Question

当涉及到图形时，我几乎无能为力所以我试图在我的iPad中使用本教程作为参考制作一个简单的绘图视图：

http://www.ipodtouchfans.com/forums/showthread.php?t=132024

我遇到的问题是屏幕上绘制的点与手指实际所在位置相差几英寸。我认为这是因为它是一个iPad应用程序而不是iPhone应用程序，但用我未受过教育的眼睛看着它，我不知道我需要改变什么。

- (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(), 0.0, 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, 0, self.view.frame.size.width, self.view.frame.size.height)];
    CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
    CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0);
    CGContextSetRGBStrokeColor(UIGraphicsGetCurrentContext(), 0.0, 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();
}
}

Answer 1

这个代码应该在ipad和iphone中的工作方式基本相同...从查看你从拾取的点减去20的代码... lastPoint.y - = 20，所以我不希望任何由于这段代码，绘图发生在用户触摸它的地方......也正如我已经说过的......这个代码应该在ipad和iphone中都一样...

Answer 2

我本身相当愚蠢的问题 - 在IB中，我从来没有将视图从水平（他们总是默认为某些原因）旋转到垂直。

将示例iPhone代码转换为iPad

2 个答案: