Is it possible to lock the scale in the QGIS 2.0.1 print composer? Every time I resize the map, the scale is adjusted. This makes trying out different map layouts really annoying.
[GIS] Resizing the map item in QGIS print composer without changing scale
print-composerqgisqgis-2
Related Solutions
The scale will inevitably effect the extent for any given area and that will be limited by the size of your paper (so an A4 sheet @ 1:50,000 scale will be approximately a half of the possible extent of an A3 sheet). Contrariwise, setting the map extent for a given area of paper will also inevitable dictate the scale. You cannot adjust one without influencing the other (which is why you have received some negative scores for this question).
You have stated that your actual extent is not as important as scale. So to resolve your dilemma, set the scale and then, with the map selected, click the 'Move item content' button (icon is a small arrow and green box, next to the 'Select/Move item' button - a large arrow).
You can now 'slide' the content of the map without changing the position of the map on the page and thereby center you map contents on your area of interest.
If the extent of the map is still not large enough at the scale you must use, then you need to increase the size of the map and that might mean splitting your map over two or more sheets and to do that effectively you can use the Atlas generator.
Tested with QGIS 3.6.1
As mentioned in the documentation, you can create a label and insert this code to get the current scale for the map with the item name Map 0:
map_get( item_variables('Map 0'), 'map_scale')
Best Answer
Update 27/07/2018: As of QGIS 3.2.1, my workaround below no longer works! If I find an alternative solution I will post here again. This is very, very annoying...
There is a way to do this.
The item's scale will now be fixed at 1:50000 and will remain so no matter how much you move or resize it.
Jyler's suggestion simply doesn't work (QGIS 2.6.0 Brighton) while I can only assume that Ardit either has the world's fastest PC and/or only works on very simple maps with a handful of layers. The automatic rescaling "feature" is incredibly annoying and I cannot imagine why the developers thought it was a good idea.