Binding feature attributes to styles and labels

[sdlime]

This bug will be used to track the implementation of the RFC 19 ​http://mapserver.gis.umn.edu/development/rfc/ms-rfc-19/ implementation.

As of the creation of this bug an initial implementation has been checked in to the main trunk. It supports:

• styles: color, outlinecolor, size and angle
• labels: color, outlinecolor, size and angle

The main remaining tasks are:

• adding a binding for a style symbol DONE
• add more test cases (e.g. what happens when you bind a string to a numeric parameter)
• removal of old properies (e.g. LABELITEMANGLE) and structure members in header files, code, lexer configuration and PHP/MapScript binding DONE
• update label and style copy routines to handle bindings DONE
• creation of setBinding and removeBinding MapScript methods for labelObj and styleObj objects (both Swig-based languages and PHP)
• update write functions in mapfile.c to look for a binding
• documentation

[hobu]

r6126

[assefa]

Steve,

Couple of points :

1) Can you describe a bit what the set/remove bindings should do ? looking into this we could have a mapscript function that cold look like this

$style->setBinding(MS_STYLE_BINDING_COLOR, "attribute_field")

There could either be 2 functions in maputil.c one for style, one for label which would essantally do something like :

msSetBindingStyle( MS_STYLE_BINDING_ENUM, field)

if (style->bindings[MS_STYLE_BINDING_COLOR].item) {

free(style->bindings[MS_STYLE_BINDING_COLOR].item)

style->numbindings--;

} style->bindings[MS_STYLE_BINDING_COLOR].item = strdup('field') style->numbindings++;

removeBinding can also be done the same way, either having a separate function in maputil or using msSetBindingStyle with a NULL,

Could this work ?

2) Is ther a possiblity to add the FONT parameter for binding ?

In both cases, I am will to add it and test with php mapscript since I need to use it for a client side tool.

Thanks

[assefa]

Another point I forgot : how would the save through mapscript work ? In my opinion, It would make sense to save the attribute bindings. Right now the it saves the last values that were using while rendering.

[sdlime]

Replying to assefa:

Steve,

Couple of points :

1) Can you describe a bit what the set/remove bindings should do ? looking into this we could have a mapscript function that cold look like this

$style->setBinding(MS_STYLE_BINDING_COLOR, "attribute_field")

There could either be 2 functions in maputil.c one for style, one for label which would essantally do something like :

msSetBindingStyle( MS_STYLE_BINDING_ENUM, field)

if (style->bindings[MS_STYLE_BINDING_COLOR].item) {

free(style->bindings[MS_STYLE_BINDING_COLOR].item)

style->numbindings--;

} style->bindings[MS_STYLE_BINDING_COLOR].item = strdup('field') style->numbindings++;

removeBinding can also be done the same way, either having a separate function in maputil or using msSetBindingStyle with a NULL,

Could this work ?

Yes, that's all I was thinking. I was going to write them as helper methods in the swig interface files, so in style.i you'd see:

int addBinding(int binding, char *item) {

if(!item) return MS_FAILURE;

if(binding < 0

binding >= MS_STYLE_BINDING_LENGTH)

return MS_FAILURE;

if(this->bindings[binding].item) {

free(this->bindings[binding].item) this->bindings[binding].index = -1; this->numbindings--;

}

this->bindings[bindings].item = strdup(item); this->numbindings++;

return MS_SUCCESS;

}

int removeBinding(int binding) {

if(binding < 0

binding >= MS_STYLE_BINDING_LENGTH)

return MS_FAILURE;

if(this->bindings[binding].item) {

free(this->bindings[binding].item) this->bindings[binding].index = -1; this->numbindings--;

}

return MS_SUCCESS;

}

I hadn't planned on writing C functions to do it although we could. We'd need a seperate set/remove function for labels and styles unless we did something like:

int msSetBinding(void *obj, int binding, char *item, int max_bindings)

Would have to pass the MS_LABEL_BINDING_LENGTH or MS_STYLE_BINDING_LENGTH for max_bindings, or just ignore that test altogether (a bad idea I think).

The one problem I see is guaranteeing that the binding item index gets populated, which happens via msLayerWhichItems() at draw time. We'll see I guess.

2) Is ther a possiblity to add the FONT parameter for binding ?

Yes, assuming you're talking font name (e.g. arial). I can do that for you if you wish. It's not hard but there are like 3 places you have to touch.

In both cases, I am will to add it and test with php mapscript since I need to use it for a client side tool.

Thanks

[sdlime]

Replying to assefa:

Another point I forgot : how would the save through mapscript work ? In my opinion, It would make sense to save the attribute bindings. Right now the it saves the last values that were using while rendering.

Whoops, forgot to fix the writers to check for a binding. Will add to the todo in the main description.

[assefa]

I think we can add the addBinding (or is it setBinding ??) and removeBinding at the mapscript level as you descibed it. I will add the php methods on both style and label adn do the tests.

as for the Font : yes I meant the font name and yes you can add it :)

I have also locally modified mapfile.c to save the bindings when the map file is written (writeStyle and writeLabel functions). It looks something like :

if(style->numbindings > 0 && style->bindings[MS_STYLE_BINDING_ANGLE].item)

fprintf(stream, " ANGLE [%s]\n", style->bindings[MS_STYLE_BINDING_ANGLE].item);

else if(style->angle != 0) fprintf(stream, " ANGLE %g\n", style->angle);

It seems to work and I would like to commit if you agree. I will also add the FONT saving when you are done binding the FONT.

Thanks

[assefa]

commited update write functions in mapfile.c to look for a binding r6248

[assefa]

Added setbinding and removebinding functions in phpmapscript on label and style objects (r6251)

[sdlime]

Added setBinding and removeBinding methods to mapscript (SWIG).

[dmorissette]

FYI I have added missing MS_LABEL_BINDING_FONT and MS_LABEL_BINDING_PRIORITY constants in PHP MapScript in r6296

[tomkralidis]

Should this be reassigned to Jeff?

[jmckenna]

Am I correct that for this ticket several existing parameters such as ANGLEITEM were totally removed, causing existing mapfiles with those parameters to break? I assumed both ways would still exist, but the docs would state "deprecated" for the old parameters. If I am correct, then I will open a new ticket to add the old parameters back into the code.

[jmckenna]

• updated mapfile reference for new attribute binding
• re: removed parameters: I've discussed this with Daniel and Howard on IRC. I have updated the docs accordingly.
• I have also created ticket#2707 to inquire about some more possible parameters to "bind" to attributes.