继承View,实现自己想要的组件,那么需要使用到setMeasuredDimension这个方法,这个方法决定了当前View的大小,请看代码:
View的代码:
- package cc.mdev.test;
-
- import android.content.Context;
- import android.graphics.Canvas;
- import android.graphics.Color;
- import android.text.TextPaint;
- import android.util.AttributeSet;
- import android.util.Log;
- import android.view.View;
-
- public class MyScrollView extends View {
-
- public MyScrollView(Context context, AttributeSet attrs) {
- super(context, attrs);
- }
-
- public MyScrollView(Context context) {
- super(context);
- }
- @Override
- protected void onDraw(Canvas canvas) {
- TextPaint paint = new TextPaint();
- paint.setAntiAlias(true);
- canvas.drawColor(Color.GRAY);
- for (int i = 10; i < 500; i++) {
- canvas.drawText("This is the scroll text.", 10, i, paint);
- i = i+15;
- }
- }
-
- @Override
- protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
- String tag="onMeasure";
- Log.e(tag, "Scroll View on measure...");
- setMeasuredDimension(200, 800);
- }
-
- @Override
- protected void onScrollChanged(int l, int t, int oldl, int oldt) {
- String tag = "onScrollChanged";
- Log.e(tag, "Scroll....");
- super.onScrollChanged(l, t, oldl, oldt);
- }
- }
布局文件:
- xml version="1.0" encoding="utf-8"?>
- <LinearLayout xmlns:android=""
- android:orientation="vertical"
- android:layout_width="fill_parent"
- android:layout_height="fill_parent"
- android:background="#fff" >
- <Button android:text="Button01"
- android:id="@+id/Button01"
- android:layout_width="wrap_content"
- android:layout_height="wrap_content">
- Button>
- <ScrollView android:layout_width="fill_parent"
- android:layout_height="fill_parent">
- <cc.mdev.test.MyScrollView android:layout_width="wrap_content"
- android:layout_height="wrap_content"/>
- ScrollView>
- LinearLayout>
效果就是自定义视图的大小为
200, 800,并且放入到ScrollView中,ScrollView会启作用,如果不使用setMeasuredDimension这个方法,那么ScrollView不会有作用。
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