How to make text scrollable (horizontal and vertical) using Cairo library?
Are there any cairo API which provide scrolling functionality without the use of gtk library?
Cairo only draws things. It has nothing to do with user interaction and thus the whole question does not really make sense, sorry.
Of course you can draw text with cairo at whatever position you want. Thus, to make text scroll you just have to redraw your text based on user input and use a slightly different position each time.
Related
Let's say you have some flutter widget, for example, a TabBar. It is rendered in a rectangular box. I need it to be rendered in an arc so that the text and the underline follow part of a circle (or better still, a bezier curve).
How can that be achieved?
This illustrates what I am trying to achieve - bent TabBar widget:
Please note that in this case, the TabBar bends following and an arc (edge of a circle). This is what I need immediately. However, in the future, I might need bending that follows the edge of an eclipse so a solution that allows it would be preferable.
Also, a solution that works for different widgets is preferred.
IMPORTANT: I do NOT want to clip a curved shape of the widget. The entire area of the widget should stay visible. Instead, I need to bend the content of the widget (=bend its render image).
Apologies for the bold font but without it, people will keep posting answers about how to clip a widget which is trivial in comparison and useless for my problem.
An answer "this is currently not supported by Flutter" from authority (e.g. high reputation in Flutter tag or Flutter a team member) will also be accepted.
One approach: Use a CustomPaint to draw lines/areas/etc freely
You can use a CustomPaint to draw whatever curved lines, areas, etc freely. Therefore, you can definitely achieve your goal - since they are nothing but curved lines, areas with curved edges, rotated texts, etc.
That will take a bit of work, but if you encapsulate it well enough, it is not that hard to implement. For example, draw a Path with filled red area, then draw a white arc, then draw several texts with calculated rotations, etc. Sounds like you can do that within maybe hundreds of lines. If you find difficulty implementing this please comment and I will explain.
Another approach: Hack Canvas such that the call to drawLine becomes indeed calls to drawPath, etc.
You may do the following to allow bend/crook for any widget (and their combination, of course), but this may need a bit of engineering. You can make your own Canvas, say, class BendCanvas implements Canvas {}. The BendCanvas.drawLine, for example, has an implementation of Canvas.drawPath with a curved path cooresponding to the input "line". Similar things hold for drawing rectangles, etc. Then you need to hack Flutter's painting logic, such that it takes in your own BendCanvas instead of the original canvas. This is a universal solution, and it is much more efficient (less code) if you plan to have a lot of bend UI; but if only on bend TabBar, maybe use the first approach.
As for the bend text
In the two approaches above, we have mainly described how you draw the bended rectangle (i.e. draw an arbitrary shaped widget). As for bending text, see: https://github.com/flutter/flutter/issues/16477 , which is still an open issue.
Remarks
It is not possible using transformations. As explained in the comments, you already see Transform does not work - it is affine or perspective, which, by definition, will not bend. Then what about other transforms? After some research there seems to be none. Then, what about looking under the scene. We know Flutter uses Skia under it to draw the UI with high performance, then let us search through Skia. However, it does not provide any transformations like bending. So there seems no use.
P.S. I am not that high reputation in Flutter tag, but I did answer >100 Flutter questions (including some dig-into-source-code style ones), and have developed >100k lines of Flutter code in the production app.
this may look like this question already appeared and in fact it was already touched in this topic Parallel drawing with GTK and Cairo in Python 3 . However is it possible there is another solution to this problem?
To start with, I have created UI in PyGtk with my custom animations executed with the use of threading (Gtk.threads_enter() and Gtk.threads_leave()). It works good and gives out no errors. I also wanted to add some kind of point cloud and I saw that Cairo may be a good fit for it with supposedly support for Gtk.DrawingArea to handle it.
Here is where problem starts. Due to Cairo using drawing event and pretty much overriding it, it draws over my UI the image I made for Gtk.DrawingArea.Image of cairo drawing over UI
So image appears in DrawingArea and is drawn once again over every UI element. I used this tutorial https://blog.fossasia.org/creating-animations-in-gtk-with-pycairo-in-susi-linux-app/ to draw Cairo animation.
