[Mapserver-dev] Labels that follow streets with bends

[John Newton]

----- Original Message ----- 
From: <woodbri at swoodbridge.com>
To: "mapserver-dev" <mapserver-dev at lists.gis.umn.edu>
Sent: Sunday, February 09, 2003 8:56 AM
Subject: [Mapserver-dev] Labels that follow streets with bends


> Hi all,
> 
> There has been some some discussion of have street labels follow 
> bends in the streets in the past. I have decided to take a pass at 
> implementing a routine to do this.
> 
> Here are my initial thoughts on this. I am looking for comments and 
> feedback.
> 
> My plan is to implement a function like this:
> 
> bchar *TextPath(
>     gdImagePtr im,
>     int *brect,
>     int fg,
>     char *fontname,
>     double ptsize,
>     int npts,
>     int *X,
>     int *Y,
>     char *string,
>     int flags);
> 
> most of these args are identical to the gdImageStingFT() call and 
> this function would work similarly to it if you pass it NULL for im. 
> The polyline would be passed in using the npts, X, Y args; and flags 
> I envision would be used to control the behavior of the function with 
> respect to
> NO_PARTIAL  - fail is polyline is too short to render the whole 
> string
> TRUNCATE  - trucate the string if it is too long
> EXTEND - virtually extend the last segment to write the whole string
> REVERSE - the direction of the polyline
> AUTO - figure out the best placement of the text so it is most 
> readable
> ABOVE|BELOW|CENTER the text on the polyline
> 
> My first pass at this will be straight forward if not brute force. I 
> will take each char in the string and see if I have enough room to 
> place it on the segment, if not place it on the next segment until I 
> run out of chars or segments. I will also probably ignore most of the 
> flags and implement it as flags = EXTEND|AUTO; I plan to write the 
> function to just call gdImageStringFTEx() to do the work, a later 
> optimization might be to clone the gdImageStringFTEx() source so I 
> can make some optimization.
> 
> This implementation has the advantage for me that I can dev and test 
> in a simplified GD only environment. On the down side real 
> performance will not be as easily tested until it is integrated into 
> mapserver.
> 
> If I implement as described above will it be easy to integrate into 
> mapserver? Issues? concerns?
> 
> -Steve W.
> 
> 
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