Develop Reference

2 or more rectangles with Canvas or using CustomDrawableView class android

I want more Rectangles in the same Canvas, so I show them in the same activity.
But using a special class (CustomDrawableView) when I add the second SetContentView(my_second_Drawable) my activity is full white.
Instead, using my_canvas.drawRect(x,y,width,height,my_paint) none rectangle appears.
I search into Web but i don't find anything.
Can you help me please?
Sorry for my English.
package com.example.prova.shaperectprove;
import android.app.Activity;
import android.graphics.Color;
import android.graphics.Paint;
import android.support.v4.app.FragmentManager;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.ColorFilter;
import android.graphics.Rect;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.ShapeDrawable;
import android.graphics.drawable.TransitionDrawable;
import android.graphics.drawable.shapes.RectShape;
import android.support.v4.app.DialogFragment;
import android.support.v7.app.AlertDialog;
import android.support.v7.app.AppCompatActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;
import android.widget.Toast;
public class MainActivity extends AppCompatActivity {
private LinearLayout myLayout,redLayout,greenLayout;
ShapeDrawable myshape;
CustomDrawableView greenDrawableView;
CustomDrawableView redDrawableView;
CustomDrawableView blueDrawableView;
Canvas mycanvas = new Canvas();
final private static String str = "Green";
#Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
//setContentView(R.layout.activity_main);
myLayout = new LinearLayout(getApplicationContext());
myLayout.setLayoutParams(new LinearLayout.LayoutParams(LinearLayout.LayoutParams.MATCH_PARENT, 50));
myLayout.setOrientation(LinearLayout.HORIZONTAL);
LinearLayout.LayoutParams myLLP = new LinearLayout.LayoutParams(200, 50);
LinearLayout.LayoutParams myLLP2 = new LinearLayout.LayoutParams(200, 50);
redLayout = new LinearLayout(getApplicationContext());
redLayout.setLayoutParams(myLLP2);
redLayout.setOrientation(LinearLayout.HORIZONTAL);
greenLayout = new LinearLayout(getApplicationContext());
greenLayout.setLayoutParams(myLLP);
greenLayout.setOrientation(LinearLayout.HORIZONTAL);
//dichiarazione
greenDrawableView = new CustomDrawableView(this);
redDrawableView = new CustomDrawableView(this);
blueDrawableView = new CustomDrawableView(this);
if (greenDrawableView.isClickable()) {
Log.i("Cliccabile", "TRUE_clickable");
}
greenDrawableView.setOnClickListener(new View.OnClickListener() {
#Override
public void onClick(View v) {
FragmentManager fm = getSupportFragmentManager();
MyDialogGreen dialogGreen = new MyDialogGreen();
dialogGreen.show(fm, str);
}
});
greenDrawableView.changeSize(10,10, 210, 60); //left,top,right,bottom
redDrawableView.changeSize(210, 10, 420, 60);
redDrawableView.changeColor(0xFFC12727);
greenLayout.addView(greenDrawableView);
redLayout.addView(redDrawableView);
myLayout.addView(greenLayout);
myLayout.addView(redLayout);
setContentView(myLayout);
}
}
package com.example.prova.shaperectprove;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.drawable.ShapeDrawable;
import android.graphics.drawable.shapes.RectShape;
import android.text.Layout;
import android.text.style.RelativeSizeSpan;
import android.view.View;
import android.widget.RelativeLayout;
public class CustomDrawableView extends View {
private ShapeDrawable mDrawable;
int x,y,width,height,drawColor = 0xFF1A9316;
public CustomDrawableView(Context context) {
super(context);
x = 20;
y = 20;
width = 200;
height = 60;
mDrawable = new ShapeDrawable(new RectShape());
mDrawable.getPaint().setColor(drawColor);
mDrawable.setBounds(x, y, width, height); /
}
protected void onDraw(Canvas canvas) {
mDrawable.draw(canvas);
}
protected void changeColor(int newColor) {
drawColor = newColor;
}
protected int getLenght()
{
return width-x; //right-left
}
protected int getHight()
{
return height-y; //bottom-top
}
protected int mygetLeft()
{
return x;
}
protected int mygetTop()
{
return y;
}
protected int mygetRight()
{
return width;
}
protected int mygetBottom()
{
return height;
}
protected void changeSize(int x, int y,int width, int height){
mDrawable.setBounds(x, y, width, height);
invalidate();
}
}

SurfaceView shows blacks screen?

