How to add a scrolling canvas using scrollview | Software Health Club

How to add a scrolling canvas using scrollview

To allow a canvas to scroll horizontally and vertically using scrollviews:

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////////////////////////////////////////////////////////////////////////////////////// public class Main extends Activity { // public this_canvas this_canvas; public DrawView draw_view; public ScrollView scroll_view; public HorizontalScrollView h_scroll_view; public LinearLayout lin_layout; public Canvas this_canvas; @Override public void onCreate(Bundle savedInstanceState) { DrawView main_draw_view; super.onCreate(savedInstanceState); requestWindowFeature(Window.FEATURE_NO_TITLE); lin_layout = new LinearLayout(this); scroll_view = new ScrollView(this); h_scroll_view = new HorizontalScrollView(this); scroll_view.setLayoutParams(new LayoutParams(LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT)); h_scroll_view.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT)); lin_layout.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT)); lin_layout.setOrientation(LinearLayout.VERTICAL); Bitmap mBitmap = Bitmap.createBitmap(630, 870, Bitmap.Config.ARGB_8888); this_canvas = new Canvas(mBitmap); main_draw_view = new DrawView(this); main_draw_view.setLayoutParams(new LayoutParams(LayoutParams.MATCH_PARENT, LayoutParams.MATCH_PARENT)); scroll_view.addView(main_draw_view); h_scroll_view.addView(scroll_view); setContentView(h_scroll_view); } ////////////////////////////////////////////////////////////////////////////////////// public class DrawView extends View { Context app_context; public DrawView(Context context) { super(context); app_context = context; DisplayMetrics metrics = new DisplayMetrics(); getWindowManager().getDefaultDisplay().getMetrics(metrics); } // onMeasure must be included otherwise one or both scroll views will be compressed to zero pixels // and the scrollview will then be invisible @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { int width = 2000; int height = 3000 + 50; // Since 3000 is bottom of last Rect to be drawn added and 50 for padding. setMeasuredDimension(width, height); } @Override public void onDraw(Canvas canvas) { this_canvas = canvas; // ToDo: Put drawing code in here } } }