I want to display a simple GIF image in a VBox using GTK+ from C. I know that I need to use a GdkPixbuf. But as usual there are no example of doing it. Can anyone provide help?
Also: In GTK+ how can we add a PNG image as background to a widget? Can anyone provide an example?
Forgot something to add this:
forgot to tell u that i am using Glade to develop GUI...
And i have created vBox in Glade and in one of the blocks of the vBox i need to display FIG Image....
Sorry of this...
gdk_pixbuf_new_from_file() -- but see unwind's answer for a better way to do it using a GtkImage widget.
You need to set the background pixmap field in the widget's style structure:
GtkRcStyle *newstyle = gtk_widget_get_modifier_style(widget);
newstyle->bg_pixmap_name[GTK_STATE_NORMAL] = g_strdup(pngfilename);
gtk_widget_modify_style(widget, newstyle);
PS. You can often find code examples by doing a Google search for the function you need an example of. The GTK docs usually don't contain examples for every single function, because that would clutter them up, and the documentation of functions like gdk_pixbuf_new_from_file() is usually pretty straightforward. I've noticed you often post this kind of question and I'm wondering if you are looking for the documentation in the right place. For example, are you using the excellent reference tool DevHelp? On the other hand, the GTK documentation is really missing some important information in a few places. If you have some improvements, why not contribute to the documentation?
A vbox in GTK+ is a widget, that displays other widgets as its children, stacking them vertically.
Unsurprisingly, there is a GTK+ widget dedicated to displaying images; it's called GtkImage. You should use the gtk_image_new_from_file() call to create one, passing it your GIF filename, and then just add that to your vbox. There's no need to create the underlying GDK image yourself.
Related
I have an SVG asset of a map, in which I have to change the color of some cities depending on the results of a network call. On the web, one normally would add a class to each path, give it some CSS, and toggle that class using JavaScript.
How can I achieve the same effect in flutter?
This can be done with the new version of jovial_svg. It supports embedded stylesheets, so you can use CSS exactly as suggested. Of course, you'd need to re-parse the SVG whenever there's a change, but that's not a big deal here.
Alternately, if it's just one set of cities, you could use SVG's currentColor, and set that value in the appropriate ScalableImage factory. But for your use case, CSS seems like the better way to go.
NOTE: At this exact moment, CSS support is in pre-release, but it should be formally released as 1.1.4 within a couple of days. In the meantime, see https://pub.dev/packages/jovial_svg/versions/1.1.4-rc.3
I have learned that in iOS 5, properties that are marked with UI_APPEARANCE_SELECTOR can be styled using appearance. Eg [[UINavigationBar appearance] setTintColor:....]. However, I seem not to be able to style all elements. UIButton, for instance, has no properties marked UI_APPEARANCE_SELECTOR, hence I am not able to use the above technique to style it.
My question is: How do I best style elements globally (all appearances in the application), when I cannot use appearance?
Right now I have defined some colors, fonts, shadow offsets etc. that I use many different places in my code. This allows me to change the look and behaviour of a lot of elements, but it still doesn't allow me to style all instances of a certain object with only one line of code.
Edit
In lack of better solutions I have created a number of categories with simple methods as the following:
+ (UIButton *)customLabelWithFrame:(CGRect)frame andText:(NSString *)text;
Also I have found that - in combination with the described categories - stretchable images are nice and useful.
With the above I am able to style in a global-ish manner, however I am not satisfied with the result and I still hope to find a better solution
What about standard subclassing or factory classes, as you mentioned yourself!?
For buttons I'm using factory classes myself.
I think a really nice solution could be the Android way of designing interfaces. Android relies on XML files to define the user interface. As a matter of fact, I'm working on a library that aims to give the projects I'm working on much the same capabilities. It's still a work in progress / experiment and as such really messy code (you have been warned!), but it might give you some ideas.
An example project can be downloaded here: http://dl.dropbox.com/u/6487838/WSLayoutManager.zip
Experiment a bit with the XML files by adding controls. Create custom control classes and instantiate them from the XML file, etc... It's fun stuff :)
I'm developing an application with Gtk and Glade. My impression is that it's common practice to create a subclass of GtkWindow for your main window, but I'm stuck on how I would construct my subclass from a GtkBuilder definition. Does anyone know how?
Subclassing GtkWindow is more common in GTK's various language bindings than it is in plain C. You didn't mention which language you were using.
