将核心图从右移到左

Question

I want to move the coreplot graph from right to left on x-axis dynamically.

For example, In core PLot Gallery example, graph is moving from left to right. FOr that I am using the code:

NSTimer *dataTimer = [NSTimer timerWithTimeInterval:1.0
                                             target:self
                                           selector:@selector(newData:)
                                           userInfo:nil
                                            repeats:YES];
[[NSRunLoop mainRunLoop] addTimer:dataTimer forMode:NSDefaultRunLoopMode];

-(void)newData:(NSTimer *)theTimer
{
CPTPlot *thePlot   = [[self getCorePLotGraph] plotWithIdentifier:@"Device1"];

CPTXYPlotSpace *plotSpace = (CPTXYPlotSpace *)[self getCorePLotGraph].defaultPlotSpace;
 NSUInteger location       = (currentIndex >= kMaxDataPoints ? currentIndex - kMaxDataPoints + 2 : 0);

CPTPlotRange *newRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromUnsignedInteger(location)
                                                      length:CPTDecimalFromUnsignedInteger(kMaxDataPoints-2)];

**CPTMutablePlotRange *xRange = [[self getCoreplotSpace].xRange mutableCopy];
[xRange expandRangeByFactor:CPTDecimalFromCGFloat(-2.0)];
[self getCoreplotSpace].xRange = xRange;**



[CPTAnimation animate:plotSpace
             property:@"xRange"
        fromPlotRange:plotSpace.xRange
          toPlotRange:newRange
             duration:CPTFloat(1.0 / kFrameRate)];

currentIndex++;


[temperatureValuesArray addObject:[NSNumber numberWithDouble:(1.0 - kAlpha) * [[temperatureValuesArray lastObject] doubleValue] + kAlpha * rand() / (double)RAND_MAX]];
[thePlot insertDataAtIndex:temperatureValuesArray.count - 1 numberOfRecords:1];
 }

In the above code, the bold code is for moving from right to left what I am trying now.

But it is not moving from right to left. Could you please help me how to do this.

Thanks

Answer 1

It looks like you copied the code from the "Real Time Plot" demo included with Core Plot (copied below). This works as you describe:

-(void)newData:(NSTimer *)theTimer
{
    CPTGraph *theGraph = (self.graphs)[0];
    CPTPlot *thePlot   = [theGraph plotWithIdentifier:kPlotIdentifier];

    if ( thePlot ) {
        if ( plotData.count >= kMaxDataPoints ) {
            [plotData removeObjectAtIndex:0];
            [thePlot deleteDataInIndexRange:NSMakeRange(0, 1)];
        }

        CPTXYPlotSpace *plotSpace = (CPTXYPlotSpace *)theGraph.defaultPlotSpace;
        NSUInteger location       = (currentIndex >= kMaxDataPoints ? currentIndex - kMaxDataPoints + 2 : 0);

        CPTPlotRange *oldRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromUnsignedInteger( (location > 0) ? (location - 1) : 0 )
                                                              length:CPTDecimalFromUnsignedInteger(kMaxDataPoints - 2)];
        CPTPlotRange *newRange = [CPTPlotRange plotRangeWithLocation:CPTDecimalFromUnsignedInteger(location)
                                                              length:CPTDecimalFromUnsignedInteger(kMaxDataPoints - 2)];

        [CPTAnimation animate:plotSpace
                     property:@"xRange"
                fromPlotRange:oldRange
                  toPlotRange:newRange
                     duration:CPTFloat(1.0 / kFrameRate)];

        currentIndex++;
        [plotData addObject:@( (1.0 - kAlpha) * [[plotData lastObject] doubleValue] + kAlpha * rand() / (double)RAND_MAX )];
        [thePlot insertDataAtIndex:plotData.count - 1 numberOfRecords:1];
    }
}

You don't need to update the xRange in this method at all—the animation will take care of that.