Android颜色全解析

​ 颜色对照表：https://blog.****.net/lm_zp/article/details/51381355

颜色表示方法

​ Android颜色由16进制表示，颜色范围为0~FFFFFF。
​ 颜色值：#AARRGGBB。透明度（A，alpha）；红色（R，red）；绿色（G，green）；蓝色（B，blue

颜色值透明度百分比和十六进制对应关系

//变化为线性变化，因此可以公式概括
//将int值转换为16进制即可
int finalAA = 255 - 255/100 * 透明度；	

透明度	十六进制
0%	0
…	…
100%	FF

代码中颜色的设置与使用

在xml中设置与使用

1、color.xml中设置
 <color name="colorPrimary">#008577</color>	//表示方法：#AARRGGBB
 2、使用
 int color1 = getResources().getColor(R.color.colorPrimary);
 if (android.os.Build.VERSION.SDK_INT >= android.os.Build.VERSION_CODES.M) {
 	int color2 = getColor(R.color.colorPrimary);
 }
 int color3 = ContextCompat.getColor(this,R.color.colorPrimary);

在java代码中设置与使用

int color1 = 0xff555555;
int color2 = Color.RED;
int color3 = Color.red(0x12345);
int color4 = Color.rgb(0xFF,0xFF,0xFF);
int color5 = Color.argb(0xFF,0xFF,0xFF,0xFF);

Android中常用颜色格式解析

​ 常用颜色格式：ARGB_8888、ARGB_4444、RGB_565、ALPHA_8

颜色格式	占用字节数	备注
ARGB_8888	4	ARGB均占一个字节
ARGB_4444	2	ARGB均占半个字节
RGB_565	2	R：5bit，G：6bit，B：5bit，综合16bit
ALPHA_8	1	A：8bit

图片大小计算方式

​ 大小 = 像素点数 * 每个像素点占用的字节大小 = 长 * 宽 * 各模式下对应的像素点占用的字节数
​ 如一张100*100，ARGB_8888格式的图片占用内存为：100 * 100 * 4 byte

颜色模型换算

​ 颜色模型：RGB，HSV
​ RGB：透明度（A，alpha）；红色（R，red）；绿色（G，green）；蓝色（B，blue）
​ HSV：色调（H, Hue，0 ~ 360），饱和度（S,Saturation，0% - 100%），明度（V, Value，0% - 100%）

软件	参数	取值范围
	H	0 ~ 360
PS	S	0 - 1（0% - 100%）
	V	0 - 1（0% - 100%）
	H	0 - 360
利用openCV中cvSplit函数在选择图像IPL_DEPTH_32F类型	S	0 - 1（0% - 100%）
	V	0 - 1（0% - 100%）
	H	0-180
利用openCV中cvSplit函数在选择图像IPL_DEPTH_8UC类型	S	0-255
	V	0-255

RGB转HSV

公式

代码：https://blog.****.net/hanshanbuleng/article/details/80383813

选择器案例

public class ColorPickerView extends View {
    private float[] colorHSV = new float[]{0f, 1f, 1f};
    private Paint colorWheelPaint;
    private Paint touchCirclePaint;
    private int radius;
    private int touchCircleX;
    private int touchCircleY;

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

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

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

    private void init(Context context) {
        setLayerType(LAYER_TYPE_SOFTWARE, null);
        //大圆
        colorWheelPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        //小圆
        touchCirclePaint = new Paint(Paint.ANTI_ALIAS_FLAG);
        touchCirclePaint.setStyle(Paint.Style.STROKE);
        touchCirclePaint.setColor(Color.WHITE);
    }

    @Override
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        int widthSpecMode = MeasureSpec.getMode(widthMeasureSpec);
        int heightSpecMode = MeasureSpec.getMode(heightMeasureSpec);
        int widthSpecSize = MeasureSpec.getSize(widthMeasureSpec);
        int heightSpecSize = MeasureSpec.getSize(heightMeasureSpec);
        //处理 wrap_content问题
        int defaultDimension = dip2px(200);
        if (widthSpecMode == MeasureSpec.AT_MOST && heightSpecMode == MeasureSpec.AT_MOST) {
            setMeasuredDimension(defaultDimension, defaultDimension);
        } else if (widthSpecMode == MeasureSpec.AT_MOST) {
            setMeasuredDimension(defaultDimension, heightSpecSize);
        } else if (heightSpecMode == MeasureSpec.AT_MOST) {
            setMeasuredDimension(widthSpecSize, defaultDimension);
        }
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
        radius = Math.min(w / 2, h / 2);
        createColorWheel();
    }

    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawCircle(getWidth(), getHeight(), radius, colorWheelPaint);
        canvas.drawCircle(touchCircleX, touchCircleY, 10, touchCirclePaint);
    }

    //设置大圆渐变颜色
    private void createColorWheel() {
        int colorCount = 12;
        int colorAngleStep = 360 / 12;
        int colors[] = new int[colorCount];
        float hsv[] = new float[]{0f, 1f, 1f};
        for (int i = 0; i < colors.length; i++) {
            hsv[0] = (i * colorAngleStep + 180) % 360;
            colors[i] = Color.HSVToColor(hsv);
        }
        SweepGradient sweepGradient = new SweepGradient(getWidth(), getHeight(), colors, null);
        RadialGradient radialGradient = new RadialGradient(getWidth(), getHeight(),
                radius, 0xFFFFFFFF, 0x00FFFFFF, Shader.TileMode.CLAMP);
        ComposeShader composeShader = new ComposeShader(sweepGradient, radialGradient, PorterDuff.Mode.SRC_OVER);
        colorWheelPaint.setShader(composeShader);
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        ViewParent parent = getParent();
        if (parent != null)
            parent.requestDisallowInterceptTouchEvent(true);
        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
            case MotionEvent.ACTION_MOVE:
                int cx = (int) (event.getX() - getWidth());
                int cy = (int) (event.getY() - getHeight());
                double d = Math.sqrt(cx * cx + cy * cy);
                if (d <= radius) {
                    //如果在大圆内
                    colorHSV[0] = (float) (Math.toDegrees(Math.atan2(cy, cx)) + 180f);
                    colorHSV[1] = Math.max(0f, Math.min(1f, (float) (d / radius)));
                    //更新touchCircle的圆心点坐标
                    touchCircleY = (int) event.getY();
                    touchCircleX = (int) event.getX();
                    postInvalidate();
                }
                break;
            case MotionEvent.ACTION_UP:
                break;
        }
        return true;
    }

    /**
     * @param color 0~360
     */
    public void setHSVColor(int color) {
        colorHSV[0] = color;
        colorWheelPaint.setColor(Color.HSVToColor(colorHSV));
        postInvalidate();
    }

    /**
     * @param value 0~1.0
     */
    public void setHSVValue(float value) {
        colorHSV[2] = value;
        colorWheelPaint.setColor(Color.HSVToColor(colorHSV));
        postInvalidate();
    }

    /**
     * @param saturation 0~1.0
     */
    public void setHSVSaturation(float saturation) {
        colorHSV[1] = saturation;
        colorWheelPaint.setColor(Color.HSVToColor(colorHSV));
        postInvalidate();
    }

    public void setColor(int color) {
        Color.colorToHSV(color, colorHSV);
    }

    public int getColor() {
        return Color.HSVToColor(colorHSV);
    }

    public int dip2px(float dpValue) {
        final float scale = getResources().getDisplayMetrics().density;
        return (int) (dpValue * scale + 0.5f);
    }
}