ColorPickerView.java

/*
 * Copyright (C) 2010 Daniel Nilsson
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.yixia.zi.widget.colorpicker;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.ComposeShader;
import android.graphics.LinearGradient;
import android.graphics.Paint;
import android.graphics.Point;
import android.graphics.PorterDuff;
import android.graphics.RectF;
import android.graphics.Shader;
import android.graphics.Paint.Align;
import android.graphics.Paint.Style;
import android.graphics.Shader.TileMode;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

/**
 * Displays a color picker to the user and allow them to select a color. A
 * slider for the alpha channel is also available. Enable it by setting
 * setAlphaSliderVisible(boolean) to true.
 * 
 * @author Daniel Nilsson
 */
public class ColorPickerView extends View {

	public interface OnColorChangedListener {
		public void onColorChanged(int color);
	}

	private final static int PANEL_SAT_VAL = 0;
	private final static int PANEL_HUE = 1;
	private final static int PANEL_ALPHA = 2;

	/**
	 * The width in pixels of the border surrounding all color panels.
	 */
	private final static float BORDER_WIDTH_PX = 1;

	/**
	 * The width in dp of the hue panel.
	 */
	private float HUE_PANEL_WIDTH = 30f;
	/**
	 * The height in dp of the alpha panel
	 */
	private float ALPHA_PANEL_HEIGHT = 20f;
	/**
	 * The distance in dp between the different color panels.
	 */
	private float PANEL_SPACING = 10f;
	/**
	 * The radius in dp of the color palette tracker circle.
	 */
	private float PALETTE_CIRCLE_TRACKER_RADIUS = 5f;
	/**
	 * The dp which the tracker of the hue or alpha panel will extend outside of
	 * its bounds.
	 */
	private float RECTANGLE_TRACKER_OFFSET = 2f;

	private static float mDensity = 1f;

	private OnColorChangedListener mListener;

	private Paint mSatValPaint;
	private Paint mSatValTrackerPaint;

	private Paint mHuePaint;
	private Paint mHueTrackerPaint;

	private Paint mAlphaPaint;
	private Paint mAlphaTextPaint;

	private Paint mBorderPaint;

	private Shader mValShader;
	private Shader mSatShader;
	private Shader mHueShader;
	private Shader mAlphaShader;

	private int mAlpha = 0xff;
	private float mHue = 360f;
	private float mSat = 0f;
	private float mVal = 0f;

	private String mAlphaSliderText = "Alpha";
	private int mSliderTrackerColor = 0xff1c1c1c;
	private int mBorderColor = 0xff6E6E6E;
	private boolean mShowAlphaPanel = false;

	/*
	 * To remember which panel that has the "focus" when 
	 * processing hardware button data.
	 */
	private int mLastTouchedPanel = PANEL_SAT_VAL;

	/**
	 * Offset from the edge we must have or else the finger tracker will get
	 * clipped when it is drawn outside of the view.
	 */
	private float mDrawingOffset;

	/*
	 * Distance form the edges of the view 
	 * of where we are allowed to draw.
	 */
	private RectF mDrawingRect;

	private RectF mSatValRect;
	private RectF mHueRect;
	private RectF mAlphaRect;

	private AlphaPatternDrawable mAlphaPattern;

	private Point mStartTouchPoint = null;

	public ColorPickerView(Context context) {
		this(context, null);
	}

	public ColorPickerView(Context context, AttributeSet attrs) {
		this(context, attrs, 0);
	}

	public ColorPickerView(Context context, AttributeSet attrs, int defStyle) {
		super(context, attrs, defStyle);
		init();
	}

	private void init() {
		mDensity = getContext().getResources().getDisplayMetrics().density;
		PALETTE_CIRCLE_TRACKER_RADIUS *= mDensity;
		RECTANGLE_TRACKER_OFFSET *= mDensity;
		HUE_PANEL_WIDTH *= mDensity;
		ALPHA_PANEL_HEIGHT *= mDensity;
		PANEL_SPACING = PANEL_SPACING * mDensity;

		mDrawingOffset = calculateRequiredOffset();

		initPaintTools();

