自动生成圆角图像
go2...@gmail.com
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2.Google自备的圆角商店（http://xach.livejournal.com/95656.html）
http://groups-beta.google.com/groups/roundedcorners?c=999999&bc=white&w=4&h=4&a=tr
说明：
c－圆角图片颜色，值为颜色名称，或不带#号的CSS样式的16进制颜色（规格RGB或RRGGBB）。其中颜色名称取自CSS2规范，包括aqua,
black, blue, fuchsia, gray, green, lime, maroon, navy, olive, purple,
red, silver, teal, white和 yellow；
bc－圆角图片背景色，与c能接受的值相同。如果省略这个参数，背景则为透明色；
w－圆角宽度，值以像素为单位，不用此参数的不用默认值为8；
h－圆角高度，值以像素为单位，不用此参数的默认值为8；
a－圆角位置：左上角值tl，右上角值tr，左下角值bl，右下角值br。
参考：
c - the color, as either a name or a CSS-style hex color spec (RGB or
RRGGBB) sans #. The color names are taken from the CSS2 spec and are as
follows: aqua, black, blue, fuchsia, gray, green, lime, maroon, navy,
olive, purple, red, silver, teal, white, and yellow (thanks, anonymous
commenter)
bc - the background color, same acceptable input as c. One twist: if
you leave out the bc parameter entirely, the background is transparent.
h - height in pixels. If you leave it out, uses a default of 8.
w - width in pixels. If you leave it out, uses a default of 8.
a - which corner to generate; tl is top left, tr is top right, bl is
bottom left, br is bottom right
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