I am currently developing an Android app which allows the user to plot a graph by hand drawing on a canvas. Now I want to make sure that the graph consists of only one path. Is there a way to implement an object that lays on the canvas (for example a mouse or whatever) which can be controlled by the user in order to sketch the graph?
So the user should touch the object and move it. If he wants to extend the path, he just can touch it again and proceed.
Sorry if it's not clear what I want to achieve, the screenshots may help.
Screenshot 1 shows, which type of graphs I want to avoid, while the second screenshot shows how the graphs should look like (don't consider the green circles, they're just indicating turning points)
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I'm trying to make an image more interactive by adding gestures (currently I'm thinking about only zoom, might add later depending on the requirement). It's a parking app by the way.
By interactive I mean that user can tap on a part of an image, let's say it's area A and labelled "A", and then a new interactive image will pop up for that area.
I'm pondering whether I should break down the image part by part in order to detect user's tapping location, or should I take the X, and Y coordinate? And if I should take the coordinate, does that mean I have to alter the code so that it'll cover different screen sizes?
Another question is.. I'm thinking of using Djikstra's algorithm for best route to be taken by user, does the algorithm need the image to be whole?
I'm also planning to add marks for vacant and occupied slots, but it is trivial for whether I should split the image to parts or not, right?
im new to this android things. And i have to develop an application that can help an autism to learn numbers. I have a few ideas and I've been trying to learn and implement the code. But it's failed. The question is how can i apply the motion code or sprite to draw a numbers or letter? For example like this, i wanna make the penguin move through the line and draw a number nine.
There is example from mybringback.com which is the image move to draw a rectangle. How can i implement it to draw a number? Im sorry if i asking too much, i just trying to get some ideas.
I think that you should first build an utility program, in order to create the "path vector".
What I mean by path vector is simply a vector of Points (where a point has x value, and y value). And your utility should let you draw whatever you want, with a simple pen. You should draw on surface and store points when mouse is down, and ignore points when mouse is up.
Then, in the main program, you will just have to read at the path of your number/letter.
I've tried to implement something like this for the Sugar OLPC platform, without serializing path into files : I was able to draw, and to view the animation. And I used the process I've just described you.
Hope it can help you.
P.S : I used the word mouse, but you guessed that I talk about finger ...
There are various ways to achieve animation effects. One approach that is quite versatile involves creating a custom View or SurfaceView in which you Override the onDraw method. Various tutorials can be found on this; the official Android discussion of it is here:
http://developer.android.com/guide/topics/graphics/2d-graphics.html#on-view
Your implementation will look something like this:
// Find elapsed time since previous draw
// Compute new position of drawable/bitmap along figure
// Draw bitmap in appropriate location
// Add line to buffer containing segments of curve drawn so far
// Render all segments in curve buffer
// Take some action to call for the rendering of the next frame (this may be done in another thread)
Obviously a simplification. For a very simplistic tutorial, see here:
http://www.techrepublic.com/blog/software-engineer/bouncing-a-ball-on-androids-canvas/1733/
Note that different implementations of this technique will require different levels of involvement by you; for example, if you use a SurfaceView, you are in charge of calling the onDraw method, whereas subclassing the normal View lets you leave Android in charge of redrawing (at the expense of limiting your ability to draw on a different thread). In this respect, Google remains your friend =]
I'd like to create a custom map. It should be or look like one picture, but according to the part of which the user clicks, it should move the user to a different location (i.e. start a different activity). I've seen it done in several games but I don't know how to do it myself.
The part of the picture should have non-geometrical borders (obviously it would be easily done with many square images). Sadly, I don't even know what term describes what I want to do so I wasn't able to find any helpful tutorials or discussed topics.
Example:
Picture: http://i236.photobucket.com/albums/ff40/iathen/mapEx.png
If the user touches the purple slide, (s)he should be leaded to activity_1
If the user touches the blue slide, (s)he should be leaded to activity_2
If the user touches the green slide, (s)he should be leaded to activity_3
In my experience there are 2 main (most used) ways to achieve this.
