绘制直线
代码
class DrawLinesView: UIView {
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
override func drawRect(rect: CGRect) {
// Drawing code
//设定绘画环境
let context = UIGraphicsGetCurrentContext()
//绘画起点
CGContextMoveToPoint(context, 100, 100)
//绘画终点
CGContextAddLineToPoint(context, 100, 200)
//绘画终点
CGContextAddLineToPoint(context, 200, 200)
//绘画起点
CGContextMoveToPoint(context, 100, 300)
//绘画终点
CGContextAddLineToPoint(context, 100, 400)
//绘画终点
CGContextAddLineToPoint(context, 200, 500)
//设定颜色
CGContextSetRGBStrokeColor(context, 1, 0, 1, 1)
//设定线条宽度
CGContextSetLineWidth(context, 5)
//绘制线条
CGContextStrokePath(context)
}
绘制矩形
代码
import UIKit
class DrawRectView: UIView {
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
override func drawRect(rect: CGRect) {
// Drawing code
//设定绘画环境
let context = UIGraphicsGetCurrentContext()
//加入矩形
CGContextAddRect(context, CGRect(x:100,y:100,width: 100,height: 100))
//填充颜色
CGContextSetRGBFillColor(context, 1, 0, 0, 1)
//绘制矩形
CGContextFillPath(context)
//设置外框的宽度
CGContextSetLineWidth(context, 5)
//设置外框颜色
CGContextSetRGBStrokeColor(context,0 ,1, 0, 1)
//绘制外框
CGContextStrokeRect(context, CGRect(x: 100, y: 100, width: 100, height: 100))
}
}
绘制圆形
代码
import UIKit
class DrawCircle: UIView {
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
override func drawRect(rect: CGRect) {
// Drawing code
let context = UIGraphicsGetCurrentContext()
//加入圆形
CGContextAddArc(context, 150, 200, 100, 0, 3.141592653 * 2, 0)
//填充颜色
CGContextSetRGBFillColor(context, 1, 0, 0, 1)
//开始绘制填充
CGContextFillPath(context)
//加入圆形
CGContextAddArc(context, 150, 200, 100, 0, 3.141592653 * 2, 0)
//设定宽度
CGContextSetLineWidth(context, 10)
//绘制
CGContextStrokePath(context)
//加入椭圆
CGContextAddEllipseInRect(context, CGRect(x: 50, y: 400, width: 200, height: 100))
//绘制
CGContextStrokePath(context)
}
}
绘制图片
代码
import UIKit
class DrawImageView: UIView {
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
override func drawRect(rect: CGRect) {
// Drawing code
var uiImage:CGImageRef?
uiImage = UIImage(named: "girl.jpg")?.CGImage
let context = UIGraphicsGetCurrentContext()
//context状态的维持和释放，不影响其他图像的绘制
CGContextSaveGState(context)
//没有如下这两个图像会翻转
CGContextTranslateCTM(context, 10, 400)
CGContextScaleCTM(context, 1, -1)
CGContextDrawImage(context, CGRect(x: 0,y: 0,width: 200,height: 200), uiImage)
CGContextRestoreGState(context)
CGContextStrokeRect(context, CGRect(x: 50, y: 100, width: 100, height: 100))
}
}
绘图板
代码
import UIKit
class DrawBoardView: UIView {
var path = CGPathCreateMutable()
override func touchesBegan(touches: Set<UITouch>, withEvent event: UIEvent?) {
let p = (touches as NSSet).anyObject()?.locationInView(self)
CGPathMoveToPoint(path, nil, p!.x, p!.y)
}
override func touchesMoved(touches: Set<UITouch>, withEvent event: UIEvent?) {
let p = (touches as NSSet).anyObject()?.locationInView(self)
CGPathAddLineToPoint(path, nil, p!.x, p!.y)
setNeedsDisplay()
}
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
override func drawRect(rect: CGRect) {
// Drawing code
let context = UIGraphicsGetCurrentContext()
CGContextAddPath(context, path)
CGContextStrokePath(context)
}
}
怎么清空画板
1.重新运行程序即可清空
2.设置个按钮点击事件实现清空之前所有操作
3.使用CGContextClearRect，
4.重新初始化path，这样重画的时候不会检测到之前有线条的path，画面就自动清空了
橡皮擦功能
较粗的和背景颜色同样的线条
绘制图像时解决翻转问题
CGContextTranslateCTM(context, 10, 400)
CGContextScaleCTM(context, 1, -1)
context状态的维持和释放
//context状态的维持和释放，不影响其他图像的绘制
CGContextSaveGState(context)
.............绘制代码
CGContextRestoreGState(context)
setNeedsDisplay()
执行这个方法时会调用drawRect重新绘图