android开发

MaterialButton 效果进阶 动画自动移动进行对齐效果

做 Android 动画效果一段时间了，感觉深深喜欢上了钻研特效。在手机上显示自己的特效是一件很不错的事情。

废话不多说，前面几天我发布了：[Material Design] 教你做一个Material风格、动画的按钮(MaterialButton)

在其中我讲解了我对 Android L 中 Material 效果的按钮的动画实现方式，今天的文章将基于其上进行进阶讲解新的特效。

在 MaterialButton 中的特效原理是：用户点击时启动一个动画，该动画是在点击位置画颜色渐变同时半径变大的圆，从而实现扩散效果；具体可点击上面的链接查看一下。在按钮中的这样的特效距离谷歌的还是有很大的差距的，下面来对比一下：

官方的：

我们上个版本的：

可以看出谷歌的是有位移效果，而我们的是原地扩散的效果，当然动画速度这个与PS的设置有关，不做比较，实际速度比上面的略快。

下面咱们就来试试做做位移的特效，先画个图给大家看看：

相信大家都能看懂，第一种就是之前的实现方式，只是在原地扩散，第二种就是新的，将在扩散的同时向中心靠拢，且为了达到更加好的视觉效果，靠拢中心的XY轴速度并不是一样的，X轴的靠拢时间=整个扩散时间，向Y轴靠拢的时间~=整个扩散时间*0.3（且都是先快后慢），现在来看看成品效果：

点击中间的时候与第一种差距不大，但是点击两边的时候将会有明显的差距，能感觉到向中心靠拢的触觉。是不是和谷歌的相比起来又近了一些了？

说了这个多的理论与演示，下面来说说整个的实现：

首先我们抽取上一篇文章的成果作为这篇的开头，具体怎么新建控件就不再做介绍了，先看看上一篇的代码成果（该代码进行了一定的修改）：

public class MaterialButton extends Button {
    private static final Interpolator ANIMATION_INTERPOLATOR = new DecelerateInterpolator();
    private static final long ANIMATION_TIME = 600;
    private Paint backgroundPaint;
    private static ArgbEvaluator argbEvaluator = new ArgbEvaluator();
    private float paintX, paintY, radius;
    public MaterialButton(Context context) {
        super(context);
        init(null, 0);
    }
    public MaterialButton(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(attrs, 0);
    }
    public MaterialButton(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init(attrs, defStyle);
    }
    @SuppressWarnings("deprecation")
    private void init(AttributeSet attrs, int defStyle) {
        ...
    }
    @SuppressWarnings("NullableProblems")
    @Override
    protected void onDraw(Canvas canvas) {
        canvas.save();
        canvas.drawCircle(paintX, paintY, radius, backgroundPaint);
        canvas.restore();
        super.onDraw(canvas);
    }
    @SuppressWarnings("NullableProblems")
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        if (event.getAction() == MotionEvent.ACTION_DOWN) {
            paintX = event.getX();
            paintY = event.getY();
            startRoundAnimator();
        }
        return super.onTouchEvent(event);
    }
    /**
     * =============================================================================================
     * The Animator methods
     * =============================================================================================
     */
    /**
     * Start Round Animator
     */
    private void startRoundAnimator() {
        float start, end, height, width;
        long time = (long) (ANIMATION_TIME * 1.85);
        //Height Width
        height = getHeight();
        width = getWidth();
        //Start End
        if (height < width) {
            start = height;
            end = width;
        } else {
            start = width;
            end = height;
        }
        float startRadius = (start / 2 > paintY ? start - paintY : paintY) * 1.15f;
        float endRadius = (end / 2 > paintX ? end - paintX : paintX) * 0.85f;
        //If The approximate square approximate square
        if (startRadius > endRadius) {
            startRadius = endRadius * 0.6f;
            endRadius = endRadius / 0.8f;
            time = (long) (time * 0.5);
        }
        AnimatorSet set = new AnimatorSet();
        set.playTogether(
                ObjectAnimator.ofFloat(this, mRadiusProperty, startRadius, endRadius),
                ObjectAnimator.ofObject(this, mBackgroundColorProperty, argbEvaluator, attributes.getColor(1), attributes.getColor(2))
        );
        // set Time
        set.setDuration((long) (time / end * endRadius));
        set.setInterpolator(ANIMATION_INTERPOLATOR);
        set.start();
    }  
    /**
     * =============================================================================================
     * The custom properties
     * =============================================================================================
     */
    private Property<MaterialButton, Float> mRadiusProperty = new Property<MaterialButton, Float>(Float.class, "radius") {
        @Override
        public Float get(MaterialButton object) {
            return object.radius;
        }
        @Override
        public void set(MaterialButton object, Float value) {
            object.radius = value;
            invalidate();
        }
    };
    private Property<MaterialButton, Integer> mBackgroundColorProperty = new Property<MaterialButton, Integer>(Integer.class, "bg_color") {
        @Override
        public Integer get(MaterialButton object) {
            return object.backgroundPaint.getColor();
        }
        @Override
        public void set(MaterialButton object, Integer value) {
            object.backgroundPaint.setColor(value);
        }
    };
}