I am trying to get my SurfaceView to work but I am getting black Screen. I tried to change the color number of canvas.drawRGB(02, 02, 150); but it was not helpful. I do not know what the reason is. I appreciate any help!
package com.test;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
public class MyBringBackSurface extends SurfaceView implements Runnable {
SurfaceHolder ourHolder;
Thread ourThread = null;
boolean isRunning;
public MyBringBackSurface(Context context) {
super(context);
ourHolder = getHolder();
ourThread = new Thread(this);
ourThread.start();
}
#Override
public void run() {
// TODO Auto-generated method stub
while (isRunning) {
if (!ourHolder.getSurface().isValid())
continue;
Canvas canvas = ourHolder.lockCanvas();
canvas.drawRGB(02, 02, 150);
ourHolder.unlockCanvasAndPost(canvas);
}
}
}

SurfaceView showing blank white screen

I am trying to draw an oval to the screen but all I am getting is a blank white canvas. Not only am I unsure whether I am drawing the oval correctly, but also am getting nothing to the screen. Does anyone know why this is happening, I think the problem is that it isnt getting to the drawing section of the thread...
package hidden;
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.graphics.PorterDuff;
import android.graphics.RectF;
import android.graphics.drawable.Drawable;
import android.graphics.drawable.shapes.OvalShape;
import android.os.Bundle;
import android.util.Log;
import android.view.MotionEvent;
import android.view.SurfaceHolder;
import android.view.SurfaceView;
import android.view.View;
import android.view.Window;
import android.view.WindowManager;
import android.view.View.OnTouchListener;
public class Surface extends Activity implements OnTouchListener
{
SurfaceView v;
protected void onCreate(Bundle savedInstanceState)
{
super.onCreate(savedInstanceState);
requestWindowFeature(Window.FEATURE_NO_TITLE);
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN, WindowManager.LayoutParams.FLAG_FULLSCREEN);
setContentView(R.layout.activity_main);
setRequestedOrientation(1);
v = new SView(this);
v.setOnTouchListener(this);
v.setZOrderOnTop(true);
setContentView(v);
}
public class SView extends SurfaceView implements Runnable
{
Thread t1 = null;
SurfaceHolder holder;
boolean isItOk = false;
public SView(Context context)
{
super(context);
holder = getHolder();
holder.setFormat(PixelFormat.TRANSPARENT);
}
public void run()
{
while(isItOk)
{
if(!holder.getSurface().isValid())
{
continue;
}
Canvas c = holder.lockCanvas();
Paint p = new Paint();
p.setColor(Color.BLUE);
//OvalShape oval = new OvalShape();
//oval.draw(c, p);
Paint paint = new Paint();
paint.setColor(Color.GREEN);
paint.setStyle(Paint.Style.STROKE);
float leftx = 20;
float topy = 20;
float rightx = 50;
float bottomy = 100;
RectF ovalBounds = new RectF(leftx, topy, rightx, bottomy);
c.drawOval(ovalBounds, paint);
holder.unlockCanvasAndPost(c);
}
}
public void pause()
{
isItOk = false;
while(true)
{
try
{
t1.join();
}
catch(InterruptedException e)
{
e.printStackTrace();
}
break;
}
t1 = null;
}
public void resume()
{
isItOk = true;
t1 = new Thread(this);
t1.start();
}
}
public boolean onTouch(View arg0, MotionEvent arg1)
{
return false;
}
}

Increase speed to redraw the Android Screen

I am new to Android.My application requires to redraw a canvas circle over and over again. However, the speed of redraw is less than what I want. How may I increase the same.
My code is as follows:
--> ImagePracActivity.java
package com.pkg.ImagPrac;
import android.app.Activity;
import android.os.Bundle;
import android.view.Window;
import android.view.WindowManager;
public class ImagePracActivity extends Activity {
//DrawView drawView;
movement mv;
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
// Set full screen view
getWindow().setFlags(WindowManager.LayoutParams.FLAG_FULLSCREEN,
WindowManager.LayoutParams.FLAG_FULLSCREEN);
requestWindowFeature(Window.FEATURE_NO_TITLE);
mv=new movement(getApplicationContext());
setContentView(mv);
mv.requestFocus();
}
}
--> movement.java
package com.pkg.ImagPrac;
import android.content.Context;
import android.content.Intent;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.Log;
import android.view.Display;
import android.view.MotionEvent;
import android.view.View;
import android.view.View.OnTouchListener;
import android.view.WindowManager;
public class movement extends View implements OnTouchListener{
Display display;
float x=0,y=0;
Paint paint=new Paint();
private boolean flag;
public movement(Context context) {
super(context);
setFocusable(true);
setFocusableInTouchMode(true);
this.setOnTouchListener(this);
paint.setColor(Color.BLUE);
paint.setAntiAlias(true);
display = ((WindowManager)
context.getSystemService(Context.WINDOW_SERVICE)).getDefaultDisplay();
x = 0;
y = display.getHeight();
}
#Override
protected void onDraw(Canvas canvas) {
if(x<(display.getWidth()/2))
{
canvas.drawCircle(x++, y--, 5, paint);
}
else if(x<(display.getWidth()))
{
canvas.drawCircle(x++, y++, 5, paint);
}
this.invalidate();
}
public boolean onTouch(View arg0, MotionEvent arg1) {
// TODO Auto-generated method stub
return false;
}
}

A would advice you to use SurfaceView class instead of View, because SurfaceView faster and allows you to have all drawing logic in separate thread. Read more about SurfaceView : http://developer.android.com/guide/topics/graphics/2d-graphics.html

try this
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setColor(Color.BLUE);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(5);

Android On Touch

I have been trying to make a program draw circles as I touch the screen with no luck, can anyone please tell me how I can do this? or GOOD tutorial that shows me how... I keep getting errors in my code
import android.content.Context;
import android.content.Intent;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.text.format.Time;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import java.lang.Math;
public class GameView extends View{
private final float x;
private final float y;
private final int r;
private final Paint mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
public GameView(Context context, float x, float y, int r) {
super(context);
setFocusable(true);
mPaint.setColor(0xFFFF0000);
this.x = x;
this.y = y;
this.r = r;
}
#Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawCircle(x, y, r, mPaint);
}
}
GameActivity.java
import android.app.Activity;
import android.content.Context;
import android.os.Bundle;
import android.os.Handler;
import android.os.Message;
import android.view.Display;
import android.view.MotionEvent;
import android.view.View;
import android.view.WindowManager;
import android.widget.FrameLayout;
public class GameActivity extends Activity {
/** Called when the activity is first created. */
#Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.main);
FrameLayout main = (FrameLayout) findViewById(R.id.my_view);
main.setOnTouchListener(new View.OnTouchListener() {
public boolean onTouch(final View v, MotionEvent e) {
final float x = e.getX();
final float y = e.getY();
final Handler handler = new Handler()
{
public void handleMessage(Message msg) {
}
};
Thread graphicThread = new Thread()
{
public void run() {
try {
//Do the drop
FrameLayout flView = (FrameLayout) v;
GameView gm = new GameView(getParent(), x,y,25);
flView.addView(gm);
Thread.sleep(1000);
handler.sendMessage(handler.obtainMessage());
}
catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
}
};
boolean isRunning=true;
graphicThread.start();
return true;
}
});
}
}

You shouldn't be using getParent() in your activity if it's not a child Activity.
Use this instead:
GameView gm = new GameView(this, x, y, 25);

As the NPE question is already answered, I want to provide an answer for the tutorial question. I have written a series (which is partly updated) which you can find here: I have written a tutorial about 2d graphics for a game. Read this: http://www.droidnova.com/2d-tutorial-series