自由手绘中的问题? [英] Issue in free hand drawing ?

问题描述

我使用以下代码在整个视图上徒手绘制:

I used below code for free hand drawing on the whole view:

UIGraphicsBeginImageContext(self.view.frame.size);
    [drawImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
    CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
    CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0);
    CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0);
    CGContextBeginPath(UIGraphicsGetCurrentContext());
    CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
    CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
    CGContextStrokePath(UIGraphicsGetCurrentContext());
    drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

现在我的要求是这样的..我应该能够在视图的特定区域上绘制.所以我修改了这样的代码..

Now my requirement is something like this .. I should be able to draw on particular area of a view. So I modified the code like this ..

UIGraphicsBeginImageContext(CGSizeMake(300, 100));
    [drawImage.image drawInRect:CGRectMake(0, 0, 400, 100)];
    CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
    CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0);
    CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0);
    CGContextBeginPath(UIGraphicsGetCurrentContext());
    CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
    CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
    CGContextStrokePath(UIGraphicsGetCurrentContext());
    drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

，但图纸不正确.请建议我该怎么做.

but the drawing is not proper. Please suggest me how to do this.

推荐答案

创建自定义视图，如:

UIView * drawingView = [[UIView alloc] initWithFrame:CGRectMake(x，y，300，300)];

UIView *drawingView = [[UIView alloc] initWithFrame:CGRectMake(x, y, 300, 300)];

[self.view addSubView:drawingView];

[self.view addSubView:drawingView];

然后修改您的代码，如下所示:

And Then modify your code something like below :

UIGraphicsBeginImageContext(drawingView.frame.size);[drawImage.image drawInRect:CGRectMake(0，0，drawingView.frame.size.width，drawingView.frame.size.height)];

UIGraphicsBeginImageContext(drawingView.frame.size); [drawImage.image drawInRect:CGRectMake(0, 0, drawingView.frame.size.width, drawingView.frame.size.height)];

CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0);
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0);
CGContextBeginPath(UIGraphicsGetCurrentContext());
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
CGContextStrokePath(UIGraphicsGetCurrentContext());
drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

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