Android Canvas (Part 1)

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public class CanvasView extends View {

    private Paint arcPaint;
    private RectF rectF;
    private Shader mShader;
    private Path mPath;
    private Bitmap bitmap;

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

    public CanvasView(Context context, AttributeSet attrs) {
        super(context, attrs);
        init();
    }

    private void init() {
        arcPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        arcPaint.setColor(Color.BLUE);
        rectF = new RectF(260, 70, 290, 115);
        mShader =
                new LinearGradient(0, 0, 100, 100, new int[] {Color.RED, Color.GREEN, Color.BLUE,
                        Color.YELLOW, Color.LTGRAY}, null, Shader.TileMode.REPEAT);

        mPath = new Path();
        mPath.reset();
        bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.ic_launcher);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        // Background fill
        canvas.drawARGB(255, 0, 180, 255);
        canvas.drawColor(Color.RED);
        // TODO PorterDuff.Mode — needs further study
        canvas.drawColor(Color.BLACK, PorterDuff.Mode.CLEAR);
        canvas.drawRGB(255, 255, 255);

        arcPaint.setColor(Color.RED);

        canvas.drawText("Circle:", 10, 50, arcPaint);
        canvas.drawCircle(100, 45, 10, arcPaint);
        arcPaint.setAntiAlias(true);
        canvas.drawCircle(150, 45, 20, arcPaint);

        canvas.drawText("Lines & Arcs:", 10, 100, arcPaint);
        arcPaint.setColor(Color.GREEN);
        canvas.drawLine(160, 90, 210, 90, arcPaint);
        canvas.drawLine(210, 75, 270, 55, arcPaint);

        arcPaint.setStyle(Paint.Style.STROKE);
        canvas.drawCircle(300, 100, 50, arcPaint);

        canvas.drawArc(rectF, 180, 180, false, arcPaint);
        rectF.set(310, 70, 340, 115);
        canvas.drawArc(rectF, 180, 180, false, arcPaint);
        rectF.set(290, 110, 310, 125);
        canvas.drawArc(rectF, 0, 180, false, arcPaint);

        canvas.drawText("Rectangles:", 50, 150, arcPaint);
        arcPaint.setColor(Color.GRAY);
        arcPaint.setStyle(Paint.Style.FILL);
        canvas.drawRect(160, 135, 210, 185, arcPaint);
        canvas.drawRect(215, 150, 260, 210, arcPaint);

        canvas.drawText("Sector & Oval:", 10, 250, arcPaint);

        arcPaint.setShader(mShader);
        rectF.set(150, 190, 290, 310);
        canvas.drawArc(rectF, 200, 130, true, arcPaint);
        rectF.set(300, 200, 420, 300);
        canvas.drawOval(rectF, arcPaint);

        canvas.drawText("Triangle:", 10, 380, arcPaint);
        mPath.moveTo(100, 330);
        mPath.lineTo(150, 430);
        mPath.lineTo(180, 350);
        mPath.close();
        canvas.drawPath(mPath, arcPaint);

        // Hexagon
        arcPaint.reset();
        arcPaint.setColor(Color.LTGRAY);
        arcPaint.setStyle(Paint.Style.STROKE);
        mPath.reset();
        mPath.moveTo(280, 400);
        mPath.lineTo(300, 400);
        mPath.lineTo(310, 410);
        mPath.lineTo(300, 420);
        mPath.lineTo(280, 420);
        mPath.lineTo(270, 410);
        mPath.close();
        canvas.drawPath(mPath, arcPaint);

        // Rounded rectangle
        arcPaint.setStyle(Paint.Style.FILL);
        arcPaint.setColor(Color.LTGRAY);
        arcPaint.setAntiAlias(true);
        canvas.drawText("Rounded Rectangle:", 10, 450, arcPaint);
        rectF.set(180, 430, 300, 470);
        canvas.drawRoundRect(rectF, 20, 15, arcPaint);

        // Bezier curve
        canvas.drawText("Bezier Curve:", 10, 310, arcPaint);
        arcPaint.reset();
        arcPaint.setStyle(Paint.Style.STROKE);
        arcPaint.setColor(Color.GREEN);
        mPath.reset();
        mPath.moveTo(180, 310);
        mPath.quadTo(250, 250, 200, 350);
        canvas.drawPath(mPath, arcPaint);

        // Points
        arcPaint.setStyle(Paint.Style.FILL);
        canvas.drawText("Points:", 10, 520, arcPaint);
        canvas.drawPoint(60, 520, arcPaint);
        canvas.drawPoints(new float[] {60, 550, 65, 560, 70, 570}, arcPaint);

        // Bitmap
        canvas.drawBitmap(bitmap, 350, 350, arcPaint);
    }
}