ios - Why does -[UIColor setFill] work without referring to a drawing context? -


it escapes me why code, inside drawrect:, works:

uibezierpath *buildingfloor = [[uibezierpath alloc] init]; // draw shape addlinetopoint [[uicolor colorwithred:1 green:0 blue:0 alpha:1.0] setfill]; // i'm sending setfill uicolor object? [buildingfloor fill]; // fills current fill color

my point is, uicolor object gets message setfill , somehow stack understands uicolor fill color, isn't weird , wrong? @ least expect setting fill calling cgcontext method... instead of representing color, uicolor goes on , change context of drawing.

could explain happening behind scenes, because i'm totally lost here?

i did check out these references before posting:

http://developer.apple.com/library/ios/#documentation/uikit/reference/uicolor_class/reference/reference.html http://developer.apple.com/library/ios/#documentation/uikit/reference/uibezierpath_class/reference/reference.html

my point is, uicolor object gets message setfill , somehow stack understands uicolor fill color, isn't weird , wrong? @ least expect setting fill calling cgcontext method... instead of representing color, uicolor goes on , change context of drawing.

it because taking place within current cgcontext. why code works if there is current cgcontext (as there is, example, in drawrect: or in uigraphicsbeginimagecontextwithoptions block).

it lot, @ stage of ios study, read drawing chapter of book: http://www.apeth.com/iosbook/ch15.html#_graphics_contexts


Comments

Post a Comment

Popular posts from this blog

linux - xterm copying to CLIPBOARD using copy-selection causes automatic updating of CLIPBOARD upon mouse selection -

i've tried various ways coerce xterm (versions 285 , 292) copy selection clipboard clipboard whenever press ctrl-shift-c. promising way far has been, in ~/.xresources, put this: xterm*vt100.translations: #override \ ctrl shift <keypress> c: copy-selection(clipboard) \n\ ctrl shift <keypress> v: insert-selection(clipboard) ctrl-shift-v works perfectly, copying has nuance... if restart xterm, highlighting text puts things in primary clipboard; expected, proper, default behavior. if hit ctrl-shift-c, copies current selection clipboard clipboard. the bug, however, if highlight text after first time pressed ctrl-shift-c, you'll see highlighting copies both primary and clipboard. cannot figure out how stop xterm updating clipboard upon selection... , doesn't make sense me in first place. i said, @ specific point in time, copy selection clipboard... yet starts updating automatically upon selection after doing once... anyone have workaround...
Read more

c++ - qgraphicsview horizontal scrolling always has a vertical delta -

Image
i've subclassed qgraphicsview custom canvas used in cad application. i've reimplemented qgraphicsview::wheelevent check keyboard modifiers control key and, if control key pressed, zoom. i'm trying implement horizontal scroll when user holds shift , uses wheel. the problem i'm having horizontal scrolling always scrolls 0.279. not huge problem, hugely annoying , points else being wrong. so, here questions: is right way implement horizontal scrolling? if not, is? how eliminate delta of 0.279? thanks in advance. code , sample output below void myview::zoom(int delta) { double factor = pow(1.2, delta/abs(delta)); this->scale(factor, factor); } void myview::scrollhorizontal(int level) { qpointf center = maptoscene(viewport()->rect().center()); qdebug() << "center: " << center.x() << ", " << center.y(); centeron(qpointf(center.x() - level, center.y())); } void myview::wheelevent(qwheeleve...
Read more