I want to draw a bitmap to the canvas.
However, I am an inexperienced programmer and don't know how to make the canvas the main screen.
Basically, I want to draw a bitmap to the main activity using a canvas. I know how to draw bitmaps to canvases but it doesn't show up anywhere that I can see (with only one activity). I want the bitmap to show up on the main activity. Any tips?
Sorry if the wording is confusing, thanks for any help.
see these links. might think they may be helpful.
https://www.linux.com/learn/tutorials/707993-how-to-draw-2d-object-in-android-with-a-canvas
http://www.linux.com/learn/tutorials/703911-2d-drawing-with-android-motion-sensors
you can try searching online..
some example
http://www.edu4java.com/en/androidgame/androidgame2.html
or some game engine which will help you to develop game with proper memory management.
https://stackoverflow.com/questions/17163446/what-is-the-best-2d-game-engine-for-android
What you are trying to do is create your own CustomView. When you are putting a button or anything in your layout file that is actually a view. Android does allow you to create your own view to manually handle things on the screen. Games are usually implemented that way. They use customview by extending SurfaceView/GLSurfaceView.
As for the solution of your problem:
create a custom view by extending the View.
add all the constructor from superclass.
override onDraw method
onDraw method will pass you a canvas for you to draw
draw whatever you like(Bitmap, line ,....) using canvas
In your layout file include the customview you just created.
<my.packagename.MyCustomView android:width .... > </my.packagename.MyCustomView>
Hope this helps.
Also you will find lots good resources on how you can create your own customview.
Related
I want to learn, how to create custom view. I have gone through multiple tutorial and didn't get what i want(I mean concept).
What i have learned
I am sharing my concept,if i am wrong please correct me.
If you want to make a minor change to the standard view then inherit itself(e.g extends seekbar) and customize it.
But if you want to make difficult or multifunction view, We should inherit View Class
When we inherit a View.
Two methods are neccessary
onDraw(Canvas canvas) // it call each time it and also can be call using invalidate.
onMeasure // it measure the actual width and size and set our viewit accordingly
Whatever you want to draw on View can be done using canvas;(Am i right).
To define additional attributes create an attrs.xml file in your res/values folder. and add <declare-styleable name="YourCustomView"> and add attributes to it.
get these attribute in the constructor of the View using TypedArray call recyle method.
My Confusions
can we draw something without using Canvas
can we draw ImageView without converting it to bitmap.
I simply want to create a custom imageView which can be rotated like
a dialView but it should rotate half(semi-circle) and also want to
draw its progress outside it. using canvas.drawArc()
What i want to achieve
I want to create my own custom knob, I have searched our google but didn't find what i want see my questions here
First Question
Second Question
Thanks in Advance....
1)You can use openGL. Otherwise you need a canvas. The canvas defines where you're drawing to, without it (or the openGL equivalent) we don't know where to draw. You might not want to draw directly to the screen, its common to draw to bitmaps in many cases.
2)Your question doesn't make a lot of sense. Why would you want to draw an ImageView, other than by letting it draw itself?
3)Easiest way to do that is to use a normal image view and call setRotation to rotate it as needed.
I have created a custom view to be shown in the action bar. It mostly works except sometimes on start I see a mirror copy of whatever I draw. The copy overlaps the original one but a few pixels away.
My onDraw() override is quite simple. All it does is draws an image that is centered in the canvas.
I am a bit confused. Am I expected to clear the canvas first in onDraw() method? Thank you in advance for your help.
It is confusing, but you'll notice in the custom view samples (that come with the sdk), the onDraw() method first calls canvas.drawColor() before anything else.
I assume it's not done automatically because it would be wasteful in the case where what you were drawing filled the entire view anyway. I just wish it was more clear that it is necessary in most cases.
Here is what I found out that others may find useful. If you set a background using setBackground(), the framework will actually draw the background before calling onDraw(). This background is drawn in the center. I too was drawing the background in onDraw() but I was drawing it from top-left. Hence, I was seeing the ghost image.
As Krylez mentioned, you may wish to call drawColor() as your first call in onDraw().
What I did was overrode setBackground() and its variations, and stored the background bitmap in a local variable.
Regards,
Peter
I am trying to implement this game, and I am confused about how to start.
Should I use ImageButtons and implement this game, or should Icreate some custom view?
I am not asking you the code, but what custom view I should create. Basically, I need a plan as to how to implement this game.
It looks like line drawing.
So extend View, implement onDraw method, and there draw lines to Canvas.
If there're other parts to draw, you may possibly use Bitmap to draw these onto the Canvas.
In Android 2.2, I want to display a few sprites and clickable animations over an existing view. I just discovered that SurfaceView cannot be transparent
I tried overriding dispatchDraw() of a LinearLayout but that doesn't seem to be callable via a Runnable Thread.
I also tried to extend Canvas directly, but that quickly turned into a mess when trying to place it in my XML layout.
Do I have to use GLSurfaceView to have a drawing view whose background is transparent?
Optimally, I'd like to just have a Canvas on which I can draw Bitmap at various coordinates, instead of dealing with the details of GL (unless GL is the only way I can do transparency).
Silly Rabbit. Just use Views and move them around wherever you want within a FrameLayout. SurfaceView is not designed for what you're trying to do.
I'm going to try Switching from Canvas to OpenGL and toss in parts of TranslucentGLSurfaceView.
I'm still open to selecting an answer that doesn't require OpenGL, just for the sake of it solving my original question.
I'd like to include a simple draw feature on my app. A friend told me I can't use canvas because I need to control the frame buffer and not redraw the entire screen every for every frame. He suggested I find a openGL 2d engine. I've searched around and I've only found Rokon which doesn't have any documentation and the examples aren't quite what I need.
Any suggestions?
I don't really understand what the problem is?
If you simply wish to redraw some portion of the canvas you can use invalidate(rect).
http://developer.android.com/reference/android/view/View.html#invalidate()
Just create a custom veiw by extending the view class. in this custome view override the onDraw method. Android itself takes care of the pixels that have been changed and calling invalidate only refreshes the pixels that have been marked dirty