Question

可能重复：
how to create an application which allows user to free hand drawing?

我正在尝试在视图上实现自由手写。我使用了一些现有的代码，当用户编写非常慢时，这种代码运行良好，就好像用户写得非常快，它没有识别所有的点（用户触摸的点是什么）。我的示例代码在这里

- (void)touchesMoved:(NSSet *)touches withEvent:(UIEvent *)event {
        mouseSwiped = YES;
    UITouch *touch = [touches anyObject];   
    CGPoint currentPoint = [touch locationInView:self];
    currentPoint.y -= 20;


    UIGraphicsBeginImageContext(self.bounds.size);
    [drawImage.image drawInRect:CGRectMake(0, 0, self.bounds.size.width, self.bounds.size.height)];
    CGContextSetLineCap(UIGraphicsGetCurrentContext(), kCGLineCapRound);
    CGContextSetLineWidth(UIGraphicsGetCurrentContext(), 5.0);
    if (mode == DrawingModePen) {
        NSLog(@"drawing");
        CGContextSetStrokeColorWithColor(UIGraphicsGetCurrentContext(), [_drawingPenColor CGColor]);
    }
    else {
        CGContextSetStrokeColorWithColor(UIGraphicsGetCurrentContext(), [[UIColor clearColor] CGColor]);

        CGContextBeginPath(UIGraphicsGetCurrentContext());


        CGContextMoveToPoint(UIGraphicsGetCurrentContext(), lastPoint.x, lastPoint.y);
        CGContextClearRect (UIGraphicsGetCurrentContext(), CGRectMake(lastPoint.x, lastPoint.y, 20, 20));
        CGContextStrokePath(UIGraphicsGetCurrentContext());

        NSLog(@"clearing");
            }
    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;
    }
}

还有其他方法可以实现吗？我见过GLPaint由apple提供。它在我的应用程序中引起内存警告也没什么用处。

Answer 1

试用Apple开发人员教程GLPaint。对于初学者来说，开发涂料应用可能会有很大帮助。

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1 个答案: