Android自定義收音機搜臺控件RadioRulerView

2019-10-23 18:30:55

字體：大中小

來源：轉載

供稿：網友

前言：像這類的自定義控件有非常多的開源項目，但還是沒有找到我項目想要的，所以簡單實現了一個，下面簡單講講實現原理。

效果圖：

Android收音機搜臺控件,Android,RadioRulerView,Android搜臺控件RadioRulerView

實現思路：

首先畫固定背景尺子，而實現這個則要計算刻度線的寬度、刻度線間的距離，以及要確定刻度線的總是，根據這些可以求出第一條刻度線的x坐標，使得整個尺子居中；下圖為尺子尺寸的計算方法：

Android收音機搜臺控件,Android,RadioRulerView,Android搜臺控件RadioRulerView

貼上關鍵代碼：

 /** * 畫固定的尺子 * @param canvas */ private void drawLine(Canvas canvas) {  canvas.save();  int height = mHeight;  int drawCount = 0;//已經畫了刻度線的個數  float xPosition;  for(int i=0; drawCount<=mMaxLineCount; i++){   xPosition = (mLineDivider*mDensity + mLineWidth)*drawCount + mLeftWidth;   if(i%5 == 0 && i%10 != 0){//刻度為5的倍數，但同時不是10的倍數    canvas.drawLine(xPosition,height*0.85f-mPaddingBottom,xPosition,height*0.15f+mPaddingTop,mLinePaint);   }else if(i%10 == 0){//刻度為10的倍數    canvas.drawLine(xPosition,height-mPaddingBottom,xPosition,mPaddingTop,mLinePaint);   }else {//普通的刻度    canvas.drawLine(xPosition,height*0.75f-mPaddingBottom,xPosition,height*0.25f+mPaddingTop,mLinePaint);   }   drawCount++;  }  canvas.restore(); }

然后畫出可以拖動的刻度線（首圖粉紅色線），要實現該功能其實不難，第一種情況：通過在onTouch里面獲取event.getX()坐標，而在這其中用到PointF類來保存x坐標，然后根據x坐標在onDraw()里面繪制即可；第二種情況：自動搜臺，這其實很簡單，開啟子線程每Thread.sleep(200)就累加一定x值即可實現；