		//Needed for receiving trackball motion events.
		setFocusable(true);
		setFocusableInTouchMode(true);
	}

	private void initPaintTools() {

		mSatValPaint = new Paint();
		mSatValTrackerPaint = new Paint();
		mHuePaint = new Paint();
		mHueTrackerPaint = new Paint();
		mAlphaPaint = new Paint();
		mAlphaTextPaint = new Paint();
		mBorderPaint = new Paint();

		mSatValTrackerPaint.setStyle(Style.STROKE);
		mSatValTrackerPaint.setStrokeWidth(2f * mDensity);
		mSatValTrackerPaint.setAntiAlias(true);

		mHueTrackerPaint.setColor(mSliderTrackerColor);
		mHueTrackerPaint.setStyle(Style.STROKE);
		mHueTrackerPaint.setStrokeWidth(2f * mDensity);
		mHueTrackerPaint.setAntiAlias(true);

		mAlphaTextPaint.setColor(0xff1c1c1c);
		mAlphaTextPaint.setTextSize(14f * mDensity);
		mAlphaTextPaint.setAntiAlias(true);
		mAlphaTextPaint.setTextAlign(Align.CENTER);
		mAlphaTextPaint.setFakeBoldText(true);

	}

	private float calculateRequiredOffset() {
		float offset = Math.max(PALETTE_CIRCLE_TRACKER_RADIUS, RECTANGLE_TRACKER_OFFSET);
		offset = Math.max(offset, BORDER_WIDTH_PX * mDensity);

		return offset * 1.5f;
	}

	private int[] buildHueColorArray() {

		int[] hue = new int[361];

		int count = 0;
		for (int i = hue.length - 1; i >= 0; i--, count++) {
			hue[count] = Color.HSVToColor(new float[] { i, 1f, 1f });
		}

		return hue;
	}

	@Override
	protected void onDraw(Canvas canvas) {
		if (mDrawingRect.width() <= 0 || mDrawingRect.height() <= 0)
			return;

		drawSatValPanel(canvas);
		drawHuePanel(canvas);
		drawAlphaPanel(canvas);
	}

	private void drawSatValPanel(Canvas canvas) {

		final RectF rect = mSatValRect;

		if (BORDER_WIDTH_PX > 0) {
			mBorderPaint.setColor(mBorderColor);
			canvas.drawRect(mDrawingRect.left, mDrawingRect.top, rect.right + BORDER_WIDTH_PX, rect.bottom + BORDER_WIDTH_PX, mBorderPaint);
		}

		if (mValShader == null) {
			mValShader = new LinearGradient(rect.left, rect.top, rect.left, rect.bottom, 0xffffffff, 0xff000000, TileMode.CLAMP);
		}

		int rgb = Color.HSVToColor(new float[] { mHue, 1f, 1f });

		mSatShader = new LinearGradient(rect.left, rect.top, rect.right, rect.top, 0xffffffff, rgb, TileMode.CLAMP);
		ComposeShader mShader = new ComposeShader(mValShader, mSatShader, PorterDuff.Mode.MULTIPLY);
		mSatValPaint.setShader(mShader);

		canvas.drawRect(rect, mSatValPaint);

		Point p = satValToPoint(mSat, mVal);

		mSatValTrackerPaint.setColor(0xff000000);
		canvas.drawCircle(p.x, p.y, PALETTE_CIRCLE_TRACKER_RADIUS - 1f * mDensity, mSatValTrackerPaint);

		mSatValTrackerPaint.setColor(0xffdddddd);
		canvas.drawCircle(p.x, p.y, PALETTE_CIRCLE_TRACKER_RADIUS, mSatValTrackerPaint);

	}

	private void drawHuePanel(Canvas canvas) {

		final RectF rect = mHueRect;

		if (BORDER_WIDTH_PX > 0) {
			mBorderPaint.setColor(mBorderColor);
			canvas.drawRect(rect.left - BORDER_WIDTH_PX, rect.top - BORDER_WIDTH_PX, rect.right + BORDER_WIDTH_PX, rect.bottom + BORDER_WIDTH_PX, mBorderPaint);
		}

		if (mHueShader == null) {
			mHueShader = new LinearGradient(rect.left, rect.top, rect.left, rect.bottom, buildHueColorArray(), null, TileMode.CLAMP);
			mHuePaint.setShader(mHueShader);
		}

		canvas.drawRect(rect, mHuePaint);

		float rectHeight = 4 * mDensity / 2;

