Custom views

Custom views


public Bundle saveState() {
        Bundle map = new Bundle();

        map.putIntArray("mAppleList", coordArrayListToArray(mAppleList));
        map.putInt("mDirection", Integer.valueOf(mDirection));
        map.putInt("mNextDirection", Integer.valueOf(mNextDirection));
        map.putLong("mMoveDelay", Long.valueOf(mMoveDelay));
        map.putLong("mScore", Long.valueOf(mScore));
        map.putIntArray("mSnakeTrail", coordArrayListToArray(mSnakeTrail));

        return map;
    }


public void restoreState(Bundle icicle) {
        setMode(PAUSE);

        mAppleList = coordArrayToArrayList(icicle.getIntArray("mAppleList"));
        mDirection = icicle.getInt("mDirection");
        mNextDirection = icicle.getInt("mNextDirection");
        mMoveDelay = icicle.getLong("mMoveDelay");
        mScore = icicle.getLong("mScore");
        mSnakeTrail = coordArrayToArrayList(icicle.getIntArray("mSnakeTrail"));
    }


@Override
    public boolean onKeyDown(int keyCode, KeyEvent msg) {

        if (keyCode == KeyEvent.KEYCODE_DPAD_UP) {
            if (mMode == READY | mMode == LOSE) {
                /*
                 * At the beginning of the game, or the end of a previous one,
                 * we should start a new game.
                 */
                initNewGame();
                setMode(RUNNING);
                update();
                return (true);
            }

            if (mMode == PAUSE) {
                /*
                 * If the game is merely paused, we should just continue where
                 * we left off.
                 */
                setMode(RUNNING);
                update();
                return (true);
            }

            if (mDirection != SOUTH) {
                mNextDirection = NORTH;
            }
            return (true);
        }

        if (keyCode == KeyEvent.KEYCODE_DPAD_DOWN) {
            if (mDirection != NORTH) {
                mNextDirection = SOUTH;
            }
            return (true);
        }

        if (keyCode == KeyEvent.KEYCODE_DPAD_LEFT) {
            if (mDirection != EAST) {
                mNextDirection = WEST;
            }
            return (true);
        }

        if (keyCode == KeyEvent.KEYCODE_DPAD_RIGHT) {
            if (mDirection != WEST) {
                mNextDirection = EAST;
            }
            return (true);
        }

        return super.onKeyDown(keyCode, msg);
    }


public TileView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);

        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.TileView);

        mTileSize = a.getInt(R.styleable.TileView_tileSize, 12);
        
        a.recycle();
    }

    public TileView(Context context, AttributeSet attrs) {
        super(context, attrs);

        TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.TileView);

        mTileSize = a.getInt(R.styleable.TileView_tileSize, 12);
        
        a.recycle();
    }

Here is a note on custom attributes


<com.ai.android.book.apptemplate2.MyTextView
   android:id="@+id/custom_text_id"
    android:layout_width="fill_parent" 
    android:layout_height="wrap_content" 
    android:text="Debut Text Appears here"
    apptemplate:custom_text="Custom Hello"
    />


public class CircleView 
extends View
{
   public CircleView(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
    }

    public CircleView(Context context, AttributeSet attrs) {
        super(context, attrs);
    }   
    public static String tag="CircleView";
    
    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) 
    {
       super.onSizeChanged(w,h,oldw,oldh);
       Log.d(tag,"onSizeChanged");
    }
    @Override
    public void onDraw(Canvas canvas) {
        super.onDraw(canvas);
       Log.d(tag,"onDraw called");
    }
}


public SnakeView(Context context, AttributeSet attrs) {
        super(context, attrs);
        initSnakeView();
   }

    public SnakeView(Context context, AttributeSet attrs, int defStyle) {
       super(context, attrs, defStyle);
       initSnakeView();
    }

Notice the 'init' method

Here is the view api

There is a form of the constructor that are called when the view is created from code and a form that is called when the view is inflated from a layout file. The second form should parse and apply any attributes defined in the layout file. 


public CircleView(Context context) {
        super(context);
    }

Here is the canvas api


public class Arcs extends GraphicsActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(new SampleView(this));
    }

    private static class SampleView extends View {
        private Paint[] mPaints;
        private Paint mFramePaint;
        private boolean[] mUseCenters;
        private RectF[] mOvals;
        private RectF mBigOval;
        private float mStart;
        private float mSweep;
        private int mBigIndex;

        private static final float SWEEP_INC = 2;
        private static final float START_INC = 15;

        public SampleView(Context context) {
            super(context);

            mPaints = new Paint[4];
            mUseCenters = new boolean[4];
            mOvals = new RectF[4];

            mPaints[0] = new Paint();
            mPaints[0].setAntiAlias(true);
            mPaints[0].setStyle(Paint.Style.FILL);
            mPaints[0].setColor(0x88FF0000);
            mUseCenters[0] = false;

