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我想了解Android的措施和布局意见。我使用自定义视图和视图组创建了一个示例应用程序。onLineout和onLayout的子视图不会调用他们的父母后requestLayout
CustomViewGroup
public class CustomViewGroup extends ViewGroup {
private static final String LOG_TAG = "CustomViewGroup";
public CustomViewGroup(Context context, AttributeSet attrs) {
super(context, attrs);
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
Log.d(LOG_TAG, String.format(Locale.ENGLISH,
getTag() + " " +
"onMeasure(widthMeasureSpec=%d, heightMeasureSpec%d)",
widthMeasureSpec, heightMeasureSpec
));
final int count = getChildCount();
for (int i = 0; i < count; i++) {
final View child = getChildAt(i);
if (child.getVisibility() != View.GONE) {
// Make or work out measurements for children here (MeasureSpec.make...)
measureChild(child, widthMeasureSpec, heightMeasureSpec);
}
}
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
Log.d(LOG_TAG, String.format(Locale.ENGLISH,
getTag() + " " +
"onLayout(changed=%b, left=%d, top=%d, right=%d, bottom=%d)",
changed, left, top, top, right, bottom
));
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
Log.d(LOG_TAG, getTag() + " " + "onDraw");
}
}
CustomView
public class CustomView extends View {
private static final String LOG_TAG = "CustomView";
public CustomView(Context context, AttributeSet attrs) {
super(context, attrs);
}
@Override
protected void onLayout(boolean changed, int left, int top, int right, int bottom) {
super.onLayout(changed, left, top, right, bottom);
Log.d(LOG_TAG, String.format(Locale.ENGLISH,
getTag() + " " +
"onLayout(changed=%b, left=%d, top=%d, right=%d, bottom=%d)",
changed, left, top, top, right, bottom
));
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
Log.d(LOG_TAG, getTag() + " " +"onDraw");
}
@Override
protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
super.onMeasure(widthMeasureSpec, heightMeasureSpec);
Log.d(LOG_TAG, String.format(Locale.ENGLISH,
getTag() + " " +
"onMeasure(widthMeasureSpec=%d, heightMeasureSpec=%d)",
widthMeasureSpec, heightMeasureSpec
));
}
}
MainActivity
public class MainActivity extends AppCompatActivity {
private View mCustomGroup1;
private View mCustomGroup2;
private View mContainer;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
Log.d("MainAct", "onCreate");
mCustomGroup1 = findViewById(R.id.requestLayout);
mCustomGroup2 = findViewById(R.id.requestLayout2);
mContainer = findViewById(R.id.activity_main);
findViewById(R.id.requestLayoutBtn).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
mCustomGroup1.requestLayout();
}
});
findViewById(R.id.requestLayoutBtn2).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
mCustomGroup2.requestLayout();
}
});
findViewById(R.id.requestLayoutContBtn).setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
mContainer.requestLayout();
}
});
}
}
activity_main.xml中
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:id="@+id/activity_main"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="ru.dmitriev.squareorderedlayout.MainActivity">
<Button
android:id="@+id/requestLayoutBtn"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="requestLayout" />
<Button
android:id="@+id/requestLayoutBtn2"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="requestLayout2" />
<Button
android:id="@+id/requestLayoutContBtn"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:text="requestLayoutCont" />
<ru.dmitriev.squareorderedlayout.CustomViewGroup
android:id="@+id/requestLayout"
android:layout_width="100dp"
android:layout_height="0dp"
android:layout_weight="1"
android:background="#7f7"
android:tag="CustomVieGroup1">
<ru.dmitriev.squareorderedlayout.CustomView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:tag="CustomView11" />
<ru.dmitriev.squareorderedlayout.CustomView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:tag="CustomView12" />
</ru.dmitriev.squareorderedlayout.CustomViewGroup>
<ru.dmitriev.squareorderedlayout.CustomViewGroup
android:id="@+id/requestLayout2"
android:layout_width="100dp"
android:layout_height="0dp"
android:layout_weight="1"
android:background="#f77"
android:tag="CustomVieGroup2">
<ru.dmitriev.squareorderedlayout.CustomView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:tag="CustomView21" />
<ru.dmitriev.squareorderedlayout.CustomView
android:layout_width="match_parent"
android:layout_height="match_parent"
android:tag="CustomView22" />
</ru.dmitriev.squareorderedlayout.CustomViewGroup>
</LinearLayout>
当活动开始，onMeasure，onLayout和onDraw被称为在视图组标记CustomVieGroup1和CustomVieGroup2。每个视图组都会在子项上调用这些方法。没关系。我明白。
当我调用requestLayout的视图组标记CustomVieGroup ，onMeasure，onLayout和onDraw被称为上CustomVieGroup 。该小组将这些方法称为他们的孩子。我明白。
当我调用requestLayout的视图组标记CustomVieGroup ，onMeasure，onLayout和onDraw被称为上CustomVieGroup 。该小组将这些方法称为他们的孩子。我也了解它。
但是当我打电话requestLayout上的观点与ID activity_main，onMeasure和onLayout不叫上CustomVieGroup1或CustomVieGroup2。为什么？我预计，onMeasure，onLayout和onDraw将两个CustomVieGroup1和CustomVieGroup2
（即视图的ID为activity_main cgildren）被调用按照documentation of requestLayout：
这将预定的布局传递视图树。
绝对正确！将'match_parent'改为'wrap_content'会有所不同 –