Android实现颜色选取圆盘

<?xml version="1.0" encoding="utf-8"?  
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
 android:orientation="vertical" 
 android:layout_width="fill_parent" 
 android:layout_height="fill_parent" 
   
<TextView 
 android:layout_width="fill_parent" 
 android:layout_height="wrap_content" 
 android:text="@string/hello" 
 android:id="@+id/tv_rgb"/  
<RelativeLayout android:id="@+id/relativeLayout1" android:layout_height="fill_parent" android:layout_width="fill_parent"  
 
 <com.myview.ColorPickerView 
  android:id="@+id/cpv" 
  android:layout_width="230dp" 
  android:layout_height="230dp" 
  android:layout_centerInParent="true" 
  android:scaleType="center" 
  android:src="@drawable/rgb" /  
 
</RelativeLayout  
</LinearLayout  

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); 
} 
} 

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); 
} 
}); 
} 
}