今天我做的是一個自定義刻度尺控件，由于項目需求需要使用刻度尺那樣滑動選擇，由于對自定義控件的認識還不夠深入，于是花了一周多時間才把這個控件給整出來，也是嘔心瀝血的經歷啊，也讓我對自定義控件有了自己的認識，廢話不多說，先上一個簡單的效果圖，大家可以看看，如有需求可以直接拿去使用

效果圖如下：只是我的一個簡單Demo，效果有點丑陋了點，希望海涵！

效果已經出來接下來就是代碼部分了，一看就只是一般的控件很難實現，于是就開始了我的自定義View之旅，每次自定義完后總是會收獲很多東西，如下是我的代碼：

package android.tst.com.myapplication; import android.annotation.SuppressLint;import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.text.Layout;import android.text.TextPaint;import android.util.AttributeSet;import android.view.MotionEvent;import android.view.VelocityTracker;import android.view.View;import android.view.ViewConfiguration;import android.widget.Scroller; /** * 卷尺控件類。由于時間比較緊，只有下班后有時間，因此只實現了基本功能。<br> * 細節問題包括滑動過程中widget邊緣的刻度顯示問題等<br> * @version create：2014年8月26日 */@SuppressLint('ClickableViewAccessibility')public class RulerView extends View { public interface OnValueChangeListener { public void onValueChange(float value); } public static final int MOD_TYPE_HALF = 2; public static final int MOD_TYPE_ONE = 10; private static final int ITEM_HALF_DIVIDER = 10; private static final int ITEM_ONE_DIVIDER = 10; private static final int ITEM_MAX_HEIGHT = 20; private static final int ITEM_MIN_HEIGHT = 10; private static final int TEXT_SIZE = 7; private float mDensity; private int mValue = 50, mMaxValue = 100, mModType = MOD_TYPE_HALF, mLineDivider = ITEM_HALF_DIVIDER; // private int mValue = 50, mMaxValue = 500, mModType = MOD_TYPE_ONE, // mLineDivider = ITEM_ONE_DIVIDER; private int mLastX, mMove; private int mWidth, mHeight; private int mMinVelocity; private Scroller mScroller; private VelocityTracker mVelocityTracker; private OnValueChangeListener mListener; @SuppressWarnings('deprecation') public RulerView(Context context, AttributeSet attrs) { super(context, attrs); mScroller = new Scroller(getContext()); mDensity = getContext().getResources().getDisplayMetrics().density; mMinVelocity = ViewConfiguration.get(getContext()) .getScaledMinimumFlingVelocity(); } /** * * 考慮可擴展，但是時間緊迫，只可以支持兩種類型效果圖中兩種類型 * * @param value * 初始值 * @param maxValue * 最大值 * @param model * 刻度盤精度：<br> * {@link MOD_TYPE_HALF}<br> * {@link MOD_TYPE_ONE}<br> */ public void initViewParam(int defaultValue, int maxValue, int model) { switch (model) { case MOD_TYPE_HALF: mModType = MOD_TYPE_HALF; mLineDivider = ITEM_HALF_DIVIDER; mValue = defaultValue * 2; mMaxValue = maxValue * 2; break; case MOD_TYPE_ONE: mModType = MOD_TYPE_ONE; mLineDivider = ITEM_ONE_DIVIDER; mValue = defaultValue; mMaxValue = maxValue; break; default: break; } invalidate(); mLastX = 0; mMove = 0; notifyValueChange(); } /** * 設置用于接收結果的監聽器 * * @param listener */ public void setValueChangeListener(OnValueChangeListener listener) { mListener = listener; } /** * 獲取當前刻度值 * * @return */ public float getValue() { return mValue; } public void setValue(int value){ mValue = value; notifyValueChange(); postInvalidate(); } public void setValueToChange(int what) { mValue += what; notifyValueChange(); postInvalidate(); } @Override protected void onLayout(boolean changed, int left, int top, int right, int bottom) { mWidth = getWidth(); mHeight = getHeight(); super.onLayout(changed, left, top, right, bottom); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); drawScaleLine(canvas); // drawWheel(canvas); drawMiddleLine(canvas); } /** * 從中間往兩邊開始畫刻度線 * * @param canvas */ private void drawScaleLine(Canvas canvas) { canvas.save(); Paint linePaint = new Paint(); linePaint.setStrokeWidth(2); linePaint.setColor(Color.rgb(141, 189, 225)); TextPaint textPaint = new TextPaint(Paint.ANTI_ALIAS_FLAG); textPaint.setColor(Color.rgb(68, 135, 188)); textPaint.setTextSize(TEXT_SIZE * mDensity); int width = mWidth, drawCount = 0; float xPosition = 0, textWidth = Layout.getDesiredWidth('0', textPaint); for (int i = 0; drawCount <= 4 * width; i++) { int numSize = String.valueOf(mValue + i).length(); // 前 xPosition = (width / 2 - mMove) + i * mLineDivider * mDensity; if (xPosition + getPaddingRight() < mWidth) { if ((mValue + i) % mModType == 0) { linePaint.setColor(Color.rgb(68, 135, 188)); canvas.drawLine(xPosition, getPaddingTop(), xPosition, mDensity * ITEM_MAX_HEIGHT, linePaint); if (mValue + i <= mMaxValue) { switch (mModType) { case MOD_TYPE_HALF: canvas.drawText( String.valueOf((mValue + i) / 2), countLeftStart(mValue + i, xPosition, textWidth), getHeight() - textWidth, textPaint); break; case