如何在iPhone上使用Core-Plot折線圖實現放大和縮小？

Question

是否可以在iPhone上使用Core-Plot Chart組件實現放大和縮小？如果有，請告訴我該怎麼做？

在此先感謝。

Answer 1

是的，我做的是通過調整像這樣的PlotSpace的方式（可能不是最好的解決辦法，但最好的我能想出）：

-(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

您可以設置plotSpace委託一些類實例符合CPTPlotSpaceDelegate協議（例如self）[plotSpace setDelegate:self];。

配置plotSpace所以它與用戶[plotSpace setAllowsUserInteraction:YES];

然後在這個類實現此方法-(BOOL)plotSpace:(CPTPlotSpace *)space shouldScaleBy:(CGFloat)interactionScale aboutPoint:(CGPoint)interactionPoint交互。如果您希望corePlot自動調整圖形大小，請返回YES。或者不，並在之前的回答中做類似的事情。

注意：如果您希望您的當前控制器類（self）成爲委託人，請確保您的界面看起來像這樣@interface CurrentController : UISomeController<...,CPTPlotSpaceDelegate>{}。所以現在它符合CPTPlotSpaceDelegate協議。

Answer 3

使用默認的用戶交互是不夠的，我是因爲：

1. 它擴展兩個X & Y軸的同時，我只是想擴大 X軸
2. 潘不允許你走過去的零它跳躍和 基本上不工作的權利..

我的解決辦法是做我自己

我加2 UIGestureRecognizer的平移，縮放

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]; 

然後我實現了代碼做什麼，我需要

潘圖

- (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)]; 
} 

範圍海圖

- (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

要縮放僅在X軸只是迫使新y規模是舊的委託：

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