Re: [AUCTeX] Embedded previews in high-DPI?

[YAMAMOTO Mitsuharu]

>>>>> On Thu, 19 May 2016 12:38:07 +0200, David Kastrup <address@hidden> said:

>> The point is that on certain systems, OS X combined with the
>> so-called "Retina" display, preview images have wrong resolution,
>> right?  If so, the proposed patch fixes this problem, in this sense
>> I don't see it as a new feature that works only on proprietary
>> systems, that is what FSF guidelines discourage, but as a bug fix
>> on a proprietary system, that is definitely not forbidden.

> No, it doesn't fix the problem of the resolution mismatch.  Instead
> it reverts to using the image-io image type (which is _not_ provided
> by GNU Emacs but rather by a third-party Mac Emacs port with
> additional MacOSX-only support, like the Mac-only proprietary PDFKit
> library
> <URL:https://developer.apple.com/library/mac/documentation/GraphicsImaging/Reference/PDFKit_Ref/index.html>)
> in order to provide the images not as bitmaps but rather as PDF
> files to be rendered by a proprietary renderer that is not supported
> by GNU Emacs (exactly because it is MacOSX-only).

The `image-io' image type in the Mac port is a fall back
implementation for the `imagemagick' image type which is provided also
on free platforms.  They have the same interface other than its name.
Supported image formats are not the same, but at least PDF is
supported on both of them.

>> On the other hand, one may argue that the patch adds a new feature,
>> namely support for high-DPI screens,

> It doesn't.  It merely exercises the proprietary PDF renderer of
> MacOSX when using a MacOSX-only variant of Emacs not maintained by
> GNU.  That has the _side-effect_ of hiding the resolution mismatch
> problems on the Mac platforms because it stops rendering of bitmaps
> under the control of either Emacs or preview-latex altogether.

Even the NS port (the default OS X port included in vanilla Emacs)
uses proprietary image renderer implementations for other image
formats: GIF, JPEG, PNG, and TIFF.

The NS port does not provide us with non-blurry image display for
Retina environments.  That's why the patch is only effective on the
Mac port and no-op on the other ports/platforms.

                                     YAMAMOTO Mitsuharu
                                address@hidden