I'm converting a project that I wrote in AIR a long time ago to native Android. In AIR, positioning views was fairly easy in x,y coordinate systems. With native Android though, I am trying to approach this in a correct way, but I'm unsure how to approach.
My view will consist of two circles in the background, with small objects within those circles that can roll around. There will be another view drawn on top of the circles to make it seem like there is glass over the circle, entrapping the small objects. The small objects are bound to the background circles.
I guess what I'm really asking is canvas drawing the best approach here, or is a view-based layout workable as well?
It sounds like your best option would be to use a SurfaceView. This is basically a hardware accelerated canvas. On of the benefits is that you can overlay standard widgets over top of it if you need to so you can mix and match custom and standard components. Here is a link to a website that walks you through getting a SurfaceView up and running
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Im looking for Android 2D framework which allows me to create canvas layer on which I can draw simple shapes like rect, oval atc (raster graphics). The canvas have to PERSIST everything I draw on it.
I found many engines (libgdx, andengine ...) but if they have capability to draw shapes, its only for one screen update. Reason becouse I dont store drawn shapes to some kind of List is becouse in app, the drawing occurs every screen update so I just want to modify canvas and dont remember anything.
Thanks for every answer.
As far as I know, android doesn't support something like that. Android uses double-buffering which means 2 alternatives "screens" that alternate each other so if you draw on one the next would be on random state.
There are tricks you can use to achieve what you want like draw both screens and then stop drawing, but android doesn't support such behavior because when you get hold of a canvas it's not certain that it returned exactly as what you did last frame, it doesn't specify what could cause an error, but if you ask me it could be anything that pops up on screen.
You don't really need an engine to do that, you can use a SurfaceView and draw on it (it supports shapes like the ones you want)
I'm making a board for Android. I use .png images for the board (background) and checker pieces. Basically, it's a game where the graphics are updated upon touch events. It's a school-assignment so I have to use View implementations. For the graphics I've considered two options:
Making a whole "BoardView" class (that extends View) and draw all the graphic components directly on the canvas using onDraw(canvas).
Using ImageView objects to represent each checker piece and the board and putting them on a Layout.
My intuition tells me to use the first method. But my thoughts are that I want to use the pre-implemented TranslateAnimation when a checker is moved. From my understandings; this forces me to use the second method, since I can't animate a Drawable.
Now, to the question: what method is best for me? And if the second; which Layout is preferred to use? I want to be able to overlap the checkers over the board image and compare the ImageView objects' positions to each other to determine where to put the checkers on the board.
Regarding to your simple requirement, I think you can adopt method 2.
Trust me, I have done this kind of stuff years ago, on a legacy linux platform. For these kind of simple game applications, you really do not need to bother with all the frame drawing stuff. Just stick with the existing UI widgets.
This is because the visible elements are all very simple, like cards, static images, blocks etc. You don't need to perform pixel drawing. I have tried to make tetris, mine sweep, and card match games. I even create simple visual effects for it using existing animation facility. That is very easy to do so.
And, of cause, as a software programmer, to write a game using the typical frame by frame approach is much more professional. But it depends on the requirements. Why not using less code to create more value?
I m working on canvas. Here I just want to draw some geometric figures on canvas which may be resized according to the touch_move positions. By figures , I just meant triangle,rectangle,circle and some polygons. Is there a way to achieve this? . I haven't seen such apps which can draw these figures over canvas. So this seems to be complicated.. Thanks in advance
See this link.
If your application does not require a significant amount of processing or frame-rate speed (perhaps for a chess game, a snake game, or another slowly-animated application), then you should consider creating a custom View component and drawing with a Canvas in View.onDraw(). The most convenient aspect of doing so is that the Android framework will provide you with a pre-defined Canvas to which you will place your drawing calls.
I'm sure you can find some open-sourced out-of-the-box solutions for this if you tried a little.
If you actually want to learn something you should read the tutorials of per example;
-Custom Views
-OpenGL
After doing the tutorials, you'll have 2 ways to draw basic shapes, a triangle and a circle I believe, already done.
I'm currently attempting to make a simple 2D CAD-type viewer app for Android. Basically the input file contains a bunch of primitives (rectangles, lines, circles, octagons, that type of thing), and the goal is to draw these to the screen at whatever coordinates/sizes they offer.
My initial instinct is to use a Canvas to draw these to, using a quadtree or some similar structure to track which items will show up on the screen at any given time.
Does anyone have any recommendations here for a better way to implement this (my graphics programming experience is minimal, and hence I'm having problems even finding a starting point to Google from)?
Thanks in advance,
-Ross
That's a very broad question so my answer will only point at classes that you should be looking at.
Extend a surfaceView to be your cadView, that way you'll be all the calculation outside the main thread.
you'll still have to draw on the canvas.
from the canvas you can getWidth() and getHeight() and use those values for base comparison on your positions.
Canvas have some primitives drawings types like arc, circle, point.
Further you can use Path to draw full figures, line, filling, quadratic, etc.
for backgrounds you can create color drawables and draw it on the canvas.
and that's pretty much it.
Say I'd like to make a memory/pairs game. I have currently made a draft that works on a Canvas, and cards are drawn into a grid.
This works for my current basic version, but I'd like show do an animation (when the card is turned, it will flip around and scale to higher size; or when the match is found, the cards would rotate around and then go back.
I can't imagine doing this on Canvas, I'd have to make a lot of timers and do the animation by hand, it seems overly complex for this simple task.
I think I could could subclass View for a control that would display a card, and then react to touch events for that control. It would also make drawing scaling of the images done by Android itself, and, most importantly, I could use Tween Animation for some effects.
My question is - would it be OK to use a View for each card in the game (I could have 5x6 or 4x5 cards), and arrange them in a GridView? Are there some pitfalls with this approach? Or should I continue with completely custom-drawn Canvas?
For such a simple game you should be fine using a collection of Views. As you mention using Views rather than trying to do it manually you get access to a lot of nice Animation functionality for free.
It also makes implement the user interface a lot simpler as you can just add onClickListeners to each view to capture user touches. If you're drawing it all manually to a Canvas then you'd have to interpret the touches yourself and decide which card was touched etc. While this isn't too hard, then I think subclassing View is a better model and will most likely result in cleaner code.
As you are only going to have 30 cards, then I can't imagine you having performance issues either - if you were thinking 100+, then maybe you'd have an issue, but I think you're fine. Also, if I understand your game correctly, the majority of your cards won't be animating most of the time so that's yet another reason not to worry - if you ever run into performance issues with the animations you can easily save off all the unanimated Views onto a Bitmap (Canvas) for the duration of the animation.