I would like to implement a simple input box with SDL and SDL_ttf. Just like the address bar in your browser.
I'm guessing what is the easiest and most efficient way to detect a mouse selection with SDL_ttf.
Let say the box display text like this:
+--------+
| abcdef |
+--------+
The user clicks between 'c' and 'd', then it drags the mouse to the left by several pixels. Now I need to detect that it has selected the 'c' character.
The SDL_ttf library has several functions to determine the metrics of a text. You can compute the whole text size with TTF_SizeUTF8 and you can also determine a glyph size for an individual character with TTF_GlyphMetrics.
Rough idea would be to create a special array with all individual characters with their respective size just to determine their positions in the box.
Do you have better ideas on how this can be implemented easily?
Text selection in immediate rendering mode should be worked on from zero , which is alot of work to do. there is the legendary stb_textedit used by many immediate gui libraries like imgui , you can find it here
https://github.com/nothings/stb/blob/master/stb_textedit.h
Related
Regular user of QGIS for moderate mapping needs. Currently using desktop version 3.24.0.
Tring to add labels to point and polygon shapefile layers. Never had an issue doing this before, but now I can only select the integer option indicated by '123'. The alphanumeric option usually indicated by 'abc' is no longer there, and i cannot create a label with any form of lettering as a result.
You can see below that the dropdown menu only has an option for integers:
Anyone else had this issue? Did you find a resolution?
Cheers,
R
Correct display of Unicode in a terminal would appear to benefit from the displaying app knowing the number of character cells used to display text. Functions like wcwidth() are a reasonable start, but there can be a lot of variation, for example what a terminal displays for invalid characters, ambiguous width Asian characters, combining characters out of context, etc.
Would it be reasonable to extend terminal apps with a new control sequence to measure with display width of a string, which display apps could use to characterize the terminal? If so, what details are worth considering, e.g. what sequence to use, whether to specify UTF-8, also how to handle terminals that do not know this hypothetical new control sequence? Would it have any likelihood of wide adoption?
If not, what is the flaw in the idea? Is perhaps reading the cursor position after display a better (and already supported) option? Or is there a good different approach?
There's no need, because the existing cursor position report (which can be used to get the position before and after printing a string) gives the length.
Adding a new control sequence to get the attributes of a character (width, combining, controls such as tab) wouldn't help much because the application still has to work with the system's locale information for performance reasons: it would drastically slow down an application if it had to ask after each character where the cursor really was.
Is it possible to write one word with left alignment and one word with right alignment in a single cell in LibreOffice Calc?
Like that: | normal Cell one | Halli _________ Hallo | normal Cell three |
Everytime I try to simulate it with many spaces between Halli and Hallo, there are format problems when I convert it to PDF.
Format the cell to have a distributed horizontal alignment [my LO 4.1.6.2 on Linux offer this option].
Stayed that way after exporting to PDF.
This is not a programming question - use SuperUser for software handling questions next time, please.
This picture illustrates my predicament:
All of the characters appear to be the same size, but the space between them is different when presented in a RichEdit control compared with when I use ExtTextOut.
I would like to present the characters the same as in the RichEdit control (ideally), in order to preserve wrap positions.
Can anyone tell me:
a) Which is the more correct representation?
b) Why the RichEdit control displays the text with no gaps between the Asian Characters?
c) Is there any way to make ExtTextOut reproduce the behaviour of the RichEdit control when drawing these characters?
d) Would this be any different if I was working on an Asian version of Windows?
Perhaps I'm being optimistic, but if anyone has any hints to offer, I'd be very interested to hear.
In case it helps:
Here's my text:
快的棕色狐狸跳在懶惰狗1 2 3 4 5 6 7 8 9 0
apologies to Asian readers, this is merely for testing our Unicode implemetation and I don't even know what language the characters are taken from, let alone whether they mean anything
In order to view the effect by pasting these characters into a RichEdit control (eg. Wordpad), you may find you have to swipe them and set the font to 'Arial'.
The rich text that I obtain is:
{\rtf1\ansi\ansicpg1252\deff0\deflang2057{\fonttbl{\f0\fnil\fcharset0 Arial;}}{\colortbl ;\red0\green0\blue0;}\viewkind4\uc1\pard\sa200\sl276\slmult1\lang9\fs22\u24555?\u30340?\u26837?\u33394?\u29392?\u29432?\u36339?\u22312?\u25078?\u24816?\u29399?1 2 3 4 5 6 7 8 9 0\par\pard\'a3 $$ \'80\'80\cf1\lang2057\fs16\par}
It doesn't appear to contain a value for character 'pitch' which was my first thought.
I don't know the answer, but there are several things to suspect:
There are several versions of the rich edit control. Perhaps you're using an older one that doesn't have all the latest typographic improvements.
There are many styles and flags that affect the behavior of a rich editcontrol, so you might want to explore which ones are set and what they do. For example, look at EM_GETEDITSTYLE.