最后通過回調把計算好的值傳遞到Activity中，任務完成！

要是不太清楚回調原理的可看我另外一篇博客：Android回調與觀察者模式的實現原理

下面貼上View的源碼：

package com.xhunmon.radiorule;import android.content.Context;import android.content.res.TypedArray;import android.graphics.Canvas;import android.graphics.Paint;import android.graphics.PointF;import android.util.AttributeSet;import android.util.SparseArray;import android.view.MotionEvent;import android.view.View;/** * user: uidq0530 ,date: 2017-04-16. * description：收音機FM搜臺尺子 * * @author xhunmon */public class RadioRulerView extends View { private static final String tag = "RadioRulerView"; private int mHeight; //view的高度 private int mWidth;  //view的寬度 private Paint mLinePaint; //固定的尺子畫筆 private int mLineWidth;//尺子刻度線的寬 private int mLineColor;//固定尺子刻度線的顏色 private int mMoveLineColor;//移動尺子刻度線的顏色 private float mDensity; private int mLineDivider; //兩條刻度線間的距離 private float mLeftWidth; //尺子離view左邊的距離 private int mMaxLineCount = 220; //總共要畫多少條刻度 private Paint mMoveLinePaint; //移動尺子的畫筆 private int mValue;  //尺子被選中的值 private float mMaxX; //onTouch中能觸摸的最大x值 private float mMinX; //onTouch中能觸摸的最小x值 private OnValueChangeListener mListener; private SparseArray<PointF> activePointers; private PointF xPoint; private int mPaddingBottom; private int mPaddingTop; private boolean mIsAuto = false; public RadioRulerView(Context context) {  this(context,null); } public RadioRulerView(Context context, AttributeSet attrs) {  this(context, attrs,0); } public RadioRulerView(Context context, AttributeSet attrs, int defStyleAttr) {  this(context, attrs, defStyleAttr,0); } public RadioRulerView(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) {  super(context, attrs, defStyleAttr, defStyleRes);  mDensity = context.getResources().getDisplayMetrics().density;  TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.RadioRulerView, defStyleAttr, defStyleRes);  mLineWidth = (int) a.getDimension(R.styleable.RadioRulerView_line_width,5*mDensity);  mLineDivider = (int) a.getDimension(R.styleable.RadioRulerView_line_divider,15*mDensity);  mLineColor = a.getColor(R.styleable.RadioRulerView_line_color,0xff888888);  mMoveLineColor = a.getColor(R.styleable.RadioRulerView_move_line_color,0xffff0000);  a.recycle();  init(); } private void init() {  activePointers = new SparseArray<>();  mLinePaint = new Paint();  mLinePaint.setAntiAlias(true);  mLinePaint.setColor(mLineColor);  mLinePaint.setStrokeWidth(mLineWidth);  mLinePaint.setStyle(Paint.Style.STROKE);  mMoveLinePaint = new Paint();  mMoveLinePaint.setAntiAlias(true);  mMoveLinePaint.setColor(mMoveLineColor);  mMoveLinePaint.setStrokeWidth(mLineWidth);  mMoveLinePaint.setStyle(Paint.Style.STROKE); } //此方法在view的尺寸確定后調用 @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) {  super.onSizeChanged(w, h, oldw, oldh);  mHeight = getHeight();  mWidth = getWidth();  mPaddingBottom = getPaddingBottom();  mPaddingTop = getPaddingTop();  mLeftWidth = (mWidth - mMaxLineCount*(mLineWidth +mLineDivider))/2;  mMaxX = mMaxLineCount*(mLineWidth +mLineDivider) + mLeftWidth;  mMinX = mLeftWidth; } @Override protected void onDraw(Canvas canvas) {  super.onDraw(canvas);  drawLine(canvas);  drawMoveLine(canvas); } /**  * 畫固定的尺子  * @param canvas  */ private void drawLine(Canvas canvas) {  canvas.save();  int height = mHeight;  int drawCount = 0;//已經畫了刻度線的個數  float xPosition;  for(int i=0; drawCount<=mMaxLineCount; i++){   xPosition = (mLineDivider*mDensity + mLineWidth)*drawCount + mLeftWidth;   if(i%5 == 0 && i%10 != 0){//刻度為5的倍數，但同時不是10的倍數    canvas.drawLine(xPosition,height*0.85f-mPaddingBottom,xPosition,height*0.15f+mPaddingTop,mLinePaint);   }else if(i%10 == 0){//刻度為10的倍數    canvas.drawLine(xPosition,height-mPaddingBottom,xPosition,mPaddingTop,mLinePaint);   }else {//普通的刻度    canvas.drawLine(xPosition,height*0.75f-mPaddingBottom,xPosition,height*0.25f+mPaddingTop,mLinePaint);   }   drawCount++;  }  canvas.restore(); } /**  * 搜索FM頻道的刻度線  * @param canvas  */ private void drawMoveLine(Canvas canvas) {  canvas.save();  xPoint = activePointers.valueAt(0);  if (xPoint != null) {   canvas.drawLine(xPoint.x,mHeight-mPaddingBottom, xPoint.x,mPaddingTop,mMoveLinePaint);   setValue(eventXValue(xPoint.x));  }else {   canvas.drawLine(mMinX,mHeight-mPaddingBottom, mMinX,mPaddingTop,mMoveLinePaint);  }  canvas.restore(); } @Override public boolean onTouchEvent(MotionEvent event) {  int pointerIndex = event.getActionIndex();  int pointerId = event.getPointerId(pointerIndex);  switch (event.getActionMasked()) {   case MotionEvent.ACTION_DOWN:   case MotionEvent.ACTION_POINTER_DOWN: {    float downX = event.getX(pointerIndex);    if(downX > mMaxX || downX < mMinX) break;    PointF position = new PointF(downX, event.getY(pointerIndex));    activePointers.put(pointerId, position);    break;   }   case MotionEvent.ACTION_MOVE: {    int pointerCount = event.getPointerCount();    for (int i = 0; i < pointerCount; i++) {     PointF point = activePointers.get(event.getPointerId(i));     if (point == null) continue;     float moveX = event.getX(i);     if(moveX > mMaxX || moveX < mMinX) break;     point.x = event.getX(i);     point.y = event.getY(i);    }    break;   }   case MotionEvent.ACTION_UP:   case MotionEvent.ACTION_POINTER_UP:   case MotionEvent.ACTION_CANCEL: {    int pointerCount = event.getPointerCount();    PointF point = activePointers.get(event.getPointerId(pointerCount-1));    if (point == null) break;    float upX = event.getX(pointerCount-1);    if(upX > mMaxX || upX < mMinX) break;    point.x = eventXValue(event.getX(pointerCount-1));    point.y = event.getY(pointerCount-1);    break;   }  }  invalidate();  return true; } /**  *作用：使得放手后MoveLine和Line重合；精確mValue  * @param x onTouch中的event.getX()  * @return  */ public int eventXValue(float x){  mLineDivider = (int) (mLineDivider*mDensity);  return (int) ((x-mLeftWidth)%(mLineWidth +mLineDivider)>((mLineWidth +mLineDivider)/2)      ? (((mLineWidth +mLineDivider)*((int)((x-mLeftWidth)/(mLineWidth +mLineDivider))+1))+mLeftWidth)      : (((mLineWidth +mLineDivider)*((int)((x-mLeftWidth)/(mLineWidth +mLineDivider))))+mLeftWidth)); } /**  * 設置最大刻度線個數  * @param count  */ public void setMaxLineCount(int count) {  mMaxLineCount = count; } /**  * 設置是否啟用自動搜索功能  * @param isAuto  */ public void setAutoSearchFM(boolean isAuto){  this.mIsAuto = isAuto; } /**  * 開始自動搜臺  */ public void startAutoSeachFM(){  if(mIsAuto)   new Thread(new SeachThread()).start(); } /**  * 搜臺要在開啟子線程  */ private class SeachThread implements Runnable{  @Override  public void run() {   while(mIsAuto){    xPoint = activePointers.valueAt(0);    if(xPoint != null){     xPoint.x += (mLineWidth + mLineDivider);     if(xPoint.x > mMaxX) xPoint.x = mLeftWidth;    }else {     PointF position = new PointF(mLeftWidth, mHeight);     activePointers.put(0, position);    }    try {     Thread.sleep(200);    } catch (InterruptedException e) {     e.printStackTrace();    }    postInvalidate();   }  } } /*****************************值傳遞的回調*************************************/ public interface OnValueChangeListener {  void onValueChange(float value); } public void setOnValueChangeListener(OnValueChangeListener listener){  mListener = listener; } private void setValue(float value) {  if(mListener != null){   mValue = (int) ((value - mLeftWidth)/(mLineDivider*mDensity + mLineWidth));   //FM的范圍從88.0 ~ 108.0   mListener.onValueChange(mValue/10f + 88);  } } /******************************************************************/}