		Point p = hueToPoint(mHue);

		RectF r = new RectF();
		r.left = rect.left - RECTANGLE_TRACKER_OFFSET;
		r.right = rect.right + RECTANGLE_TRACKER_OFFSET;
		r.top = p.y - rectHeight;
		r.bottom = p.y + rectHeight;

		canvas.drawRoundRect(r, 2, 2, mHueTrackerPaint);

	}

	private void drawAlphaPanel(Canvas canvas) {

		if (!mShowAlphaPanel || mAlphaRect == null || mAlphaPattern == null)
			return;

		final RectF rect = mAlphaRect;

		if (BORDER_WIDTH_PX > 0) {
			mBorderPaint.setColor(mBorderColor);
			canvas.drawRect(rect.left - BORDER_WIDTH_PX, rect.top - BORDER_WIDTH_PX, rect.right + BORDER_WIDTH_PX, rect.bottom + BORDER_WIDTH_PX, mBorderPaint);
		}

		mAlphaPattern.draw(canvas);

		float[] hsv = new float[] { mHue, mSat, mVal };
		int color = Color.HSVToColor(hsv);
		int acolor = Color.HSVToColor(0, hsv);

		mAlphaShader = new LinearGradient(rect.left, rect.top, rect.right, rect.top, color, acolor, TileMode.CLAMP);

		mAlphaPaint.setShader(mAlphaShader);

		canvas.drawRect(rect, mAlphaPaint);

		if (mAlphaSliderText != null && mAlphaSliderText != "") {
			canvas.drawText(mAlphaSliderText, rect.centerX(), rect.centerY() + 4 * mDensity, mAlphaTextPaint);
		}

		float rectWidth = 4 * mDensity / 2;

		Point p = alphaToPoint(mAlpha);

		RectF r = new RectF();
		r.left = p.x - rectWidth;
		r.right = p.x + rectWidth;
		r.top = rect.top - RECTANGLE_TRACKER_OFFSET;
		r.bottom = rect.bottom + RECTANGLE_TRACKER_OFFSET;

		canvas.drawRoundRect(r, 2, 2, mHueTrackerPaint);

	}

	private Point hueToPoint(float hue) {

		final RectF rect = mHueRect;
		final float height = rect.height();

		Point p = new Point();

		p.y = (int) (height - (hue * height / 360f) + rect.top);
		p.x = (int) rect.left;

		return p;
	}

	private Point satValToPoint(float sat, float val) {

		final RectF rect = mSatValRect;
		final float height = rect.height();
		final float width = rect.width();

		Point p = new Point();

		p.x = (int) (sat * width + rect.left);
		p.y = (int) ((1f - val) * height + rect.top);

		return p;
	}

	private Point alphaToPoint(int alpha) {

		final RectF rect = mAlphaRect;
		final float width = rect.width();

		Point p = new Point();

		p.x = (int) (width - (alpha * width / 0xff) + rect.left);
		p.y = (int) rect.top;

		return p;

	}

	private float[] pointToSatVal(float x, float y) {

		final RectF rect = mSatValRect;
		float[] result = new float[2];

		float width = rect.width();
		float height = rect.height();

		if (x < rect.left) {
			x = 0f;
		} else if (x > rect.right) {
			x = width;
		} else {
			x = x - rect.left;
		}

		if (y < rect.top) {
			y = 0f;
		} else if (y > rect.bottom) {
			y = height;
		} else {
			y = y - rect.top;
		}

		result[0] = 1.f / width * x;
		result[1] = 1.f - (1.f / height * y);

		return result;
	}

	private float pointToHue(float y) {

		final RectF rect = mHueRect;

		float height = rect.height();

		if (y < rect.top) {
			y = 0f;
		} else if (y > rect.bottom) {
			y = height;
		} else {
			y = y - rect.top;
		}

		return 360f - (y * 360f / height);
	}

	private int pointToAlpha(int x) {

		final RectF rect = mAlphaRect;
		final int width = (int) rect.width();

		if (x < rect.left) {
			x = 0;
		} else if (x > rect.right) {
			x = width;
		} else {
			x = x - (int) rect.left;
		}

		return 0xff - (x * 0xff / width);

