如何缩放视图以适应 Android 动画中的内容大小？

Question

我正在使用 CardView 作为 Recycler Adapter 的一个项目。

起初，所有项目不会显示全部内容，（我将其剪切并放置'......'代替）
但是点击它之后，被点击的项目会缩放它的高度以适应内容的高度。（这里我将文字设置为全部内容，希望卡片可以缩放以适应它）

看起来像：

I know how to animate the height to the specific target height.. but in this case, I don't know how to measure the height needed to show the whole content, each item should have different target height.

我该怎么做？

Answer 1

你可以做的是让 View 测量自身，不限制其高度。请注意对 view.getWidth() 的调用，您只能在 View 布局后执行此操作，因为您在 onClick() 中调用它应该没问题。

int widthSpec = View.MeasureSpec.makeMeasureSpec(view.getWidth(), View.MeasureSpec.EXACTLY);
int heightSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
view.measure(widthSpec, heightSpec);
int targetHeight = view.getMeasuredHeight();

假设您的视图是一个设置了这些属性的 TextView：

android:layout_height="wrap_content"
android:maxLines="1"
android:ellipsize="end"

完整的例子是

// this is the height measured with maxLines 1 and height
// to wrap_content
final int startHeight = view.getHeight();

// you want to measure the TextView with all text lines
view.setMaxLines(Integer.MAX_VALUE);

int widthSpec = View.MeasureSpec.makeMeasureSpec(view.getWidth(), View.MeasureSpec.EXACTLY);
int heightSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
view.measure(widthSpec, heightSpec);

// final height of the TextView
int targetHeight = view.getMeasuredHeight();

// this is the value that will be animated from 0% to 100%
final int heightSpan = targetHeight-startHeight;

// remove that wrap_content and set the starting point
view.getLayoutParams().height = startHeight;
view.setLayoutParams(view.getLayoutParams());

Animation animation = new Animation(){
    @Override
    protected void applyTransformation(float interpolatedTime, Transformation t) {
        view.getLayoutParams().height = (int) (startHeight + heightSpan*interpolatedTime);
        view.setLayoutParams(view.getLayoutParams());
    }
};

animation.setDuration(1000);
view.startAnimation(animation);

Answer 2

你可以很简单地做到这一点。第一次给TextView设置文本时，这样写：

int minLineNumber = 2;
textView.setMaxLines(minLineNumber); // 2 is your number of line for the first time

当点击它时：

textView.setMaxLines(Integer.MAX_VALUE); // set the height like wrap_content

如果你想要动画，你有这样的东西：

ObjectAnimator animation = ObjectAnimator.ofInt(
        textView,
        "maxLines",
        textView.getLineCount());

int duration = (textView.getLineCount() - minLineNumber) * 50;
        animation.setDuration(duration);
        animation.start();

如果您的 TextView 中的文本太多，最好使用固定的持续时间，而不是取决于高度。

如何缩放视图以适应 Android 动画中的内容大小？

How to scale the view to fit the content size in Android animation?

android

view

android-animation

android-layout

android-wrap-content