貼上Activity代碼：

package com.xhunmon.radiorule;import android.app.Activity;import android.os.Bundle;import android.view.View;import android.widget.Button;import android.widget.CheckBox;import android.widget.CompoundButton;import android.widget.TextView;public class MainActivity extends Activity implements RadioRulerView.OnValueChangeListener,  CompoundButton.OnCheckedChangeListener, View.OnClickListener { private TextView mShow; private RadioRulerView mRule; private CheckBox mCbAuto; private Button mBtStart; @Override protected void onCreate(Bundle savedInstanceState) {  super.onCreate(savedInstanceState);  setContentView(R.layout.activity_main);  mShow = (TextView) findViewById(R.id.tv);  mRule = (RadioRulerView) findViewById(R.id.rule);  mCbAuto = (CheckBox) findViewById(R.id.cb_auto);  mBtStart = (Button) findViewById(R.id.bt_start);  mRule.setMaxLineCount(200);//FM從88.0 ~ 108.0總共有200頻道  mRule.setOnValueChangeListener(this);  mCbAuto.setOnCheckedChangeListener(this);  mBtStart.setOnClickListener(this); } @Override public void onValueChange(float value) {  mShow.setText("FM："+value); } @Override public void onCheckedChanged(CompoundButton buttonView, boolean isChecked) {  if(isChecked){   mRule.setAutoSearchFM(true);  }else {   mRule.setAutoSearchFM(false);  } } @Override public void onClick(View v) {  if(v.getId() == R.id.bt_start){   mRule.startAutoSeachFM();  } }}

整個項目都放在github上面了，歡迎做客與討論：
https://github.com/xhunmon/RadioRule

以上就是本文的全部內容，希望對大家的學習有所幫助，也希望大家多多支持VEVB武林網。

注：相關教程知識閱讀請移步到Android開發頻道。

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