Api Demo - .graphics(14)

package com.example.android.apis.graphics;

import android.os.Bundle;
import android.app.Dialog;
import android.content.Context;
import android.graphics.*;
import android.view.MotionEvent;
import android.view.View;

public class ColorPickerDialog extends Dialog {

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

    private OnColorChangedListener mListener;
    private int mInitialColor;

    private static class ColorPickerView extends View {
        private Paint mPaint;
        private Paint mCenterPaint;
        private final int[] mColors;
        private OnColorChangedListener mListener;
        
        ColorPickerView(Context c, OnColorChangedListener 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);//环形渐变，第1，2参数指定渐变中心；
            
            mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);//该画笔用来绘制外部圆环。
            mPaint.setShader(s);//环形渐变灰覆盖掉画笔颜色。
            mPaint.setStyle(Paint.Style.STROKE);
            mPaint.setStrokeWidth(32);
            
            mCenterPaint = new Paint(Paint.ANTI_ALIAS_FLAG);//该画笔用来绘制内圆。内圆点亮时显示。
            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;//外圆环的半径（减去画笔1/2宽度)。
            
            canvas.translate(CENTER_X, CENTER_X);//平移画布
            
            canvas.drawOval(new RectF(-r, -r, r, r), mPaint);    //画外间圆环。        
            canvas.drawCircle(0, 0, CENTER_RADIUS, mCenterPaint);//画内圆
            
            if (mTrackingCenter) {//当触摸状态为移动时
                int c = mCenterPaint.getColor();//取当前内圆颜色
                mCenterPaint.setStyle(Paint.Style.STROKE);//画笔设为描边风格
                
                if (mHighlightCenter) {//当移动范围在内圆上时
                    mCenterPaint.setAlpha(0xFF);//中间圆环透明度为100%
                } else {
                    mCenterPaint.setAlpha(0x80);//中间圆环透明度为80%
                }
                canvas.drawCircle(0, 0,
                                  CENTER_RADIUS + mCenterPaint.getStrokeWidth(),
                                  mCenterPaint);
                
                mCenterPaint.setStyle(Paint.Style.FILL);//画完中间圆环将画笔风格还原。
                mCenterPaint.setColor(c);//画完中间圆环将画笔颜色还原。
            }
        }
        
        @Override
        protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
            setMeasuredDimension(CENTER_X*2, CENTER_Y*2);//设定View尺寸为宽高2倍
        }
        
        private static final int CENTER_X = 100;
        private static final int CENTER_Y = 100;
        private static final int CENTER_RADIUS = 32;

        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 ave(int s, int d, float p) {//修正色值
            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;//确定颜色位于mColor数组7个元素分成的6个区间的哪一个。
            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);//在颜色区间内分别取该点颜色A,R,G,B。
            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 rotateColor(int color, float rad) {//利用ColorMatrix取色
            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;//是否落在内圆
            
            switch (event.getAction()) {
                case MotionEvent.ACTION_DOWN:
                    mTrackingCenter = inCenter;//如果触摸落点在内圆里，则为确认模式，否则为取色模式。
                    if (inCenter) {
                        mHighlightCenter = true;//如果触摸落点在内圆里，则显示中间圆环。
                        invalidate();
                        break;
                    }
                case MotionEvent.ACTION_MOVE:
                    if (mTrackingCenter) {//如果为确认模式，
                        if (mHighlightCenter != inCenter) {
                            mHighlightCenter = inCenter;
                            invalidate();
                        }
                    } else {//如果为选色模式
                        float angle = (float)java.lang.Math.atan2(y, x);//反正切求圆心角度
                        // 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));//取色；
                        invalidate();
                    }
                    break;
                case MotionEvent.ACTION_UP:
                    if (mTrackingCenter) {
                        if (inCenter) {
                            mListener.colorChanged(mCenterPaint.getColor());
                        }
                        mTrackingCenter = false;    // so we draw w/o halo
                        invalidate();
                    }
                    break;
            }
            return true;
        }
    }

    public ColorPickerDialog(Context context,
                             OnColorChangedListener listener,
                             int initialColor) {
        super(context);
        
        mListener = listener;
        mInitialColor = initialColor;
    }

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        OnColorChangedListener l = new OnColorChangedListener() {//设置颜色监听
            public void colorChanged(int color) {
                mListener.colorChanged(color);
                dismiss();
            }
        };

        setContentView(new ColorPickerView(getContext(), l, mInitialColor));
        setTitle("Pick a Color");
    }
}