Many Asian fonts come in two versions on Windows. One is optimized for horizontal layout, and the other for vertical layout. That latter usually has the same name, but has # prepended to it. Perhaps you are using the wrong one in the rich edit control.
UPDATE: By messing around with Wordpad, I was able to reproduce the problem with the crowded text in the rich edit control.
Open a new document in Wordpad on Windows 7. Note that the selected font is Calibri.
Paste the sample text into the document.
Text appears correct, but Wordpad changed the font to SimSun.
Select the text and change the font back to Calibri or Arial.
The text will now be overcrowded, very similar to your example. Thus it appears the fundamental problem is with font linking and fallback. ExtTextOut is probably selecting an appropriate font for the script automatically. Your challenge is to figure out how to identify the right font for the script and set that font in the rich edit control.
This will only help with part of your problem, but there is a way to draw text to a DC that will look exactly the same as it does with RichEdit: what's called the windowless RichEdit control. It not exactly easy to use: I wrote a CodeProject article on it a few years back. I used this to solve the problem of a scrollable display of blocks of text, each one of which can be edited by clicking on it: the normal drawing is done with the windowless RichEdit, and the editing by showing a "real" RichEdit control on the top of it.
That would at least get you the text looking the same in both cases, though unfortunately both cases would show too little character spacing.
One further thought: if you could rely on Microsoft Office being installed, you could also try later versions of RichEdit that come with office. There's more about these on Murray Sargent's blog, as well as some interesting articles on font binding that might also help.
ExtTextOut allows you to specify the logical spacing between records. It has the parameter lpDx which is a const pointer to an array of values that indicate the distance between origins of adjacent character cells. The Microsoft API documentation notes that if you don't set it, then it sets it's own default spacing. I would have to say that's why ExtTextOut is working fine.
In particular, when you construct a EMR_EXTTEXTOUTW record in EMF, it populates an EMR_TEXT structure with this DX array - which looking at one of your comments, allowed the RichEdit to insert the EMF with the information contained in the record, whereby if you didn't set a font binding then the RTF record does some matching to work out what font to use.
In terms of the RichEdit control, the following article might be useful:
Use Font Binding in a Rich Edit Control
After character sets are assigned, Rich Edit scans the text around the
insertion point forward and backward to find the nearest fonts that
have been used for the character sets. If no font is found for a
character set, Rich Edit uses the font chosen by the client for that
character set. If the client hasn't specified a font for the character
set, Rich Edit uses the default font for that character set. If the
client wants some other font, the client can always change it, but
this approach will work most of the time. The current default font
choices are based on the following table. Note that the default fonts
are set per-process, and there are separate lists for UI usage and for
non-UI usage.
If you haven't set the characterset, then it further explains that it falls back to ANSI_CHARSET. However, it's most definitely a lot more complicated than that, as that blog article by Murray Sargent (a programmer at Microsoft) shows.
Before you throw me out into the cold with your bold assertions that this is not programming related, please hear me out.
I'm looking for a visual metaphor (Icon) to suggest the idea of inversion of a filter. So if a user has a filter which reduces a list of 10 items to 4, I want a button that will allow the user to invert the filter to display only the other 6.
Another wrinkle is that the UI will also have a button for removing the filter nearby.
While this certainly isn't a nuts-and-bolts programming question, I think it's relevant to the process of software creation. As a developer it's relatively easy to construct the mechanisms to perform complex filters, but it's all for naught if normal users find the presentation confusing.
If an icon doesn't jump to mind for you, then there probably isn't one that will have obvious meaning to your users either. You're better off using a text label for this.
If it must be an icon, then it doesn't matter much what it is, since users won't be able to guess it any way, but at least try to make it visually distinct and memorable if not particularly intuitive. MS Access uses a funnel to represent "filtering." Maybe use an upside-down or white-on-black funnel for inversion? (An X'ed-out funnel means "don't filter").
Whatever. Like I said, it doesn't matter much.
Maybe it's not the most appropriate, but what about the logical inverter icon?
Maybe something like this: Invert Selection?
If you really need an image, I'd suggest looking at image editing programs like GIMP or Photoshop and seeing how their "invert selection" buttons look.
16x16 pixels is enough to draw two small list boxes with an arced arrow going from one to the other where the second has an inverted selection list of the first.
alt text http://img524.imageshack.us/img524/6782/4092009000139am.png
I think the 3 icons above could be used in one spot with each user click causing a rotation through the 3 of them. I think the above icon set offers the following benefits:
F - clearly communicates it is for a filter control.
Red and Green - clearly communicate ON and OFF action.
The line above F means inversion (I think - based on memories of boolean algebra at university - I could be wrong?)
The use of yellow while still maintaining the F, links the new action (filter inverted) to the previous filter actions let still communicates it is different to the filter simply being turned on or off.
On icon click rotation could be, (starting) Red - Green - Yellow - Red. This is a widely understood rotation pattern that the user would quickly pick-up. Therefore no need for additional filter on/off button.
Simpler solution - a user only needs to look at a single icon (even perhaps only with peripheral vision) to deduce the current state of the control.