在 UITableView 中绘制 CGImage

发布于 2024-12-02 16:53:38 字数 762 浏览 1 评论 0原文

所以，我有一个自定义单元格，我需要在 tableView 中将所有图像绘制为 CGImage，但我无法让它工作。我创建了一个测试项目并使用简单的视图测试了代码。一切都很完美，当我将相同的代码复制粘贴到我的自定义单元格时，它停止工作。这是代码：

-(void)drawRect:(CGRect)rect {
    CGRect contentRect = self.contentView.bounds;
    CGFloat boundsX = contentRect.origin.x;

    UIImage *karmaImage = [UIImage imageNamed:@"karma.png"];
    [self drawImage:karmaImage withRect:CGRectMake(boundsX + 255, 16, 14, 14)];
}
-(void)drawImage:(UIImage *)image withRect:(CGRect)rect {
    CGImageRef imageRef = CGImageRetain(image.CGImage);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextTranslateCTM(context, 0, rect.size.height);
    CGContextScaleCTM(context, 1.0, -1.0);
    CGContextDrawImage(context, rect, imageRef);
}

有解决方案吗？

原文

So, I have a custom cell and I need to draw all images as CGImage in tableView, but I can't get it working. I have created a test project and tested the code with simple views. Everything worked perfect, and when I copypasted the same code to my custom cell it stopped working. Here is the code:

-(void)drawRect:(CGRect)rect {
    CGRect contentRect = self.contentView.bounds;
    CGFloat boundsX = contentRect.origin.x;

    UIImage *karmaImage = [UIImage imageNamed:@"karma.png"];
    [self drawImage:karmaImage withRect:CGRectMake(boundsX + 255, 16, 14, 14)];
}
-(void)drawImage:(UIImage *)image withRect:(CGRect)rect {
    CGImageRef imageRef = CGImageRetain(image.CGImage);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextTranslateCTM(context, 0, rect.size.height);
    CGContextScaleCTM(context, 1.0, -1.0);
    CGContextDrawImage(context, rect, imageRef);
}

Any solutions?

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奢华的一滴泪 2024-12-09 16:53:38

Apple 建议将自定义视图添加到 UITableViewCell 的 contentView，而不是更改 UITableViewCell 本身。请参阅 TimeZoneCell 对于例子。

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故人如初 2024-12-09 16:53:38

在你的drawRect方法中，你可能应该调用[super drawRect:rect];

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把人绕傻吧 2024-12-09 16:53:38

好的，问题是具有自定义背景颜色的单元格的 contentView 隐藏了图像。这是正确的代码：

-(void) drawRect:(CGRect)rect{
    [super drawRect:rect];
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetFillColorWithColor(context, [UIColor colorWithRed:(232.0/255.0) green:(232.0/255.0) blue:(232.0/255.0) alpha:1.0].CGColor);
    CGContextFillRect(context, rect);
    UIImage *karmaImg = [UIImage imageNamed:@"karma.png"]; 
    [self drawImage:karmaImg withContext:context atPoint:CGPointMake(boundsX + 255, 16)];
}


-(void)drawImage:(UIImage *)image withContext:(CGContextRef)context atPoint:(CGPoint)point {
    if(image) {
        CGContextDrawImage(context, CGRectMake(point.x, point.y, image.size.width, image.size.height), image.CGImage);
    } else {
        NSLog(@"Error: Image failed to load.");
    }
}

OK, the problem was that contentView of the cell with custom background color was hiding the image. Here is the right code:

-(void) drawRect:(CGRect)rect{
    [super drawRect:rect];
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetFillColorWithColor(context, [UIColor colorWithRed:(232.0/255.0) green:(232.0/255.0) blue:(232.0/255.0) alpha:1.0].CGColor);
    CGContextFillRect(context, rect);
    UIImage *karmaImg = [UIImage imageNamed:@"karma.png"]; 
    [self drawImage:karmaImg withContext:context atPoint:CGPointMake(boundsX + 255, 16)];
}


-(void)drawImage:(UIImage *)image withContext:(CGContextRef)context atPoint:(CGPoint)point {
    if(image) {
        CGContextDrawImage(context, CGRectMake(point.x, point.y, image.size.width, image.size.height), image.CGImage);
    } else {
        NSLog(@"Error: Image failed to load.");
    }
}

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