            mPaints[1] = new Paint(mPaints[0]);
            mPaints[1].setColor(0x8800FF00);
            mUseCenters[1] = true;

            mPaints[2] = new Paint(mPaints[0]);
            mPaints[2].setStyle(Paint.Style.STROKE);
            mPaints[2].setStrokeWidth(4);
            mPaints[2].setColor(0x880000FF);
            mUseCenters[2] = false;

            mPaints[3] = new Paint(mPaints[2]);
            mPaints[3].setColor(0x88888888);
            mUseCenters[3] = true;

            mBigOval = new RectF(40, 10, 280, 250);

            mOvals[0] = new RectF( 10, 270,  70, 330);
            mOvals[1] = new RectF( 90, 270, 150, 330);
            mOvals[2] = new RectF(170, 270, 230, 330);
            mOvals[3] = new RectF(250, 270, 310, 330);

            mFramePaint = new Paint();
            mFramePaint.setAntiAlias(true);
            mFramePaint.setStyle(Paint.Style.STROKE);
            mFramePaint.setStrokeWidth(0);
        }

        private void drawArcs(Canvas canvas, RectF oval, boolean useCenter,
                              Paint paint) {
            canvas.drawRect(oval, mFramePaint);
            canvas.drawArc(oval, mStart, mSweep, useCenter, paint);
        }

        @Override protected void onDraw(Canvas canvas) {
            canvas.drawColor(Color.WHITE);

            drawArcs(canvas, mBigOval, mUseCenters[mBigIndex],
                     mPaints[mBigIndex]);

            for (int i = 0; i < 4; i++) {
                drawArcs(canvas, mOvals[i], mUseCenters[i], mPaints[i]);
            }

            mSweep += SWEEP_INC;
            if (mSweep > 360) {
                mSweep -= 360;
                mStart += START_INC;
                if (mStart >= 360) {
                    mStart -= 360;
                }
                mBigIndex = (mBigIndex + 1) % mOvals.length;
            }
            invalidate();
        }
    }
}

Search for: html color codes

Figuring out html color

Here are named colors

Set the paint's color. Note that the color is an int containing alpha as well as r,g,b. This 32bit value is not premultiplied, meaning that its alpha can be any value, regardless of the values of r,g,b. See the Color class for more details.

Here is the api for android.graphics.Color

The Color class defines methods for creating and converting color ints. Colors are represented as packed ints, made up of 4 bytes: alpha, red, green, blue. The values are unpremultiplied, meaning any transparency is stored solely in the alpha component, and not in the color components. The components are stored as follows (alpha << 24) | (red << 16) | (green << 8) | blue. Each component ranges between 0..255 with 0 meaning no contribution for that component, and 255 meaning 100% contribution. Thus opaque-black would be 0xFF000000 (100% opaque but no contributions from red, green, or blue), and opaque-white would be 0xFFFFFFFF" 


BLACK: 0xff000000
alpha is FF, all 0s

BLUE: 0xff0000ff
Transparent: 0x00000000

onSizeChanged and invalidate in Android

Search for: onSizeChanged and invalidate in Android

onSizeChanged

Search Google for: onSizeChanged

Search Android Developers Group for: onSizeChanged

Search Android Beginers Group for: onSizeChanged

Search Google Code for: onSizeChanged

Search Android Issues Database for: onSizeChanged

Here is a bit of thought generating post

onSizeChanged() is invoked as part of the layout pass, and you cannot/should not requestLayout() during a layout pass. It is correct to post a requestLayout() on the event queue to indicate that you have changed the View hierarchy during a layout pass. 


post(new Runnable() {

    public void run() {

        requestLayout();

    }

});

invalidate during a layout phase in android

Search for: invalidate during a layout phase in android

is onSizeChanged always followed by an OnDraw?

Search for: is onSizeChanged always followed by an OnDraw?

top, left, bottom, right are relative to its parent


1. Triggered by layout phase
2. specifically called by layout() of the base view
3. More specifically by setFrame() of the base view
4. will not be called if there is no change to the size
5. invalidate of the base view called as well
6. base view has recorded its size before calling onsizechanged
7. base view has an empty implementation for this method
8. onDraw will be triggered because of invalidate in a subsequent
   draw phase
9. it is wrong to call requestLayout because it is already in a 
   layout phase. if needed post to a thread to call it
10. You can choose to use measurements from the base view if you choose

onmeasure and wrap_content

Search for: onmeasure and wrap_content

Why is wrap_content taking all the remaining space?

Search for: Why is wrap_content taking all the remaining space?

Here is another fellow having the same problem

onmeasure getDefaultSize wrap_content

Search for: onmeasure getDefaultSize wrap_content

How to save android view state?

Search for: How to save android view state?

Here is an indepth conversation about this subject