	}

	@Override
	public boolean onTrackballEvent(MotionEvent event) {

		float x = event.getX();
		float y = event.getY();

		boolean update = false;

		if (event.getAction() == MotionEvent.ACTION_MOVE) {

			switch (mLastTouchedPanel) {

			case PANEL_SAT_VAL:

				float sat,
				val;

				sat = mSat + x / 50f;
				val = mVal - y / 50f;

				if (sat < 0f) {
					sat = 0f;
				} else if (sat > 1f) {
					sat = 1f;
				}

				if (val < 0f) {
					val = 0f;
				} else if (val > 1f) {
					val = 1f;
				}

				mSat = sat;
				mVal = val;

				update = true;

				break;

			case PANEL_HUE:

				float hue = mHue - y * 10f;

				if (hue < 0f) {
					hue = 0f;
				} else if (hue > 360f) {
					hue = 360f;
				}

				mHue = hue;

				update = true;

				break;

			case PANEL_ALPHA:

				if (!mShowAlphaPanel || mAlphaRect == null) {
					update = false;
				} else {

					int alpha = (int) (mAlpha - x * 10);

					if (alpha < 0) {
						alpha = 0;
					} else if (alpha > 0xff) {
						alpha = 0xff;
					}

					mAlpha = alpha;

					update = true;
				}

				break;
			}

		}

		if (update) {

			if (mListener != null) {
				mListener.onColorChanged(Color.HSVToColor(mAlpha, new float[] { mHue, mSat, mVal }));
			}

			invalidate();
			return true;
		}

		return super.onTrackballEvent(event);
	}

	@Override
	public boolean onTouchEvent(MotionEvent event) {

		boolean update = false;

		switch (event.getAction()) {

		case MotionEvent.ACTION_DOWN:

			mStartTouchPoint = new Point((int) event.getX(), (int) event.getY());

			update = moveTrackersIfNeeded(event);

			break;

		case MotionEvent.ACTION_MOVE:

			update = moveTrackersIfNeeded(event);

			break;

		case MotionEvent.ACTION_UP:

			mStartTouchPoint = null;

			update = moveTrackersIfNeeded(event);

			break;

		}

		if (update) {

			if (mListener != null) {
				mListener.onColorChanged(Color.HSVToColor(mAlpha, new float[] { mHue, mSat, mVal }));
			}

			invalidate();
			return true;
		}

		return super.onTouchEvent(event);
	}

	private boolean moveTrackersIfNeeded(MotionEvent event) {

		if (mStartTouchPoint == null)
			return false;

		boolean update = false;

		int startX = mStartTouchPoint.x;
		int startY = mStartTouchPoint.y;

		if (mHueRect.contains(startX, startY)) {
			mLastTouchedPanel = PANEL_HUE;

			mHue = pointToHue(event.getY());

			update = true;
		} else if (mSatValRect.contains(startX, startY)) {

			mLastTouchedPanel = PANEL_SAT_VAL;

			float[] result = pointToSatVal(event.getX(), event.getY());

			mSat = result[0];
			mVal = result[1];

			update = true;
		} else if (mAlphaRect != null && mAlphaRect.contains(startX, startY)) {

			mLastTouchedPanel = PANEL_ALPHA;

			mAlpha = pointToAlpha((int) event.getX());

			update = true;
		}

		return update;
	}

	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {

		int width = 0;
		int height = 0;

		int widthMode = MeasureSpec.getMode(widthMeasureSpec);
		int heightMode = MeasureSpec.getMode(heightMeasureSpec);

		int widthAllowed = MeasureSpec.getSize(widthMeasureSpec);
		int heightAllowed = MeasureSpec.getSize(heightMeasureSpec);

		widthAllowed = chooseWidth(widthMode, widthAllowed);
		heightAllowed = chooseHeight(heightMode, heightAllowed);

		if (!mShowAlphaPanel) {
			height = (int) (widthAllowed - PANEL_SPACING - HUE_PANEL_WIDTH);

