画线
- (void)drawRect:(CGRect)rect {
// Drawing code
UIBezierPath *path = [UIBezierPath bezierPath];
[path moveToPoint:CGPointMake(100, 100)];
[path addLineToPoint:CGPointMake(100, 130)];
[path stroke];
}
连接处样式
/* Line join styles. */
typedef CF_ENUM(int32_t, CGLineJoin) {
kCGLineJoinMiter,
kCGLineJoinRound,
kCGLineJoinBevel
};
顶角样式
/* Line cap styles. */
typedef CF_ENUM(int32_t, CGLineCap) {
kCGLineCapButt,
kCGLineCapRound,
kCGLineCapSquare
};
画扇型
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect {
// Drawing code
// 圆角矩形
// UIBezierPath *path = [UIBezierPath bezierPathWithRoundedRect:CGRectMake(20, 20, 200, 200) cornerRadius:100];
// 圆弧
// Center：圆心
// startAngle:弧度
// clockwise:YES:顺时针 NO：逆时针
// 扇形
CGPoint center = CGPointMake(125, 125);
UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter:center radius:100 startAngle:0 endAngle:M_PI_2 clockwise:YES];
// 添加一根线到圆心
[path addLineToPoint:center];
// 封闭路径，关闭路径：从路径的终点到起点
// [path closePath];
// [path stroke];
// 填充：必须是一个完整的封闭路径,默认就会自动关闭路径
[path fill];
}
重绘
// 重绘，系统会先创建与view相关联的上下文，然后再调用drawRect
[self setNeedsDisplay];
下载的进度条制作
// 注意：drawRect不能手动调用，因为图形上下文我们自己创建不了，只能由系统帮我们创建，并且传递给我们
- (void)drawRect:(CGRect)rect {
// Drawing code
// 创建贝瑟尔路径
CGFloat radius = rect.size.width * 0.5;
CGPoint center = CGPointMake(radius, radius);
CGFloat endA = -M_PI_2 + _progress * M_PI * 2;
UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter:center radius:radius - 2 startAngle:-M_PI_2 endAngle:endA clockwise:YES];
[path stroke];
}
画饼图
- (void)drawRect:(CGRect)rect
{
CGFloat radius = self.bounds.size.width * 0.5;
CGPoint center = CGPointMake(radius, radius);
CGFloat startA = 0;
CGFloat angle = 0;
CGFloat endA = 0;
// 第一个扇形
angle = 25 / 100.0 * M_PI * 2;
endA = startA + angle;
UIBezierPath *path = [UIBezierPath bezierPathWithArcCenter:center radius:radius startAngle:startA endAngle:endA clockwise:YES];
// 添加一根线到圆心
[path addLineToPoint:center];
// 描边和填充通用
[[UIColor redColor] set];
[path fill];
// 第二个扇形
startA = endA;
angle = 25 / 100.0 * M_PI * 2;
endA = startA + angle;
UIBezierPath *path1 = [UIBezierPath bezierPathWithArcCenter:center radius:radius startAngle:startA endAngle:endA clockwise:YES];
// 添加一根线到圆心
[path1 addLineToPoint:center];
// 描边和填充通用
[[UIColor greenColor] set];
[path1 fill];
// 第二个扇形
startA = endA;
angle = 50 / 100.0 * M_PI * 2;
endA = startA + angle;
UIBezierPath *path2 = [UIBezierPath bezierPathWithArcCenter:center radius:radius startAngle:startA endAngle:endA clockwise:YES];
// 添加一根线到圆心
[path2 addLineToPoint:center];
// 描边和填充通用
[[UIColor blueColor] set];
[path2 fill];
}
绘制文字
- (void)drawRect:(CGRect)rect {
// 绘制文字
NSString *str = @"asfdsfsdfasfdsfsdfasfdsfsdfasfdsfsdfasfdsfsdfasfdsfsdfasfdsfsdfasfdsfsdfasfdsfsdfasfdsfsdfasfdsfsdfasfdsfsdfasfdsfsdf";
// 不会换行
//[str drawAtPoint:CGPointZero withAttributes:nil];
[str drawInRect:self.bounds withAttributes:nil];
}
绘制图片
- (void)drawRect:(CGRect)rect {
// Drawing code
