I believe I may have just found the "missing link" for me from the
following post. This will allow me to have a SurfaceView and still
override onDraw, onTouchEvent, etc. I am going to give it a try and
if it works I will post my results on the forum.
You cannot access the onDraw-method of a SurfaceView instance declared
and added to the layout like this:
<SurfaceView
android:layout_width="fill_parent"
android:layout_height="fill_parent" />
The declaration above creates an instance of android.view.SurfaceView
and adds it to your layout. You cannot change the behavior of the
onDraw-method on that instance any more than you can change code/
behaviour in any other already compiled class.
To achieve what you are asking for, you can create your own subclass
of SurfaceView:
public MySurfaceView extends SurfaceView implements Callback {
And then, to add that to your layout instead of the orignal vanilla
SurfaceView, you simply refer to the fully qualified name of your
class as an XML element in your layout:
<myapp.views.MySurfaceView
android:layout_width="fill_parent"
android:layout_height="fill_parent" />
On Jan 4, 7:06 pm, JamesColeman <[email protected]>
wrote:
> Still have not figured this one out. From the post I viewed on this
> forum, it appears that when I extend View and setContentView(new
> MyView(this)), there is a problem getting the size of the screen space
> available for Canvas drawing functions, not including title bars,
> keyboards etc..
>
> So I have been pursuing xlm layout files with a surface view for my
> Canvas Drawing functions and a linear layout for my buttons.
> Unfortunately almost all the Android Graphic samples extend View and
> setContentView(new MyView(this)).
>
> As far as I can tell I want to do something thing like
>
> setContentView(R.layout.main); Where main has a LinearLayout with
> a SurfaceLayout and another LinearLayout for my buttons.
>
> then get my SurfaceView with
>
> SurfaceView DrawingSurfaceView =(SurfaceView)
> findViewById(R.id.DrawingSurfaceView);
>
> And that is where I get lost. When the Android Graphics samples
> create a class to extend View, they override onTouchEvent to get Up,
> Down and Move events, and OnDraw to get the canvas and paint on it.
>
> So once I get my surface view using
>
> SurfaceView SurfaceView =(SurfaceView)
> findViewById(R.id.DrawingSurfaceView);
>
> 1. How do I get the canvas from the SurfaceView so I can draw on it,
> or do I assign a Canvas to the SurfaceView and draw on it?
> 2. Do I need to override OnDraw or can I just use Canvas draw commands
> to draw on the canvas when a onTouchEvent or some other event occurs?
> 2. How do I override the onTouchEvent for just the SurfaceView?
>
> Thanks!
>
> On Dec 30 2011, 6:16 pm, JamesColeman
>
>
>
>
>
>
>
> <[email protected]> wrote:
> > Hello;
>
> > This is my first post here. I am a BlackBerry developer trying to
> > move to Android before my BlackBerry sales totally dry up. I gone
> > through many samples and have read quite a few post about the subject
> > of determining the size of the area I have to perform GraphicsActivity
> > commands, title bar height, etc. I feel even more lost now. I am
> > hoping someone will not mind helping me out to find the proper path to
> > head down.
>
> > I want to be able to display; the systems title bar, my applications
> > title bar, a drawable "canvas" for Android.graphics.Canvas functions,
> > and buttons at the bottom of the screen.
>
> > The GraphicsActivity and Android.graphics.Canvas functions look like
> > the ones I want to use. However, I have run into a few road blocks and
> > concerns.
>
> > 1. The only samples I have found so far that use GraphicsActivity use
> > setContentView(new MyView(this)). I have not found one that uses an
> > XLM layout to deal with different screen sizes and buttons.
>
> > 2. If I use do a custom View using setContentView(new MyView(this)),
> > I have not found a way to get the size of the area I have available
> > for the Graphics Activity/Canvas functions, which is the screen size
> > minus the size of the system title bar and my title bar. I have
> > found several post on" title bar/screen size" and they seem to have
> > gotten into some heated discussions with no resolution. Therefor I
> > have no way of knowing the size of the area for the Canvas functions
> > is. This brings up several concerns.
> > 1. How I can place my buttons at the bottom of the screen if I am
> > using setContentView(new MyView(this)) in liue of the XML layout files
> > or how can I use XML layout files with the GraphicsActivity?
> > 2. How can I scale a bitmap to the size of the view available for
> > the Android.graphics.Canvas functions if I do not know the size of the
> > area it is going in.
>
> > My only other concern at this point is weather or not I can save the
> > resulting Canvas to a picture file like a Jpeg. However, I have not
> > researched this issue yet.
>
> > Can someone point me in the right direction for accomplishing my goals
> > of:
>
> > 1. Display the System title bar, my title bar, a row of buttons
> > at the bottom of the screen and the rest of the space is used for the
> > Android.graphics.Canvas functions. I will need to be able to
> > determine the dimensions of the area used for the
> > Android.graphics.Canvas functions so I can draw objects and scale
> > them. Ultimately I would like to save the final "Canvas" to a Jpeg
> > file.
>
> > Thanks for the assistance!
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