Fab 和 Dialog 之间的过渡效果

来源：互联网发布：电脑主机淘宝编辑：程序博客网时间：2024/05/29 16:53

效果图：

实现原理分析

共享元素过渡动画：一个共享元素过渡动画决定两个Activity之间的过渡怎么共享它们的视图，包括了

changeBounds：改变目标视图的布局边界；
changeClipBounds：裁剪目标视图的边界；
changeTransform：改变目标视图的缩放比例和旋转角度；
changeImageTransform：改变目标图片的大小和缩放比例。
使用方式：假设Activity从A跳转到B，那么将A中原来的startActivity改为如下代码：

//单个共享元素的调用方式startActivity(intent,ActivityOptions.makeSceneTransitionAnimation(this, view, "share").toBundle());//多个共享元素的调用方式startActivity(intent,ActivityOptions.makeSceneTransitionAnimation(this,                Pair.create(view, "share"),                Pair.create(fab, "fab")).toBundle());

然后在B的onCreate方法中添加如下代码：

//声明需要开启Activity过渡动画getWindow().requestFeature(Window.FEATURE_CONTENT_TRANSITIONS);

其次还要在Activity A和B的布局文件中为共享元素组件添加android:transitionName="xxx"属性。

2.源码中的Dialog实际上是Activity，并设置了android:windowIsTranslucent为true，所以从fab到dialog的动画效果实际上是Activity的过渡动画。但是，如果单纯的只是使用Activity的共享元素过渡动画，将fab作为共享元素的话，效果并不好，不是那么的舒服。

3.为了让过渡效果更加舒服，这里添加了两个渐变效果，一个是color，从fab的颜色到dialog的背景颜色的渐变；另一个是cornerRadius，即圆角幅度的渐变。请看下面的代码实现：

/** * MorphTransition扩展自ChangeBounds(共享元素的动画的一种)，它在原有动画基础上添加了color和cornerRadius的动画效果，这个类实际上是整合了MorphFabToDialog和MorphDialogToFab两个类的作用 * <p/> * A transition that morphs a circle into a rectangle, changing it's background color. */public class MorphTransition extends ChangeBounds {     private static final String PROPERTY_COLOR = "color";    private static final String PROPERTY_CORNER_RADIUS = "cornerRadius";    private static final String[] TRANSITION_PROPERTIES = {            PROPERTY_COLOR,            PROPERTY_CORNER_RADIUS    };     private int startColor = Color.TRANSPARENT;    private int endColor = Color.TRANSPARENT;    private int startCornerRadius = 0;    private int endCornerRadius = 0;    private boolean isShowViewGroup = false;     public MorphTransition(int startColor, int endColor, int startCornerRadius, int endCornerRadius, boolean isShowViewGroup) {        super();        setStartColor(startColor);        setEndColor(endColor);        setStartCornerRadius(startCornerRadius);        setEndCornerRadius(endCornerRadius);        setIsShowViewGroup(isShowViewGroup);    }     public MorphTransition(Context context, AttributeSet attrs) {        super(context, attrs);    }     @Override    public String[] getTransitionProperties() {        return TRANSITION_PROPERTIES;    }     @Override    public void captureStartValues(TransitionValues transitionValues) {        super.captureStartValues(transitionValues);        final View view = transitionValues.view;        if (view.getWidth() <= 0 || view.getHeight() <= 0) {            return;        }        transitionValues.values.put(PROPERTY_COLOR, startColor);        transitionValues.values.put(PROPERTY_CORNER_RADIUS, startCornerRadius);//view.getHeight() / 2    }     @Override    public void captureEndValues(TransitionValues transitionValues) {        super.captureEndValues(transitionValues);        final View view = transitionValues.view;        if (view.getWidth() <= 0 || view.getHeight() <= 0) {            return;        }        transitionValues.values.put(PROPERTY_COLOR, endColor);//ContextCompat.getColor(view.getContext(), R.color.dialog_background_color)        transitionValues.values.put(PROPERTY_CORNER_RADIUS, endCornerRadius);    }     @Override    public Animator createAnimator(final ViewGroup sceneRoot, TransitionValues startValues, final TransitionValues endValues) {        Animator changeBounds = super.createAnimator(sceneRoot, startValues, endValues);        if (startValues == null || endValues == null || changeBounds == null) {            return null;        }         Integer startColor = (Integer) startValues.values.get(PROPERTY_COLOR);        Integer startCornerRadius = (Integer) startValues.values.get(PROPERTY_CORNER_RADIUS);        Integer endColor = (Integer) endValues.values.get(PROPERTY_COLOR);        Integer endCornerRadius = (Integer) endValues.values.get(PROPERTY_CORNER_RADIUS);         if (startColor == null || startCornerRadius == null || endColor == null || endCornerRadius == null) {            return null;        }         MorphDrawable background = new MorphDrawable(startColor, startCornerRadius);        endValues.view.setBackground(background);         Animator color = ObjectAnimator.ofArgb(background, background.COLOR, endColor);        Animator corners = ObjectAnimator.ofFloat(background, background.CORNER_RADIUS, endCornerRadius);         ////......         AnimatorSet transition = new AnimatorSet();        transition.playTogether(changeBounds, corners, color);        transition.setDuration(300);        transition.setInterpolator(AnimationUtils.loadInterpolator(sceneRoot.getContext(), android.R.interpolator.fast_out_slow_in));        return transition;    }     public void setEndColor(int endColor) {        this.endColor = endColor;    }     public void setEndCornerRadius(int endCornerRadius) {        this.endCornerRadius = endCornerRadius;    }     public void setStartColor(int startColor) {        this.startColor = startColor;    }     public void setStartCornerRadius(int startCornerRadius) {        this.startCornerRadius = startCornerRadius;    }     public void setIsShowViewGroup(boolean isShowViewGroup) {        this.isShowViewGroup = isShowViewGroup;    }}

