Android how to programmatically create scrollview

问题:

Alright I'm trying to build an activity that has a horizontal scrollview, that the user can swipe through, to view different "pages". My train of thought is these "pages" will be views. The following is a mockup of my idea (to mess around to see if it works)

I've experimented with this as follows:

My content view is set to the the scrollview. (unsure if this is an incorrect approach)

I create the scrollview, and place a view into it as follows:

private void setupScrollView()
{
    Display display = getWindowManager().getDefaultDisplay();
    DisplayMetrics outMetrics = new DisplayMetrics ();
    display.getMetrics(outMetrics);

    float density  = getResources().getDisplayMetrics().density;
    float dpHeight = outMetrics.heightPixels / density;
    float dpWidth  = outMetrics.widthPixels / density;

    int width = (int)MeasureUtils.convertDpToPixel(dpWidth, getApplicationContext());
    int height = (int)MeasureUtils.convertDpToPixel(dpHeight, getApplicationContext());

    _scrollView = new HorizontalScrollView(getApplicationContext());
    _scrollView.setBackgroundColor(Color.CYAN);
    _scrollView.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));

     Log.i("DEBUG", "Screen dp width = " + dpWidth + " screen dp height = " + dpHeight);

    TextView view = new TextView(getApplicationContext());
    view.setBackgroundColor(Color.RED);
    view.setText("TEST");

    view.setX(0); // Start at the left of the scrollview.

    view.setWidth(width); // Size it so that it fills to the right of the scrollview.

    TextView view2 = new TextView(getApplicationContext());
    view2.setBackgroundColor(Color.GREEN);
    view2.setText("TEST2");

    view2.setX(width); // Start the second "page/view" offscreen to the right where i can scroll to it

    view.setWidth(width); // Fill the screen width

    LinearLayout layout = new LinearLayout(getApplicationContext());
    layout.setBackgroundColor(Color.MAGENTA);

    layout.addView(view);

    layout.addView(view2);

    _scrollView.addView(layout);
}

The idea above is that I will see a view, that takes up the screen, representing a page. This view should be "RED" in color. I can then scroll horizontally to the right and see the second view (view2) representing the next page. This view should be "GREEN" in color. This does not happen. I end up seeing what looks like 1/3rd or 1/2 of my screen being view1, the linearlayout taking up almost the whole screen (a bit of a gap to the right edge where the CYAN from the scrollview bleeds through).

Am I approaching this the wrong way, and/or is it possible to make this work the way I'm going at it?

回答1:

You probably do not want to use a horizontalscroll view to create "pages". Try looking at PageViewer

This automatically builds in all the sywpe and inflating logic for you.

Basically you will get a call to inflate a certain page. There you can then create your view (dynamically if you wish) and then just return the root to be rendered.

回答2:

Alright I've figured out what I was doing wrong, and it turned out to be something very small...

The complete code is here:

    private void setupScrollView()
{
    Display display = getWindowManager().getDefaultDisplay();
    DisplayMetrics outMetrics = new DisplayMetrics ();
    display.getMetrics(outMetrics);

    float density  = getResources().getDisplayMetrics().density;
    float dpHeight = outMetrics.heightPixels / density;
    float dpWidth  = outMetrics.widthPixels / density;

    int width = (int)MeasureUtils.convertDpToPixel(dpWidth, getApplicationContext());
    int height = (int)MeasureUtils.convertDpToPixel(dpHeight, getApplicationContext());

    _scrollView = new HorizontalScrollView(getApplicationContext());
    _scrollView.setBackgroundColor(Color.CYAN);
    _scrollView.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT));

    Log.i("DEBUG", "Screen dp width = " + dpWidth + " screen dp height = " + dpHeight);

    TextView view = new TextView(getApplicationContext());
    view.setBackgroundColor(Color.RED);
    view.setText("TEST");

    view.setX(0);

    view.setWidth(width);
    view.setHeight(height - 50);

    TextView view2 = new TextView(getApplicationContext());
    view2.setBackgroundColor(Color.GREEN);
    view2.setText("TEST2");

    view2.setX(0);

    view2.setWidth(width);
    view2.setHeight(height - 50);

    LinearLayout layout = new LinearLayout(getApplicationContext());
    layout.setBackgroundColor(Color.MAGENTA);

    layout.addView(view);

    layout.addView(view2);

    _scrollView.addView(layout);


}

This creates a horizontal scrollview programmatically, as I had, but the problem was that I was setting the second view to be "width" away, when it should be set to "0"as can be seen by:

view2.setX(0);

With that, I get 2 "views" that resemble pages in my scrollview that I can swipe through. Each taking up the whole page.

Hate having the code close and it being a simple fix that I missed :|

Hope this helps anyone else that tries to do it this way. I'm going to look into the PageViewer as Frank suggested.