Question

我试图调整绘画应用程序的苹果示例（使用触摸）以使用缩放视图而不是全屏幕上的视图，无论我尝试将图像缩放到不同的尺寸时，线条都没有在正确的位置绘制，鞋帮我用手指滑动它的下方。

例如，如果我尝试在视图的下半部分绘制它工作正常并且绘制手指触摸的线，如果我尝试在视图的上半部分绘制它绘制我的手指下面的线触摸。

任何人都可以指出我应该更改什么才能使代码正常工作？

如果我将下面的代码改为1004而不是500，一切正常。

我使用的代码是：

//CLASS IMPLEMENTATIONS:
- (void)viewDidLoad
{
[super viewDidLoad];
drawImage = [[UIImageView alloc] initWithImage:nil];
drawImage.frame = CGRectMake(0, 350, 768, 500);
drawImage.backgroundColor=[UIColor blackColor];
[self.view addSubview:drawImage];
self.view.backgroundColor = [UIColor lightGrayColor];
mouseMoved = 0;
// Do any additional setup after loading the view from its nib.
}
- (void)touchesBegan:(NSSet *)touches withEvent:(UIEvent *)event {

mouseSwiped = NO;
UITouch *touch = [touches anyObject];

if ([touch tapCount] == 2) {
    drawImage.image = nil;

    return;
}

lastPoint = [touch locationInView:self.view];
lastPoint.y -= 20;

}


- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
mouseSwiped = YES;

UITouch *touch = [touches anyObject];   
CGPoint currentPoint = [touch locationInView:self.view];
currentPoint.y -= 20;


UIGraphicsBeginImageContext(self.view.frame.size);
[drawImage.image drawInRect:CGRectMake(0, 0, self.view.frame.size.width, self.view.frame.size.height)];
CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0);
CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0);
CGContextBeginPath(UIGraphicsGetCurrentContext());
CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), currentPoint.x, currentPoint.y);
CGContextStrokePath(UIGraphicsGetCurrentContext());
drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

lastPoint = currentPoint;

mouseMoved++;

if (mouseMoved == 10) {
    mouseMoved = 0;
}

}

- (void)touchesEnded:(NSSet *)touches withEvent:(UIEvent *)event {

UITouch *touch = [touches anyObject];

if ([touch tapCount] == 2) {
    drawImage.image = nil;
    return;
}


if(!mouseSwiped) {
    UIGraphicsBeginImageContext(self.view.frame.size);
    [drawImage.image drawInRect:CGRectMake(0, 350, self.view.frame.size.width, self.view.frame.size.height)];
    CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
    CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0);
    CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 1.0, 0.0, 0.0, 1.0);
    CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
    CGContextAddLineToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
    CGContextStrokePath(UIGraphicsGetCurrentContext());
    CGContextFlush(UIGraphicsGetCurrentContext());
    drawImage.image = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
}
}

调整绘图视图的大小绘制苹果的例子

0 个答案: