将参数传递给drawRect答案

【问题标题】：Passing parameters to drawRect将参数传递给drawRect
【发布时间】：2013-06-05 15:45:28
【问题描述】：

我有几个 UIView 类都绘制相同的东西，但颜色和 alpha 设置不同。我尝试传递参数，但无法弄清楚如何将 drawRect 部分放在需要的位置。

我是这样画的：

CGRect positionFrame = CGRectMake(widthCoordinate,heightCoordinate,20.9f,16.5f);
DrawHexBlue *hex = [[DrawHexBlue alloc] initWithFrame:positionFrame];
[self.imageView addSubview:hex];

我的 DrawHexBlue 类是这样的：

- (id)initWithFrame:(CGRect)frame{
self = [super initWithFrame:frame];
if (self)
{
    [self setOpaque:YES];
    [self setBackgroundColor:[UIColor clearColor]];
}
return self;

}

- (void)drawRect:(CGRect)rect{    
UIBezierPath *aPath = [UIBezierPath bezierPath];
[[UIColor whiteColor] setStroke];
[[UIColor blueColor] setFill];

// Set the starting point of the shape.
[aPath moveToPoint:CGPointMake(7, 0)];

// Draw the lines.
[aPath addLineToPoint:CGPointMake(16.2, 0)];
[aPath addLineToPoint:CGPointMake(20.9, 8.7)];
[aPath addLineToPoint:CGPointMake(16.2, 16.5)];
[aPath addLineToPoint:CGPointMake(6.7, 16.5)];
[aPath addLineToPoint:CGPointMake(2.1, 8.7)];
[aPath closePath];

[aPath setLineWidth:1.0f];
[aPath fillWithBlendMode:kCGBlendModeNormal alpha:0.75];
[aPath stroke];
}

我为我需要的每种新颜色和新的 alpha 值创建一个新类。当然必须有一种更好的方法来使用一个类并且只需更改参数/值...？

【问题讨论】：

标签： ios uiview drawrect

【解决方案1】：

创建一个UIView 子类并添加属性：

@interface YourView : UIView

@property (nonatomic, strong) UIColor *strokeColor;
@property (nonatomic, strong) UIColor *fillColor;

@end

那么在drawRect:你就可以访问这个属性了：

- (void)drawRect:(CGRect)rect{    
    UIBezierPath *aPath = [UIBezierPath bezierPath];
    [self.strokeColor setStroke];
    [self.fillColor setFill];

而且你可以在创建的时候在视图上设置：

YourView *hex = [[YourView alloc] initWithFrame:positionFrame];
hex.strokeColor = [UIColor whiteColor];
hex.fillColor = [UIColor blueColor];

【讨论】：

【解决方案2】：

是的。

使用属性。

进行绘图的视图应该在其头文件中有这些代码行：

@property (nonatomic, strong) UIColor *colorToDraw;

- (id)initWithFrame:(CGRect)frame color:(UIColor *)color;

你的init 方法应该是这样的：

- (id)initWithFrame:(CGRect)frame color:(UIColor *)color
{
    self = [super initWithFrame:frame];
    if (self)
    {
        [self setOpaque:YES];
        [self setBackgroundColor:[UIColor clearColor]];
        self.colorToDraw = color;
    }
    return self;
}

带有drawRect 的：

- (void)drawRect:(CGRect)rect{    
    UIBezierPath *aPath = [UIBezierPath bezierPath];
    [[UIColor whiteColor] setStroke];
    [self.colorToDraw setFill];

    // Set the starting point of the shape.
    [aPath moveToPoint:CGPointMake(7, 0)];

// Draw the lines.
    [aPath addLineToPoint:CGPointMake(16.2, 0)];
    [aPath addLineToPoint:CGPointMake(20.9, 8.7)];
    [aPath addLineToPoint:CGPointMake(16.2, 16.5)];
    [aPath addLineToPoint:CGPointMake(6.7, 16.5)];
    [aPath addLineToPoint:CGPointMake(2.1, 8.7)];
    [aPath closePath];
    
    [aPath setLineWidth:1.0f];
    [aPath fillWithBlendMode:kCGBlendModeNormal alpha:0.75];
    [aPath stroke];
}

现在，你可以这样画了：

CGRect positionFrame = CGRectMake(widthCoordinate,heightCoordinate,20.9f,16.5f);   
DrawHexBlue *hex = [[DrawHexBlue alloc] initWithFrame:positionFrame color:[UIColor orangeColor]]; //Or whatever.
[self.imageView addSubview:hex];

不过，您可能希望将子类的名称更改为不表示它会绘制蓝色的名称。

【讨论】：

【解决方案3】：

创建属性来存储颜色和 alpha 数据。

@interface DrawHex : UIView
// ...
@property (nonatomic) CGFloat pathAlpha;
@property (nonatomic, strong) UIColor *strokeColor;
@property (nonatomic, strong) UIColor *fillColor;    
@end

在你的这个类的init方法中为它们设置一些默认值，例如：

self.fillColor = [UIColor blueColor];
self.strokeColor = [UIColor whiteColor];
self.pathAlpha = 0.75;

然后在drawRect 中使用属性而不是硬编码值：

[self.strokeColor setStroke];
[self.fillColor setFill];
//...
[aPath fillWithBlendMode:kCGBlendModeNormal alpha:self.pathAlpha];

然后在您的视图控制器中您可以更改它们：

DrawHex *hex = [[DrawHex alloc] initWithFrame:positionFrame];
hex.fillColor = [UIColor redColor];
// you get the idea

【讨论】：