别裁伪体亲风雅，转益多师是汝师。这篇文章主要讲述Android自定义竖直方向SeekBar相关的知识，希望能为你提供帮助。
写在前面 因为有这样的一个场景， 需要实现竖直方向的多色进度条， 然后在网上也找了下， 没看到符合需要的， 于是自定义了一个， 效果如下：

文章图片

具体实现 本来想定义水平的， 然后旋转一下， 后来发现还不如直接定义竖直方向来的直接， 就直接在竖直方向画了下。
首先讲一下思路， 就是通过继承View， 然后通过onDraw()方法进行绘制。具体绘制的时候， 需要处理一些小细节。比如， 我们需要画一个圆形的滑动块， 那么我们的背景色带就不能把整个宽度占满， 要不然， 小圆块只能和色带一样宽了， 效果不是很好看， 所以在绘制的时候应该把背景画的宽度小于View的实际宽度。
接下来我要贴代码了：

@ Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); int h = getMeasuredHeight(); int w = getMeasuredWidth(); mRadius = (float) w/2; sLeft = w * 0.25f; // 背景左边缘坐标 sRight = w * 0.75f; // 背景右边缘坐标 sTop = 0; sBottom = h; sWidth = sRight - sLeft; // 背景宽度 sHeight = sBottom - sTop; // 背景高度 x = (float) w/2; //圆心的x坐标 y = (float) (1-0.01*progress)*sHeight; //圆心y坐标 drawBackground(canvas); drawCircle(canvas); paint.reset(); }

【Android自定义竖直方向SeekBar】再看下画背景：

private void drawBackground(Canvas canvas){ RectF rectBlackBg = new RectF(sLeft, sTop, sRight, sBottom); linearGradient= new LinearGradient(sLeft,sTop,sWidth,sHeight,colorArray,null, Shader.TileMode.MIRROR); paint.setAntiAlias(true); paint.setStyle(Paint.Style.FILL); //设置渲染器 paint.setShader(linearGradient); canvas.drawRoundRect(rectBlackBg, sWidth/2, sWidth/2, paint); }

这里使用LinearGradient实现多种颜色渐变， 默认初始化定义如下:

private int endColor= Color.WHITE; private int thumbColor= Color.BLACK; private int thumbBorderColor= Color.WHITE; private int colorArray[]= {startColor, middleColor, endColor};

然后看下画圆的操作：

private void drawCircle(Canvas canvas){ Paint thumbPaint = new Paint(); y = y < mRadius ? mRadius : y; //判断thumb边界 y = y > sHeight-mRadius ? sHeight-mRadius : y; thumbPaint.setAntiAlias(true); thumbPaint.setStyle(Paint.Style.FILL); thumbPaint.setColor(thumbColor); canvas.drawCircle(x, y, mRadius, thumbPaint); thumbPaint.setStyle(Paint.Style.STROKE); thumbPaint.setColor(thumbBorderColor); thumbPaint.setStrokeWidth(2); canvas.drawCircle(x, y, mRadius, thumbPaint); }

这里通过画布画了一个圆形， 内部填充和外边沿。
上面的过程已经可以使效果展示出来了， 但是无法操作， 我们还需要给它加上事件才行：

@ Override public boolean onTouchEvent(MotionEvent event) { this.y = event.getY(); progress= (sHeight-y)/sHeight*100; switch(event.getAction()) { case MotionEvent.ACTION_DOWN: break; case MotionEvent.ACTION_UP: if (onStateChangeListener!= null){ onStateChangeListener.onStopTrackingTouch(this, progress); } break; case MotionEvent.ACTION_MOVE: if (onStateChangeListener!= null){ onStateChangeListener.OnStateChangeListener(this, progress); } setProgress(progress); this.invalidate(); break; }return true; } public interface OnStateChangeListener{ void OnStateChangeListener(View view, float progress); void onStopTrackingTouch(View view, float progress); }public void setOnStateChangeListener(OnStateChangeListener onStateChangeListener){ this.onStateChangeListener= onStateChangeListener; }

这里写了个回调接口， 然后我们在Activity中就可以接收到相应的滑动进度， 进而进行操作， 当然， 这里我们还得再加一个方法， 以便改变seekbar的状态：

public void setProgress(float progress) { this.progress = progress; invalidate(); }

到这里， 功能基本就OK了， 然后我们可以在Activity中去使用它了,下面是布局中的引用：

< ?xml version= " 1.0" encoding= " utf-8" ?> < LinearLayout xmlns:android= " http://schemas.android.com/apk/res/android" android:orientation= " vertical" android:layout_width= " match_parent" android:layout_height= " match_parent" android:background= " @ color/bgColor" > < include layout= " @ layout/bar_simple_title" /> < LinearLayout android:layout_width= " match_parent" android:layout_height= " match_parent" android:orientation= " horizontal" android:gravity= " center" > < RelativeLayout android:layout_marginTop= " 20dp" android:layout_width= " wrap_content" android:layout_height= " match_parent" android:layout_marginRight= " 35dp" > < TextView android:id= " @ + id/tv_inner_temper" android:layout_width= " wrap_content" android:layout_height= " wrap_content" android:text= " @ string/inner_temperature" android:layout_centerHorizontal= " true" /> < com.tfxiaozi.widget.VerticalColorSeekBar android:id= " @ + id/vpb_inner_temper" android:layout_width= " 20dp" android:layout_height= " 300dp" android:layout_centerHorizontal= " true" android:layout_marginTop= " 30dp" /> < TextView android:id= " @ + id/tv_current_temper" android:layout_below= " @ id/vpb_inner_temper" android:layout_width= " wrap_content" android:layout_height= " wrap_content" android:text= " @ string/current_temperature" /> < /RelativeLayout> < RelativeLayout android:layout_marginLeft= " 35dp" android:layout_marginTop= " 20dp" android:layout_width= " wrap_content" android:layout_height= " match_parent" > < TextView android:id= " @ + id/tv_brightness" android:layout_width= " wrap_content" android:layout_height= " wrap_content" android:text= " @ string/brightness" android:layout_centerHorizontal= " true" /> < com.tfxiaozi.widget.VerticalColorSeekBar android:id= " @ + id/vpb_brightness" android:layout_width= " 20dp" android:layout_height= " 300dp" android:layout_centerHorizontal= " true" android:layout_marginTop= " 30dp" /> < TextView android:id= " @ + id/tv_current_brightness" android:layout_below= " @ id/vpb_brightness" android:layout_width= " wrap_content" android:layout_height= " wrap_content" android:layout_centerHorizontal= " true" android:text= " 0" /> < /RelativeLayout> < /LinearLayout> < /LinearLayout>

怎么使用就很简单了：

package com.tfxiaozi.activity.setting; import android.graphics.Color; import android.os.Bundle; import android.view.View; import android.widget.ImageView; import android.widget.TextView; import com.tfxiaozi.R; import com.tfxiaozi.activity.BaseActivity; import com.tfxiaozi.utils.ToastUtils; import com.tfxiaozi.widget.VerticalColorSeekBar; /** * Created by dongqiang on 2016/10/16. */ public class ManualSettingActivity extends BaseActivity implements View.OnClickListener, VerticalColorSeekBar.OnStateChangeListener {private TextView tvCurrentTemper, tvCurrentBrightness, tvMainTitle; private ImageView ivBack; private VerticalColorSeekBar vpbInnerTemper; private VerticalColorSeekBar vpbBrightness; @ Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_manual_setting); initViews(); initEvents(); initData(); }private void initViews() { tvMainTitle = (TextView) findViewById(R.id.title_main_text); tvMainTitle.setText(getString(R.string.manual_setting)); tvMainTitle.setVisibility(View.VISIBLE); ivBack = (ImageView) findViewById(R.id.title_back); ivBack.setVisibility(View.VISIBLE); tvCurrentTemper = (TextView) findViewById(R.id.tv_current_temper); tvCurrentBrightness = (TextView) findViewById(R.id.tv_current_brightness); vpbInnerTemper = (VerticalColorSeekBar)findViewById(R.id.vpb_inner_temper); vpbBrightness = (VerticalColorSeekBar) findViewById(R.id.vpb_brightness); vpbInnerTemper.setColor(Color.RED, Color.YELLOW, Color.GREEN, Color.BLUE, Color.TRANSPARENT); vpbBrightness.setColor(Color.BLUE, Color.WHITE, Color.YELLOW, Color.BLUE, Color.TRANSPARENT); }private void initEvents() { ivBack.setOnClickListener(this); vpbInnerTemper.setOnStateChangeListener(this); vpbBrightness.setOnStateChangeListener(this); }private void initData() { vpbInnerTemper.setProgress(50); vpbBrightness.setProgress(70); }@ Override public void onClick(View v) { switch (v.getId()) { case R.id.title_back: finish(); break; } }@ Override public void OnStateChangeListener(View view, float progress) {}@ Override public void onStopTrackingTouch(View view, float progress) { int viewId = view.getId(); switch (viewId) { case R.id.vpb_inner_temper: if (progress < 0) { progress = 0; } if(progress > 100) { progress = 100; } ToastUtils.showShort(this, " progress= " + progress); break; case R.id.vpb_brightness: if (progress < 0) { progress = 0; } if(progress > 100) { progress = 100; } ToastUtils.showShort(this, " progress1= " + progress); break; }} }

到这里就结束了， 最后还是附上自定义View的整个代码吧：

package com.tfxiaozi.widget; import android.content.Context; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.LinearGradient; import android.graphics.Paint; import android.graphics.RectF; import android.graphics.Shader; import android.util.AttributeSet; import android.util.Log; import android.view.MotionEvent; import android.view.View; /** * Created by dongqiang on 2016/10/21. */ public class VerticalColorSeekBar extends View{private static final String TAG = VerticalColorSeekBar.class.getSimpleName(); private int startColor= Color.BLACK; private int middleColor = Color.GRAY; private int endColor= Color.WHITE; private int thumbColor= Color.BLACK; private int thumbBorderColor= Color.WHITE; private int colorArray[]= {startColor, middleColor, endColor}; private float x,y; private float mRadius; private float progress; private float maxCount = 100f; private float sLeft, sTop, sRight, sBottom; private float sWidth,sHeight; private LinearGradient linearGradient; private Paint paint = new Paint(); protected OnStateChangeListener onStateChangeListener; public VerticalColorSeekBar(Context context) { this(context, null); }public VerticalColorSeekBar(Context context, AttributeSet attrs) { super(context, attrs); }@ Override protected synchronized void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); setMeasuredDimension(getMeasuredWidth(), getMeasuredHeight()); }public void setColor(int startColor,int middleColor, int endColor,int thumbColor,int thumbBorderColor){ this.startColor= startColor; this.middleColor = middleColor; this.endColor= endColor; this.thumbColor= thumbColor; this.thumbBorderColor= thumbBorderColor; colorArray[0] = startColor; colorArray[1] = middleColor; colorArray[2] = endColor; }@ Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); int h = getMeasuredHeight(); int w = getMeasuredWidth(); mRadius = (float) w/2; sLeft = w * 0.25f; // 背景左边缘坐标 sRight = w * 0.75f; // 背景右边缘坐标 sTop = 0; sBottom = h; sWidth = sRight - sLeft; // 背景宽度 sHeight = sBottom - sTop; // 背景高度 x = (float) w/2; //圆心的x坐标 y = (float) (1-0.01*progress)*sHeight; //圆心y坐标 drawBackground(canvas); drawCircle(canvas); paint.reset(); }private void drawBackground(Canvas canvas){ RectF rectBlackBg = new RectF(sLeft, sTop, sRight, sBottom); linearGradient= new LinearGradient(sLeft,sTop,sWidth,sHeight,colorArray,null, Shader.TileMode.MIRROR); paint.setAntiAlias(true); paint.setStyle(Paint.Style.FILL); //设置渲染器 paint.setShader(linearGradient); canvas.drawRoundRect(rectBlackBg, sWidth/2, sWidth/2, paint); }private void drawCircle(Canvas canvas){ Paint thumbPaint = new Paint(); y = y < mRadius ? mRadius : y; //判断thumb边界 y = y > sHeight-mRadius ? sHeight-mRadius : y; thumbPaint.setAntiAlias(true); thumbPaint.setStyle(Paint.Style.FILL); thumbPaint.setColor(thumbColor); canvas.drawCircle(x, y, mRadius, thumbPaint); thumbPaint.setStyle(Paint.Style.STROKE); thumbPaint.setColor(thumbBorderColor); thumbPaint.setStrokeWidth(2); canvas.drawCircle(x, y, mRadius, thumbPaint); }@ Override public boolean onTouchEvent(MotionEvent event) { this.y = event.getY(); progress= (sHeight-y)/sHeight*100; switch(event.getAction()) { case MotionEvent.ACTION_DOWN: break; case MotionEvent.ACTION_UP: if (onStateChangeListener!= null){ onStateChangeListener.onStopTrackingTouch(this, progress); } break; case MotionEvent.ACTION_MOVE: if (onStateChangeListener!= null){ onStateChangeListener.OnStateChangeListener(this, progress); } setProgress(progress); this.invalidate(); break; }return true; }public interface OnStateChangeListener{ void OnStateChangeListener(View view, float progress); void onStopTrackingTouch(View view, float progress); }public void setOnStateChangeListener(OnStateChangeListener onStateChangeListener){ this.onStateChangeListener= onStateChangeListener; }public void setProgress(float progress) { this.progress = progress; invalidate(); } }

结束 到这里就真的结束啦， 就当记录一下吧， 然后也希望帮到有需要的人。有更好的实现也可以告诉我哈~

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