Android: Drawing on Canvas in Scrollview

Question

I'm pretty much new in programing for Android. My app is sample app from api demos on developer android website. When I change parameters in that sample drawing it gets larger . That drawing needs to be displayed in scroll view (it doesn't need to be shrinked to fit the screen). This is the code I used:

DrawPoints.java

    public class DrawPoints extends myActivity {


    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.routes); 

    }

    public static class SampleView extends View {
        private Paint   mPaint = new Paint();
        private float[] mPts;

       /*here comes declaration of parametars



        private void buildPoints() {

        /*here comes some coding*/

            }
        }

        public SampleView(Context context, AttributeSet attributeset) {
            super(context, attributeSet);

            buildPoints();
        }

        @Override 
        protected void onDraw(Canvas canvas) {
            Paint paint = mPaint;

            //here also comes code
        }
    }
}

here is xml Code:

routes.xml

<?xml version="1.0" encoding="utf-8"?>
    <ScrollView 
            xmlns:android="http://schemas.android.com/apk/res/android"
            android:id="@+id/scrollView1"
            android:layout_width="fill_parent"
            android:layout_height="fill_parent" >
        <HorizontalScrollView 
                android:id="@+id/scrollView2"
                android:layout_width="fill_parent"
                android:layout_height="fill_parent">

                    <!-- This code is just to make sure that scroll views work how 
                        I want them to work, image size is 625*351 px
                     <ImageView
                        android:id="@+id/image_View1"
                        android:layout_width="fill_parent"
                        android:layout_height="fill_parent"
                        android:src="@drawable/bus_design"
                            /> -->
                     <my.package.DrawPoints.SampleView
                        android:layout_width="fill_parent" 
                        android:layout_height="fill_parent" /> 


        </HorizontalScrollView>
    </ScrollView>

When I run that application and push the button in main activity application crashes. Drawing looks like Figure1 when I'm not using xml layout or scrollviews:

http://i.stack.imgur.com/za5MP.png Figure1

I also tried to use this code after method setContentView:

View v = new SampleView(this);
addContentView(v, new ViewGroup.LayoutParams(ViewGroup.LayoutParams.FILL_PARENT,
            ViewGroup.LayoutParams.FILL_PARENT));

and also this one:

View v = new SampleView(this);
    ScrollView.LayoutParams lp = new ScrollView.LayoutParams(1000, 1000);

    addContentView(v, lp);

when I use codes, shown above, app displays Figure1 without scrollview, it seems like second content view overwrites that xml but it doesn't show correctly. After that I tried to use this code after setContentView:

View v = new SampleView(this);
    FrameLayout fl = new FrameLayout(this);
    fl.findViewById(R.id.FrameLayout1);
    fl.addView(v);

Frame layout (FrameLayout1) is added in routes.xml file after horizontal scroll view. When application runs I get blank screen without Figure1. Does Anyone have an idea how to upgrade my code that would display Figure1 in ScrollView?

Thanks in advance!

Answer 1

write this line in your touchevent of custom View class

getParent().requestDisallowInterceptTouchEvent(true)