沿iOS中的路径均匀间隔绘制图像 [英] Draw images evenly spaced along a path in iOS
问题描述
我想要做的是将手指移过屏幕（touchesMoved）并沿着touchesMoved生成的点绘制均匀间隔的图像（可能是CGImageRefs）。我可以绘制线条，但我想要生成的东西看起来像这样（对于这个例子我使用箭头的图像，但它可能是任何图像，可能是我的狗的照片:)）主要的是用手指在iPhone或iPad上绘图时，图像均匀分布。
What I want to do is move my finger across the screen (touchesMoved) and draw evenly spaced images (perhaps CGImageRefs) along the points generated by the touchesMoved. I can draw lines, but what I want to generate is something that looks like this (for this example I am using an image of an arrow but it could be any image, could be a picture of my dog :) ) The main thing is to get the images evenly spaced when drawing with a finger on an iPhone or iPad.
推荐答案
假设您已经拥有跟踪用户触摸的代码在屏幕上移动他们的触摸，听起来你想要检测他们何时移动了等于图像长度的距离，此时你想要在他们的触摸下绘制另一个图像副本。
Assuming that you already have code that tracks the user's touch as they move their touch around the screen, it sounds like you want to detect when they have moved a distance equal to the length of your image, at which time you want to draw another copy of your image under their touch.
为实现这一目标，我认为你需要：
To achieve this, I think you will need to:
- 计算你的长度（宽度）图片
- 实现代码，将图像副本绘制到视图上，旋转到任意角度
- 每次用户访问uch移动（例如in touchesMoved :)：
- 计算每次移动时触摸的增量并生成该delta的长度（例如sqrt（dx ^ 2 + dy ^） 2））
- 累积自上次拍摄图像以来的距离
- 如果距离已达到图像的长度，请绘制一份触摸当前位置下的图像，适当旋转（可能根据从最后一个图像的位置到当前位置的向量）
- calculate the length (width) of your image
- implement code to draw copies of your image onto your view, rotated to any angle
- each time the user's touch moves (e.g. in touchesMoved:):
- calculate the delta of the touch each time it moves and generate the "length" of that delta (e.g. something like sqrt(dx^2 + dy^2))
- accumulate the distance since the last image was drawn
- if the distance has reached the length of your image, draw a copy of your image under the touch's current position, rotated appropriately (probably according to the vector from the position of the last image to the current position)
听起来怎么样？
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