使用自定义视图Android绘制边框

Question

我正在尝试通过绘制自定义视图来绘制自定义边框.以下是边框一侧的示例:

package com.sparkydev.guessaphrase;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.drawable.ShapeDrawable;
import android.graphics.drawable.shapes.RectShape;
import android.util.AttributeSet;
import android.view.View;

public class LeftBorder extends View {
    private ShapeDrawable vertRect, horizRect;

    public LeftBorder(Context context, AttributeSet attributeset) {
        super(context, attributeset);

        int width = this.getWidth();
        int height = this.getHeight();

        vertRect = new ShapeDrawable(new RectShape());
            vertRect.getPaint().setColor(Color.RED);
            vertRect.setBounds(0, 0, width/10, height);
        horizRect = new ShapeDrawable(new RectShape());
            horizRect.getPaint().setColor(Color.RED);
            horizRect.setBounds(0, 0, width, height/9);

    }

    protected void onDraw(Canvas canvas){
        vertRect.draw(canvas);
        horizRect.draw(canvas);
    }

}

而另一方的定义几乎相同.XML定义如下:

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
  xmlns:android="http://schemas.android.com/apk/res/android"
  android:layout_width="fill_parent"
  android:layout_height="fill_parent"
  android:background="@drawable/wallpaper">


    <!-- Declares left border's position, which is
    drawn programmatically.-->
    <com.sparkydev.guessaphrase.LeftBorder
        android:id="@+id/leftborder"
        android:layout_alignParentLeft="true"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        />



        <!-- Used a FrameLayout to contain
        the menu buttons.-->
        <FrameLayout 
        android:id="@+id/FrameLayout01" 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content"
        >

            <!-- Menu buttons -->

        </FrameLayout>


    <!-- Declares right border position (on right
    of screen, below the left border) -->
    <com.sparkydev.guessaphrase.RightBorder
        android:layout_alignParentRight="true"
        android:layout_width="fill_parent"
        android:layout_height="wrap_content"
        android:layout_below="@id/leftborder"
    />



</RelativeLayout>

问题是,边界根本没有出现.背景显示,但没有别的.

Answer 1

从"构建自定义组件"开发指南中,在创建自定义视图时,它将具有100x100的设置大小,直到您另行指定.看看这与你看到的问题有什么关系.

" 如果你希望组件显示某些内容,你几乎肯定会想要覆盖onMeasure()并且也可能需要覆盖onDraw().虽然两者都有默认行为,但默认情况下onDraw()什么都不做,默认情况下onMeasure()总是设置100x100的大小 - 这是可能不是你想要的."