Android仿微信SwitchButton
16lz
2021-01-26
首先我们来看一下微信中switchButton的效果, 就是下图那个样子, 打开微信玩一下就知道了。
Screenshot_20170404-171429.png
惯例, 先上实现的效果
switchbutton.gif
接下来, 我就说明如何一步步实现这个效果控件。
1.定义背景和中间圆球的颜色
public class SwitchButton extends View { public SwitchButton(Context context) { this(context, null); } public SwitchButton(Context context, @Nullable AttributeSet attrs) { this(context, attrs, 0); } public SwitchButton(Context context, @Nullable AttributeSet attrs, int defStyleAttr) { super(context, attrs, defStyleAttr); TypedArray typedArray = context.getTheme().obtainStyledAttributes(attrs, R.styleable.SwitchView, defStyleAttr, R.style.def_switch_view); int indexCount = typedArray.getIndexCount(); for (int i = 0; i < indexCount; i++) { int attr = typedArray.getIndex(i); switch (attr) { case R.styleable.SwitchView_switch_bg_color: //背景颜色 switchViewBgColor = typedArray.getColor(attr, Color.BLACK); break; case R.styleable.SwitchView_switch_ball_color: //圆球颜色 switchViewBallColor = typedArray.getColor(attr, Color.BLACK); break; } } typedArray.recycle(); initData(); } }
在这里, 背景颜色和圆球颜色是从自定义属性中取的, 如果没有定义, 就取默认的颜色。
2.初始化一些东西, 比如创建两个画笔
private void initData() { mBallPaint = createPaint(switchViewBallColor, 0, Paint.Style.FILL, 0); mBgPaint = createPaint(switchViewBgColor, 0, Paint.Style.FILL, 0); ... }
3.在onSizeChanged方法里定义一些长度和宽度
@Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { mViewHeight = h; mViewWidth = w; // 默认描边宽度是控件宽度的1/30, 比如控件宽度是120dp, 描边宽度就是4dp switchViewStrockWidth = w * 1.0f / 30; mStrokeRadius = mViewHeight / 2; mSolidRadius = (mViewHeight - 2 * switchViewStrockWidth) / 2; BALL_X_RIGHT = mViewWidth - mStrokeRadius; mSwitchBallx = mStrokeRadius; mBgStrokeRectF = new RectF(0, 0, mViewWidth, mViewHeight); }
在这里, 定义了圆球的半径, 圆球中心的初始x坐标, 和用来画圆角矩形的矩形, 特别注意这里的switchViewStrockWidth指的是如下图这段
Paste_Image.png
4.在onMeasure方法里定义控件的宽度和高度
@Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); int widthMode = MeasureSpec.getMode(widthMeasureSpec); int heightMode = MeasureSpec.getMode(heightMeasureSpec); int measureWidth; int measureHeight; switch (widthMode) { case MeasureSpec.UNSPECIFIED: case MeasureSpec.AT_MOST://wrap_content measureWidth = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, DEF_W, getResources().getDisplayMetrics()); widthMeasureSpec = MeasureSpec.makeMeasureSpec(measureWidth, MeasureSpec.EXACTLY); break; case MeasureSpec.EXACTLY: break; } switch (heightMode) { case MeasureSpec.UNSPECIFIED: case MeasureSpec.AT_MOST://wrap_content measureHeight = (int) TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, DEF_H, getResources().getDisplayMetrics()); heightMeasureSpec = MeasureSpec.makeMeasureSpec(measureHeight, MeasureSpec.EXACTLY); break; case MeasureSpec.EXACTLY: break; } super.onMeasure(widthMeasureSpec, heightMeasureSpec); }
这里默认高是60dp, 高是120dp, 自己定义时最好也按照这个比例, 否则会显得不和谐
5.这里是最重要的, 在onDraw方法里画背景和圆球
@Override protected void onDraw(Canvas canvas) { drawSwitchBg(canvas); drawSwitchBall(canvas); } private void drawSwitchBall(Canvas canvas) { canvas.drawCircle(mSwitchBallx, mStrokeRadius, mSolidRadius, mBallPaint); } private void drawSwitchBg(Canvas canvas) { canvas.drawRoundRect(mBgStrokeRectF, mStrokeRadius, mStrokeRadius, mBgPaint); }
到这里的时候, 就能看到画好的背景和圆球了, 但却是静态的, 还不能动
6.定义枚举变量, 用来记录开关的状态
private enum State { OPEN, CLOSE } private State mCurrentState;
7.当button被点击时, 改变圆球的x坐标和背景画笔的颜色, 调用invalidate重绘界面
设置点击事件
private void initData() { ... setOnClickListener(this); }
在 onClick方法里
@Override public void onClick(View v) { mCurrentState = (mCurrentState == State.CLOSE ? State.OPEN : State.CLOSE); //绿色 #1AAC19 //灰色 #999999 if (mCurrentState == State.CLOSE) { animate(BALL_X_RIGHT, mStrokeRadius, greenColor, greyColor); } else { animate(mStrokeRadius, BALL_X_RIGHT, greyColor, greenColor); } if (mOnCheckedChangeListener != null) { if (mCurrentState == State.OPEN) { mOnCheckedChangeListener.onCheckedChanged(this, true); } else { mOnCheckedChangeListener.onCheckedChanged(this, false); } } } private void animate(int from, int to, int startColor, int endColor) { ValueAnimator translate = ValueAnimator.ofFloat(from, to); translate.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() { @Override public void onAnimationUpdate(ValueAnimator animation) { mSwitchBallx = ((float) animation.getAnimatedValue()); postInvalidate(); } }); ValueAnimator color = ValueAnimator.ofObject(new ColorEvaluator(), startColor, endColor); color.addUpdateListener(new ValueAnimator.AnimatorUpdateListener() { @Override public void onAnimationUpdate(ValueAnimator animation) { switchViewBgColor = ((int) animation.getAnimatedValue()); mBgPaint.setColor(switchViewBgColor); postInvalidate(); } }); AnimatorSet animatorSet = new AnimatorSet(); animatorSet.playTogether(translate, color); animatorSet.setDuration(200); animatorSet.addListener(new AnimatorListenerAdapter() { @Override public void onAnimationStart(Animator animation) { setClickable(false); } @Override public void onAnimationEnd(Animator animation) { setClickable(true); } }); animatorSet.start(); }
需要说明的是, 这里的难点在于如何让圆球和x坐标在指定时间内圆滑地变换到另一个值, 以及如何让颜色如何从灰色圆滑地变换到绿色。这里我使用的是值动画(因为暂时没有想到更好的方法)。坐标值的变换比较简单。颜色变化这里用到了估值器ArgbEvaluator
8.暴露接口获取开关的状态
这里我就不贴代码了, 很简单的
总的来说, 还是挺简单的, 也就200多行代码。参考demo: ATDragViewDemo
Paste_Image.png
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