How to draw a triangle shape and add it to a relative or linear android layout

Question

I am developing a small Android application in which I use my own linear layout class. In this class, I tried to draw one small triangle and tried to include it in my linear layout, but I could not do it. I tried this in the following ways ...

@SuppressLint("DrawAllocation") public class SimpleLin extends LinearLayout { public String TAG = "CustomviewActivity"; LinearLayout parentLayout; public SimpleLin(Context context) { super(context); LayoutInflater inflater = (LayoutInflater)context.getSystemService(Context.LAYOUT_INFLATER_SERVICE); if(inflater != null){ view = inflater.inflate(R.layout.main2, this);d.lin_llt); parentLayout.setBackgroundResource(R.drawable.bcd); } } public SimpleLin(Context context, AttributeSet attrs) { super( context, attrs ); context1= context; } protected void onDraw(Canvas canvas) { super.onDraw(canvas); Log.i("############################", "inside ondraw"); Paint p = new Paint(); p.setStyle(Style.FILL); p.setColor(Color.RED); Point point = new Point(); point.x = 80; point.y = 80; Path path = getEquilateralTriangle(point, 70, Direction.SOUTH); Bitmap b = Bitmap.createBitmap(500, 500, Bitmap.Config.ARGB_8888); canvas.drawPath(path, p); } public static Path getEquilateralTriangle(Point p1, int width, Direction direction) { Point p2 = null, p3 = null; if (direction == Direction.NORTH) { p2 = new Point(p1.x + width, p1.y); p3 = new Point(p1.x + (width / 2), p1.y - width); } else if (direction == Direction.SOUTH) { p2 = new Point(p1.x + width,p1.y); p3 = new Point(p1.x + (width / 2), p1.y + width); } else if (direction == Direction.EAST) { p2 = new Point(p1.x, p1.y + width); p3 = new Point(p1.x - width, p1.y + (width / 2)); } else if (direction == Direction.WEST) { p2 = new Point(p1.x, p1.y + width); p3 = new Point(p1.x + width, p1.y + (width / 2)); } Path path = new Path(); path.moveTo(p1.x, p1.y); path.lineTo(p2.x, p2.y); path.lineTo(p3.x, p3.y); return path; } public enum Direction { NORTH, SOUTH, EAST, WEST; } @SuppressWarnings("deprecation") public void initialiseImages() { invalidate(); } } 

I call the initialiseImages method from my activity, where I wanted to use this custom layout. So the problem is that it does not call my draw method when using invalidate (). That's why he does not draw my triangle. and I am also confused how to include this triangle in my parentlayout .. There are errors in my code. How to draw such shapes in android ... Need help ... Thanks ...

Answer 1

Custom linear layout code (I changed the code to make it easier for you to understand)

 import android.content.Context; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.graphics.Paint.Style; import android.graphics.Path; import android.graphics.Point; import android.util.AttributeSet; import android.util.Log; import android.widget.LinearLayout; /** * @author Atrix1987 * */ public class CustomView extends LinearLayout { /** * @param context */ public CustomView(Context context) { super(context); commonConstructor(context); } /** * @param context * @param attrs */ public CustomView(Context context, AttributeSet attrs) { super(context, attrs); commonConstructor(context); } /** * */ Paint trianglePaint; /** * */ Path trianglePath; /** * @param context */ private void commonConstructor(Context context) { trianglePaint = new Paint(); trianglePaint.setStyle(Style.FILL); trianglePaint.setColor(Color.RED); Point point = new Point(); point.x = 80; point.y = 80; trianglePath = getEquilateralTriangle(point, 70, Direction.SOUTH); } @Override protected void onDraw(Canvas canvas) { Log.i("Sample", "inside ondraw"); //avoid creating objects in onDraw canvas.drawPath(trianglePath, trianglePaint); } private Path getEquilateralTriangle(Point p1, int width, Direction direction) { Log.i("Sample", "inside getEqui"); Point p2 = null, p3 = null; if (direction == Direction.NORTH) { p2 = new Point(p1.x + width, p1.y); p3 = new Point(p1.x + (width / 2), p1.y - width); } else if (direction == Direction.SOUTH) { p2 = new Point(p1.x + width, p1.y); p3 = new Point(p1.x + (width / 2), p1.y + width); } else if (direction == Direction.EAST) { p2 = new Point(p1.x, p1.y + width); p3 = new Point(p1.x - width, p1.y + (width / 2)); } else if (direction == Direction.WEST) { p2 = new Point(p1.x, p1.y + width); p3 = new Point(p1.x + width, p1.y + (width / 2)); } Path path = new Path(); path.moveTo(p1.x, p1.y); path.lineTo(p2.x, p2.y); path.lineTo(p3.x, p3.y); return path; } public enum Direction { NORTH, SOUTH, EAST, WEST; } } 

Code for action (for simplicity and as a shortcut I did this, you can also specify it in xml and just setContentView):

 import android.app.Activity; import android.graphics.Color; import android.os.Bundle; import android.widget.LinearLayout; import android.widget.LinearLayout.LayoutParams; /** * @author Atrix1987 * */ public class SampleActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); CustomView cv = new CustomView(getApplicationContext()); cv.setBackgroundColor(Color.WHITE); setContentView(cv, new LinearLayout.LayoutParams(LayoutParams.FILL_PARENT, LayoutParams.FILL_PARENT)); } } 

Check out the developer site for custom submission links to learn more.

Hope this helps.

PFB screenshot

Answer 2

If you want to use drawable, you can use http://looksok.wordpress.com/2013/08/24/android-triangle-arrow-defined-as-an-xml-shape/ , unfortunately I can not claim credit