MOD_TYPE_ONE: canvas.drawText(String.valueOf(mValue + i), xPosition - (textWidth * numSize / 2), getHeight() - textWidth, textPaint); break; default: break; } } } else { linePaint.setColor(Color.rgb(141, 189, 225)); // linePaint.setColor(Color.rgb(68, 135, 188)); canvas.drawLine(xPosition, getPaddingTop(), xPosition, mDensity * ITEM_MIN_HEIGHT, linePaint); } } // 后 xPosition = (width / 2 - mMove) - i * mLineDivider * mDensity; if (xPosition > getPaddingLeft()) { if ((mValue - i) % mModType == 0) { linePaint.setColor(Color.rgb(68, 135, 188)); canvas.drawLine(xPosition, getPaddingTop(), xPosition, mDensity * ITEM_MAX_HEIGHT, linePaint); if (mValue - i >= 0) { switch (mModType) { case MOD_TYPE_HALF: canvas.drawText( String.valueOf((mValue - i) / 2), countLeftStart(mValue - i, xPosition, textWidth), getHeight() - textWidth, textPaint); break; case MOD_TYPE_ONE: canvas.drawText(String.valueOf(mValue - i), xPosition - (textWidth * numSize / 2), getHeight() - textWidth, textPaint); break; default: break; } } } else { linePaint.setColor(Color.rgb(141, 189, 225)); canvas.drawLine(xPosition, getPaddingTop(), xPosition, mDensity * ITEM_MIN_HEIGHT, linePaint); } } drawCount += 2 * mLineDivider * mDensity; } canvas.restore(); } /** * 計算沒有數字顯示位置的輔助方法 * * @param value * @param xPosition * @param textWidth * @return */ private float countLeftStart(int value, float xPosition, float textWidth) { float xp = 0f; if (value < 20) { xp = xPosition - (textWidth * 1 / 2); } else { xp = xPosition - (textWidth * 2 / 2); } return xp; } /** * 畫中間的紅色指示線、陰影等。指示線兩端簡單的用了兩個矩形代替 * * @param canvas */ private void drawMiddleLine(Canvas canvas) { // TOOD 常量太多，暫時放這，最終會放在類的開始，放遠了怕很快忘記 int gap = 12, indexWidth = 2, indexTitleWidth = 24, indexTitleHight = 10, shadow = 6; String color = '#66999999'; canvas.save(); Paint redPaint = new Paint(); redPaint.setStrokeWidth(indexWidth); redPaint.setColor(Color.RED); canvas.drawLine(mWidth / 2, 0, mWidth / 2, mHeight, redPaint); canvas.restore(); } @Override public boolean onTouchEvent(MotionEvent event) { int action = event.getAction(); int xPosition = (int) event.getX(); if (mVelocityTracker == null) { mVelocityTracker = VelocityTracker.obtain(); } mVelocityTracker.addMovement(event); switch (action) { case MotionEvent.ACTION_DOWN: mScroller.forceFinished(true); mLastX = xPosition; mMove = 0; break; case MotionEvent.ACTION_MOVE: getParent().requestDisallowInterceptTouchEvent(true); mMove += (mLastX - xPosition); changeMoveAndValue(); break; case MotionEvent.ACTION_UP: case MotionEvent.ACTION_CANCEL: countMoveEnd(); countVelocityTracker(event); getParent().requestDisallowInterceptTouchEvent(false); return false; // break; default: break; } mLastX = xPosition; return true; } private void countVelocityTracker(MotionEvent event) { mVelocityTracker.computeCurrentVelocity(1000); float xVelocity = mVelocityTracker.getXVelocity(); if (Math.abs(xVelocity) > mMinVelocity) { mScroller.fling(0, 0, (int) xVelocity, 0, Integer.MIN_VALUE, Integer.MAX_VALUE, 0, 0); } } private void changeMoveAndValue() { int tValue = (int) (mMove / (mLineDivider * mDensity)); if (Math.abs(tValue) > 0) { mValue += tValue; mMove -= tValue * mLineDivider * mDensity; if (mValue <= 0 || mValue > mMaxValue) { mValue = mValue <= 0 ? 0 : mMaxValue; mMove = 0; mScroller.forceFinished(true); } notifyValueChange(); } postInvalidate(); } private void countMoveEnd() { int roundMove = Math.round(mMove / (mLineDivider * mDensity)); mValue = mValue + roundMove; mValue = mValue <= 0 ? 0 : mValue; mValue = mValue > mMaxValue ? mMaxValue : mValue; mLastX = 0; mMove = 0; notifyValueChange(); postInvalidate(); } private void notifyValueChange() { if (null != mListener) { if (mModType == MOD_TYPE_ONE) { mListener.onValueChange(mValue); } if (mModType == MOD_TYPE_HALF) { mListener.onValueChange(mValue / 2f); } } } @Override public void computeScroll() { super.computeScroll(); if (mScroller.computeScrollOffset()) { if (mScroller.getCurrX() == mScroller.getFinalX()) { // over countMoveEnd(); } else { int xPosition = mScroller.getCurrX(); mMove += (mLastX - xPosition); changeMoveAndValue(); mLastX = xPosition; } } } @Override public boolean dispatchTouchEvent(MotionEvent event) { getParent().requestDisallowInterceptTouchEvent(true); return super.dispatchTouchEvent(event); }}

這是我的自定義View部分的代碼，下面就是在布局中的使用了

<TextView android: android:layout_width='match_parent' android:layout_height='wrap_content' android:padding='10dp' android:gravity='center' android:textColor='@android:color/holo_red_dark'/> <android.tst.com.myapplication.RulerView android: android:layout_width='match_parent' android:layout_height='60dp'/> <LinearLayout android:layout_width='match_parent' android:orientation='horizontal' android:layout_height='wrap_content'> <Button android: android:layout_width='0dp' android:layout_height='wrap_content' android:text='+' android:textSize='25sp' android:gravity='center' android:layout_marginRight='15dp' android:layout_weight='1'/> <Button android: android:layout_width='0dp' android:layout_height='wrap_content' android:text='-' android:layout_marginLeft='15dp' android:textSize='25sp' android:gravity='center' android:layout_weight='1'/></LinearLayout>

如上根據效果圖，我需要一個TextView進行顯示，還有就是我的自定義刻度尺控件了，接下來就是兩個Button控件加減。

接下來就是在Activity中的使用了

首先需要一個Handler進行更新TextView中的值

Handler handler = new Handler() { @Override public void handleMessage(Message msg) { tv_values.setText(rv_view.getValue() + 'Kg'); }; };

其次就是初始化相關的操作了

private void deployRulerView(){ rv_view= (RulerView) findViewById(R.id.rv_view); btn_jia= (Button) findViewById(R.id.btn_jia); btn_jian= (Button) findViewById(R.id.btn_jian); tv_values= (TextView) findViewById(R.id.tv_values); //設置RulerView的初始值 rv_view.setValue(60); //初始化刻度尺范圍 rv_view.initViewParam(60, 200, RulerView.MOD_TYPE_ONE); rv_view.setValueChangeListener(new RulerView.OnValueChangeListener() { @Override public void onValueChange(float value) { handler.sendMessage(new Message()); } }); tv_values.setText(60+'KG'); //給兩個控件添加監聽事件 btn_jia.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { rv_view.setValueToChange(1); } }); btn_jian.setOnClickListener(new View.OnClickListener() { @Override public void onClick(View v) { rv_view.setValueToChange(-1); } }); }

到這里整個過程已經完成了，如果不好的地方盡情吐槽，整個過程，最復雜的莫過于自定義中的繪制過程，但是一切的問題當你靜下心好好去實現時，那一切的問題都就不存在了。

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好吧啦網。