在上述代码中我们实现了点击时进行扩散的效果，初始化控件部分由于我加入了许多的代码这里删除了，具体可以看看我的项目实现，最后会给出地址。

现在基于此开工！

首先我们建立 两个新的属性 分别X坐标与Y坐标属性：

private Property<MaterialButton, Float> mPaintXProperty = new Property<MaterialButton, Float>(Float.class, "paintX") {
        @Override
        public Float get(MaterialButton object) {
            return object.paintX;
        }
        @Override
        public void set(MaterialButton object, Float value) {
            object.paintX = value;
        }
    };
    private Property<MaterialButton, Float> mPaintYProperty = new Property<MaterialButton, Float>(Float.class, "paintY") {
        @Override
        public Float get(MaterialButton object) {
            return object.paintY;
        }
        @Override
        public void set(MaterialButton object, Float value) {
            object.paintY = value;
        }
    };

在这两个属性中并未调用第一篇所说的 “ invalidate();”方法进行界面刷新，因为该方法应该放在持续时间最长的半径属性中调用。

之后我们获取到高宽 以及根据高和宽 计算出对应的 开始半径与结束半径：

<span style="white-space:pre">    </span>float start, end, height, width, speed = 0.3f;
        long time = ANIMATION_TIME;
        //Height Width
        height = getHeight();
        width = getWidth();
        //Start End
        if (height < width) {
            start = height;
            end = width;
        } else {
            start = width;
            end = height;
        }
        start = start / 2 > paintY ? start - paintY : paintY;
        end = end * 0.8f / 2f;
        //If The approximate square approximate square
        if (start > end) {
            start = end * 0.6f;
            end = end / 0.8f;
            time = (long) (time * 0.65);
            speed = 1f;
        }

我们首先比较了高与宽的长度 把短的赋予为开始半径 长的赋予为结束半径。

第二步，我们把开始长度除以2  得出其一半的长度 然后与 点击时的Y轴坐标比较，如果Y轴较长则取Y，如果不够则取其相减结果。这样能保证点击开始时的半径能刚好大于其高或者宽（短的一边），这样就不会出现小圆扩散的效果，看起来将会由椭圆的效果（当然以后将会直接画出椭圆）

第三步，我们运算出结束半径，同时保证结束半径为长的一边的一半的8/10 这样的效果是不会出现布满整个控件的情况。8/10 的空间刚好是个不错的选择。

第四步，判断开始长度是否大于结束长度，如果是（近似正方形情况）,进行一定规则的重新运算，保证其开始半径能刚好与控件长度差不多（0.48左右），结束半径能刚刚布满控件，同时减少动画时间

