now i have a new task, and i think this is quite outrageous. my superior asked me to make a graph digitizer. the graph image is put together with the linechart from the flex to provide the axes. the thing that can be done now is click a point on the line (on canvas) and the coordinate will show at the datagrid (coordinate detected from the line chart axes). And my problem is, when we load the line graph image onto the panel, he asked me to show datatip where ever the cursor passed the line of the graph in the image. is it possible? if the line provided from the flex line chart, it can be done. but the thing is the line came from the image (graph image).
this is not an easy one...! The only thing that comes to mind is using the chart mousemove event to get the coordinates into the image, then checking to see if the relevant pixel colour is line colour rather than background or axis colour. Very hacky but it's a thought. In straight HTML you might be able to set up an image map on the server that corresponds to the line region, but I'm not sure that's possible in Flex. You'd have to be sure that the image size as shown in Flex was the same as its native size, or else do some suitable calculations to work back - but then to display correctly against the axis that would be necessary anyway.
thanks for your thought richard, that's a deep stuff you mentioned there.
haha. i'll sort it out with my colleagues too.