Enhancement for the printing control

[jokd]

It would be nice to:

• - See the scale
• - Be able to set the scale
• - Get higher resolution
• - Optional north arrow
• - Date/time for creation
• - Custom logo
• - Change rotation of map with GUI
• - Have a legend (Prints should be able to include a legend #1382)
• - Preview fits to screen size
• - Render overlays nicer
• - Remove portrait/landscape bar when using custom size
• - Add a local grid of type letter and number (for rescue services use) (Print - Add a local grid #963)
• - Printpreview for embedded maps cannot be closed
• - Localization of labels (now hard coded to Swedish)
• - Use new button in print control to toggle map interaction (Print - Use new button in print control to toggle map interaction #1157)
• - Return the user to the map window after pressing the browser back button (Print - Return the user to the map window after pressing the browser back button #1156)
• - Set print settings' default values and visibility with named print templates (Print - Set print settings' default values and visibility with named print templates #1119)
• - Higher DPI should not alter style (Symbols getting smaller when printing higher resolutions #1293)
• - Labels in tile image layers should not repeat too often when printed (rendermode: image / single tile layer prop for print #1537)

[tonnyandersson]

It is possible to obtain a higher resolution just by passing a scale parameter to html2canvas. It won't make a huge difference, but it gives a noticable bump in overall image quality. As one might expect, increasing the scale has the greatest impact on regular HTML elements like texts and logos, but it will affect the map element as well. See comparison below.

Default scale (150% zoom)

2x scale (150% zoom)

4x scale (150% zoom)

Please note that the difference in the map image quality is slightly (slightly) more distinct in an actual print.

This is a quick and dirty way to achieve a slightly better image quality. However, to obtain a higher resolution on the map element as well, and thus greatly improve the overall export quality, would require a bit more work than just adding a simple parameter.

[jokd]

How is file size affected?

[tonnyandersson]

Quite a bit. At default scale, the export above, originally an A4 PDF, weighs in at 451 kB. At 4x scale, the file size is 2447 kB.

[jokd]

I can live with that if the vector features are crispy and clear, are they?
What do 2x looks like?

[tonnyandersson]

Added a 2x screenshot to my first comment. 1080 kB as A4 PDF. And no, vector features are not crispy and clear since such features are a part of the map canvas, just like the basemap.

You can tinker with this by adding scale as a parameter to convertHtml2canvas here: https://github.com/origo-map/origo/blob/master/src/utils/download.js#L64

[jokd]

4x gets my vote. Could it be an option for the control?
Would be nice to get this in before the release.

[tonnyandersson]

It's a whole lot faster to just hardcode it. It's a quick fix, a temporary workaround. No point in putting too much time into it. File sizes and export/download times are acceptable, even for A3 exports.

But that's just, like, my opinion.

[jokd]

Then I think we should set it to 4x. At least for now.

[jokd]

Overlays are rendered poorly:

I suggest we either rework the css or close overlays when entering print mode

[tonnyandersson]

Good point.