当然，我现在才发现了一个BUG，在第二步的地方的BUG，大家看看，希望能提出是哪里的BUG；就当是一个互动！该BUG将会在下个版本修复。

之后我们建立每个属性的动画，并给每个属性动画设置对应的时间：

//PaintX
 ObjectAnimator aPaintX = ObjectAnimator.ofFloat(this, mPaintXProperty, paintX, width / 2);
 aPaintX.setDuration(time);
 //PaintY
 ObjectAnimator aPaintY = ObjectAnimator.ofFloat(this, mPaintYProperty, paintY, height / 2);
 aPaintY.setDuration((long) (time * speed));
 //Radius
 ObjectAnimator aRadius = ObjectAnimator.ofFloat(this, mRadiusProperty, start, end);
 aRadius.setDuration(time);
 //Background
 ObjectAnimator aBackground = ObjectAnimator.ofObject(this, mBackgroundColorProperty, argbEvaluator, attributes.getColor(1), attributes.getColor(2));
 aBackground.setDuration(time);

可以看见Y轴的时间乘以了一个speed变量，该变量默认是0.3 如果是近似正方形将初始化为1以便能同时对齐到中心位置，在上一步中有对应变量。

然后咱们把所有的属性动画添加到一个动画集并设置其速度方式为：先快后慢。最后启动该动画集。

//AnimatorSet
AnimatorSet set = new AnimatorSet();
set.playTogether(aPaintX, aPaintY, aRadius, aBackground);
set.setInterpolator(ANIMATION_INTERPOLATOR);
set.start();

