Question

我见过this和this，但这并不能说明我的疑问。

我有一个自定义的imageView类，基本上是一个子类。我需要在特定像素值的UIView上添加子图像视图。当我使用自定义imageview（绘制rect）绘制这些图像时，我的图像被反转。

请帮助我在框架中需要进行哪些更改，以便图像不会反转。

下面是图片。 inverted

CustomImageView.m

@implementation CustomImageView
@synthesize customImage;

- (id)initWithFrame:(CGRect)frame {

    self = [super initWithFrame:frame];
    if (self) {
        self.backgroundColor = [UIColor clearColor];
        // Initialization code.
    }
    return self;
}

- (void)drawRect:(CGRect)rect{
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextDrawImage(context, rect, customImage.CGImage);
    [super drawRect:rect];
}

- (void)dealloc {
    [customImage release];
    [super dealloc];
}


@end

CustomImageView.h

@interface CustomImageView : UIView
{

}
@property(nonatomic,retain)UIImage *customImage;
@end

我正在使用如下

-(void)drawArrowImagewithStartX:(CGFloat)X1 startY:(CGFloat)Y1 andEndX:(CGFloat)X2     endY:(CGFloat)Y2
{
    CustomImageView *arrowImageView = [[CustomImageView alloc]     initWithFrame:CGRectZero];
    CGRect startPointFrame = CGRectZero;
    CGRect endPointFrame = CGRectZero;
    CGFloat arrowWidth = 0.0;
    CGFloat arrowHeight = 0.0;

    CGFloat y1 = -(Y1+194.0);
    CGFloat y2 = -(Y1+194.0);
    if (isMapZoomed) {
        startPointFrame = CGRectMake(X1, Y1, 16.0, 16.0);
        endPointFrame = CGRectMake(X2, Y2, 16.0, 16.0);
        arrowWidth = 5.0;
        arrowHeight = 25.0;
    }
    else {
        startPointFrame = CGRectMake(X1, y1, 8.0, 8.0);
        endPointFrame = CGRectMake(X2, y2, 8.0, 8.0);
        arrowWidth = 10.0;
        arrowHeight = 50.0;
    }

    CustomImageView *startImageView = [[CustomImageView alloc]     initWithFrame:CGRectZero];
    startImageView.frame = startPointFrame;
    if (stepNo == 0) 
        startImageView.customImage = [UIImage imageNamed:KStartFlag];
    else 
        startImageView.customImage = [UIImage imageNamed:KStartPoint];

    CustomImageView *endImageView = [[CustomImageView alloc] initWithFrame:CGRectZero];
    endImageView.frame = endPointFrame;
    if (stepNo == ([self.allPOIDetailsArray count]-1)) 
        endImageView.customImage = [UIImage imageNamed:KEndFlag];
    else
        endImageView.customImage = [UIImage imageNamed:KEndPoint];

    if(X1 == X2){
        if (y1 > y2){
            arrowImageView.frame = CGRectMake(X2, (y1-(y1-y2)/2), arrowWidth,     arrowHeight);
            arrowImageView.customImage =[UIImage imageNamed:KArrowUp];
        }
        else{
            arrowImageView.frame = CGRectMake(X1, (y1+(y2-y1)/2), 5.0, 25.0);
            arrowImageView.customImage =[UIImage imageNamed:KArrowDown];
            }
    }
    else {
        if (X1 > X2) {
            arrowImageView.frame = CGRectMake((X1-(X1-X2)/2), y2, 25.0, 5.0);
            arrowImageView.customImage = [UIImage imageNamed:KArrowLeft];
        }
        else{
            arrowImageView.frame = CGRectMake((X1+(X2-X1)/2), y1, 25.0, 5.0);
            arrowImageView.customImage = [UIImage imageNamed:KArrowRight];
        }
    }

    for(UIView *subvw in self.zoomingView.subviews)
        if ([subvw isKindOfClass:[UIImageView class]]) {
            for (UIView *subview in subvw.subviews)
                [subview removeFromSuperview];
        [subvw addSubview:startImageView];
        [subvw addSubview:endImageView];
        [subvw addSubview:arrowImageView];
        NSLog(@"Subview frame %@",NSStringFromCGRect(subvw.frame));
        NSLog(@"\n\nImage frame %@ %@",NSStringFromCGRect(arrowImageView.frame),NSStringFromCGRect(startImageView.frame));
    }
[arrowImageView release];
[startImageView release];
[endImageView release];
}

Answer 1

是的，这是正常行为。

Uikit topleft corner coordinate（0,0）
OpenGL / CoreGraphics bottomleft坐标（0,0）

因此你的图像看起来是倒置的。

您可以通过以下方式解决此问题：

根据视图的高度向上移动原点。
否定（乘以-1） y轴。

Answer 2

两个世界中最好的，使用UIImage的drawAtPoint:或drawInRect:，同时仍指定自定义上下文：

UIGraphicsPushContext(context);
[image drawAtPoint:CGPointZero];
UIGraphicsPopContext();

您也无法使用CGContextTranslateCTM或CGContextScaleCTM修改上下文。

drawRect在iPhone（模拟器）中反转imageView

2 个答案: