Android - First Step IV

Tips

Best Image configuration

The best quality for image is Bitmap.Config.ARGB_8888

Create a message in the view

Toast.makeText(getApplicationContext(), path.toString(),
                Toast.LENGTH_LONG).show(); 

Permission to storage files

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/> 

Get external directories

        File path = Environment
                .getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES); 

Count the time

        SystemClock.uptimeMillis()

Make a pause

        postInvalidateDelayed(time_ms);

 Resources for all screen devices

Create a folder inside res folder and then a folder called  drawable-nodpi.  All the resources inside this folder will used without consider the device resolution screen.

Redraw the View

The method postInvalidateDelayed(int ms) notifies the system from a non-UIThread and the View gets redrawn in the next eventloop on the UIThread as soon as possible.

postInvalidateDelayed(40);

Views

How create an ImageView 

        Bitmap bitmap = Bitmap.createBitmap(8, 8, Bitmap.Config.ARGB_8888);
        Canvas c = new Canvas(bitmap);
        c.drawColor(0xff808080);
       
        Paint paint = new Paint();
        paint.setColor(0x800000ff);
        c.drawLine(0, 0, 3, 3, paint);
       
        ImageView v = new ImageView(this);
        v.setImageBitmap(bitmap);
        setContentView(v);

How create a View

Every time the view is draw always call the method OnDraw().

     //Same code as above

 View v = new View(this){
            @Override
            protected void onDraw(Canvas canvas) {
              
                canvas.drawColor(0xff808080);
                canvas.drawBitmap(bitmap, 10, 10, null);
                canvas.scale(arg0, arg1)
                super.onDraw(canvas);
            }
          
        };

How enable the menu option

Override the method onOptionsItemSelected and use the following code inside the if sentence.

@Override

public boolean onOptionsItemSelected(MenuItem item) {

// TODO Auto-generated method stub

int id = item.getItemId();

        if(id == R.id.action_settings) {

            Intent i = new Intent(this,MenuActivity.class);

            startActivity(i);

            return true;

        }

return super.onOptionsItemSelected(item);

}