4.上面的代码中用到了MorphDrawable类，它继承自Drawable，并添加了前面提到的那两个属性以用于产生属性动画，默认是没有为那两个属性添加set/get方法的，所以需要进行扩展。关于属性动画可以看以前的读书笔记，重要代码如下：

/** * 形态和颜色可以发生变化的Drawable，形态变化是通过cornerRadius来实现的，颜色变化是通过paint的color来实现的 * 该类在Drawable的基础上添加了cornerRadius和color两个属性，前者是float类型，后者是int类型 * <p/> * A drawable that can morph size, shape (via it's corner radius) and color.  Specifically this is * useful for animating between a FAB and a dialog. */public class MorphDrawable extends Drawable {     private Paint paint;    private float cornerRadius;     public static final Property<MorphDrawable, Float> CORNER_RADIUS = new Property<MorphDrawable, Float>(Float.class, "cornerRadius") {         @Override        public void set(MorphDrawable morphDrawable, Float value) {            morphDrawable.setCornerRadius(value);        }         @Override        public Float get(MorphDrawable morphDrawable) {            return morphDrawable.getCornerRadius();        }    };     public static final Property<MorphDrawable, Integer> COLOR = new Property<MorphDrawable, Integer>(Integer.class, "color") {         @Override        public void set(MorphDrawable morphDrawable, Integer value) {            morphDrawable.setColor(value);        }         @Override        public Integer get(MorphDrawable morphDrawable) {            return morphDrawable.getColor();        }    };     public MorphDrawable(@ColorInt int color, float cornerRadius) {        this.cornerRadius = cornerRadius;        paint = new Paint(Paint.ANTI_ALIAS_FLAG);        paint.setColor(color);    }     public float getCornerRadius() {        return cornerRadius;    }     public void setCornerRadius(float cornerRadius) {        this.cornerRadius = cornerRadius;        invalidateSelf();    }     public int getColor() {        return paint.getColor();    }     public void setColor(int color) {        paint.setColor(color);        invalidateSelf();    }     @Override    public void draw(Canvas canvas) {        canvas.drawRoundRect(getBounds().left, getBounds().top, getBounds().right, getBounds()                .bottom, cornerRadius, cornerRadius, paint);//hujiawei    }     @Override    public void getOutline(Outline outline) {        outline.setRoundRect(getBounds(), cornerRadius);    }     @Override    public void setAlpha(int alpha) {        paint.setAlpha(alpha);        invalidateSelf();    }     @Override    public void setColorFilter(ColorFilter cf) {        paint.setColorFilter(cf);        invalidateSelf();    }     @Override    public int getOpacity() {        return paint.getAlpha();    } }

5.有了前面的准备之后，就可以在dialog中配置进入和退出的动画效果了，重要代码如下：

//DialogActivity.javapublic void setupSharedEelementTransitions2() {    ArcMotion arcMotion = new ArcMotion();    arcMotion.setMinimumHorizontalAngle(50f);    arcMotion.setMinimumVerticalAngle(50f);     Interpolator easeInOut = AnimationUtils.loadInterpolator(this, android.R.interpolator.fast_out_slow_in);     //hujiawei 100是随意给的一个数字，可以修改，需要注意的是这里调用container.getHeight()结果为0    MorphTransition sharedEnter = new MorphTransition(ContextCompat.getColor(this, R.color.fab_background_color),            ContextCompat.getColor(this, R.color.dialog_background_color), 100, getResources().getDimensionPixelSize(R.dimen.dialog_corners), true);    sharedEnter.setPathMotion(arcMotion);    sharedEnter.setInterpolator(easeInOut);     MorphTransition sharedReturn = new MorphTransition(ContextCompat.getColor(this, R.color.dialog_background_color),            ContextCompat.getColor(this, R.color.fab_background_color), getResources().getDimensionPixelSize(R.dimen.dialog_corners), 100,  false);    sharedReturn.setPathMotion(arcMotion);    sharedReturn.setInterpolator(easeInOut);     if (container != null) {        sharedEnter.addTarget(container);        sharedReturn.addTarget(container);    }    getWindow().setSharedElementEnterTransition(sharedEnter);    getWindow().setSharedElementReturnTransition(sharedReturn);}

6.从上面的分析可以看出，这个方案比较容易扩展，只要是该类型的动画，使用开始和结束时的对应颜色和圆角值就可以构造相应的MorphTransition，将MorphTransition设置为Activity的进入或者退化动画即可。

原文：http://Fab and Dialog Morphing Animation

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