I want to put a Canvas with an image in my window, and then I want to pack widgets on top of it, so the Canvas acts as a background.
Is it possible to have two states for the pack manager: one for one set of widgets and another for another set?
The answer to your specific question is no. You can't have two states or otherwise use pack two different ways in the same parent.
However, what I think you want to accomplish is simple. Use the built-in features of the canvas to create an image item that is part of the canvas, then pack things into the canvas as if it were a frame.
You can accomplish a similar thing by creating a label widget with an image, then pack your other widgets into the label.
One advantage to using a canvas is you can easily tile an image to fill the whole canvas with a repeating background image so as the window grows the image will continue to fill the window (of course you can just use a sufficiently large original image...)
I believe that Bryan's answer is probably the best general solution. However, you may also want to look at the place geometry manager. The place geometry manager lets you specify the exact size and position of the widget... which can get tedious quickly, but will get the job done.
... turned out to be unworkable because I wanted to add labels and more canvases to it, but I can't find any way to make their backgrounds transparent
If it is acceptable to load an additional extension, take a look at Tkzinc. From the web site,
Tkzinc (historically called Zinc) widget is very similar to the Tk Canvas in that they both support structured graphics. Like the Canvas, Tkzinc implements items used to display graphical entities. Those items can be manipulated and bindings can be associated with them to implement interaction behaviors. But unlike the Canvas, Tkzinc can structure the items in a hierarchy, has support for scaling and rotation, clipping can be set for sub-trees of the item hierarchy, supports muti-contour curves. It also provides advanced rendering with the help of OpenGL, such as color gradient, antialiasing, transparencies and a triangles item.
I'm currently using it on a tcl project and am quite pleased with the results. Extensions for tcl, perl, and python are available.
Not without swapping widget trees in and out, which I don't think can be done cleanly with Tk. Other toolkits can do this a little more elegantly.
COM/VB/MFC can do this with an ActiveX control - you can hide/show multiple ActiveX controls in the same region. Any of the containers will let you do this by changing the child around. If you're doing a windows-specific program you may be able to accomplish it this way.
QT will also let you do this in a similar manner.
GTK is slightly harder.
Related
I'm attempting to adapt martineau's excellent answer on how to use tkinter to highlight and select an area of an image with a mouse. My goal is to modify the code to support huge images, such as 10000x6000 pixels or more!
This is my first attempt at using tkinter, and it's much more challenging than expected.
The three options which I've considered and experimented with are:
Load the image, then scale the image to the size available in the window before placing it on the canvas. This in turn requires that I know the scale factor, so I can reverse the scaling when operating on the original image.
Add scrollbars to the side/button on the visible part of the image in the canvas. (My preferred option).
Don't add scrollbars, but use the cursor keys to scroll the visible part of the image in the canvas.
I've tried to do all of them, but ran into various kinds of trouble:
I used root.state('zoomed') to maximize the window, then placed a button to top of the window using tk.Button(...).pack(fill=tk.X) before placing the canvas as in the linked code using self.canvas = tk.Canvas(...). At this time I discovered two issues: It turns out that I can't maximize the canvas to the remaining space in the window using self.canvas.pack(fill=tk.BOTH) (it only expands the width). Another more crucial issue was that I could not read the actual width/height value that the canvas was expanded to, (or get there available space in the window before placing the canvas), and without these values, I can't calculate the scaling factor. :-(
I tried to follow various methods of adding scrollbars to the packed canvas but they all, with one exception, required to use the grid method and I quickly found that pack and grid methods were conflicting methods. After several attempts at rewriting the code to use the grid method, I gave up. The place method seemed promising, except that it will require me to size the canvas manually and then place the scrollbars at calculated offsets to the canvas... and all of this required that I have the same values that were needed to calculate the scaling factor above. :-(
I didn't get very far with this, as it seems I can't get (keyboard?) binds to work at all (On windows with Python 3.10.6). Shouldn't something like self.canvas.bind("<Right>", lambda event: print("Ping")) followed by self.canvas.focus_set() (perhaps with root instead of the canvas) work?
I'm sure I'm overlooking something basic, but after a few evenings looking at this I've gotten nowhere. :-(
I hope some of you can provide help and/or pointers allowing me to get further.
Ohh, for completeness, I'm trying to hack together a small tool that does the following:
On startup requests and load an image file. (Adding a button to perform the load/re-load is nice to have, but not strictly needed. )
Display the image file and allow an area of the image to be selected with the mouse.
