Drawing multiple custom views

问题:

I'm trying to draw multiple custom views in a layout but only the first view I add it's drawn.

My custom view class is:

public ButtonView(Context context, int k) {
    super(context);
    this.setX(20+k*80);
    init();
}

private void init(){
    paint = new Paint(Paint.ANTI_ALIAS_FLAG);
    paint.setColor(0x99ffffff);
}

@Override
protected void onDraw(Canvas cv){
    cv.drawText(""+getX(), 0, 80, paint);
}

I'm displaying the text of the x coordinate in order to know which view is drawn.

This is the code of onCreate of my main activity.

blay = (LinearLayout) this.findViewById(R.id.buttonslayout);
for(int k=0; k<10; k++){
    ButtonView e = new ButtonView(this,k);
    blay.addView(e);
}

When I run the application only the first view is drawn. I get a "20.0" displayed in white in the correct position, but the rest of the views are not showing. By debugging the app I realize that the instances of the views are created but for some reason they are not displayed. Also I tried to use invalidate and override onMeasure method but still not working.

回答1:

I have modified your custom view please check if this is working.I guess the main problem with your code was that one view was occupying the whole screen. So I overridden onMeasure function

    package com.example.stack2;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.View;

public class ButtonView extends View{
    public ButtonView(Context context, int k) {
        super(context);
        //this.setX(20+k*80);
        init();
    }

    public ButtonView(Context context, AttributeSet attrs, int defStyleAttr,
            int defStyleRes) {
        super(context, attrs, defStyleAttr, defStyleRes);
        // TODO Auto-generated constructor stub
    }

    public ButtonView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);
        // TODO Auto-generated constructor stub
    }

    public ButtonView(Context context, AttributeSet attrs) {
        super(context, attrs);
        // TODO Auto-generated constructor stub
    }

    public ButtonView(Context context) {
        super(context);
        // TODO Auto-generated constructor stub
    }

    Paint paint;
    private void init(){
        paint = new Paint();
        paint.setColor(Color.BLACK);
        paint.setTextSize(20); 
    }
    protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
        // TODO Auto-generated method stub
        super.onMeasure(widthMeasureSpec, heightMeasureSpec);
        //e.measure(0, 0);
        getLayoutParams().width=100;
    }
    @Override
    protected void onDraw(Canvas cv){
        super.onDraw(cv);

        cv.drawText(""+getX(), 0, cv.getHeight()/2, paint);
    }
}

Also make sure the orientation of your linear layout is horizontal

回答2:

Try to set some different color to each view..you will be able to see them. Also set layout params to your custom views.