Android View中的setMeasuredDimension方法
阿新 • • 發佈:2019-01-30
繼承View,實現自己想要的元件,那麼需要使用到setMeasuredDimension這個方法,這個方法決定了當前View的大小,請看程式碼:
View的程式碼:
- 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);
- }
- }
佈局檔案:
- <?xml version="1.0" encoding="utf-8"?> <LinearLayout xmlns:android="http://schemas.android.com/apk/res/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>
效果就是自定義檢視的大小為
200, 800,並且放入到ScrollView中,ScrollView會啟作用,如果不使用setMeasuredDimension這個方法,那麼
ScrollView不會有作用。