Perform some software analysis on the selected part of the image when a button is pressed.
im doing an tkinter app in a computer, im using the grid() method to place the widgets. At first of the program i use this code to make the window size like the screen size:
an = self.root.winfo_screenwidth()
al = self.root.winfo_screenheight()
self.tam = '%dx%d'%(an,al)
self.root.geometry(self.tam)
And it works, but this app will be used through a remote desktop with different devices (different screen sizes).
How can I do that the widgets fill on the window like the original design? Thanks
Without any concrete examples of your code, there's no way to give more specific advice than to say that the solution is to design your program so that it resizes well.
Tkinter excels at making widgets fit, so as long as you use the options at your disposal (fill and expand for pack, row and column weights and other options for grid), and you don't hard-code any widths and heights, your GUI will easily work on a variety of systems.
Concrete pieces of advice:
don't use place except in very rare circumstances. While place supports relative positioning and sizing, it requires more work than pack and grid
design the GUI to work on the smallest display possible, and then make sure that when you manually resize the window it behaves properly
When using grid, make sure you always have at least one row and one column with a non-zero weight so that it knows how to allocate extra space
When using pack make sure you use expand and fill properly
Don't turn off the ability for the user to resize the window
I wanted to know if anyone knew where to start in terms of recreating this sort of functionality?
http://www.learningnuke.com/wp-content/uploads/nukewipepreview.png
In the picture you can drag the centre line to reveal Image A or Image B or parts of each, interactively.
I want to be able to wipe/reveal across two images, maybe it's possible doing some sort of interactive crop of sorts.
Wanting to add this feature to a window in Maya, so maybe with QT, but not essential.
Just some pointers would be great.
I can tell you that this is possible via Qt/PyQt in maya. You can create a dialog that displays QPixmaps with some form of mouse interaction to control their display. I would forget about trying to extend the actual Render View as this would be a pain in the ass.
Just focus on a Qt solution. Unfortunately beyond this, I'm not sure what more I can offer unless you have a specific question about its implementation.
I would probably stack the QPixmaps on top of each other inside of custom QLabel widgets. The QLabel would have a custom mousepress/move event that would resize maybe the right edge to simulate the wipe effect, and reveal the one stacked underneath.
Also, it does resemble the functionality of a QSplitter so that might also work, with an image on each side of the layout and a custom style to the split bar.
I am trying to convert my Python Code to Java. I need a GUI that is similar to python where I can use widgetname.place(x,y) to place objects anywhere I want in the window. I want to be able to specify where the object is placed in the window. I have tried GridLayout, GridBagLayout, BoxLayout and FlowLayout. None of those are allowing me to secify x and y coordinates to place my objects(text fields, labels, buttons) where ever I want. I need to be able to specify where the object goes on the screen using x and y coordinates.
Anyone have any ideas?
This can be done setting your LayoutManager to null, but it's highly discouraged precisely because it annihilates the goal of layouts, which is to be able to have good-looking frames, regardless of the look and feel, screen resolution, etc.
You'd better learn how to use layout managers, because that's the good way to design a GUI.
There's a Swing tutorial that gives a concise example on positioning widgets absolutely.
If you do start using LayoutManagers I recommend using TableLayout because it far easier and more powerful than GridBagLayout.
http://java.sun.com/products/jfc/tsc/articles/tablelayout/
Hopefully your need to do absolute positioning is relatively small because it's not flexible should the user resize the window, and your components need to change their size. If you are trying to build a component that renders to X,Y to draw graphics you can subclass JComponent and override paint().
What's the main difference between the Tkinter geometry managers grid and pack?
What do you use for your projects ?
If grid is better to align object, what the main purpose of pack?
grid is used to lay out widgets in a grid. Another answer says it "overlays a graph" which is a bit of a misnomer. It doesn't overlay anything, it merely arranges widgets along row and column boundaries. It is great for creating tables and other structured types of layouts.
pack lays things out along the sides of a box. It excels at doing layouts where everything is on a single row or in a single column (think rows of buttons in a toolbar or dialog box). It's also useful for very simple layouts such as a navigator on the left and a main work area on the right. It can be used to create very complex layouts but it gets tricky until you fully understand the packing algorithm.
You cannot use both grid and pack with widgets that have a common parent. Your app may work but it is much more likely to get into an infinite loop as each manager tries to layout the widgets, then the other notices the widgets change size and try to adjust, etc. etc.
The third manage is place. Place is great for doing either absolute positioning (ie: place widget at a given x/y) or relative (eg: place a widget on the right edge of some other widget).
While you cannot mix grid and pack within the same container (a container is typically a frame), you can use both grid and pack within a single application. This is very, very common since each has strengths and weaknesses. I use both on a regular basis.