保持y轴固定在地方？ [英] Keeping the y-axis fixed at place?

问题描述

这是继续这个问题的代码.... 只允许在core-plot barchart中水平滚动？

this is the code in the continuation of this question....Allow horizontal scrolling only in the core-plot barchart?

-(BOOL)pointingDeviceDraggedAtPoint:(CGPoint)interactionPoint
{
    if ( !self.allowsUserInteraction || !self.graph.plotArea ) {
        return NO;
    }
    CGPoint pointInPlotArea = [self.graph.plotArea convertPoint:interactionPoint toLayer:self.graph.plotArea];

    if ( isDragging ) {

        pointInPlotArea.y = lastDragPoint.y;//-- Madhup Changed it for allwoing scrolling only in horizontal direction --//




        //-- Madhup Changed it for allwoing scrolling only in horizontal direction --//

        //CGPoint displacement = CGPointMake(pointInPlotArea.x-lastDragPoint.x, pointInPlotArea.y-lastDragPoint.y);
        CGPoint displacement = CGPointMake(pointInPlotArea.x-lastDragPoint.x, 0);
          //--******************************--//
        CGPoint pointToUse = pointInPlotArea;

        // Allow delegate to override
        if ( [self.delegate respondsToSelector:@selector(plotSpace:willDisplaceBy:)] ) {
            displacement = [self.delegate plotSpace:self willDisplaceBy:displacement];
            pointToUse = CGPointMake(lastDragPoint.x+displacement.x, lastDragPoint.y+displacement.y);
        }

        NSDecimal lastPoint[2], newPoint[2];
        [self plotPoint:lastPoint forPlotAreaViewPoint:lastDragPoint];
        [self plotPoint:newPoint forPlotAreaViewPoint:pointToUse];

        CPPlotRange *newRangeX = [[self.xRange copy] autorelease];
        CPPlotRange *newRangeY = [[self.yRange copy] autorelease];
        NSDecimal shiftX = CPDecimalSubtract(lastPoint[0], newPoint[0]);
        NSDecimal shiftY = CPDecimalSubtract(lastPoint[1], newPoint[1]);
        newRangeX.location = CPDecimalAdd(newRangeX.location, shiftX);
        newRangeY.location = CPDecimalAdd(newRangeY.location, shiftY);

        // Delegate override
        if ( [self.delegate respondsToSelector:@selector(plotSpace:willChangePlotRangeTo:forCoordinate:)] ) {
            newRangeX = [self.delegate plotSpace:self willChangePlotRangeTo:newRangeX forCoordinate:CPCoordinateX];
            newRangeY = [self.delegate plotSpace:self willChangePlotRangeTo:newRangeY forCoordinate:CPCoordinateY];
        }

        self.xRange = newRangeX;
        self.yRange = newRangeY;

        //-- Madhup Changed it for keeping y axis fixed  --//
        NSLog(@"%@",self.graph.axisSet.axes);

        NSMutableArray *axisArr= [[NSMutableArray alloc] initWithArray:self.graph.axisSet.axes];
        CPXYAxis *yAxis = [axisArr objectAtIndex:1];
        CGPoint point = yAxis.position;
        point.y -= lastDragPoint.x;
        yAxis.position = point;
        [axisArr replaceObjectAtIndex:1 withObject:yAxis];
        self.graph.axisSet.axes = axisArr;
        [axisArr release];

        NSLog(@"%@",self.graph.axisSet.axes);
            //--******************************--//

        lastDragPoint = pointInPlotArea;



        return YES;
    }

    return NO;
}

现在从代码中你可以看到我能够停止滚动的地图只在水平方向，但仍然我不能保持y轴固定。我已经在这个方法中写了一些代码，但它似乎不工作。

Now from the code you people can see that i am able to stop the scrolling of map only in horizontal direction, but still I am not able to keep the y-axis fixed. I have written some code for that in this method too but it does not seem to be working.

推荐答案

如果你想修复滚动时添加此行

if you want to fix axis when scrolling add this lines

CPTXYAxisSet *axisSet = (CPTXYAxisSet *)_graph.axisSet;

axisSet.xAxis.axisConstraints = [CPTConstraints constraintWithLowerOffset:0.0];
axisSet.yAxis.axisConstraints = [CPTConstraints constraintWithLowerOffset:0.0];

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