dancr-rbcatut
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@@ -585,6 +585,46 @@
{{image_right("123-08-mask.png")}}
+ The ((<cairo_mask()|URL:http://www.cairographics.org/manual/cairo-cairo-t.html#cairo-mask>)) and ((<cairo_mask_surface()|URL:http://www.cairographics.org/manual/cairo-cairo-t.html#cairo-mask-surface>)) operations allow transfer according to the transparency/opacity of a second source pattern or surface. Where the pattern or surface is opaque, the current source is transferred to the destination. Where the pattern or surface is transparent, nothing is transferred.
+
+ :Ruby Cairo Library Fails To Support Gradients
+ (12.3.1.2.5.A1){{br}}
+
+ {{br}}{{image_right("1203-p08-mask-in-C.png")}}
+ # Your code goes between the two dashed lines:
+ # -- your code - start ----------------------------------------- -s-
+
+ linearg = Cairo.pattern_create_linear(0, 0, 1, 1)
+ linearg.add_color_stop_rgb(0, 0, 0.3, 0.8)
+ linearg.add_color_stop_rgb(1, 0, 0.8, 0.3)
+
+ radialg = Cairo.pattern_create_radial(0.5, 0.5, 0.25, 0.5, 0.5, 0.75)
+ radialg.add_color_stop_rgba(0, 0, 0, 0, 1)
+ radialg.add_color_stop_rgba(0.5, 0, 0, 0, 0)
+
+ cr.set_source(linearg)
+ cr.mask(radialg)
+ # -- your code - end ------------------------------------------- -e-
+
+ The above code in Ruby is completely unsupported. While ((*Cairo.pattern_create_linear*)) and ((*Cairo.pattern_create_radial*)), nor ((*Cairo::Context#add_color_stop_rgb/rgba*)) and ((*Cairo::Context#add_color_stop_rgb/rgba*)) do not exist at all, "Cairo::Context#set_source" and "Cairo::Context#mask" are not adequately documented, most likely because their parameters also are nowhere explained nor mentioned except in error messages. Namely, the line "cr.set_source(linearg)" would produce the following error message: ((*"`set_source': not a cairo pattern"*)), and the line "cr.mask(radialg): ((*"`mask': not a cairo surface".*))
+
+
+
+{{br}}
+{{br}}
+
+== Drawing with Cairo
+(12.3.2){{br}}
+
+
+
+
+
+{{br}}
+
+=== Preparing and Selecting a Source
+(12.3.2.1){{br}}
+{{image_right("1203-p09-setsourcergba-in-C.png")}}
{{br}}