Android - 如何为 RecyclerView 添加点划线分隔线?
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【中文标题】Android - 如何为 RecyclerView 添加点划线分隔线?【英文标题】:Android - How to add a dashed/dotted separator line for RecyclerView? 【发布时间】:2017-02-01 16:38:22 【问题描述】:我使用this answer 中的代码为我的RecyclerView
s 创建了一个实心分隔线。
但是,我希望这条线是虚线/点线。
我已经有一个 line_dashed.xml
资源,我在我的应用程序的其他地方使用它:
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="line" >
<stroke
android:color="@color/blue"
android:dashGap="12dp"
android:dashWidth="12dp"
android: />
</shape>
但是,如果我尝试将此作为可通过调用recyclerView.addItemDecoration(new SimpleDividerItemDecoration(getContext()))
访问的可绘制资源,则根本不会画线。
如何解决所以显示虚线?
【问题讨论】:
【参考方案1】:只需将您的可绘制资源添加到此项目装饰器中即可。
DividerItemDecoration decorator = new DividerItemDecoration(ContextCompat.getDrawable(getContext(), R.drawable.line_dashed));
recyclerView.addItemDecoration(decorator);
和 DividerItemDecorator 类:
public class DividerItemDecoration extends RecyclerView.ItemDecoration
private Drawable mDivider;
private int mPaddingLeft;
public DividerItemDecoration(Drawable divider)
mDivider = divider;
mPaddingLeft = 0;
public DividerItemDecoration(Drawable divider, int paddingLeft)
mDivider = divider;
mPaddingLeft = paddingLeft;
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state)
super.getItemOffsets(outRect, view, parent, state);
if (mDivider == null) return;
if (parent.getChildAdapterPosition(view) < 1) return;
if (getOrientation(parent) == LinearLayoutManager.VERTICAL)
outRect.top = mDivider.getIntrinsicHeight();
else
outRect.left = mDivider.getIntrinsicWidth();
@Override
public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state)
if (mDivider == null)
super.onDrawOver(c, parent, state);
return;
if (getOrientation(parent) == LinearLayoutManager.VERTICAL)
final int left = parent.getPaddingLeft() + mPaddingLeft;
final int right = parent.getWidth() - parent.getPaddingRight();
final int childCount = parent.getChildCount();
for (int i = 1; i < childCount; i++)
final View child = parent.getChildAt(i);
final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
final int size = mDivider.getIntrinsicHeight();
final int top = child.getTop() - params.topMargin;
final int bottom = top + size;
mDivider.setBounds(left, top, right, bottom);
mDivider.draw(c);
else //horizontal
final int top = parent.getPaddingTop();
final int bottom = parent.getHeight() - parent.getPaddingBottom();
final int childCount = parent.getChildCount();
for (int i = 1; i < childCount; i++)
final View child = parent.getChildAt(i);
final RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
final int size = mDivider.getIntrinsicWidth();
final int left = child.getLeft() - params.leftMargin;
final int right = left + size;
mDivider.setBounds(left, top, right, bottom);
mDivider.draw(c);
private int getOrientation(RecyclerView parent)
if (parent.getLayoutManager() instanceof LinearLayoutManager)
LinearLayoutManager layoutManager = (LinearLayoutManager) parent.getLayoutManager();
return layoutManager.getOrientation();
else
throw new IllegalStateException("DividerItemDecoration can only be used with a LinearLayoutManager.");
我应该测试过它。
更新:
android:layerType="software"
在recyclerView的xml中添加这个参数 还将尺寸添加到您的可绘制形状中:
<size android:/>
【讨论】:
你有没有像@ban-geoengineering 显示的那样用 datted drawable 测试它?真的有用吗? @Roman_Donchenko 检查更新,此更改确实有效。 它对我有用 - 有一个变化:我必须将<size android:height="2dp"/>
添加到我的 line_dashed.xml 才能看到它 - 即,我必须指定一个高度2dp
而不是 1dp
。任何想法为什么?
我也必须指定高度为 2dp 而不是 1dp 才能完成这项工作。有什么想法吗?
是的,它在高度为2dp
而不是1dp
时工作。【参考方案2】:
目前你可以使用 DividerItemDecoration 的盒子。
recyclerView.apply
layoutManager = LinearLayoutManager(this@YourFragment.context)
adapter = this@YourFragment.adapter
addItemDecoration(
DividerItemDecoration(
this@YourFragment.context,
DividerItemDecoration.VERTICAL
).apply
context.getDrawable(R.drawable.divider)?.let
setDrawable(it)
)
使用下一个形状 XML:
<?xml version="1.0" encoding="utf-8"?>
<shape xmlns:android="http://schemas.android.com/apk/res/android"
android:shape="line">
<size android: />
<solid android:color="@color/primary" />
<stroke
android:
android:color="@color/primary"
android:dashWidth="5dp"
android:dashGap="5dp" />
</shape>
注意:笔划宽度必须小于线高。在另一种情况下,线不会被绘制。
【讨论】:
这点对我来说很关键:``` 注意:笔划宽度必须小于线的高度。在另一种情况下,将不绘制线。 ```【参考方案3】:在Android中画虚线不是那么容易的事。像您展示的那样可拖动,甚至只是在 canwas (canvas.drawLine(..., paintWithDashEffect)
) 上绘制虚线并不总是有效(不适用于所有设备)。您可以使用android:layerType="software"
或绘制路径。恕我直言,更好的解决方案是根本不画虚线(只画线)。但是如果你真的需要虚线,你可以使用@fearless 回答或者这样的想法:
public class DividerItemDecoration extends RecyclerView.ItemDecoration
private Paint mPaint;
private int mDividerSize;
public DividerItemDecoration(int dividerSize)
mDividerSize = dividerSize;
mPaint = new Paint();
mPaint.setColor(ContextCompat.getColor(context, R.color.colorAccent));
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeWidth(dividerSize);
mPaint.setPathEffect(new DashPathEffect(new float[]dashGap,dashWidth,0));
@Override
public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state)
outRect.bottom = mDividerSize;
@Override
public void onDrawOver(Canvas c, RecyclerView parent, RecyclerView.State state)
int left = parent.getPaddingLeft();
int right = parent.getWidth() - parent.getPaddingRight();
int childCount = parent.getChildCount();
Path path = new Path();
for (int i = 0; i < childCount; i++)
View child = parent.getChildAt(i);
RecyclerView.LayoutParams params = (RecyclerView.LayoutParams) child.getLayoutParams();
int top = child.getBottom() + params.bottomMargin + mDividerSize/2;
path.moveTo(left, top);
path.lineTo(right, top);
c.drawPath(path, mPaint);
【讨论】:
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