如何使 UITouches 偏移？

Question

下图中，我画的是A点，就在我手指接触的地方。

如何使图像显示在实际触摸上方约 40pt。 (二)

我正在使用经典的 coreGraphic UITouch 代码。像这样：

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

    // add the first touch
    UITouch *touch = [touches anyObject];

    previousPoint1 = [touch previousLocationInView:self];
    currentPoint = [touch locationInView:self];

    //transform = CGAffineTransformTranslate(self.transform, 5.0, 10.0)

    // init the bezier path
    self.currentTool = [self toolWithCurrentSettings];
    self.currentTool.lineWidth = self.lineWidth;
    self.currentTool.lineColor = self.lineColor;
    self.currentTool.lineAlpha = self.lineAlpha;


        [self.pathArray addObject:self.currentTool];
        [self.undoStates addObject:[self.currentTool captureToolState]];

        [self.currentTool setInitialPoint:currentPoint];
    }

    // call the delegate
    if ([self.delegate respondsToSelector:@selector(drawingView:willBeginDrawUsingTool:)]) {
        [self.delegate drawingView:self willBeginDrawUsingTool:self.currentTool];
    }
}

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

    // save all the touches in the path
    UITouch *touch = [touches anyObject];

    previousPoint2 = previousPoint1;
    previousPoint1 = [touch previousLocationInView:self];
    currentPoint = [touch locationInView:self];

        [self.currentTool moveFromPoint:previousPoint1 toPoint:currentPoint];
        [self setNeedsDisplay];
    }

}

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

    // make sure a point is recorded
    [self touchesMoved:touches withEvent:event];

            CGPoint point = [[touches anyObject] locationInView:self];
            [self.currentTool setInitialPoint:point];
            self.draggableTextView = ((ACEDrawingDraggableTextTool *)self.currentTool).labelView;

            [self.pathArray addObject:self.currentTool];

            [self finishDrawing];

        [self finishDrawing];
    }
}

- (void)touchesCancelled:(NSSet *)touches withEvent:(UIEvent *)event
{
    // make sure a point is recorded
    [self touchesEnded:touches withEvent:event];
}

如有任何帮助，我们将不胜感激。

Answer 1

previousPoint1 = [touch previousLocationInView:self];
currentPoint = [touch locationInView:self];
// add these 2 lines below:
previousPoint1 = CGPointMake(previousPoint1.x, previousPoint1.y+40);
currentPoint = CGPointMake(currentPoint.x, currentPoint.y+40);

如何使 UITouches 偏移？

How can I make UITouches offset?

core-graphics

ios