Android 实现颜色选取圆盘

先看效果图

xml布局

ColorPickerView颜色选取圆盘

package com.myview;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PointF;
import android.graphics.drawable.BitmapDrawable;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.widget.ImageView;

public class ColorPickerView extends ImageView {
	Context context;
	private Bitmap iconBitMap;
	float iconRadius;// 吸管圆的半径
	float iconCenterX;
	float iconCenterY;
	PointF iconPoint;// 点击位置坐标

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

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

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

	Paint mBitmapPaint;
	Bitmap imageBitmap;
	float viewRadius;// 整个view半径
	float radius;// 图片半径

	/**
	 * 初始化画笔
	 */
	private void init() {
		iconBitMap = BitmapFactory.decodeResource(context.getResources(),
				R.drawable.pickup);// 吸管的图片
		iconRadius = iconBitMap.getWidth() / 2;// 吸管的图片一半

		mBitmapPaint = new Paint();
		iconPoint = new PointF();

		imageBitmap = ((BitmapDrawable) getDrawable()).getBitmap();
		radius = imageBitmap.getHeight() / 2;// 图片半径

		// // 初始化
		iconPoint.x = radius;
		iconPoint.y = radius;

	}

	@Override
	protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
		// TODO Auto-generated method stub
		super.onMeasure(widthMeasureSpec, heightMeasureSpec);
	}

	Canvas canvas;

	@Override
	protected void onDraw(Canvas canvas) {
		// TODO Auto-generated method stub
		super.onDraw(canvas);
		this.canvas = canvas;

		viewRadius = this.getWidth() / 2;// 整个view半径

		canvas.drawBitmap(iconBitMap, iconPoint.x - iconRadius, iconPoint.y
				- iconRadius, mBitmapPaint);
	}

	@SuppressLint("ClickableViewAccessibility")
	@Override
	public boolean onTouchEvent(MotionEvent event) {
		float x = event.getX();
		float y = event.getY();
		int pixel;
		int r;
		int g;
		int b;
		switch (event.getAction()) {
		case MotionEvent.ACTION_MOVE:
			proofLeft(x, y);
			pixel = getImagePixel(iconPoint.x, iconPoint.y);
			r = Color.red(pixel);
			g = Color.green(pixel);
			b = Color.blue(pixel);
			if (mChangedListener != null) {
				mChangedListener.onMoveColor(r, g, b);
			}
			if (isMove) {
				isMove = !isMove;
				invalidate();
			}
			break;
		case MotionEvent.ACTION_UP:
			pixel = getImagePixel(iconPoint.x, iconPoint.y);
			r = Color.red(pixel);
			g = Color.green(pixel);
			b = Color.blue(pixel);
			if (mChangedListener != null) {
				mChangedListener.onColorChanged(r, g, b);
			}
			break;

		default:
			break;
		}
		return true;
	}

	public int getImagePixel(float x, float y) {

		Bitmap bitmap = imageBitmap;
		// 为了防止越界
		int intX = (int) x;
		int intY = (int) y;
		if (intX < 0)
			intX = 0;
		if (intY < 0)
			intY = 0;
		if (intX >= bitmap.getWidth()) {
			intX = bitmap.getWidth() - 1;
		}
		if (intY >= bitmap.getHeight()) {
			intY = bitmap.getHeight() - 1;
		}
		int pixel = bitmap.getPixel(intX, intY);
		return pixel;

	}

	/**
	 * R = sqrt(x * x + y * y)
	 * point.x = x * r / R + r
	 * point.y = y * r / R + r
	 */
	private void proofLeft(float x, float y) {

		float h = x - viewRadius; // 取xy点和圆点 的三角形宽
		float w = y - viewRadius;// 取xy点和圆点 的三角形长
		float h2 = h * h;
		float w2 = w * w;
		float distance = (float) Math.sqrt((h2 + w2)); // 勾股定理求 斜边距离
		if (distance > radius) { // 如果斜边距离大于半径，则取点和圆最近的一个点为x,y
			float maxX = x - viewRadius;
			float maxY = y - viewRadius;
			x = ((radius * maxX) / distance) + viewRadius; // 通过三角形一边平行原理求出x,y
			y = ((radius * maxY) / distance) + viewRadius;
		}
		iconPoint.x = x;
		iconPoint.y = y;

		isMove = true;
	}

	boolean isMove;

	public void setOnColorChangedListenner(OnColorChangedListener l) {
		this.mChangedListener = l;
	}

	private OnColorChangedListener mChangedListener;

	// 内部接口 回调颜色 rgb值
	public interface OnColorChangedListener {
		// 手指抬起，确定颜色回调
		void onColorChanged(int r, int g, int b);

		// 移动时颜色回调
		void onMoveColor(int r, int g, int b);
	}
}

MyViewActivity主界面

package com.myview;

import com.myview.ColorPickerView.OnColorChangedListener;

import android.app.Activity;
import android.os.Bundle;
import android.widget.TextView;
import android.widget.Toast;

public class MyViewActivity extends Activity {
	
	TextView tv_rgb;
	
    /** Called when the activity is first created. */
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
        
        tv_rgb=(TextView)this.findViewById(R.id.tv_rgb);
        
        ColorPickerView cpv=(ColorPickerView)this.findViewById(R.id.cpv);
		cpv.setOnColorChangedListenner(new OnColorChangedListener() {
			/**
			 * 手指抬起，选定颜色时
			 */
			@Override
			public void onColorChanged(int r, int g, int b) {
				if(r==0 && g==0 && b==0){
					return;
				}
				Toast.makeText(MyViewActivity.this, "选取 RGB:"+r+","+g+","+b, Toast.LENGTH_SHORT).show();
			}

			/**
			 * 颜色移动的时候
			 */
			@Override
			public void onMoveColor(int r, int g, int b) {
				if(r==0 && g==0 && b==0){
					return;
				}
				tv_rgb.setText("RGB:"+r+","+g+","+b);
			}
		});
    }
}

详细项目代码：

http://download.csdn.net/detail/zhengjingle/9460618