Question

我正在尝试在Android应用程序的屏幕上四处移动textview。但是在将textview拖动到最终位置后，它随机移动到其他相对位置。


private final class TextViewTouchListener implements View.OnTouchListener {

            @Override
            public boolean onTouch(View view, MotionEvent event) {
                ClipData data = ClipData.newPlainText("", "");
                View.DragShadowBuilder shadowBuilder = new View.DragShadowBuilder(view);
                //start dragging the item touched
                view.startDrag(data, shadowBuilder, view, 0);
                return true;
            }
        }


private final class TextViewDragListener implements View.OnDragListener {

            @Override
            public boolean onDrag(View v, DragEvent event) {
                final float x = event.getX();
                final float y =event.getY();

// handling the case when the textview gets dragged out of screen
                leftMargin = Math.min(x, mDisplaySize.x - textview.getWidth());
                topargin = Math.min(y, mDisplaySize.y - textview.getHeight());

                final FrameLayout.LayoutParams params = (FrameLayout.LayoutParams) textView.getLayoutParams();
                params.leftMargin = (int) leftMargin;
                params.topMargin = (int) topargin;
                params.rightMargin = 0;
                params.bottomMargin = 0;

            textView.setLayoutParams(params);

                return true;
            }
        }

Seems like I am handling it wrong. Can someone help me what exactly I am doing wrong.

Answer 1

如果只想在屏幕上移动视图，则无需使用拖放；您只可以使用MotionEvent.ACTION_DOWN的{{1}}和MotionEvent.ACTION_MOVE事件来更新屏幕上视图的x和y位置。

为避免将视图移出屏幕，我们将使用其View.OnTouchListener

计算根视图的宽度和高度

因此，您的布局将具有一个包含getViewTreeObserver()的根视图，您想在屏幕上四处移动。

TextView

您的行为将是：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/root_layout"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <TextView
        android:id="@+id/textview"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Hello World" />

</RelativeLayout>

结果

在Android应用上在屏幕上移动Textview

1 个答案: