Many hyperlinks are disabled.
Use anonymous login
to enable hyperlinks.
Overview
Comment: | Editorial pass on 507 |
---|---|
Downloads: | Tarball | ZIP archive |
Timelines: | family | ancestors | descendants | both | trunk |
Files: | files | file ages | folders |
SHA3-256: |
75f5c2c7044300a86a970e49750c99db |
User & Date: | dkf 2018-12-13 11:00:29.084 |
Context
2018-12-14
| ||
14:30 | Docuement current (failed) approach to set write metadata. check-in: bbe903ab13 user: oehhar tags: trunk | |
2018-12-13
| ||
13:37 | New TIP 530 check-in: 99daffc5b5 user: leon tags: trunk | |
11:00 | Editorial pass on 507 check-in: 75f5c2c704 user: dkf tags: trunk | |
2018-12-11
| ||
10:42 | TIP 429: Added implementation link check-in: 23b8985271 user: oehhar tags: trunk | |
Changes
Changes to tip/507.md.
︙ | ︙ | |||
12 13 14 15 16 17 18 | # Abstract Tk needs scalable images on high resolution mobile devices. This TIP proposes to let Tk be able to read an [SVG][] image (plus information about orientation and pixel scale) and make it into a photo image. It is therefore a (lossy and single direction) conversion operation from an [SVG][] format to a pixel format. # Rationale | | | | > > > > > | | | > > > | | | > > > | 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 | # Abstract Tk needs scalable images on high resolution mobile devices. This TIP proposes to let Tk be able to read an [SVG][] image (plus information about orientation and pixel scale) and make it into a photo image. It is therefore a (lossy and single direction) conversion operation from an [SVG][] format to a pixel format. # Rationale Tk is running on desktop and mobile devices. However, the out-of-the-box photo image formats do not scale and are too tiny on high resolution mobile devices. The same goes for the image formats provided by the [Img][] extension. The response to this challenge in general (on the web, in applications, etc.) has been to adopt the [SVG][] format, as that is scalable and does not typically depend on being rendered at a particular resolution. Moreover, there is already a Tk image extension to do the conversion, [tksvg][]. The implementation is using the [nanosvg][] library It has no other external dependencies and is only 2 header files. [nanosvg][] was choosen because it: - has a suitable license - is written in 2 plain C header files and can be easily included - is really lightweight - is tested with tksvg - can render images - has no other external dependencies # Specification The already existing [tksvg][] extension will be adapted and included in Tk. A new photo image format will be created. The photo image format name is **svg**. The new format will support a small list of options. Note that scope still exists in the future for full integration of SVG as its own full image type (which would allow more options for rendering) instead of having the side-trip via the photo image's pixel buffer, but this is out of scope of this TIP. A description of the features and limitations of the current implementation is in section [Supported SVG](#Supported-SVG). It will be also described in the photo(n) man page. The **svg** image format has the following format suboptions: > **svg** **-dpi** _dpiValue_ **-scale** _scaleValue_ **-unit** _unitValue_ *dpiValue* is used in conversion between given coordiantes and screen resolution. The value must be greater then 0.0. The default value is `96`. *scaleValue* is used to scale the resulting image. The value must be greater then 0.0. The default value is `1.0`. *unitValue* is the unit of all coordinates in the svg data. Available units are `px` (default, coordinates in pixel), `pt` (1/72 inch), `pc` (12 pt), `mm`, `cm` and `in`. The given format options are only used at creation time of the image and are not preserved in the image. This means that: 1. `$img data -format svg` triggers the error _"image string format "svg" is not supported"_; Tk cannot convert a photo image into an [SVG][]. 2. In this: $img configure -format {svg -scale 2} $img configure -format {svg -dpi 96} the second call takes `-scale` as the default value (1). There is no intention to provide a reverse mechanism for saving a photo image as an SVG image. <a name="Supported-SVG"></a> # Supported SVG The **svg** format supports a wide range of [SVG][] features, however some features (e.g. 'text') are missing and silently ignored when reading the [SVG][] data. ## Elements |
︙ | ︙ | |||
217 218 219 220 221 222 223 | # Copyright This document has been placed in the public domain. [nanosvg]: <https://github.com/memononen/nanosvg> [tksvg]: <https://github.com/auriocus/tksvg> [SVG]: <http://www.w3.org/TR/SVG11/> | | < | 228 229 230 231 232 233 234 235 | # Copyright This document has been placed in the public domain. [nanosvg]: <https://github.com/memononen/nanosvg> [tksvg]: <https://github.com/auriocus/tksvg> [SVG]: <http://www.w3.org/TR/SVG11/> [Img]: <https://sourceforge.net/projects/tkimg/> |