Add CPAnnotation classes about core-plot HOT 10 CLOSED

Changed to enhancement.

CPAnnotation could be a subclass of the new CPBorderedLayer class.

It would probably be a good idea to put all annotations in a special annotation 
layer above all other layers in the 
graph hierarchy.

Issue 91 has been merged into this issue.

Annotations have been added. They can be anchored to the plot space or to a 
layer (usually the plot area or graph). The annotation content can be any 
CPLayer, including a CPBorderedLayer if a border is needed.

Of the features described above, the only one not implemented yet is the 
pointing line and/or arrow.

The legend class should be a subclass of CPBorderedLayer, not CPAnnotation. 
This way, the legend can be added as an annotation on the graph. Legends are 
described in issue #90 and will not be discussed here any further.

I tried to add an image annotation to a barplot. It works fine in iOS 
simulator, but the image annotation not shown on the device.  I am using Xcode 
4.2.  Tested on two devices, one is iOS 4.3, another one is iOS5.0.1.

The piece of code I tried is below:


    CPTPlotSpaceAnnotation *imageAnnotation;
    CGRect imageRect = CGRectMake(50, 50 ,30, 30);
    CPTLayer *newImagelLayer = [[CPTLayer alloc] initWithFrame:imageRect];
    newLabelLayer.contents = (id)[[UIImage imageNamed:@"test.png"] CGImage];
    imageAnnotation = [[CPTPlotSpaceAnnotation alloc] initWithPlotSpace:plotSpace anchorPlotPoint:nil];
    imageAnnotation.contentLayer = newImagelLayer;
    [barPlot addAnnotation:imageAnnotation];
    [newImagelLayer release];
    [imageAnnotation release];

Is this a known issue?  I don't understand why it works in simulator but not on 
device.

Don't set the contents of a CPTLayer. Instead, use a CPTBorderedLayer and set 
the fill. One way to create the fill is like this:

[CPTFill fillWithImage:[CPTImage imageWithCGImage:[[UIImage 
imageNamed:@"test.png"] CGImage]]]

Moved to GitHub issue #2.

https://github.com/core-plot/core-plot/issues/2