Is there a way to somehow make drawing calls from PyGTK to redraw UI elements, so they are not overdrawn by Cairo?
I answered my own question. Draw call needs to be in its own class for DrawingArea as in example https://blog.fossasia.org/creating-animations-in-gtk-with-pycairo-in-susi-linux-app/
I tried to connect it with my own main class but then it was redrawing whole window instead of redrawing only DrawingArea. So when you want to use Cairo, remember to make DrawingArea a custom class.
I am working on a game using GTK3 as a rendering technique (terrible idea, but it's a school project).
My gameobjects are made of Image widgets and are placed in a Fixed container. It's working pretty well, however when i move widgets beoynd right or bottom border, the window automatically grows along with it.
I want the window to stay at the sam size, event if widget leaves its area and becomes invisible. It works when i move widget past the upper or left border.
I tried using gtk_widget_set_vexpand and gtk_widget_set_hexpand. My window is set as not resizable (gtk_window_set_resizable).
Is there any way I can achieve this?
This isn't the right way to use GTK+. GTK+ is intended for laying out widgets in a GUI program.
There are better options for animating 2D elements. One that works with GTK+ natively is the Clutter library. You can also integrate SDL or OpenGL or something like that if you so choose.
That being said, you can also use GtkLayout instead of GtkFixed, or put the GtkFixed in a GtkScrolledWindow and hide the scrollbars and set the scroll policy to prevent scrolling. It's still technically misuse, and in fact GtkFixed (and possibly GtkLayout too but the docs don't say) is really not supposed to be used anymore unless absolutely necessary because it doesn't give you automatic support for tricky UI layout problems, but it doesn't have extra dependencies.
I'm using the workaround described here to vertically align text in a multiline UILabel to the top. Unfortunately that solves only half of the problem because I also want to collapse the remaining space and move other labels below the label to move up and consume the space.
Is there anyone way to achieve this without having to resort to calculating the Frame's of the other views yourself and thus taking over the layouting?
Here's a screenshot of my problem. To make it easier I've colored the background of the relevant labels. The Blue label is supposed to move up and consume the unused space of the red label. The Red Label is configured for 3 Lines and Font-Autoshrink is off.
You must re-calculate your label frames and then rearrange your labels in the view.
Or you can try to use CoreText to make more complex layouts without the need to cope with these frames rearrangement. On GitHub there is a nice work BSD-licensed, called NSAttributedString+HTML: https://github.com/Cocoanetics/NSAttributedString-Additions-for-HTML which tries to port in the iOS the same methods already available in OSX. It is based on CoreText and with this class you can write your page as html and render it on screen without using UIWebView (and without its limitations). Based on your screenshot, it would be easy to achieve the wished result with simple html.
I'm investigating the feasibility of using Raphael for a user-research project. One of the features allows for users to drag images onto a canvas and we record where they placed it. The pool of images is potentially quite large and we'll have them in a scrollable box in the tool.
I put together a quick wireframe of the issue I'm looking into since it'll probably be clearer than my explanation.
Please see the wireframe:
I'd stick with straight HTML/CSS and use jQueryUI draggables, as you mention in your comment.
You don't appear to need any of the drawing/display features SVG offers, yet if you went that route, you'd have to build your own custom scrolling behavior (instead of setting a CSS overflow-y rule) and picture layout algorithms (again instead of using CSS floats or something).
You can create a scrollable region using Raphael.
Create the viewport with fixed
dimensions (say 800x600)
Draw the images with increasing y value. After few images, the y value will go beyond 600. It will be drawn but will not be visible in the viewport.
Create a scrollbar using raphael rects. Attach drag events to the scrollbar handle rect.
When the handle is moved, translate all the images accordingly.
For e.g. lets assume in step 2, you had drawn all the images and the bottom most point of the end image is having y value 2000. Assuming the scrollbar has length 500, each dx movement of the handle will have to translate 2000/500 = 4dx. You can calculate the handle length similarly using ratios.
Since everything inside a single Raphael paper the dragging of images will work seamlessly. You will have to maintain the positions of each images.
You might find this demo similar
Remember you can always use getBBox when you drop. In this case it's rects but images would be the same..
http://irunmywebsite.com/raphael/additionalhelp.php?q=bearbones