Android: Activity, View, onDraw, Canvas

Drawing on canvas overriding onDraw() method
Assuming using RelativeLayout in xml and with id "layout1"


public class SecondActivity extends Activity {

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
        //setContentView(new MyView(this));
        RelativeLayout layout = (RelativeLayout)(this.findViewById(R.id.layout1));
        layout.addView(new MyView(this));
    }
 
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_second, menu);
        return true;
    }
    class MyView extends View{
   public MyView(Context context) {
super(context);
// TODO Auto-generated constructor stub
}
// if required to add this custom view using xml or the graphical layout in eclipse. have to add this constructor
         public MyView(Context context, AttributeSet attrs) {
super(context, attrs);
// TODO Auto-generated constructor stub
}

protected void onDraw(Canvas canvas){
    System.out.println("draw canvas");
    Paint paint = new Paint();
    paint.setColor(0xFFFF0000);
    Rect rect = new Rect();
    rect.set(100, 100, 200, 150);
    canvas.drawRect(rect, paint);
   }
    }
}




C#: Console

To capture key press, print at specific position of console window

class Program
    {
        static void Main(string[] args)
        {
            int i = 0;
            bool running = true;
            int pos = 0;
            int lengthOfLine = 1;
            int diff = 0;
            while (running)
            {
                //Console.Clear();
                if (Console.CursorTop - pos > diff)
                {
                    pos = Console.CursorTop;
                }
                else
                {
                    Console.CursorTop = pos;
                }
                Console.WriteLine("i = " + (i++));
                diff = Console.CursorTop - pos;
             
                if (Console.KeyAvailable)
                {
                    ConsoleKeyInfo key = Console.ReadKey(true);
                    if (key.Key == ConsoleKey.I)
                    {
                        Console.WriteLine("I pressed");
                        //running = false;
                    }
                    else if (key.Key == ConsoleKey.X)
                    {
                        Console.WriteLine("Exit");
                        running = false;
                    }
                }
                Thread.Sleep(40);
            }

        }
    }

android: loading and displaying images on canvas

copy and paste image into res\drawable folder in project folder

R.java in "gen" should include this image with an id. Note: filename to be all lower-case

// loading, assuming written in a View class

Bitmap bmp = BitmapFactory.decodeResource(this.getResources(), R.drawable.image_id); 

// displaying
canvas.drawBitmap(bmp, 50, 30, null);

Android: 2d drawing surface

To create a canvas for custom drawing, eg,: for 2d games without using opengl
Create a new class extending SurfaceView, add constructor with 2 arguments (so that it can be used in graphical editor in eclipse too), implement interface SurfaceHolder.Callback

import android.content.Context;
import android.util.AttributeSet;
import android.view.*;

public class MySurface extends SurfaceView implements SurfaceHolder.Callback{
SurfaceHolder holder;

public MySurface(Context context, AttributeSet attrs) {
super(context, attrs);
// TODO Auto-generated constructor stub
holder = this.getHolder();
holder.addCallback(this);

}

public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub
System.out.println("surface changed");
}

public void surfaceCreated(SurfaceHolder holder) {
// TODO Auto-generated method stub
System.out.println("surface created");
}

public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub
System.out.println("surface destroyed");
}

}

This new custom UI will be available for the xml layout file in Eclipse

can create a draw() method to contain all drawing code in there. then call draw() when surfaceCreated(...)

void draw(){
canvas = holder.lockCanvas();
Paint paint = new Paint();
paint.setColor(0xFFFF0000); // ARGB, red
canvas.drawRect(new Rect(10, 20, 100, 50), paint);
holder.unlockCanvasAndPost(canvas);
}


Threading can be used if animation is needed, for example for games.

Sample code snippet:

public class MySurface extends SurfaceView implements SurfaceHolder.Callback, Runnable{
SurfaceHolder holder;
Canvas canvas;
MySprite s = new MySprite();
boolean isRunning = true;
long time = 0;

static final int DELAY = 10;

public MySurface(Context context, AttributeSet attrs) {
super(context, attrs);
// TODO Auto-generated constructor stub
holder = this.getHolder();
holder.addCallback(this);

}

synchronized void draw(){
canvas = holder.lockCanvas();
canvas.drawColor(0xFFDDDDDD); // ARGB , fill whole canvas

// call draw in sprite
s.draw(canvas);

holder.unlockCanvasAndPost(canvas);
}

synchronized void update(){
s.update();
System.out.println((System.currentTimeMillis() - time) + " ms");
time = System.currentTimeMillis();
}

public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
// TODO Auto-generated method stub
System.out.println("surface changed");
}

public void surfaceCreated(SurfaceHolder holder) {
// TODO Auto-generated method stub
System.out.println("surface created");

isRunning = true;
Thread thread = new Thread(this);
thread.start();

time = System.currentTimeMillis();
}

public void surfaceDestroyed(SurfaceHolder holder) {
// TODO Auto-generated method stub
System.out.println("surface destroyed");
isRunning = false;
}

public void run() {
// TODO Auto-generated method stub
try{
while(isRunning){
update();
draw();
Thread.sleep(DELAY);
}
}
catch(Exception ex){
System.out.println(ex.getMessage());
}
}
}
MySprite is a custom class which contains x, y, width, height, its own draw(), update(), init(), cleanup() methods.

wxpython with new WebView

using version 2.9.4

import wx
import wx.html2

app = wx.App(False)
frame = wx.Frame(None, -1, 'A Simple Frame')
browser = wx.html2.WebView.New(frame)
browser.LoadURL("http://www.google.com")
frame.Show()
app.MainLoop()



tried loading local html file with some javascript.
worked so far. tested with jquery. ok too.

import os
browser.LoadURL(os.path.realpath("test.html"))