如何缩放图形,使用CGContextRef创建

Question

我正在使用CGContextRef绘制线图.我可以放大缩小此图表以清楚地显示线条.

我正在使用此代码.

CGContextRef context=UIGraphicsGetCurrentContext();
CGContextBeginPath(context);

CGMutablePathRef path=CGPathCreateMutable();
CGPathMoveToPoint(path, NULL, lastPointX, lastPointY);
CGPathAddLineToPoint(path, NULL, newPointX, newPointY);

CGContextAddPath(context, path);
CGContextSetLineWidth(context, lineWidth);
CGContextSetStrokeColorWithColor(context, lineColor);
CGContextStrokePath(context);
CGPathRelease(path);

if (isFilling) {
    CGMutablePathRef path=CGPathCreateMutable();
    CGPathMoveToPoint(path, NULL, newPointX, newPointY);
    CGPathAddLineToPoint(path, NULL, newPointX, self.bounds.size.height);
    CGPathAddLineToPoint(path, NULL, lastPointX, self.bounds.size.height);
    CGPathAddLineToPoint(path, NULL, lastPointX, lastPointY);
    CGPathCloseSubpath(path);

    CGContextAddPath(context, path);
    CGContextSetFillColorWithColor(context, fillingColor);
    CGContextFillPath(context);
    CGPathRelease(path);
}

注意: - 我不想缩放视图.我想重新绘制线条以清楚地显示.

Answer 1

您必须在UIScrollView上绘制此图表，或者您可以在UIScrollView上添加视图 ，然后您就可以放大和缩小该图表。为此，您应该实现UIScrollView的以下方法：

- (UIView*)viewForZoomingInScrollView:(UIScrollView *)scrollView {
}
- (void)scrollViewDidZoom:(UIScrollView *)scrollView {
}

作为参考，您可以遵循这个不错的教程：

http://www.raywenderlich.com/10518/how-to-use-uiscrollview-to-scroll-and-zoom-content

它会告诉你实现以下方法：

- (void)centerContentsOfScrollView:(UIScrollView *)scrollView
{
}
- (void)scrollViewDoubleTapped:(UITapGestureRecognizer*)recognizer
{
}
- (void)scrollViewTwoFingerTapped:(UITapGestureRecognizer*)recognizer
{
}