objective c - Drawing line on a CALayer in OSx -

i know if can me painting on layers.

the situation this

i programming on kind of screen http://multitouch.com, 12 touches simultaneously. in app developing, can manage multiple images. can rotate, scale move @ same time images (maximum 12 touches on screen!) accomplish use layers performances. every image represented calayer, create calayer's , set image 'contents'. hierarchy this.

i have nsview.

• nsview "container_view"
• calayer "images_layer" sublayer of "container_view" layer (they have same frame)
• calayer "img_1_layer", calayer "img_2_layer", calayer "img_3_layer", etc sublayer of "images_layer"

as told before, can rotate, scale , move images.

double tap on single image, lock whole screen, can still rotate , move image 2 fingers.

now user can draw 1 finger on image.

the main problem have not experience graphics , example on internet draw line on view.

the question how draw finger on calayer. have calayer, cannot have nsview

many thantk in advance, sergio

---

hi mazyod, calayer class provides image big.

please try understand context

mainwindow root naturally

nsviewcontroller called mainviewcontroller custom nsview root view - view called container , it's set contentview of mainwindow

calayer called images_layer - it's layer added sublayer of container's layer

calayer called img_layer - it's layer added sublayer of images_layer (i have 1 of each image, set contents naturally, cgimageref)

when click on image (imglayer), 3 methods fired usual:

ontouchpointdown - x, y etc ontouchpointmove - x, y etc ontouchpointup - x, y etc

ok, have found.

• set layer's delegate
• override method in delegate
• call layer setneeddisplay method when need

- (void)drawlayer:(calayer *)layer incontext:(cgcontextref)ctx

{

nsgraphicscontext *gc = [nsgraphicscontext graphicscontextwithgraphicsport:ctx flipped:no]; [nsgraphicscontext savegraphicsstate];  [nsgraphicscontext setcurrentcontext:gc];  // draw points bezier path  [nsgraphicscontext restoregraphicsstate]; 

}