Question

是否可以在iPhone上使用Core-Plot Chart组件实现放大和缩小？如果是这样，请建议我怎么做？

提前致谢。

Answer 1

是的，我这样做是通过像这样调整PlotSpace（可能不是最好的解决方案，但是我能想到的最好的解决方案）：

-(void)zoomOut 
{
    CPXYPlotSpace *plotSpace = (CPXYPlotSpace *)graph.defaultPlotSpace;

    graphScaleX+=5;
    graphScaleY+=5;

    plotSpace.xRange = [CPPlotRange plotRangeWithLocation:plotSpace.xRange.location length:CPDecimalFromFloat(graphScaleX)];
    plotSpace.yRange = [CPPlotRange plotRangeWithLocation:plotSpace.yRange.location length:CPDecimalFromFloat(graphScaleY)];
}

-(void)zoomIn
{
    CPXYPlotSpace *plotSpace = (CPXYPlotSpace *)graph.defaultPlotSpace;

    graphScaleX-=5;
    graphScaleY-=5;

    plotSpace.xRange = [CPPlotRange plotRangeWithLocation:plotSpace.xRange.location length:CPDecimalFromFloat(graphScaleX)];
    plotSpace.yRange = [CPPlotRange plotRangeWithLocation:plotSpace.yRange.location length:CPDecimalFromFloat(graphScaleY)];
}

Answer 2

您可以将plotSpace委托设置为符合CPTPlotSpaceDelegate协议的某个类实例（例如self）[plotSpace setDelegate:self];。

配置plotSpace，使其与用户[plotSpace setAllowsUserInteraction:YES];

进行交互

然后在该类中实现此方法-(BOOL)plotSpace:(CPTPlotSpace *)space shouldScaleBy:(CGFloat)interactionScale aboutPoint:(CGPoint)interactionPoint。如果您希望corePlot自动调整图表大小，请返回YES。或者不做，并在之前的回答中做一些事情。

注意：如果您希望当前的控制器类（self）成为委托，请确保您的界面看起来像@interface CurrentController : UISomeController<...,CPTPlotSpaceDelegate>{}。所以现在它符合CPTPlotSpaceDelegate协议。

Answer 3

使用默认用户交互对我来说还不够，因为：

它可以扩展X＆amp; Y轴同时，我只想缩放 X轴
潘不允许你经过零而且它会跳跃基本上不能正常工作..

我的解决方案是自己动手

我为Pan，Zoom添加了2个UIGestureRecognizer

    UIPanGestureRecognizer* pan = [[UIPanGestureRecognizer alloc] initWithTarget:self action:@selector(panChart:)];
    [pan setMinimumNumberOfTouches:1];
    [pan setMaximumNumberOfTouches:1];
    [self.view addGestureRecognizer:pan];

    UIPinchGestureRecognizer* scale = [[UIPinchGestureRecognizer alloc] initWithTarget:self action:@selector(scaleChart:)];
    [self.view addGestureRecognizer:scale];

然后我实现了代码来完成我需要的工作

Pan Chart

- (void)panChart:(UIPinchGestureRecognizer *)gestureRecognizer {
    CPTGraph *theGraph = [graphs objectAtIndex:0];
    CPTXYPlotSpace *plotSpace = (CPTXYPlotSpace *)theGraph.defaultPlotSpace;

    CGPoint point = [gestureRecognizer  locationInView:self.view];

    if([(UIPanGestureRecognizer*)gestureRecognizer state] == UIGestureRecognizerStateBegan) {

        firstX = point.x;
        firstY = point.y;
        originX = chartBounds.origin.x;
        originY = chartBounds.origin.y;
        //NSLog(@"first (%f,%f)", firstX, firstY);
    }
    CGRect frame = theGraph.frame;

    float xMove =  ((firstX-point.x)/(frame.size.width/chartBounds.size.width));
    float yMove = ((firstY-point.y)/(frame.size.height/chartBounds.size.height));
    if(firstX-point.x == 0){
        xMove = 0;
    }
    if(firstY-point.y == 0){
        yMove = 0;
    }
    //NSLog(@"frame: (%f, %f)",frame.size.width, frame.size.height);
    //NSLog(@"touch (%f,%f)",firstX-point.x,firstY-point.y);
    //NSLog(@"move (%f,%f)",xMove,yMove);

    chartBounds.origin.x = originX+xMove;
    chartBounds.origin.y = originY-yMove;

    plotSpace.xRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromFloat(chartBounds.origin.x) length:CPTDecimalFromFloat(chartBounds.size.width)];
    plotSpace.yRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromFloat(chartBounds.origin.y) length:CPTDecimalFromFloat(chartBounds.size.height)];
}

比例表

- (void)scaleChart:(UIPinchGestureRecognizer *)gestureRecognizer {

if (kMaxDataPoints < kDataPointsHistory) {

    if ([gestureRecognizer scale] < 1) {
        if(kMaxDataPoints/10 < 1){
            kMaxDataPoints += 1;
        }else{
           kMaxDataPoints += kMaxDataPoints/10; 
        }
    }
}

if (kMaxDataPoints > 5) {
    if ([gestureRecognizer scale] > 1){
        if(kMaxDataPoints/10 < 1){
            kMaxDataPoints -= 1;
        }else{
            kMaxDataPoints -= kMaxDataPoints/10; 
        }
    }
}

if(kMaxDataPoints <= 5){
    kMaxDataPoints = 5;
}
if(kMaxDataPoints > kDataPointsHistory){
    kMaxDataPoints = kDataPointsHistory;
}

chartBounds.size.width = kMaxDataPoints;
CPTGraph *theGraph = [graphs objectAtIndex:0];
CPTXYPlotSpace *plotSpace = (CPTXYPlotSpace *)theGraph.defaultPlotSpace;

plotSpace.xRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromFloat(chartBounds.origin.x) length:CPTDecimalFromFloat(chartBounds.size.width)];

//Need to calculate if its horizontal or vertical pinch gesture (not doing that yet :) )
//plotSpace.yRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromFloat(chartBounds.origin.y) length:CPTDecimalFromFloat(chartBounds.size.height)];
}

Answer 4

要仅在x轴上缩放，只需强制新y尺度为委托中的旧y尺度：

-(BOOL)plotSpace:(CPTPlotSpace *)space shouldScaleBy:(CGFloat)interactionScale aboutPoint:(CGPoint)interactionPoint;

如何在iPhone上使用Core-Plot折线图实现放大和缩小？

4 个答案: