Android自定義控件ViewGroup實現標簽云（四）

2019-12-12 05:50:37

字體：大中小

來源：轉載

供稿：網友

前言：

前面幾篇講了自定義控件繪制原理Android自定義控件基本原理詳解（一），Android自定義控件之自定義屬性（二），Android自定義控件之自定義組合控件（三），常言道：“好記性不如爛筆頭，光說不練假把式?。。　保鳛橐幻麑W渣就是因為沒有遵循這句名言才淪落于此，所以要謹遵教誨，注重理論與實踐相結合，今天通過自定義ViewGroup來實現一下項目中用到的標簽云。

需求背景：

公司需要實現一個知識點的標簽顯示，每個標簽的長度未知，如下圖所示

基本繪制流程：

繪制原理這里不再介紹大致介紹下繪制流程
•構造函數獲取自定義屬性
•onMeasure()方法，測量子控件的大小
•onLayout()方法，對子控件進行布局

1.）自定義屬性

 <declare-styleable name="TagsLayout">  <attr name="tagVerticalSpace" format="dimension" />  <attr name="tagHorizontalSpace" format="dimension" /></declare-styleable>

2.）構造函數中獲取自定義屬性值

private int childHorizontalSpace; private int childVerticalSpace; public TagsLayout(Context context, AttributeSet attrs) {  super(context, attrs);  TypedArray attrArray = context.obtainStyledAttributes(attrs, R.styleable.TagsLayout);  if (attrArray != null) {   childHorizontalSpace = attrArray.getDimensionPixelSize(R.styleable.TagsLayout_tagHorizontalSpace, 0);   childVerticalSpace = attrArray.getDimensionPixelSize(R.styleable.TagsLayout_tagVerticalSpace, 0);   attrArray.recycle();  } }

3.）onMeasure函數測量子控件大小，然后設置當前控件大小

 /**  * 負責設置子控件的測量模式和大小 根據所有子控件設置自己的寬和高  */ @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {  super.onMeasure(widthMeasureSpec, heightMeasureSpec);  // 獲得它的父容器為它設置的測量模式和大小  int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);  int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);  int modeWidth = MeasureSpec.getMode(widthMeasureSpec);  int modeHeight = MeasureSpec.getMode(heightMeasureSpec);  // 如果是warp_content情況下，記錄寬和高  int width = 0;  int height = 0;  /**   * 記錄每一行的寬度，width不斷取最大寬度   */  int lineWidth = 0;  /**   * 每一行的高度，累加至height   */  int lineHeight = 0;  int count = getChildCount();  int left = getPaddingLeft();  int top = getPaddingTop();  // 遍歷每個子元素  for (int i = 0; i < count; i++) {   View child = getChildAt(i);   if (child.getVisibility() == GONE)    continue;   // 測量每一個child的寬和高   measureChild(child, widthMeasureSpec, heightMeasureSpec);   // 得到child的lp   MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();   // 當前子空間實際占據的寬度   int childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin + childHorizontalSpace;   // 當前子空間實際占據的高度   int childHeight = child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin + childVerticalSpace;   /**    * 如果加入當前child，則超出最大寬度，則的到目前最大寬度給width，類加height 然后開啟新行    */   if (lineWidth + childWidth > sizeWidth - getPaddingLeft() - getPaddingRight()) {    width = Math.max(lineWidth, childWidth);// 取最大的    lineWidth = childWidth; // 重新開啟新行，開始記錄    // 疊加當前高度，    height += lineHeight;    // 開啟記錄下一行的高度    lineHeight = childHeight;    child.setTag(new Location(left, top + height, childWidth + left - childHorizontalSpace, height + child.getMeasuredHeight() + top));   } else {// 否則累加值lineWidth,lineHeight取最大高度    child.setTag(new Location(lineWidth + left, top + height, lineWidth + childWidth - childHorizontalSpace + left, height + child.getMeasuredHeight() + top));    lineWidth += childWidth;    lineHeight = Math.max(lineHeight, childHeight);   }  }  width = Math.max(width, lineWidth) + getPaddingLeft() + getPaddingRight();  height += lineHeight;  sizeHeight += getPaddingTop() + getPaddingBottom();  height += getPaddingTop() + getPaddingBottom();  setMeasuredDimension((modeWidth == MeasureSpec.EXACTLY) ? sizeWidth : width, (modeHeight == MeasureSpec.EXACTLY) ? sizeHeight : height); }

通過遍歷所有子控件調用measureChild函數獲取每個子控件的大小，然后通過寬度疊加判斷是否換行，疊加控件的高度，同時記錄下當前子控件的坐標，這里記錄坐標引用了自己寫的一個內部類Location.java

 /**  * 記錄子控件的坐標  */ public class Location {  public Location(int left, int top, int right, int bottom) {   this.left = left;   this.top = top;   this.right = right;   this.bottom = bottom;  }  public int left;  public int top;  public int right;  public int bottom; }

4.)onLayout函數對所有子控件重新布局

 @Override protected void onLayout(boolean changed, int l, int t, int r, int b) {  int count = getChildCount();  for (int i = 0; i < count; i++) {   View child = getChildAt(i);   if (child.getVisibility() == GONE)    continue;   Location location = (Location) child.getTag();   child.layout(location.left, location.top, location.right, location.bottom);  } }

這里直接遍歷所有子控件調用子控件的layout函數進行布局。

如何使用：
1）.布局問自己中直接引用

<?xml version="1.0" encoding="utf-8"?><LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:lee="http://schemas.android.com/apk/res-auto" android:layout_width="match_parent" android:layout_height="match_parent" android:orientation="vertical"> <com.whoislcj.views.TagsLayout  android:id="@+id/image_layout"  android:layout_width="match_parent"  android:layout_height="wrap_content"  android:layout_margin="10dp"  lee:tagHorizontalSpace="10dp"  lee:tagVerticalSpace="10dp" /></LinearLayout>

2）.代碼添加標簽

TagsLayout imageViewGroup = (TagsLayout) findViewById(R.id.image_layout); ViewGroup.MarginLayoutParams lp = new ViewGroup.MarginLayoutParams(ViewGroup.LayoutParams.WRAP_CONTENT, ViewGroup.LayoutParams.WRAP_CONTENT);  String[] string={"從我寫代碼那天起，我就沒有打算寫代碼","從我寫代碼那天起","我就沒有打算寫代碼","沒打算","寫代碼"};  for (int i = 0; i < 5; i++) {   TextView textView = new TextView(this);   textView.setText(string[i]);   textView.setTextColor(Color.WHITE);   textView.setBackgroundResource(R.drawable.round_square_blue);   imageViewGroup.addView(textView, lp);  }

具體效果

3.）最后附上TagsLayout全部代碼

public class TagsLayout extends ViewGroup { private int childHorizontalSpace; private int childVerticalSpace; public TagsLayout(Context context, AttributeSet attrs) {  super(context, attrs);  TypedArray attrArray = context.obtainStyledAttributes(attrs, R.styleable.TagsLayout);  if (attrArray != null) {   childHorizontalSpace = attrArray.getDimensionPixelSize(R.styleable.TagsLayout_tagHorizontalSpace, 0);   childVerticalSpace = attrArray.getDimensionPixelSize(R.styleable.TagsLayout_tagVerticalSpace, 0);   attrArray.recycle();  } } /**  * 負責設置子控件的測量模式和大小 根據所有子控件設置自己的寬和高  */ @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {  super.onMeasure(widthMeasureSpec, heightMeasureSpec);  // 獲得它的父容器為它設置的測量模式和大小  int sizeWidth = MeasureSpec.getSize(widthMeasureSpec);  int sizeHeight = MeasureSpec.getSize(heightMeasureSpec);  int modeWidth = MeasureSpec.getMode(widthMeasureSpec);  int modeHeight = MeasureSpec.getMode(heightMeasureSpec);  // 如果是warp_content情況下，記錄寬和高  int width = 0;  int height = 0;  /**   * 記錄每一行的寬度，width不斷取最大寬度   */  int lineWidth = 0;  /**   * 每一行的高度，累加至height   */  int lineHeight = 0;  int count = getChildCount();  int left = getPaddingLeft();  int top = getPaddingTop();  // 遍歷每個子元素  for (int i = 0; i < count; i++) {   View child = getChildAt(i);   if (child.getVisibility() == GONE)    continue;   // 測量每一個child的寬和高   measureChild(child, widthMeasureSpec, heightMeasureSpec);   // 得到child的lp   MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams();   // 當前子空間實際占據的寬度   int childWidth = child.getMeasuredWidth() + lp.leftMargin + lp.rightMargin + childHorizontalSpace;   // 當前子空間實際占據的高度   int childHeight = child.getMeasuredHeight() + lp.topMargin + lp.bottomMargin + childVerticalSpace;   /**    * 如果加入當前child，則超出最大寬度，則的到目前最大寬度給width，類加height 然后開啟新行    */   if (lineWidth + childWidth > sizeWidth - getPaddingLeft() - getPaddingRight()) {    width = Math.max(lineWidth, childWidth);// 取最大的    lineWidth = childWidth; // 重新開啟新行，開始記錄    // 疊加當前高度，    height += lineHeight;    // 開啟記錄下一行的高度    lineHeight = childHeight;    child.setTag(new Location(left, top + height, childWidth + left - childHorizontalSpace, height + child.getMeasuredHeight() + top));   } else {// 否則累加值lineWidth,lineHeight取最大高度    child.setTag(new Location(lineWidth + left, top + height, lineWidth + childWidth - childHorizontalSpace + left, height + child.getMeasuredHeight() + top));    lineWidth += childWidth;    lineHeight = Math.max(lineHeight, childHeight);   }  }  width = Math.max(width, lineWidth) + getPaddingLeft() + getPaddingRight();  height += lineHeight;  sizeHeight += getPaddingTop() + getPaddingBottom();  height += getPaddingTop() + getPaddingBottom();  setMeasuredDimension((modeWidth == MeasureSpec.EXACTLY) ? sizeWidth : width, (modeHeight == MeasureSpec.EXACTLY) ? sizeHeight : height); } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) {  int count = getChildCount();  for (int i = 0; i < count; i++) {   View child = getChildAt(i);   if (child.getVisibility() == GONE)    continue;   Location location = (Location) child.getTag();   child.layout(location.left, location.top, location.right, location.bottom);  } } /**  * 記錄子控件的坐標  */ public class Location {  public Location(int left, int top, int right, int bottom) {   this.left = left;   this.top = top;   this.right = right;   this.bottom = bottom;  }  public int left;  public int top;  public int right;  public int bottom; }}

總結：
至此有關簡單的自定義控件已經介紹的差不多了，項目中很復雜的控件現在涉及的比較少，以后用到之后再做記錄。

上一篇：Android自定義控件基本原理詳解（一）

下一篇：Android GestureDetector手勢滑動使用實例講解