以上就是最新的动画效果的实现原理及代码了，当然我们可以将其合并到第一篇的代码中，并使用一个 Bool 属性来控制使用哪一种动画：

public class MaterialButton extends Button {
    private static final Interpolator ANIMATION_INTERPOLATOR = new DecelerateInterpolator();
    private static final long ANIMATION_TIME = 600;
    private Paint backgroundPaint;
    private static ArgbEvaluator argbEvaluator = new ArgbEvaluator();
    private float paintX, paintY, radius;
    private Attributes attributes;
    public MaterialButton(Context context) {
        super(context);
        init(null, 0);
    }
    public MaterialButton(Context context, AttributeSet attrs) {
        super(context, attrs);
        init(attrs, 0);
    }
    public MaterialButton(Context context, AttributeSet attrs, int defStyle) {
        super(context, attrs, defStyle);
        init(attrs, defStyle);
    }
    @SuppressWarnings("deprecation")
    private void init(AttributeSet attrs, int defStyle) {
        ...
    }
    @SuppressWarnings("NullableProblems")
    @Override
    protected void onDraw(Canvas canvas) {
        canvas.save();
        canvas.drawCircle(paintX, paintY, radius, backgroundPaint);
        canvas.restore();
        super.onDraw(canvas);
    }
    @SuppressWarnings("NullableProblems")
    @Override
    public boolean onTouchEvent(MotionEvent event) {
        if (attributes.isMaterial() && event.getAction() == MotionEvent.ACTION_DOWN) {
            paintX = event.getX();
            paintY = event.getY();
            if (attributes.isAutoMove())
                startMoveRoundAnimator();
            else
                startRoundAnimator();
        }
        return super.onTouchEvent(event);
    }
    /**
     * =============================================================================================
     * The Animator methods
     * =============================================================================================
     */
    /**
     * Start Round Animator
     */
    private void startRoundAnimator() {
        float start, end, height, width;
        long time = (long) (ANIMATION_TIME * 1.85);
        //Height Width
        height = getHeight();
        width = getWidth();
        //Start End
        if (height < width) {
            start = height;
            end = width;
        } else {
            start = width;
            end = height;
        }
        float startRadius = (start / 2 > paintY ? start - paintY : paintY) * 1.15f;
        float endRadius = (end / 2 > paintX ? end - paintX : paintX) * 0.85f;
        //If The approximate square approximate square
        if (startRadius > endRadius) {
            startRadius = endRadius * 0.6f;
            endRadius = endRadius / 0.8f;
            time = (long) (time * 0.5);
        }
        AnimatorSet set = new AnimatorSet();
        set.playTogether(
                ObjectAnimator.ofFloat(this, mRadiusProperty, startRadius, endRadius),
                ObjectAnimator.ofObject(this, mBackgroundColorProperty, argbEvaluator, attributes.getColor(1), attributes.getColor(2))
        );
        // set Time
        set.setDuration((long) (time / end * endRadius));
        set.setInterpolator(ANIMATION_INTERPOLATOR);
        set.start();
    }
    /**
     * Start Move Round Animator
     */
    private void startMoveRoundAnimator() {
        float start, end, height, width, speed = 0.3f;
        long time = ANIMATION_TIME;
        //Height Width
        height = getHeight();
        width = getWidth();
        //Start End
        if (height < width) {
            start = height;
            end = width;
        } else {
            start = width;
            end = height;
        }
        start = start / 2 > paintY ? start - paintY : paintY;
        end = end * 0.8f / 2f;
        //If The approximate square approximate square
        if (start > end) {
            start = end * 0.6f;
            end = end / 0.8f;
            time = (long) (time * 0.65);
            speed = 1f;
        }
        //PaintX
        ObjectAnimator aPaintX = ObjectAnimator.ofFloat(this, mPaintXProperty, paintX, width / 2);
        aPaintX.setDuration(time);
        //PaintY
        ObjectAnimator aPaintY = ObjectAnimator.ofFloat(this, mPaintYProperty, paintY, height / 2);
        aPaintY.setDuration((long) (time * speed));
        //Radius
        ObjectAnimator aRadius = ObjectAnimator.ofFloat(this, mRadiusProperty, start, end);
        aRadius.setDuration(time);
        //Background
        ObjectAnimator aBackground = ObjectAnimator.ofObject(this, mBackgroundColorProperty, argbEvaluator, attributes.getColor(1), attributes.getColor(2));
        aBackground.setDuration(time);
        //AnimatorSet
        AnimatorSet set = new AnimatorSet();
        set.playTogether(aPaintX, aPaintY, aRadius, aBackground);
        set.setInterpolator(ANIMATION_INTERPOLATOR);
        set.start();
    }
    /**
     * =============================================================================================
     * The custom properties
     * =============================================================================================
     */
    private Property<MaterialButton, Float> mPaintXProperty = new Property<MaterialButton, Float>(Float.class, "paintX") {
        @Override
        public Float get(MaterialButton object) {
            return object.paintX;
        }
        @Override
        public void set(MaterialButton object, Float value) {
            object.paintX = value;
        }
    };
    private Property<MaterialButton, Float> mPaintYProperty = new Property<MaterialButton, Float>(Float.class, "paintY") {
        @Override
        public Float get(MaterialButton object) {
            return object.paintY;
        }
        @Override
        public void set(MaterialButton object, Float value) {
            object.paintY = value;
        }
    };
    private Property<MaterialButton, Float> mRadiusProperty = new Property<MaterialButton, Float>(Float.class, "radius") {
        @Override
        public Float get(MaterialButton object) {
            return object.radius;
        }
        @Override
        public void set(MaterialButton object, Float value) {
            object.radius = value;
            invalidate();
        }
    };
    private Property<MaterialButton, Integer> mBackgroundColorProperty = new Property<MaterialButton, Integer>(Integer.class, "bg_color") {
        @Override
        public Integer get(MaterialButton object) {
            return object.backgroundPaint.getColor();
        }
        @Override
        public void set(MaterialButton object, Integer value) {
            object.backgroundPaint.setColor(value);
        }
    };
}

在最后附上两种方式运行后的效果对比图：

**还不错吧？**要是感觉比较和你的胃口，这里有我的整个项目：

Genius-Android

APK与动画MP4

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每天进步一点点
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