I have this program where it draws a bar graph in a JFrame. The bars of the bar graph change color when I click on them. So my question is whats the best way to approach this? The bruteforce way,i.e. calculate the mouse click and see if it falls within the bars' range, or extends the BufferedImage class and have it implement mouselistener? Because if i were to create a class that extends a jpanel and override its paintcomponent method, it would for sure not run efficiently. And the bars of the bar graph will be animating also, as in values will be fed to the program and the graphs get updated all the time.
I would personally go for the "listen for clicks over the whole component and work out which bar a click falls on". It shouldn't be hard to do - just division to work out which bar, then a bounds check to work out if the particular bar is long enough for that point to be painted.
Introducing "one control per bar" feels like a recipe for trouble in terms of getting layout etc right. I'm sure it can be done - and I'm sure those with more GUI experience have less trouble with layout than I do - but I strongly suspect it would much more work.
Related
My boss has put me in charge of building a production dashboard to track the efficiency of the workers on a production line. He wants a progress bar to fill up in relation to the time and change colors if the worker is running on time or if they're behind, etc. I need to know if you can have multiple colors for one JProgressBar that changes as the bar fills up to show those changes. I'm referring to
Is this even possible? If not, what's my best course of action to go about doing this? I've thought about putting multiple JProgressBars together and doing some calculations to find out which section needs to be which color, unless there's a better way to go about it.
Looking at the link I posted above, you might be able to create multiple progressbars, setting the width of them to something predetermined (length of a task), placing them side-by-side, then setting those colors for each piece individually. Looking around I don't see anything for setting colors to from n to m to a certain value.
Make a progress bar whose foreground colour is "transparent". Put a graphic behind it with all the colours you want. As the progress bar fills up, the transparent part of it will expose the graphic behind it.
Been building up a little game in java, already asked a few questions about the usage of JPanel in it, and used them to paint the graphics and the main part of the screens.
Now i have a little doubt about other components. My intention is to add on the corner a pair of bars to show health and mana of an entity (like in a rpg game), and wondered which was the best approach for it.
Thought about making a new JPnale with a pair of JProgressBar to set the ammount of it, but then i wondered if it would be better to paint it completely and fill a pair of rectangles.
I mean, doing a pair of new JProgressBar() for it, or a pair of g.fillRect() and then paint the ammounts.
I guess that easiest is to set the JProgress, as i can set values and text if i want, maybe, but not sure about it and if it would run smoother without overwhelming it with JComponents.
Also, if want to add buttons would be better the JButton, or paint a rectangle and check for containment of the mouse pointer with an event (I have this approach at some points where there is not KeyBinding). Should i change that?
Thank you beforehand :)
I'm writing an answer because i haven't got enough reputation to comment :(
I think is better if you paint it in your graphics engine. Use Rectangles is of course a better idea than use a new JPanel with JProgressBar.
But i think that it's even better if you use Images to build your own Progress Bar.
You can create them or find them on internet.
For example you can take an Image for the Progress Bar Background, and another Image for the Foreground (the part that will fill the Bar). Then you can set their X and Y position and then just change the Foreground Width in relation with the entity health to fill or empty the Progress Bar.
I have been able to create a grid using an image file (serves as the empty circles), a loop, and GridLayout, but I am well aware that there's more functionality needed (like for dropping the token, though no animation is necessary yet) so I scrapped it and now I'm back to an empty grid. I am stuck and I'm not really sure how I can accomplish this. My code is a mess at the moment so I'm not sure if it'd even make sense for me to post it.
My main problem is how to build a grid, which will then just be filled with a solid color (I'm cancelling using an image file, it seems a little more complicated as far as I'm concerned) with empty circles, that I will be able to fill up with an image file of a token once the player clicks on a button that corresponds to the column he chose (and then reset everything after the game is over). In other words, a rectangle of solid color and with empty circles to be filled up by tokens, but not with solid color, but an image file.
I have been trying to familiarize myself with paint() but I only started learning GUI last week so there are still likely some more things I'll have to learn to probably understand it in a considerable degree.
I am running out of options tantamount to my knowledge of GUI (Swing in particular) and I have been trying to work on this for a week now.
Any hints?
There are multiple possible ways to solve this, but one easy one is to give a JPanel a GridLayout, and then fill it with JLabels with ImageIcons that show empty circles. When the column is selected, the appropriate JLabel is given a new ImageIcon via setIcon that shows a color filled circle.
Also,
Always strive to separate your program logic code from your GUI code, since the better your separation, the easier will be your ability to debug and enhance.
Work on small problems one at a time. Don't move on to the next problem until the current small step is solved.
Work out your logic and ideas on paper first before committing it to code.
Don't "work with paint". If you need to do Swing graphics, you'll want to override a JPanel or JComponent's paintComponent method. The paint method also concerns itself with drawing borders and children, and so overriding it can have nasty and unexpected side effects on these. Also paint is not double buffered by default, and this can lead to bad animation once you start working with animation.
Edit
You state in comment:
Will it be okay to use JButton though? Because that was what i used during my first attempt. I can use setIcon with it too right?
Do you mean use a JButton instead of a JLabel? That would work, and yes you can call setIcon on JButtons, but would make all your rectangles look like buttons. So if that's OK, then do it. Otherwise, you could still use JLabels, and then create a row grid of JButtons to put below or above your game grid, and then have the user press those buttons, and in their ActionListeners have them change the icons of a JLabel in the selected column.
