[Qgis-user] script to simplify 'Set to Map Canvas Extent'

Mon May 15 05:08:39 PDT 2017

Sorry you found that hard to find.

If it helps, I also have had to show QGIS to some quite non technical people. Everyone I’ve shown QGIS to found the concept of item properties pretty easy to grasp. Even the ones that needed to have vector and raster explained a multiple times.

Setting up templates will also make things easier for non technical people.

> On 15 May 2017, at 19:38, Willem Coetzer <W.Coetzer at saiab.ac.za> wrote:
> 
> It makes perfect sense to people like us, but it does nothing for someone who simply wants to refresh the extent. I'll admit that it's not a technical question, but one of software usability. That there are different levels of users with different proficiencies will remain a fact of life. Look at it this way: I've been doing GIS for about 15 years. This is the first time that I've had to google such basic functionality or post to a user group about it. If QGIS developers want to see QGIS become the preferred option, they would do well to look at human factors. 
> 
> -----Original Message-----
> From: Ramon Andinach [mailto:custard at westnet.com.au] 
> Sent: 15 May 2017 01:31 PM
> To: Willem Coetzer
> Cc: qgis-user at lists.osgeo.org
> Subject: Re: [Qgis-user] script to simplify 'Set to Map Canvas Extent'
> 
> But there is a button to do that. 
> 
> UI is not my strong point. But here’s the logic as I see it.
> 
> First the mantra - The Print Composer is not just the Map item.
> 
> I admit that the button is not on the toolbar, but it doesn’t belong there. If you look at what is on the toolbar it’s things that :
> a) add items to the composer,
> b) apply to the whole composer (like the zoom or export buttons - also the refresh button) or
> c) that apply to any item that’s on the composer window (like the group/ungroup buttons) So *whole* of composer things.
> 
> Things that are particular to an object/item on the composer are in “Item Properties” tab. For example, which layers are in the Legend are an property of the Legend so when you select the Legend object you can change this in Item Properties.
> 
> Since refresh extent would *only* apply to the map object (item) the button to “Set to map canvas extent" *is* in “Item Properties" when have the map frame selected. It’s a property of the map item, so it makes sense for it to be there.
> Select the map object and look in the Item Properties. 
> 
> What you suggest leads to that ugly situation where half the screen is full of buttons and someone will suggest that horrible R-word that MSOffice uses.
> 
> Hope that makes some sort of sense.
> 
> Ramon.
> 
> 
>> On 15 May 2017, at 18:04, Willem Coetzer <W.Coetzer at saiab.ac.za> wrote:
>> 
>> Thank you Ramon. At the very least, then, a separate button to 'Refresh Extent' in the composer. In ArcView it was really easy to add a button to the interface and associate a line or two of Avenue code with it. So in addition to suggesting that future versions should have a 'Refresh Extent' button already there, I'm saying that the ability to easily add a button (for whatever reason) would also be useful. And right now I'm wondering if someone can help me with the latter, as a way to make it easier to refresh the extent (as I say I did find a script but it's not precisely what I have in mind - it must simply refresh the extent of the active composer).
>> 
>> -----Original Message-----
>> From: Ramon Andinach [mailto:custard at westnet.com.au]
>> Sent: 15 May 2017 11:53 AM
>> To: Willem Coetzer
>> Cc: qgis-user at lists.osgeo.org
>> Subject: Re: [Qgis-user] script to simplify 'Set to Map Canvas Extent'
>> 
>> Hi Willem,
>> 
>> I can give you an example of where I really, really don’t want the extent to be updated with the refresh button.
>> 
>> One of the things I use QGIS for requires making a series of maps using two or more of a set of layers.
>> So I can have a composer set to a wide view to give a regional overview, and another composer set to a narrower more local view. I can then turn on one set of layers and generate maps at both scales with that set. After that I can change to set B, hit refresh to check it looks right (and I didn’t forget a layer) then have maps for set B straight up.
>> (I keep different QGIS projects, with a similar set of composers for 
>> each project area I work in. Once I’ve got the map extents set, then I 
>> don’t have to meddle with the composers too much. You sound a lot like 
>> you’re expecting to people to recreate maps on the fly over and over 
>> again - this is really time consuming.)
>> 
>> Another reason might be that you’ve got your composer set up and you zoom into somewhere on the map to check a detail, fix it and you want to see what it looks like on the map - but you don’t want to zoom back out. 