static CGFloat _snowY = 0;
// 超出裁剪区域的内容全部裁剪掉
// 注意：裁剪必须放在绘制之前
UIRectClip(CGRectMake(0, 0, 50, 50));
UIImage *image = [UIImage imageNamed:@"001"];
// 默认绘制的内容尺寸跟图片尺寸一样大
// [image drawAtPoint:CGPointZero];
// [image drawInRect:rect];
// 绘图平铺
[image drawAsPatternInRect:rect];
}
绘制雪花
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect {
// 如果以后想绘制东西到view上面，必须在drawRect方法里面，不管有没有手动获取到上下文
// 修改雪花y值
UIImage *image = [UIImage imageNamed:@"雪花"];
[image drawAtPoint:CGPointMake(50, _snowY)];
_snowY += 10;
if (_snowY > rect.size.height) {
_snowY = 0;
}
}
// 如果在绘图的时候需要用到定时器，通常CADisplayLink
// NSTimer很少用于绘图，因为调度优先级比较低，并不会准时调用
- (void)awakeFromNib
{
// 创建定时器
// [NSTimer scheduledTimerWithTimeInterval:0.1 target:self selector:@selector(timeChange) userInfo:nil repeats:YES];
CADisplayLink *link = [CADisplayLink displayLinkWithTarget:self selector:@selector(timeChange)];
// 添加主运行循环
[link addToRunLoop:[NSRunLoop mainRunLoop] forMode:NSDefaultRunLoopMode];
}
// CADisplayLink:每次屏幕刷新的时候就会调用，屏幕一般一秒刷新60次
// 1秒 2次
- (void)timeChange
{
// 注意：这个方法并不会马上调用drawRect,其实这个方法只是给当前控件添加刷新的标记，等下一次屏幕刷新的时候才会调用drawRect
[self setNeedsDisplay];
}
图形上下文栈
// 如果以后用贝瑟尔绘制图形【path stroke】,上下文的状态由贝瑟尔路径状态
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect {
// Drawing code
// 1.获取上下文
CGContextRef ctx = UIGraphicsGetCurrentContext();
#pragma mark - 第一根
// 2.描述路径
// 第一根
UIBezierPath *path = [UIBezierPath bezierPath];
[path moveToPoint:CGPointMake(10, 125)];
[path addLineToPoint:CGPointMake(240, 125)];
// 把路径添加到上下文
// .CGPath 可以UIkit的路径转换成CoreGraphics路径
CGContextAddPath(ctx, path.CGPath);
// 设置上下文状态
CGContextSetLineWidth(ctx, 10);
[[UIColor redColor] set];
#pragma ----------
// 保存一份上下文的状态
CGContextSaveGState(ctx);
#pragma ---------
// 设置上下文状态
CGContextSetLineWidth(ctx, 5);
[[UIColor yellowColor] set];
// 渲染上下文
CGContextStrokePath(ctx);
#pragma mark - 第二根
// 2.描述路径
// 第二根
path = [UIBezierPath bezierPath];
[path moveToPoint:CGPointMake(125, 10)];
[path addLineToPoint:CGPointMake(125, 240)];
// 把路径添加到上下文
// .CGPath 可以UIkit的路径转换成CoreGraphics路径
CGContextAddPath(ctx, path.CGPath);
// 还原上一次保存的上下文状态
CGContextRestoreGState(ctx);
// 渲染上下文
CGContextStrokePath(ctx);
}
平移旋转等矩阵操作
// Only override drawRect: if you perform custom drawing.
// An empty implementation adversely affects performance during animation.
- (void)drawRect:(CGRect)rect {
// 1.获取上下文
CGContextRef ctx = UIGraphicsGetCurrentContext();
// 2.描述路径
UIBezierPath *path = [UIBezierPath bezierPathWithOvalInRect:CGRectMake(-100, -50, 200, 100)];
[[UIColor redColor] set];
// 上下文矩阵操作
// 注意:矩阵操作必须要在添加路径之前
// 平移
CGContextTranslateCTM(ctx, 100, 50);
// 缩放
CGContextScaleCTM(ctx, 0.5, 0.5);
// 旋转
CGContextRotateCTM(ctx, M_PI_4);
// 3.把路径添加上下文
CGContextAddPath(ctx, path.CGPath);
#pragma 此后的平移缩放旋转操作无效 但是颜色设置有效
// 平移
CGContextTranslateCTM(ctx, 300, 200);
// 缩放
CGContextScaleCTM(ctx, 2, 2);
// 旋转
CGContextRotateCTM(ctx, M_PI);
[[UIColor blueColor] set];
// 4.渲染上下文
CGContextFillPath(ctx);
}
