如何在约束布局中动态设置 ImageView 的位置

Question

我在 ConstraintLayout 中有一个动态创建的 ImageView。一旦我运行应用程序，ImageView 就会显示在左上角，因为没有为 ImageView.

定义位置

如何动态设置 ImageView 的位置（比如 CENTER）？

我写了下面的代码：

ConstraintLayout layout = (ConstraintLayout) findViewById(R.id.constraintLayout);

ImageView imageView = new ImageView(ChooseOptionsActivity.this);
imageView.setImageResource(R.drawable.redlight);

layout.addView(imageView);

setContentView(layout);

非常感谢任何建议。

Answer 1

您需要使用应用于 ImageView 的 ConstraintSet 使其居中。 ConstraintSet 的文档可以在 here.

中找到

This class allows you to define programmatically a set of constraints to be used with ConstraintLayout. It lets you create and save constraints, and apply them to an existing ConstraintLayout. ConstraintsSet can be created in various ways...

也许这里最棘手的事情是视图如何居中。 here.

对居中技术的一个很好的描述

对于您的示例，以下代码就足够了：

    // Get existing constraints into a ConstraintSet
    ConstraintSet constraints = new ConstraintSet();
    constraints.clone(layout);
    // Define our ImageView and add it to layout
    ImageView imageView = new ImageView(this);
    imageView.setId(View.generateViewId());
    imageView.setImageResource(R.drawable.redlight);
    layout.addView(imageView);
    // Now constrain the ImageView so it is centered on the screen.
    // There is also a "center" method that can be used here.
    constraints.constrainWidth(imageView.getId(), ConstraintSet.WRAP_CONTENT);
    constraints.constrainHeight(imageView.getId(), ConstraintSet.WRAP_CONTENT);
    constraints.center(imageView.getId(), ConstraintSet.PARENT_ID, ConstraintSet.LEFT,
            0, ConstraintSet.PARENT_ID, ConstraintSet.RIGHT, 0, 0.5f);
    constraints.center(imageView.getId(), ConstraintSet.PARENT_ID, ConstraintSet.TOP,
            0, ConstraintSet.PARENT_ID, ConstraintSet.BOTTOM, 0, 0.5f);
    constraints.applyTo(layout);

如何在约束布局中动态设置 ImageView 的位置

How can I set an ImageView's position dynamically in Constraint Layout

android

android-constraintlayout