Android史上最强分割线全攻略
借鉴自
https://blog.csdn.net/megatronkings/article/details/52156312
说实话,分割线这个东西,真的太难太难了!!!
难在何处?难在用最对的方式去实现它!
1.view——管理代码不便,绘制开销大。非常非常不好
2.图片——修改不便,增加apk体积。非常非常不好
3.Java代码——使用不便,增加代码量。非常非常不好
4.layer-list通过覆盖实现——过度绘制,修改不便。非常非常不好
5.shape——设置成background会自动填充,无法实现!
6.自定义控件——做模块化的时候,需要移植这个库。不太好
7.不充满的底部分割线的这种情况,实现起来更难——又一限制条件
所以他难
本人在探索了2个小时后,终于得出了结论
1.LinearLayout——虽然background这个属性会自动填充,不能用,但是他有divider属性!
2.其他布局——自定义控件
3.RecyclerView——ItemDecoration
下面我将给出这些情况的代码,你可以直接拷去用。
代码原理就不解释了,太简单了。有问题留言。
LinearLayout充满的底部分割线(其他方向的分割线也一样)
<?xml version="1.0" encoding="utf-8"?> <shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle"> <size android:height="1dp"/> <solid android:color="@color/colorAccent"/> </shape>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="wrap_content" android:divider="@drawable/line_bottom" android:showDividers="end"android:orientation="vertical" xmlns:tools="http://schemas.android.com/tools">
效果
LinearLayout不充满的底部分割线
<?xml version="1.0" encoding="utf-8"?> <inset xmlns:android="http://schemas.android.com/apk/res/android" android:drawable="@drawable/line_bottom" android:insetLeft="15dp"> </inset>
<?xml version="1.0" encoding="utf-8"?> <shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle"> <size android:height="1dp"/> <solid android:color="@color/colorAccent"/> </shape>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="wrap_content" android:divider="@drawable/line_bottom_not_full"android:showDividers="end" android:orientation="vertical" xmlns:tools="http://schemas.android.com/tools">
效果
其他布局:网上开源库很多,不过我不太喜欢用别人的库,所以自己实现了一个(实现了主流的RelativeLayout和FrameLayout)
attrs
<?xml version="1.0" encoding="utf-8"?> <resources> <declare-styleable name="BorderRelativeLayout"> <attr name="margin_start" format="dimension"/>线到起始端的margin <attr name="margin_end" format="dimension"/>线到末端的margin <attr name="width" format="dimension"/>线的宽度 <attr name="color" format="color"/>线的颜色 <attr name="position" format="string"/>线的位置:left、top、right、bottom </declare-styleable> </resources>
border relative layout
package com.example.filemanager; import android.content.Context; import android.content.res.TypedArray; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; import android.util.AttributeSet; import android.util.Log; import android.widget.RelativeLayout; // TODO: 2018/5/3 如果你想多弄几条线 或者位置有特殊需求 自己改写呗! public class BorderRelativeLayout extends RelativeLayout {private static final String TAG = "xbh"; public BorderRelativeLayout(Context context, AttributeSet attrs) {super(context, attrs); //params TypedArray ta = context.obtainStyledAttributes(attrs, R.styleable.BorderRelativeLayout); startMargin = ta.getDimension(R.styleable.BorderRelativeLayout_margin_start, 0); endMargin = ta.getDimension(R.styleable.BorderRelativeLayout_margin_end, 0); width = ta.getDimension(R.styleable.BorderRelativeLayout_width, 0); int color = ta.getColor(R.styleable.BorderRelativeLayout_color, Color.GRAY); position = ta.getString(R.styleable.BorderRelativeLayout_position); ta.recycle(); //init paint paint.setColor(color); }//拿到绘制坐标:position、margin、width private static final String LEFT = "left"; private static final String TOP = "top"; private static final String RIGHT = "right"; private static final String BOTTOM = "bottom"; private float startMargin; private float endMargin; private float width; private final String position; private float left; private float top; private float right; private float bottom; @Override protected void onLayout(boolean changed, int l, int t, int r, int b) {super.onLayout(changed, l, t, r, b); int w = getWidth(); int h = getHeight(); if (LEFT.equals(position)) {left = 0; top = startMargin; right = width; bottom = h - endMargin; } else if (TOP.equals(position)) {left = startMargin; top = 0; right = w - endMargin; bottom = width; } else if (RIGHT.equals(position)) {left = w - width; top = startMargin; right = w; bottom = h - endMargin; } else if (BOTTOM.equals(position)) {left = startMargin; top = h - width; right = w - endMargin; bottom = h; }}// private final Paint paint = new Paint(); @Override protected void dispatchDraw(Canvas canvas) {super.dispatchDraw(canvas); canvas.drawRect(left, top, right, bottom, paint); } }
使用
<com.example.filemanager.BorderRelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" android:layout_width="match_parent" android:layout_height="wrap_content" android:showDividers="end" android:divider="@drawable/line_bottom_not_full" android:orientation="vertical" xmlns:tools="http://schemas.android.com/tools" xmlns:app="http://schemas.android.com/apk/res-auto" app:margin_start="0dp" app:margin_end="0dp" app:width="1dp" app:position="left" app:color="#000">
测试了下非常好用。
frame layout你只需要改个名,继承自frame layout即可。
RecyclerView
列表的情况上面就不适用了,因为最后一个item我们不期望有线。
rv.addItemDecoration(new DividerItemDecoration(activity, DividerItemDecoration.VERTICAL));
这行代码就会为我们处理的很好。
效果如下
如果我们对他默认的样式不满意呢?
我们可以通过setDrawable的方式去设置我们drawable文件夹下自己定义的线。但是这导致的后果是我们最后一个item也有了线。所以我们需要自定义ItemDecoration。
(解决方案学习自:https://www.jianshu.com/p/26b33e1181e3 自己重写了一个DividerItemDecoration)
static class DividerItemDecoration extends RecyclerView.ItemDecoration {public static final int HORIZONTAL = LinearLayout.HORIZONTAL; public static final int VERTICAL = LinearLayout.VERTICAL; private static final String TAG = "DividerItem"; private static final int[] ATTRS = new int[]{android.R.attr.listDivider}; private Drawable mDivider; private boolean mIsShowBottomDivider; /** * Current orientation. Either {@link #HORIZONTAL} or {@link #VERTICAL}. */ private int mOrientation; private final Rect mBounds = new Rect(); public DividerItemDecoration(Context context, int orientation) {mIsShowBottomDivider = false; final TypedArray a = context.obtainStyledAttributes(ATTRS); mDivider = a.getDrawable(0); if (mDivider == null) {Log.w(TAG, "@android:attr/listDivider was not set in the theme used for this " + "DividerItemDecoration. Please set that attribute all call setDrawable()"); }a.recycle(); setOrientation(orientation); }/** * Sets the orientation for this divider. This should be called if * {@link RecyclerView.LayoutManager} changes orientation. * * @param orientation {@link #HORIZONTAL} or {@link #VERTICAL} */ public void setOrientation(int orientation) {if (orientation != HORIZONTAL && orientation != VERTICAL) {throw new IllegalArgumentException("Invalid orientation. It should be either HORIZONTAL or VERTICAL"); }mOrientation = orientation; }/** * Sets the {@link Drawable} for this divider. * * @param drawable Drawable that should be used as a divider. */ public void setDrawable(@NonNull Drawable drawable) {if (drawable == null) {throw new IllegalArgumentException("Drawable cannot be null."); }mDivider = drawable; }@Override public void onDraw(Canvas c, RecyclerView parent, RecyclerView.State state) {if (parent.getLayoutManager() == null || mDivider == null) {return; }if (mOrientation == VERTICAL) {drawVertical(c, parent, state); } else {drawHorizontal(c, parent, state); }}private void drawVertical(Canvas canvas, RecyclerView parent, RecyclerView.State state) {canvas.save(); final int left; final int right; //noinspection AndroidLintNewApi - NewApi lint fails to handle overrides. if (parent.getClipToPadding()) {left = parent.getPaddingLeft(); right = parent.getWidth() - parent.getPaddingRight(); canvas.clipRect(left, parent.getPaddingTop(), right, parent.getHeight() - parent.getPaddingBottom()); } else {left = 0; right = parent.getWidth(); }final int childCount = parent.getChildCount(); final int lastPosition = state.getItemCount() - 1; for (int i = 0; i < childCount; i++) {final View child = parent.getChildAt(i); final int childRealPosition = parent.getChildAdapterPosition(child); //mIsShowBottomDivider false的时候不绘制最后一个view的divider if (mIsShowBottomDivider || childRealPosition < lastPosition) {parent.getDecoratedBoundsWithMargins(child, mBounds); final int bottom = mBounds.bottom + Math.round(child.getTranslationY()); final int top = bottom - mDivider.getIntrinsicHeight(); mDivider.setBounds(left, top, right, bottom); mDivider.draw(canvas); }}canvas.restore(); }private void drawHorizontal(Canvas canvas, RecyclerView parent, RecyclerView.State state) {canvas.save(); final int top; final int bottom; //noinspection AndroidLintNewApi - NewApi lint fails to handle overrides. if (parent.getClipToPadding()) {top = parent.getPaddingTop(); bottom = parent.getHeight() - parent.getPaddingBottom(); canvas.clipRect(parent.getPaddingLeft(), top, parent.getWidth() - parent.getPaddingRight(), bottom); } else {top = 0; bottom = parent.getHeight(); }final int childCount = parent.getChildCount(); final int lastPosition = state.getItemCount() - 1; for (int i = 0; i < childCount; i++) {final View child = parent.getChildAt(i); final int childRealPosition = parent.getChildAdapterPosition(child); //mIsShowBottomDivider false的时候不绘制最后一个view的divider if (mIsShowBottomDivider || childRealPosition < lastPosition) {parent.getLayoutManager().getDecoratedBoundsWithMargins(child, mBounds); final int right = mBounds.right + Math.round(child.getTranslationX()); final int left = right - mDivider.getIntrinsicWidth(); mDivider.setBounds(left, top, right, bottom); mDivider.draw(canvas); }}canvas.restore(); }@Override public void getItemOffsets(Rect outRect, View view, RecyclerView parent, RecyclerView.State state) {if (mDivider == null) {outRect.set(0, 0, 0, 0); return; }if (mOrientation == VERTICAL) {//parent.getChildCount() 不能拿到item的总数 //https://stackoverflow.com/questions/29666598/android-recyclerview-finding-out-first // -and-last-view-on-itemdecoration int lastPosition = state.getItemCount() - 1; int position = parent.getChildAdapterPosition(view); if (mIsShowBottomDivider || position < lastPosition) {outRect.set(0, 0, 0, mDivider.getIntrinsicHeight()); } else {outRect.set(0, 0, 0, 0); }} else {int lastPosition = state.getItemCount() - 1; int position = parent.getChildAdapterPosition(view); if (mIsShowBottomDivider || position < lastPosition) {outRect.set(0, 0, mDivider.getIntrinsicWidth(), 0); } else {outRect.set(0, 0, 0, 0); }}} }
自定义的样式
<?xml version="1.0" encoding="utf-8"?> <shape xmlns:android="http://schemas.android.com/apk/res/android" android:shape="rectangle"> <size android:height="1dp"/> <solid android:color="@color/colorAccent"/> </shape>
使用自定义的样式
//rv RecyclerView rv = (RecyclerView) fvb(R.id.rv); rv.setAdapter(new Adapter()); rv.setLayoutManager(new LinearLayoutManager(activity)); DividerItemDecoration decoration = new DividerItemDecoration(activity, DividerItemDecoration.VERTICAL); decoration.setDrawable(activity.getResources().getDrawable(R.drawable.border_bottom_not_full)); rv.addItemDecoration(decoration);
大功告成。分割线的不同情形的最佳实现思路一直是让人头疼的地方,甚至在难以满足需求的时候忍不住直接用view。看了本文后,您可以开开心心地搞定分割线啦!
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