ruby-****@sourc*****
ruby-****@sourc*****
2013年 3月 27日 (水) 12:26:25 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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@@ -327,7 +327,7 @@
Another thing to be aware of when modifying scale is the line thickness. Namely, it too is affected when switching between single digit scale settings to settings in hundreds of pixels. This may become very confusing if one is not careful, particularly when your line thickness becomes larger than your object or a geometric shape you are drawing.
:Default Scale Example
- (12.3.1.2.1.B1){{br}}
+ (12.3.1.2.1.A2){{br}}
{{image_left("1203-p04-scale_1,1-rect_0,0,50,50-in-drwArea-w-rulers-line-colors-c-s1.png")}}
For your convenience I also include an example using the default scale, i.e.:((*scale(1,1)*)) and pixels as x,y coordinates used in arguments to shape drawing methods. I also included the image collage, showing three different aspects of the graphics presentation. The first is the usual top Gtk window. For the second and the third, which are the images of the entire cairo drawing area, and the image only of the cr.rectangle(0, 0, 50, 50) respectively, I use GIMP graphic editor with rulers, to enlarge the relevant parts of drawing area and more clearly expose the sizes of both items. I intentionally changed Michael's rectangle's coordinates x1, y1 from (0.25, 0.25) to (0, 0), so the 0.5x0.5 square (now in pixels (50x50) is drawn directly from the 'centre' of the graphics coordinate system (in which, as you know the positive x axis runs from the top left corner of the drawing area to the right, and the positive y coordinate runs down along the left.) If you look carefu
lly, you will see, that the line thickness along x,y axis is only 1/2 of the true size (at the right and at the bottom sides of the square.) I changed the colour of the line from black (0, 0, 0) to pinkish (0.5, 0, 0) in order to better facilitate viewing of different colouration schemes in graphic editors (see the dashed line in the image above on the left).
@@ -359,10 +359,10 @@
window.show_all
Gtk.main
- Feel free to experiment with both, the original Michael's version of stroke.rb of code above (12.3.1.2.1), and my version (12.3.1.2.1.B1) using the default scale(1, 1), rather than scale(120, 120). Most importantly, you have to realize that the two examples use different kinds of coordinate arguments in shape drawing methods.
+ Feel free to experiment with both, the original Michael's version of stroke.rb of code above (12.3.1.2.1), and my version (12.3.1.2.1.A2) using the default scale(1, 1), rather than scale(120, 120). Most importantly, you have to realize that the two examples use different kinds of coordinate arguments in shape drawing methods.
:Rule of thumb
- (12.3.1.2.1.1R){{br}}
+ (12.3.1.2.1.A3){{br}}
As a rule of thumb, for scale(1, 1) drawings you should use pixels, and for drawings whose scale argument values resemble image size in pixels (i.e. values in hundreds rather than single digits) you should use relative notation in the form of small fractions not much larger than 5 or 10. Though, if you insist and do not care to simplify your work, you can try using very large or very small fractions when needed. (For instance line thickness 0.01 on one end, and say 150 on the other, is rather disconcerting, if you are not an abstract minded person, and prefer to operate in with naked eye observable reality.) I just think, the above rule of thumb makes sense.