Hi, I think we have a conceptual problem in the theming system that needs addressing, specifically related to frame elements that can have borders partially clipped away, such as dialogs and panels.
Let's recap the current state of things: Frame SVGs are so-called nine- patches, i.e. there's an element for the center, one for every corner, and one for every edge. A dialog will usually draw all of these elements, and the dialog content goes into the grid cell filled with the center element, filling it. When the dialog bumps up against a screen edge, the border row/column on that side gets disabled. Now we need to consider how themes tend to distribute the visual over the nine-cell grid. Many themes have rounded corners, which means the size of the corner cells must be large enough to fit the curve of the corner. This causes all of the border rows/columns to be of a certain width. Both the rounded corners, and the fact that many themes like to have a visually strongly defined border (i.e. a visible, contrasting outline of some kind) means the sides of the center rectangle are usually a small distance from what an onlooker visually perceives as the inside edge of the dialog. In other words, there is a margin between the con- tent and the inside edge of the dialog. When a border row/column gets disabled, this margin disappears, causing a visually uneven/asymmetrical result. Content appears not centered, with different margins between content and opposing inside edges (one of them now a screen edge). This is a problem for dialogs spawned from panels, and for the panel itself. The latter especially often causes grief and unhappy feedback from users and designers. Right now, many applets try to hack around this by adding their own inside margins depending on how they're used and their position. This is doomed to fail however (I know, I tried in Plasma 1), because: - The location enum doesn't provide enough information, specifically it has no notion of when something is in a corner, and popup applets can't access the margins prop for the popup dialog. - Much more importantly, the applet can't actually know what margin is correct, because it doesn't know anything about the design of the theme. This is a critical point: The width of the border row or column as the distance to the visually perceived inside edge, because this depends on the specifics of the design. In a theme that implements an outline design (e.g. say a 2px pink border or whatever), the perceived inside edge is where that outline begins. So, how do we fix this? A naive approach would be to disable the border row/column just as we do now, but then extend the center rectangle by the same width as the border would normally be, and then apply an inside margin between the edge of the center rectangle and the edge of the content equal to that width as well. This doesn't actually fix the problem however because again, the visually perceived inside edge isn't equal to the width of the whole border element. To really address this, we thus need to allow theme authors to pro- vide another set of hint elements in their SVGs that specify a width to use for that center rect edge <-> content edge margin on edges with disabled borders. Other hint elements already exist: Theme authors can specify a set of width hints that substitute for the actual widths of the border elements - but these substitutes aren't used when a border is disabled. So, bottom line: Four new hints and code to make use of them are needed IMHO. This would finally unfuck a lot of bad asymmetry and hacks in panels, panel popups and the like. Thoughts? Cheers, Eike _______________________________________________ Plasma-devel mailing list Plasma-devel@kde.org https://mail.kde.org/mailman/listinfo/plasma-devel