The first (my favorite):
Get the data from a PNG
You should write multiple layers to a canvas. These layers constitute your "zones" (blue, green, purple in the image). To obtain the data of these areas, you get it from PNGs (with transparencies off course) to write the canvas with whatever you want. You must store the values where there can be a tap from the user (non-transparent areas). Notice that this values can be scaled up/down depending on the map size, screen resolution, map dimensions, etc.
Once you've written the layers to the canvas you should check for a match of the user tap and the stored areas you have. You should take into consideration here the order in which the user tap is processed in your code. For instance, in your image, the purple layer is on top so it must be processed first, the blue as second, and the green as the last one. This way you can have an "island" inside a bigger area.
The second way:
Generate the boundaries programmaticaly
I think this solution is self-explanatory. The only I've faced with this variant is that when the surfaces boundaries get messy, it's really complicated to generate the proper equations.
EDIT:
Using the first approach you can employ multiple PNGs to load data or use a single PNG with data coded into the bytes (i.e. RGB values). It's up to you to decide which one to implement.
Hope it helps!
Since a touchscreen itself isn't very accurate, your collision detection for the buttons doesn't need to be either. It would be a waste of time to try to make a complicated collision detection algorithm to detect a touch within those weird shapes.
Since you are making a game, I assume you know how to handle custom touch events, as well as canvas (at least). There are many ways to do what you want, but in the specific example image you linked is kind of a special case.
You could create a giant bounding circle around the three blobs, and then check if the user touched within the bounds of the circle (ie check if the distance from the touch to the center of the circle is less than or equal to the radius). Once you determine that it is, you could check which section of the circle it falls into by splitting it up into 3 equal sections. Requires some math, but shouldn't be that complicated.
It wouldn't be a perfect solution, but it should be good enough. Although, you might have to change the buttons a little so they aren't so stretched out horizontally, otherwise a bounding circle wouldn't be ideal.
Personally, in my games I always have "nodes" that represent the visual elements of the game, such as buttons. Instead of using a large image like you are doing, I would create separate images for each button, and then check their collisions with touch events independently. That way I could have each button check with their own individual bounding circles, or, if absolutely necessary, I could even have custom algorithms for each individual button.
These aren't perfect solutions. If you do want a pixel-perfect solution, you'll need to implement some polygon collision detection algorithms
One thing to consider is screen size and ratio. The only constants you should use are for percentages.
I had a question regarding Android programming. I have created an application to take in data via Bluetooth and I would like to use that input as sort of a "game controller" to move an image around a screen. For instance, if the "up" command was given, the image (or even a colored circle) would move a few pixels up.
Can someone point me in the right direction? I thought of using a canvas and redrawing the image every so often but I don't know how to do this and I thought there might be a better/simpler way. I don't need anything fancy.
What i would do. Catch the up command, then have a class lets call it Circle which will hold the current circles position, size etc.
Whenever you catch the up command or left or right or any kind of command, you would redraw the image in that position. I would also use a custom surface view for the drawing and an Activity for catching all the inputs and passing them onto the object.
I would check out
http://www.javacodegeeks.com/2011/07/android-game-development-moving-images.html
and read through the whole series, if you have the time. It is quite a good read.
How Android screens go beyond the simple controls that have Android, look at this for example.
How come so that each key responds independently? Is it a single image, several or a drawing?
How to put each circle in the specific country? What if I want a country to be selected?
You can make your own controls by subclassing a view and overriding it's methods. The onDraw method gives you a canvas where you can place just about anything. Check the official android API or this post to get your started.
For the first image, my guess is that it is one image and the position of each click is translated to the corresponding key on the piano. The second image might also be a single image with separate overlays for each country and circle to set the desired color and place the numbers (that's what I would probably do, but it can be done differently).
If you require more flexibility than fixed images, take a look at creating 2D graphics.