But having said this, I mainly recommend that you use what works best for you. The learning will be in the creating, no matter what you create.
Edit 2
You ask:
do you think it'll be possible/a nice approach to store jlabels in an array and then lay them out in a panel?
Absolutely, either an array of JLabel[] or a List<JLabel> I think is not only possible but in fact essential for this to work well. I think that you're definitely on the right track here.
This program will have an infinite canvas (ie as long as the user scrolls, it becomes bigger) with a tiled background image, and you can drag and drop blocks and draw arrows between blocks. Obviously I won't use a layout manager for placing blocks and lines, since they will be absolutely positioned (any link on this, possibily with a snapping feature?). The problem arises with blocks and lines. Basically I'll have two options:
Using a simple layout for each building block. This is the simplest and clearest approach, but does it scale well when you have hundreds of objects? This may not be uncommon, just imagine a database with 50 tables and dozens of relationships
Drawing everything with primitives (rectangles, bitmaps, etc). This seems too complicated (especially things like text padding and alignment) but may be more scalable if you have a large number of objects. Also there won't be any event handler
Please give me some hints based on your experience. I have never drawn with Java before - well I did something rather basic with PHP and on Android. Here is a simple preview
DISCLAIMER
You are not forced to answer this. I am looking for someone who did something like this before, what's the use of writing I can check an open source project? Do you know how difficult it is to understand someone else's code? I'm talking about implementations details here... Moreover, there is no guarantee that he's right. This project is just for study and will be funny, I don't want to sell it or anything and I don't need your authorization to start it.
Measuring and drawing text isn't such a pain, since java has built in classes for doing that. you may want to take a look at the 2D Text Tutorial for more information. In fact, I did some text drawing computations with a different graphics engine which is much more primitive, and in the end it was rather easy (at least for the single-line drawing, for going multiline see the previous link).
For the infinite canvas problem, that's also something I always wanted to be able to do. A quick search here at stackoverflow gives this which sounds nice, althought I'm not sure I like it. What you can do, is use the way GIMP has a scroll area that can extend as you move - catch the click of the middle mouse button for marking the initial intention to move the viewport. Then, when the mouse is dragged (while the button is clicked) move the viewport of the jscrollpane by the offset between the initial click and the current position. If we moved outside the bounds of the canvas, then you should simply enlarge the canvas.
In case you are still afraid of some of the manual drawing, you can actually have a JPanel as your canvas, with a fixed layout. Then you can override it's paint method for drawing the connectors, while having child components (such as buttongs and text areas) for other interaction (and each component may override it's own paint method in case it wants to have a custom-painted rect).
In my last drawing test in java, I made an application for drawing bezier curves (which are basically curves made of several control points). It was a JPanel with overidden paint method that drew the curve itself, and buttons with custom painting placed on the location of the control points. Clicking on the control point actually was clicking on a button, so it was easy to detect the matching control point (since each button had one control point associated with it). This is bad in terms of efficiency (manual hit detection may be faster) but it was easy in terms of programming.
Anyway, This idea can be extended by having one child JPanel for each class rectangle - this will provide easy click detection and custom painting, while the parent will draw the connectors.
So in short - go for nested JPanels with custom drawing, so that you can also place "on-canvas" widgets (and use real swing widgets such as text labels to do some ready drawing) while also having custom drawing (by overriding the paint method of the panels). Note that the con of this method is that some swing look-and-feel's may interfere with your drawing, so may need to mess a bit with that (as far as I remember, the metal and nimbus look-and-feel's were ok, and they are both cross-platform).
How would I go about writing my own scrollbar using standard Java 2D.
I really don't want to use swing, and I've already made up my own component parts for everything else such as buttons etc.
I'm not really looking for code, rather the math involved in the event changes and the drawing.
Why on earth would you want to write your own java GUI toolkit? You already have the choice of Swing and SWT, can you really do better than these two teams?
If you've already written the rest of the toolkit, I don't understand why the scrollbar would stump you. Without knowing anything about your event system, or how your custom components are structured, it's impossible to give much advise. I don't see this being particularly maths intensive - just maintain the height of the scrollable component, and the view it's in, and the scrollbar size should match the proportion of the component that is visible. The position of the scrollbar should match which part of the component is visible (this will have to be scaled). Specifically, what do you want to know?
Java is now open. I'd go look at the source for the Swing and/or SWT as they are already implemented. The math seems fairly straight forward. You have a Bar and a Container. To simplify we will only discuss length (the dimension in which the scrollbar moves). The container is of a certain length. The bar is of a length that is equal to or less than the container. It is useful to define the center and the two endpoints of the scrollbar. You can have the scrollbar start at 0 at the top and 1 at the bottom or 0 at the top and 100 at the bottom with the important part being defining your scrollbar in the same manner. Then you can check the endpoints for collision with the edge to stop the bar from moving. If the mouse is held down with the cursor over the coordinates inside the bar, the bar starts caring about where the cursor is and will paint the scrollbar and whatever the scrollbar is ultimately supposed to be affecting. So, you would take the page to be affected and map it to 0 and 1 * the scale in pixels of the scrollbar. Then you get to worry about the arrows at either end and how big of a jump each click is and dealing with mousedown events etc.etc. Use what is given don't reinvent the wheel.
While not Java2D, this straightforward code snippet might help:
http://processing.org/learning/topics/scrollbar.html