			//If calculated height (based on the width) is more than the allowed height.
			if (height > heightAllowed) {
				height = heightAllowed;
				width = (int) (height + PANEL_SPACING + HUE_PANEL_WIDTH);
			} else {
				width = widthAllowed;
			}
		} else {

			width = (int) (heightAllowed - ALPHA_PANEL_HEIGHT + HUE_PANEL_WIDTH);

			if (width > widthAllowed) {
				width = widthAllowed;
				height = (int) (widthAllowed - HUE_PANEL_WIDTH + ALPHA_PANEL_HEIGHT);
			} else {
				height = heightAllowed;
			}

		}

		setMeasuredDimension(width, height);
	}

	private int chooseWidth(int mode, int size) {
		if (mode == MeasureSpec.AT_MOST || mode == MeasureSpec.EXACTLY) {
			return size;
		} else { // (mode == MeasureSpec.UNSPECIFIED)
			return getPrefferedWidth();
		}
	}

	private int chooseHeight(int mode, int size) {
		if (mode == MeasureSpec.AT_MOST || mode == MeasureSpec.EXACTLY) {
			return size;
		} else { // (mode == MeasureSpec.UNSPECIFIED)
			return getPrefferedHeight();
		}
	}

	private int getPrefferedWidth() {

		int width = getPrefferedHeight();

		if (mShowAlphaPanel) {
			width -= (PANEL_SPACING + ALPHA_PANEL_HEIGHT);
		}

		return (int) (width + HUE_PANEL_WIDTH + PANEL_SPACING);

	}

	private int getPrefferedHeight() {

		int height = (int) (200 * mDensity);

		if (mShowAlphaPanel) {
			height += PANEL_SPACING + ALPHA_PANEL_HEIGHT;
		}

		return height;
	}

	@Override
	protected void onSizeChanged(int w, int h, int oldw, int oldh) {
		super.onSizeChanged(w, h, oldw, oldh);

		mDrawingRect = new RectF();
		mDrawingRect.left = mDrawingOffset + getPaddingLeft();
		mDrawingRect.right = w - mDrawingOffset - getPaddingRight();
		mDrawingRect.top = mDrawingOffset + getPaddingTop();
		mDrawingRect.bottom = h - mDrawingOffset - getPaddingBottom();

		setUpSatValRect();
		setUpHueRect();
		setUpAlphaRect();
	}

	private void setUpSatValRect() {

		final RectF dRect = mDrawingRect;
		float panelSide = dRect.height() - BORDER_WIDTH_PX * 2;

		if (mShowAlphaPanel) {
			panelSide -= PANEL_SPACING + ALPHA_PANEL_HEIGHT;
		}

		float left = dRect.left + BORDER_WIDTH_PX;
		float top = dRect.top + BORDER_WIDTH_PX;
		float bottom = top + panelSide;
		float right = left + panelSide;

		mSatValRect = new RectF(left, top, right, bottom);
	}

	private void setUpHueRect() {
		final RectF dRect = mDrawingRect;

		float left = dRect.right - HUE_PANEL_WIDTH + BORDER_WIDTH_PX;
		float top = dRect.top + BORDER_WIDTH_PX;
		float bottom = dRect.bottom - BORDER_WIDTH_PX - (mShowAlphaPanel ? (PANEL_SPACING + ALPHA_PANEL_HEIGHT) : 0);
		float right = dRect.right - BORDER_WIDTH_PX;

		mHueRect = new RectF(left, top, right, bottom);
	}

	private void setUpAlphaRect() {

		if (!mShowAlphaPanel)
			return;

		final RectF dRect = mDrawingRect;

		float left = dRect.left + BORDER_WIDTH_PX;
		float top = dRect.bottom - ALPHA_PANEL_HEIGHT + BORDER_WIDTH_PX;
		float bottom = dRect.bottom - BORDER_WIDTH_PX;
		float right = dRect.right - BORDER_WIDTH_PX;

		mAlphaRect = new RectF(left, top, right, bottom);

		mAlphaPattern = new AlphaPatternDrawable((int) (5 * mDensity));
		mAlphaPattern.setBounds(Math.round(mAlphaRect.left), Math.round(mAlphaRect.top), Math.round(mAlphaRect.right), Math.round(mAlphaRect.bottom));