That said, the way I subclass GtkWindow in C is to create the contents of the window in Glade, but not the window itself. In Glade 3 (IIRC) you can right-click on a widget in the palette and choose "Add widget as toplevel" to place a non-toplevel widget without a container.
Then write code for your subclass of GtkWindow, let's call it MyAppWindow. I won't go into that in this answer since there are plenty of examples in the GObject documentation. In the init function (my_app_window_init()) load the Glade file, use gtk_builder_get_object() to get a pointer to the outermost widget in the Glade file, and use gtk_container_add() to add it to the window you are constructing. Then use gtk_builder_connect_signals() as you normally would.
You have to set all the window's properties manually this way, since you can't do it in Glade, but other than that I've found it works quite well.
it is not common practice to subclass GtkWindow.
i don't think it is possible to subclass toplevel window created from gtkbuilder definition.
gtkbuilder needs to know about your subclassed widget before creation.
If you really want to create your own subclass of GtkWindow ptomato describes the basic steps well. It is also possible to create plugins for glade to make your custom widgets available. But this is not very easy, and most likely not what you want to do.
Most applications only use standard widgets without subclassing any of them. Then loading a glade file with gtkbuilder (or libglade) you don't need to have a special class for your GUI (like in some other RAD tools) instead you just get a set of objects. The API lets you look them up by name (and the window is basically just one of them). A common approach is to look up all widgets you are going to interact with and store them in global variables when the program starts up. Or if you need several instances of the window you can create a struct to store them in. Or you can simple lookup the widgets each time you need them. Note that the set of objects you get is completely dynamic. You can for example move the widgets between different windows just as if you created the GUI programmatically.
I have a JFace TableViewer with an SWT Table, and I would like to custom render the content of some cells. I would like to use an SWT Control to render the cell content.
I would prefer to have only one instance of the Control doing the rendering, but if I have to instantiate one for each row, that would be acceptable.
Next, the solution MUST be compatible with the ContentProvider/LabelProvider approach (I am using EMF). This means that I cannot use the solution described in Sniplet 126 (http://dev.eclipse.org/viewcvs/index.cgi/org.eclipse.swt.snippets).
Next, I though about using custom drawing. But here the catch is, that I have to send individual drawing operations to the graphics context. I was trying to have the Control render the content for me by calling redraw() or print(GC) upon SWT.PaintItem, but that just lead to uncontrollable flickering.
At this point, my best guess is to use SWT.PaintItem to do the drawing. This will result in duplicate code, as I already have a Control that can render the content the way I'd like it. I'd like to prevent this redundancy.
Any help is appreciated!
Well, after banging my head against a wall several times I made some progress. Specifically, I found this formu entry:
http://www.eclipsezone.com/eclipse/forums/t115489.html
It actually offers two solutions: The first solution actually uses widgets (not recommended due to performance, but I knew that before). I will try this out, and may post here how it goes.
The second solution suggests using StyledCellLabelProvider. I looked into this before, but it isn't powerful enough for my purposes. At least that's what I think right now.
I am trying to create GTK Widget like shows in following Images
Is it possible to create it in GTK+ under C,
I tried using GtkExpander but it is not working out ...
Can any one Help....
Stripping the arrow is quite trivial. Just append the following code to you $HOME/.gtkrc-2.0 (or create it if not found):
style "pradeep" {
GtkExpander::expander-size = 0
GtkExpander::expander-spacing = 0
}
widget "*.GtkExpander" style "pradeep"
This is done by customizing the appearance using resource files. You can get the same result programmatically by changing the GtkExpander style properties.
Furthermore, you can connect your own callback to its "activate" signal and switch the background color of the widget whenever is active or not. And a lot more...
Just remember someone loves to have a consistent user interface.
If what you want is to duplicate the look, then there are two very inefficient solutions to the problem:
Write your own GTK theme engine (see Murrine or Clearlooks).
Replace your entire program by a GtkDrawingArea widget and use Cairo to draw exactly the look you want. You'll be on your own then, though, so you'll have to write all your widget placement algorithms, buttons, expanders, menus, and whatnot, from scratch.
GTK isn't really meant for this sort of thing. The whole point of GTK is that you design your user interface with the standard widgets, and they just work with whatever theme, language, or accessibility technologies your users need to use. If you design your own look and there's no way to change it, then someone with color blindness or poor eyesight won't be able to use it. Or the text will get all misaligned if someone uses your application in another language. Or at the very least, maybe someone just likes a black desktop with white lettering, and your application will stick out and look really ugly on that user's computer. If you really need to make it look exactly that way, then probably GTK isn't the right tool for you.