>> 
>> I really like that the extent for each composer is fixed - unless I 
>> choose to change it. It seems perfectly intuitive to me :)
>> 
>> 
>> 
>> On a slight tangent, I notice that Christine did answer the question you asked. 
>> Did you mean to ask, “Is there a way to automate creating a map?"
>> or,
>> "Can I create a button that combines functions in the Composer window?"
>> instead?
>> In current QGIS, the composer is pretty isolated from the rest of the program, as it’s not possible to directly make changes to composers through scripts. This is a limitation of the libraries used in the composer. I know there’s been a major overhaul of the Composer in the upcoming QGIS 3 release, and I’m pretty sure this is one of the changes.
>> I’m sure Nyall will correct me if I’m wrong.
>> 
>> Ramon.
>> 
>> 
>>> On 15 May 2017, at 16:00, Willem Coetzer <W.Coetzer at saiab.ac.za> wrote:
>>> 
>>> I was amazed that QGIS doesn't have a button to simplify this critical function. Thank you Christine, I do appreciate the response. I found a script that makes a new composer and then zooms to the extent of the map canvas in the new composer, but the script is not ideal (dependent on objects that won't always be present e.g. the filename of the QGIS template). Ideally one should be able to create a new button on a toolbar and then simply associate the 'Set to Map Canvas Extent' function with the button. If that is not possible I guess the next best thing would be a python script that does the same i.e. zooms to the extent of the map in the active composer.
>>> 
>>> I teach basic GIS skills to non-technical people and without this simple function it will be very hard to make any progress. Even the default procedure is too complex for them to remember.
>>> 
>>> I strongly suggest that QGIS developers look at this.
>>> 
>>> I really expected the 'Refresh' button to refresh the zoom extent as well. Why wouldn't a user want to refresh the zoom extent when refreshing the display of layers? It doesn't make sense to me.
>>> 
>>> If anyone can help with that script I'd be grateful.
>>> 
>>> 
>>> 
>>> Somerset StreetWillem Coetzer
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>>> -----Original Message-----
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>>> 1. refresh zoom extent in composer (Willem Coetzer)  2. Re: refresh 
>>> zoom extent in composer (Christine)
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>>> ---------------------------------------------------------------------
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>>> Message: 1
>>> Date: Sat, 13 May 2017 10:44:44 +0000
>>> From: Willem Coetzer <W.Coetzer at saiab.ac.za>
>>> To: "qgis-user at lists.osgeo.org" <qgis-user at lists.osgeo.org>
>>> Subject: [Qgis-user] refresh zoom extent in composer
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>>> 
>>> If the zoom extent in the view changes, is there a way to update the composer to reflect the same extent or do you need to create a new composer?
>>> 
>>> Thanks
>>> 
>>> 
>>> [cid:image40e5f3.PNG at 44bf3bf6.42823550]<http://www.saiab.ac.za/>
>>> 
>>> 
>>> 
>>> 
>>> Somerset Street
>>>      Willem Coetzer
>>> 
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>>> ------------------------------
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>>> Message: 2
>>> Date: Sat, 13 May 2017 06:42:50 -0700 (MST)
>>> From: Christine <geo.guide at web.de>
>>> To: qgis-user at lists.osgeo.org
>>> Subject: Re: [Qgis-user] refresh zoom extent in composer
>>> Message-ID: <1494682970839-5320434.post at n6.nabble.com>
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>>> 
>>> Willem Coetzer wrote
>>>> If the zoom extent in the view changes, is there a way to update the 
>>>> composer to reflect the same extent or do you need to create a new 
>>>> composer?
>>> 
>>> Dear Willem,
>>> you don't need to create a new composer. Procedure may depend on your QGIS version, in elder versions the window to select an item may be missing.
>>> 
>>> First select the map item in the composer view (right column). In the item properties tab (below) scroll to the extents section. There you can find the two buttons "set to map canvas extent" and "view extent in map canvas".
>>> 
>>> Click the first one to transfer your map window extent coordinates 
>>> (your
>>> "view") to your composer map extents (your "composer"). That's what you wanted to do as I understand it.
>>> 
>>> With the second button you might do the reverse: transfer the composer map extent coordinates (your "composer") to your map window (your "view").
>>> 
>>> Regards, Christine
>>> 
>>> 
>>> 
>>> 
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> 