	}

	/**
	 * Set a OnColorChangedListener to get notified when the color selected by the
	 * user has changed.
	 * 
	 * @param listener
	 */
	public void setOnColorChangedListener(OnColorChangedListener listener) {
		mListener = listener;
	}

	/**
	 * Set the color of the border surrounding all panels.
	 * 
	 * @param color
	 */
	public void setBorderColor(int color) {
		mBorderColor = color;
		invalidate();
	}

	/**
	 * Get the color of the border surrounding all panels.
	 */
	public int getBorderColor() {
		return mBorderColor;
	}

	/**
	 * Get the current color this view is showing.
	 * 
	 * @return the current color.
	 */
	public int getColor() {
		return Color.HSVToColor(mAlpha, new float[] { mHue, mSat, mVal });
	}

	/**
	 * Set the color the view should show.
	 * 
	 * @param color The color that should be selected.
	 */
	public void setColor(int color) {
		setColor(color, false);
	}

	/**
	 * Set the color this view should show.
	 * 
	 * @param color The color that should be selected.
	 * @param callback If you want to get a callback to your
	 * OnColorChangedListener.
	 */
	public void setColor(int color, boolean callback) {

		int alpha = Color.alpha(color);
		int red = Color.red(color);
		int blue = Color.blue(color);
		int green = Color.green(color);

		float[] hsv = new float[3];

		Color.RGBToHSV(red, green, blue, hsv);

		mAlpha = alpha;
		mHue = hsv[0];
		mSat = hsv[1];
		mVal = hsv[2];

		if (callback && mListener != null) {
			mListener.onColorChanged(Color.HSVToColor(mAlpha, new float[] { mHue, mSat, mVal }));
		}

		invalidate();
	}

	/**
	 * Get the drawing offset of the color picker view. The drawing offset is the
	 * distance from the side of a panel to the side of the view minus the
	 * padding. Useful if you want to have your own panel below showing the
	 * currently selected color and want to align it perfectly.
	 * 
	 * @return The offset in pixels.
	 */
	public float getDrawingOffset() {
		return mDrawingOffset;
	}

	/**
	 * Set if the user is allowed to adjust the alpha panel. Default is false. If
	 * it is set to false no alpha will be set.
	 * 
	 * @param visible
	 */
	public void setAlphaSliderVisible(boolean visible) {

		if (mShowAlphaPanel != visible) {
			mShowAlphaPanel = visible;

			/*
			 * Reset all shader to force a recreation. 
			 * Otherwise they will not look right after 
			 * the size of the view has changed.
			 */
			mValShader = null;
			mSatShader = null;
			mHueShader = null;
			mAlphaShader = null;
			;

			requestLayout();
		}

	}

	public void setSliderTrackerColor(int color) {
		mSliderTrackerColor = color;

		mHueTrackerPaint.setColor(mSliderTrackerColor);

		invalidate();
	}

	public int getSliderTrackerColor() {
		return mSliderTrackerColor;
	}

	/**
	 * Set the text that should be shown in the alpha slider. Set to null to
	 * disable text.
	 * 
	 * @param res string resource id.
	 */
	public void setAlphaSliderText(int res) {
		String text = getContext().getString(res);
		setAlphaSliderText(text);
	}

	/**
	 * Set the text that should be shown in the alpha slider. Set to null to
	 * disable text.
	 * 
	 * @param text Text that should be shown.
	 */
	public void setAlphaSliderText(String text) {
		mAlphaSliderText = text;
		invalidate();
	}

	/**
	 * Get the current value of the text that will be shown in the alpha slider.
	 * 
	 * @return
	 */
	public String getAlphaSliderText() {
		return mAlphaSliderText;
	}
}