在iPad App中绘制带发光效果的线条

Question

I have integrate draw line in my application i have not used OpenGL or any other similar framework.

So now i want to give glow effect to their lines so how can i give it?

Thanks in advance.

Answer 1

Set the shadow in your graphics context to have a zero size offset, a blur of around 6-10 (change according to taste) and the same colour as your stroke colour. This will give all subsequent drawing a glow effect. The command is

CGContextSetShadowWithColor()

Documented here .

Answer 2

-(void)drawRect:(CGRect)rect{

[curImage drawAtPoint:CGPointMake(0, 0)];

 CGPoint mid1 = midPoint(previousPoint1, previousPoint2); 

 CGPoint mid2 = midPoint(currentPoint, previousPoint1);

    CGContextRef context = UIGraphicsGetCurrentContext(); 

    [self.layer renderInContext:context];

    CGContextMoveToPoint(context, mid1.x, mid1.y);
    // Use QuadCurve is the key
    CGContextAddQuadCurveToPoint(context, previousPoint1.x, previousPoint1.y, mid2.x, mid2.y); 

    CGContextSetLineCap(context, kCGLineCapRound);
    CGContextSetLineWidth(context, self.lineWidth);
    CGContextSetStrokeColorWithColor(context, self.lineColor.CGColor);
        //------------  Glow Lines ----------

    if (appDel.BrushType == 201) // (201 is glow brush type)
    {
        CGContextSetLineWidth(context, 7);

        CGColorSpaceRef space = CGColorSpaceCreateDeviceRGB();

        CGFloat components[4]={appDel.R_color/255.0,appDel.G_color/255.0,appDel.B_color/255.0,1.0};
        CGColorRef color1 = CGColorCreate(space, components);

        CGContextSetShadowWithColor(context, CGSizeMake( 0.0, 0.0 ), 15, color1);

        CGContextStrokePath(UIGraphicsGetCurrentContext());

    }
    //--------------
    CGContextStrokePath(context);
    [super drawRect:rect];

    [curImage release];


}