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path: root/mobileapp/src/smoots/udesign/colorpicker/ColorPickerView.java
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package smoots.udesign.colorpicker;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.RectF;
import android.graphics.Shader;
import android.graphics.SweepGradient;
import android.view.MotionEvent;
import android.view.View;

public class ColorPickerView extends View {
	private final Paint mPaint;
	private final Paint mCenterPaint;
	private final int[] mColors;
	private final ColorPickerListener mListener;

	ColorPickerView(Context c, ColorPickerListener l, int color) {
		super(c);
		mListener = l;
		mColors = new int[] { 0xFFFF0000, 0xFFFF00FF, 0xFF0000FF,
				0xFF00FFFF, 0xFF00FF00, 0xFFFFFF00, 0xFFFF0000 };
		Shader s = new SweepGradient(0, 0, mColors, null);

		mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
		mPaint.setShader(s);
		mPaint.setStyle(Paint.Style.STROKE);
		mPaint.setStrokeWidth(32);

		mCenterPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
		mCenterPaint.setColor(color);
		mCenterPaint.setStrokeWidth(5);
	}

	private boolean mTrackingCenter;
	private boolean mHighlightCenter;

	@Override
	protected void onDraw(Canvas canvas) {
		float r = CENTER_X - mPaint.getStrokeWidth() * 0.5f;

		canvas.translate(CENTER_X, CENTER_X);

		canvas.drawOval(new RectF(-r, -r, r, r), mPaint);
		canvas.drawCircle(0, 0, CENTER_RADIUS, mCenterPaint);

		if (mTrackingCenter) {
			int c = mCenterPaint.getColor();
			mCenterPaint.setStyle(Paint.Style.STROKE);

			if (mHighlightCenter) {
				mCenterPaint.setAlpha(0xFF);
			} else {
				mCenterPaint.setAlpha(0x80);
			}
			canvas.drawCircle(0, 0, CENTER_RADIUS
					+ mCenterPaint.getStrokeWidth(), mCenterPaint);

			mCenterPaint.setStyle(Paint.Style.FILL);
			mCenterPaint.setColor(c);
		}
	}

	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		setMeasuredDimension(CENTER_X * 2, CENTER_Y * 2);
	}

	private static final int CENTER_X = 100;
	private static final int CENTER_Y = 100;
	private static final int CENTER_RADIUS = 32;


	private int ave(int s, int d, float p) {
		return s + java.lang.Math.round(p * (d - s));
	}

	private int interpColor(int colors[], float unit) {
		if (unit <= 0)
			return colors[0];
		if (unit >= 1)
			return colors[colors.length - 1];

		float p = unit * (colors.length - 1);
		int i = (int) p;
		p -= i;

		// now p is just the fractional part [0...1) and i is the index
		int c0 = colors[i];
		int c1 = colors[i + 1];
		int a = ave(Color.alpha(c0), Color.alpha(c1), p);
		int r = ave(Color.red(c0), Color.red(c1), p);
		int g = ave(Color.green(c0), Color.green(c1), p);
		int b = ave(Color.blue(c0), Color.blue(c1), p);

		return Color.argb(a, r, g, b);
	}

	/*

	private int floatToByte(float x) {
		int n = java.lang.Math.round(x);
		return n;
	}

	private int pinToByte(int n) {
		if (n < 0) {
			n = 0;
		} else if (n > 255) {
			n = 255;
		}
		return n;
	}

	private int rotateColor(int color, float rad) {
		float deg = rad * 180 / 3.1415927f;
		int r = Color.red(color);
		int g = Color.green(color);
		int b = Color.blue(color);

		ColorMatrix cm = new ColorMatrix();
		ColorMatrix tmp = new ColorMatrix();

		cm.setRGB2YUV();
		tmp.setRotate(0, deg);
		cm.postConcat(tmp);
		tmp.setYUV2RGB();
		cm.postConcat(tmp);

		final float[] a = cm.getArray();

		int ir = floatToByte(a[0] * r + a[1] * g + a[2] * b);
		int ig = floatToByte(a[5] * r + a[6] * g + a[7] * b);
		int ib = floatToByte(a[10] * r + a[11] * g + a[12] * b);

		return Color.argb(Color.alpha(color), pinToByte(ir), pinToByte(ig),
				pinToByte(ib));
	}
	*/

	private static final float PI = 3.1415926f;

	@Override
	public boolean onTouchEvent(MotionEvent event) {
		float x = event.getX() - CENTER_X;
		float y = event.getY() - CENTER_Y;
		boolean inCenter = java.lang.Math.sqrt(x * x + y * y) <= CENTER_RADIUS;

		switch (event.getAction()) {
		case MotionEvent.ACTION_DOWN:
			mTrackingCenter = inCenter;
			if (inCenter) {
				mHighlightCenter = true;
				invalidate();
				break;
			}
		case MotionEvent.ACTION_MOVE:
			if (mTrackingCenter) {
				if (mHighlightCenter != inCenter) {
					mHighlightCenter = inCenter;
					invalidate();
				}
			} else {
				float angle = (float) java.lang.Math.atan2(y, x);
				// need to turn angle [-PI ... PI] into unit [0....1]
				float unit = angle / (2 * PI);
				if (unit < 0) {
					unit += 1;
				}
				mCenterPaint.setColor(interpColor(mColors, unit));
				invalidate();
			}
			break;
		case MotionEvent.ACTION_UP:
			if (mTrackingCenter) {
				if (inCenter) {
					mListener.onColorChanged(mCenterPaint.getColor());
				}
				mTrackingCenter = false; // so we draw w/o halo
				invalidate();
			}
			break;
		}
		return true;
	}
}