Question

我正在使用CGContext函数绘制的CGImage创建精灵。我还有一个作为菜单实现的换色机制。但即使我清除了上下文并改变了颜色，用于绘图的颜色仍然保持不变。有没有人有什么问题？

CGContextSaveGState(UIGraphicsGetCurrentContext());
    UIGraphicsBeginImageContext(CGSizeMake(40, 40));
    if ([color isEqualToString:@"black"]) {
        CGContextSetRGBFillColor(UIGraphicsGetCurrentContext(), 0,0,0, 1);
    }
    else if ([color isEqualToString:@"red"]) {
        CGContextSetRGBFillColor(UIGraphicsGetCurrentContext(), 1.0,0,0, 1);
    }
    else if ([color isEqualToString:@"green"]) {
        CGContextSetRGBFillColor(UIGraphicsGetCurrentContext(), 0,1.0,0, 1);
    }
    else if ([color isEqualToString:@"blue"]) {
        CGContextSetRGBFillColor(UIGraphicsGetCurrentContext(), 0,0,1.0, 1);
    }
    CGRect rect1 = CGRectMake(0,0,40,40);
    CGContextAddEllipseInRect(UIGraphicsGetCurrentContext(),rect1);
    CGContextFillPath(UIGraphicsGetCurrentContext());
    UIImage *myImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    CGContextFlush(UIGraphicsGetCurrentContext()) ;
    CGContextRestoreGState(UIGraphicsGetCurrentContext());

    CCSprite *newSprite = [CCSprite spriteWithCGImage:[myImage CGImage] key:@"blackCircle"];
    [itemsArray addObject:newSprite];
    [newSprite setPosition:point];
    [self addChild:newSprite];

Answer 1

你确定你的颜色变量是否被设置，并且它是正确的字符串编码来传递isEqualToString测试？（即你确定你实际上是在设置代码来设置颜色）。

我将上面的代码复制到视图控制器的viewDidLoad方法中，直到从上下文创建图像，然后将图像添加到视图的imageview子视图中，颜色就出现了。

这是我在视图控制器的viewDidLoad方法中放入的代码 - 视图最后有一个蓝色圆圈，所以看起来你的代码应该可以工作：

CGContextSaveGState(UIGraphicsGetCurrentContext());
UIGraphicsBeginImageContext(CGSizeMake(40, 40));
NSString *color = @"blue";
 if ([color isEqualToString:@"black"]) {
    CGContextSetRGBFillColor(UIGraphicsGetCurrentContext(), 1,0,0, 1);
}
else if ([color isEqualToString:@"red"]) {
    CGContextSetRGBFillColor(UIGraphicsGetCurrentContext(), 1.0,0,0, 1);
}
else if ([color isEqualToString:@"green"]) {
    CGContextSetRGBFillColor(UIGraphicsGetCurrentContext(), 0,1.0,0, 1);
}
else if ([color isEqualToString:@"blue"]) {
    CGContextSetRGBFillColor(UIGraphicsGetCurrentContext(), 0,0,1.0, 1);
}
CGRect rect1 = CGRectMake(0,0,40,40);
CGContextAddEllipseInRect(UIGraphicsGetCurrentContext(),rect1);
CGContextFillPath(UIGraphicsGetCurrentContext());
UIImage *myImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
CGContextFlush(UIGraphicsGetCurrentContext()) ;
CGContextRestoreGState(UIGraphicsGetCurrentContext());

UIImageView *imgV = [[UIImageView alloc] initWithFrame:CGRectMake(30,30,200,200)];
imgV.image = myImage;
[self.view addSubview:imgV];

Answer 2

您需要添加完整的颜色代码参数，如此...

CGContextSetRGBFillColor(UIGraphicsGetCurrentContext(), 1.0/255,0.0/255,0.0/255, 1.0);

CGContextSetRGBFillColor无法正常工作

2 个答案: