在 iPhone/iPad 中画线 [英] Drawing a line in iPhone / iPad

问题描述

当用户可以画线时，我想开发一个应用程序......但我不想画直线，而是想在用户画线时显示线.当用户从 A 点到 B 点时，我想拉直这条线(如果用户想要的话).

I would like to develop an app when the user can draw lines... but I do not want to draw straight lines but want to show the line as the users draws it. When the user gets from point A to B I would like to straighten the line (if the users wants this).

为了能够做到这一点，我想将视图更改为从 0,0(左上角)开始到 320,480(对于 iPhone)和 768,1024(对于 iPad)(右下角)结束的网格.

To be able to do this I want to change my view into a grid starting at 0,0 (top left) and ending at 320,480 (for iPhone) and 768,1024 (for iPad) (bottom right).

对于这个问题，我的 A 点位于 10,10，B 点位于 100,100.

For this question I have point A at 10,10 and point B at 100,100.

我的问题:
- 如何创建这个网格?
- 如何创建这些点?
- 如何在不拉直的情况下绘制这条线?
- 如何画直线?

My question:
- How do I create this grid?
- How do I create these points?
- How do I draw this line without straightening it?
- How do I draw the straighten line?

我的问题是我熟悉创建普通"用户界面应用程序.我不熟悉 Open-GL 等.

My problem is that I am familiar with creating "normal" UI apps. I am not familiar with Open-GL ect.

我希望有人可以帮助我.

I hope someone can help me with this.

最好的问候，
保罗·皮伦

Best regards,
Paul Peelen

推荐答案

你继承你的 UIView 并覆盖 - (void)drawRect:(CGRect)rect 方法.

You subclass your UIView and override the - (void)drawRect:(CGRect)rect method.

您可以在其中获取图形上下文:

In there you grab a graphics context:

CGContextRef context = UIGraphicsGetCurrentContext();

然后你用它来调用 Core Graphics，比如:

And you use that to make Core Graphics calls, like:

CGContextRef context = UIGraphicsGetCurrentContext();
CGContextBeginPath (context);
for (k = 0; k < count; k += 2) {
    CGContextMoveToPoint(context, s[k].x, s[k].y);
    CGContextAddLineToPoint(context, s[k+1].x, s[k+1].y);
}
CGContextStrokePath(context);

查看 Quartz 2D 编程指南了解所有详细信息.

Look up the Quartz 2D Programming Guide for all the details.

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