i'm trying implement uiimageview subclass allow user draw in image view using fingers. contentmode of uiimageview set aspect fill. noticed when draw code executes , resulting image extracted graphics context being scaled in scale fill type format not want. wondering if knows how achieve extracting image , maintaining aspect ratio of image.
class drawimageview : uiimageview { var lasttouchpoint = cgpoint.zero var isswiping = false override func touchesbegan(_ touches: set<uitouch>, event: uievent?) { isswiping = false if let touchpoint = touches.first { lasttouchpoint = touchpoint.location(in: self) } } override func touchesmoved(_ touches: set<uitouch>, event: uievent?) { isswiping = true if let touchpoint = touches.first { let currentpoint = touchpoint.location(in: self) uigraphicsbeginimagecontext(frame.size) image?.draw(in: cgrect(x:0, y:0, width:frame.size.width, height:frame.size.height)) if let context = uigraphicsgetcurrentcontext() { context.move(to: lasttouchpoint) context.addline(to: currentpoint) context.setlinecap(cglinecap.round) context.setlinewidth(9.0) context.setstrokecolor(red: 0/255.0, green: 0/255.0, blue: 0/255.0, alpha: 1.0) context.strokepath() image = uigraphicsgetimagefromcurrentimagecontext() uigraphicsendimagecontext() lasttouchpoint = currentpoint } } } override func touchesended(_ touches: set<uitouch>, event: uievent?) { if(!isswiping) { uigraphicsbeginimagecontext(frame.size) image?.draw(in: cgrect(x:0, y:0, width:frame.size.width, height:frame.size.height)) if let context = uigraphicsgetcurrentcontext() { context.setlinecap(cglinecap.round) context.setlinewidth(9.0) context.setstrokecolor(red: 0/255.0, green: 0/255.0, blue: 0/255.0, alpha: 1.0) context.move(to: lasttouchpoint) context.addline(to: lasttouchpoint) context.strokepath() image = uigraphicsgetimagefromcurrentimagecontext() uigraphicsendimagecontext() } } } }
with code:
uigraphicsbeginimagecontext(frame.size) image?.draw(in: cgrect(x:0, y:0, width:frame.size.width, height:frame.size.height)) you saying "draw full image - regardless of size or aspect ratio - rectangle of width x height dimensions." so, if image has "native" size of, say, 300 x 200, , frame 200 x 200, that's image going drawn.
to avoid that, need calculate proper rect draw into. using sizes, you'd want (for aspect-fill):
image?.draw(in: cgrect(x:-50, y:0, width:frame.size.width + 50, height:frame.size.height)) of course, instead of hard-coded values, you'd run quick calculations determine actual numbers.
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