以编程方式更改约束布局中的指南百分比

Question

我有像这样的约束布局的指南

<android.support.constraint.Guideline
    android:layout_width="wrap_content"
    android:layout_height="wrap_content"
    android:id="@+id/guideline8"
    app:layout_constraintGuide_percent="0.5"
    android:orientation="vertical"/>

后来我想app:layout_constraintGuide_percent有条件地将值更改为其他值.我怎样才能做到这一点.

Answer 1

有两种方法可以做到:

• 运用 ConstraintLayout.LayoutParams

此方法从中获取特定参数ConstraintLayout并对其进行修改.

Guideline guideLine = (Guideline) findViewById(R.id.your_guideline);
ConstraintLayout.LayoutParams params = (ConstraintLayout.LayoutParams) guideLine.getLayoutParams();
params.guidePercent = 0.45f; // 45% // range: 0 <-> 1
guideLine.setLayoutParams(params);

• 运用 ConstraintSet

此方法包括克隆ConstraintLayout属性,修改它们然后应用于View.

但它很慢.

ConstraintLayout constraintLayout = (ConstraintLayout) findViewById(R.id.your_constraint_with_guideline);
ConstraintSet constraintSet = new ConstraintSet();
constraintSet.clone(constraintLayout);        
constraintSet.setGuidelinePercent(R.id.your_guideline, 0.07f); // 7% // range: 0 <-> 1
TransitionManager.beginDelayedTransition(constraintLayout);
constraintSet.applyTo(constraintLayout);

创建视差效果

为了测试这些方法,我使用a GuideLine和a 创建了一个视差动画ScrollView.

在AndroidManifest.xml,你的内部Activity,补充一点:android:hardwareAccelerated="true".

     <activity 
        android:name=".MainActivity"
        android:configChanges="keyboardHidden|orientation|screenSize"
        android:hardwareAccelerated="true">
     ...

MainActivity.java

Guideline guideTopInfo;
ConstraintLayout constraintLayout;
ConstraintLayout.LayoutParams params;
ConstraintSet constraintSet;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);

    guideTopInfo = (Guideline) findViewById(R.id.guideline2);
    constraintLayout = (ConstraintLayout) findViewById(R.id.constraint_root);
    params = (ConstraintLayout.LayoutParams) guideTopInfo.getLayoutParams();

    //constraintSet = new ConstraintSet();
    //constraintSet.clone(constraintLayout);

    final ScrollView scrollView = (ScrollView) findViewById(R.id.scroll_front);
    scrollView.getViewTreeObserver().addOnScrollChangedListener(new ViewTreeObserver.OnScrollChangedListener() {
        @Override
        public void onScrollChanged() {
            float percentage = scrollView.getScrollY() * 0.0001f; // 0.001f faster // 0.00001f slower parallax animation

            Log.d("mLog", String.valueOf(percentage));
            if(percentage >= 0) {
                // my XML percentage value was 12%
                params.guidePercent = 0.12f - percentage; // up
                //params.guidePercent = 0.12f + percentage; // downm
                guideTopInfo.setLayoutParams(params);

                //constraintSet.setGuidelinePercent(R.id.guideline2, 0.12f - percentage);
                //TransitionManager.beginDelayedTransition(constraintLayout);
                //constraintSet.applyTo(constraintLayout);
            }
        }
    });
}

关于视差的另一个答案,如果有人有兴趣的话.;)

Answer 2

此代码会将guidePercent更改为0

ConstraintLayout.LayoutParams lp = (ConstraintLayout.LayoutParams) guideline.getLayoutParams();
lp.guidePercent = 0;
guideline.setLayoutParams(lp);

Answer 3

你把它放在中心做它和我一起工作我希望它有帮助

<androidx.constraintlayout.widget.Guideline
                    android:layout_width="wrap_content"
                    android:layout_height="wrap_content"
                    android:orientation="vertical"
                    app:layout_constraintEnd_toEndOf="parent"
                    app:layout_constraintGuide_percent="0.5"
                    app:layout_constraintStart_toStartOf="parent" />

Answer 4

guideline.setGuidelinePercent(value: Float)

这足以在运行时更改指南百分比。