当我使用四边形曲线点时,我遇到了点问题。我想将不透明度设置为我的线条,但我也看到了这里的点数。 这是我的代码..
CGPoint midPoint(CGPoint p1,CGPoint p2)
{
return CGPointMake ((p1.x + p2.x) * 0.5,(p1.y + p2.y) * 0.5);
}
-(void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event//upon touches
{
UITouch *touch = [touches anyObject];
previousPoint1 = [touch locationInView:self.view];
previousPoint2 = [touch locationInView:self.view];
currentTouch = [touch locationInView:self.view];
}
-(void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event//upon moving
{
UITouch *touch = [touches anyObject];
previousPoint2 = previousPoint1;
previousPoint1 = currentTouch;
currentTouch = [touch locationInView:self.view];
CGPoint mid1 = midPoint(previousPoint2, previousPoint1);
CGPoint mid2 = midPoint(currentTouch, previousPoint1);
UIGraphicsBeginImageContext(CGSizeMake(1024, 768));
[imgDraw.image drawInRect:CGRectMake(0, 0, 1024, 768)];
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSetLineCap(context,kCGLineCapRound);
CGContextSetLineWidth(context, slider.value);
CGContextSetBlendMode(context, blendMode);
CGContextSetRGBStrokeColor(context,red, green, blue, 0.5);
CGContextBeginPath(context);
CGContextMoveToPoint(context, mid1.x, mid1.y);
CGContextAddQuadCurveToPoint(context, previousPoint1.x, previousPoint1.y, mid2.x, mid2.y);
CGContextStrokePath(context);
imgDraw.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsGetCurrentContext();
endingPoint=currentTouch;
}
任何答案都将不胜感激。
答案 0 :(得分:1)
您需要做的是保留用户目前输入的所有点的列表,并始终将所有点重新绘制为同一路径的一部分。
你需要一个数组来存储点。像
这样的东西CGPoint points[kMaxNumPoints];
而不是previousPoint1 / 2等。然后在touchesMoved:
中,您将遍历循环中的点。像这样:
CGContextBeginPath (context);
CGContextMoveToPoint (context, points [ 0 ].x, point [ 0 ].y);
for (int i = 1; i < currNumPoints; i++)
{
// I wasn't sure from your example if you wanted the mid point here instead of the
// previous point. But you get the idea.
CGContextAddQuadCurveToPoint (context, points [ i - 1 ].x, points [ i - 1 ].y, point [ i ].x, point [ i ].y);
}
CGContextStrokePath (context);