Example of creating a brush on iOS (double stroke effect)

Define a UIView: The main is to add a uiimageview in this view, drawing all in this uiimageview inside

@property (nonatomic) cgpoint prepoint;  The point at which the finger precedes the move event @property (nonatomic) cgpoint oppsitepoint;  The point of the finger before entering the move event @property (nonatomic, retain) uiimageview* drawimage;-(ID) initWithFrame: (cgrect) frame{self    = [Super Initwithframe:frame];    if (self) {        ///initialization code        self.drawimage = [[Uiimageview alloc] initwithimage:nil];        Self.drawImage.frame = Self.frame;        [Self addsubview:_drawimage];            }    return self;}

Then handle the finger events

#pragma mark-deal touch-(void) Touchesbegan: (Nsset *) touches withevent: (uievent *) event{NSLog (@ "Touchesbegan");    The following two sentences know the point of the finger on the screen of the information uitouch* touch = [touches anyobject];        Cgpoint point = [Touch locationinview:self];        if (touch) {self.prepoint = point;        _oppsitepoint = point;    _oppsitepoint.x = 320.0f-point.x;    }}-(void) touchesmoved: (Nsset *) touches withevent: (uievent *) event{NSLog (@ "touchesmoved");    uitouch* touch = [touches anyobject];        if (touch) {Cgpoint point = [Touch locationinview:self];        Uigraphicsbeginimagecontext (self.frame.size);                                                [_drawimage.image drawinrect:cgrectmake (0, 0, _drawimage.frame.size.width, _drawimage.frame        . Size.Height)];        Cgcontextsetlinecap (Uigraphicsgetcurrentcontext (), kcglinecapround);        Cgcontextsetlinewidth (Uigraphicsgetcurrentcontext (), 2.0f); Cgcontextsetrgbstrokecolor (Uigraphicsgetcurrentcontext (), 0.314, 0.486, 0.859, 1.0);        Cgcontextbeginpath (Uigraphicsgetcurrentcontext ());         Cgcontextmovetopoint (Uigraphicsgetcurrentcontext (), _prepoint.x, _PREPOINT.Y);                Cgcontextaddquadcurvetopoint (Uigraphicsgetcurrentcontext (), _prepoint.x, _prepoint.y, Point.x, POINT.Y);        Cgcontextmovetopoint (Uigraphicsgetcurrentcontext (), _oppsitepoint.x, _OPPSITEPOINT.Y); Cgcontextaddquadcurvetopoint (Uigraphicsgetcurrentcontext (), _oppsitepoint.x, _oppsitepoint.y, 320.0f-point.x,               POINT.Y);        Cgcontextaddlinetopoint (Uigraphicsgetcurrentcontext (), Point.x, POINT.Y);        Cgcontextstrokepath (Uigraphicsgetcurrentcontext ());        _drawimage.image = Uigraphicsgetimagefromcurrentimagecontext ();                Uigraphicsendimagecontext ();        _prepoint = point;        _oppsitepoint = point;                    _oppsitepoint.x = 320.0f-point.x;        }}-(void) touchesended: (Nsset *) touches withevent: (uievent *) event{NSLog (@ "touchesended"); The effect of this paragraph is if the screenClick to draw a point uigraphicsbeginimagecontext (self.frame.size);                                            [_drawimage.image drawinrect:cgrectmake (0, 0, _drawimage.frame.size.width, _drawimage.frame    . Size.Height)];    Cgcontextsetlinecap (Uigraphicsgetcurrentcontext (), kcglinecapround);    Cgcontextsetlinewidth (Uigraphicsgetcurrentcontext (), 3.0f);    Cgcontextsetrgbstrokecolor (Uigraphicsgetcurrentcontext (), 0.314, 0.486, 0.859, 1.0);    Cgcontextbeginpath (Uigraphicsgetcurrentcontext ());    Cgcontextmovetopoint (Uigraphicsgetcurrentcontext (), _prepoint.x, _PREPOINT.Y);    Cgcontextaddlinetopoint (Uigraphicsgetcurrentcontext (), _prepoint.x, _PREPOINT.Y);    Cgcontextstrokepath (Uigraphicsgetcurrentcontext ());    _drawimage.image = Uigraphicsgetimagefromcurrentimagecontext ();    Uigraphicsendimagecontext (); Self.istouch = NO;}

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