Question

我试图使图像按钮的透明区域不可点亮时会出现非法异常。如何解决此问题：我已实施OnTouchListner并已实施loadBitmapFromView(View v)

代码是：

 package com.sunojsworkshop;

import android.os.Bundle;
import android.app.Activity;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;

import android.view.MotionEvent;
import android.view.View;

import android.view.View.OnTouchListener;

import android.widget.ImageButton;
import android.widget.Toast;

public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


        ImageButton imgView= (ImageButton) findViewById(R.id.imageButton1);
         imgView.setDrawingCacheEnabled(true);
         imgView.setOnTouchListener(new OnTouchListener(){




        //private final OnTouchListener changeColorListener = new OnTouchListener() { 

             public boolean onTouch(View v, MotionEvent event) {        
                  Bitmap bmp = loadBitmapFromView(v);     
                  int color = bmp.getPixel((int) event.getX(),(int) event.getY());         
                 if (color == Color.TRANSPARENT)            
                  return false;        
                  else {             
                 //code to execute
                 Toast.makeText(MainActivity.this, "Image button is being clicked", Toast.LENGTH_SHORT).show();             
                 return true;         
                      }     
                    }

        public Bitmap loadBitmapFromView(View v) {
            // TODO Auto-generated method stub

                 Bitmap b = Bitmap.createBitmap( v.getLayoutParams().width, v.getLayoutParams().height, Bitmap.Config.ARGB_8888);                
                 Canvas c = new Canvas(b);
                 v.layout(0, 0, v.getLayoutParams().width, v.getLayoutParams().height);
                 v.draw(c);
                 return b;
            }


                 });


    }


}

XML是：

 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:paddingBottom="@dimen/activity_vertical_margin"
    android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:background="@drawable/worldfinal"
    tools:context=".MainActivity" >

    <TextView
        android:id="@+id/textView1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="SELECT A DESIRED COUNTRY" />

    <ImageButton
        android:id="@+id/imageButton1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentRight="true"
        android:layout_below="@+id/textView1"
        android:layout_marginRight="28dp"
        android:layout_marginTop="93dp"
        android:src="@drawable/india1" 
        android:background="@android:color/transparent"  />

和Log是：

 08-06 13:13:24.162: E/AndroidRuntime(329): FATAL EXCEPTION: main
08-06 13:13:24.162: E/AndroidRuntime(329): java.lang.IllegalArgumentException: width and height must be > 0
08-06 13:13:24.162: E/AndroidRuntime(329):  at android.graphics.Bitmap.nativeCreate(Native Method)
08-06 13:13:24.162: E/AndroidRuntime(329):  at android.graphics.Bitmap.createBitmap(Bitmap.java:477)
08-06 13:13:24.162: E/AndroidRuntime(329):  at com.sunojsworkshop.MainActivity$1.loadBitmapFromView(MainActivity.java:49)
08-06 13:13:24.162: E/AndroidRuntime(329):  at com.sunojsworkshop.MainActivity$1.onTouch(MainActivity.java:35)
08-06 13:13:24.162: E/AndroidRuntime(329):  at android.view.View.dispatchTouchEvent(View.java:3881)
08-06 13:13:24.162: E/AndroidRuntime(329):  at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869)
08-06 13:13:24.162: E/AndroidRuntime(329):  at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869)
08-06 13:13:24.162: E/AndroidRuntime(329):  at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869)
08-06 13:13:24.162: E/AndroidRuntime(329):  at android.view.ViewGroup.dispatchTouchEvent(ViewGroup.java:869)
08-06 13:13:24.162: E/AndroidRuntime(329):  at com.android.internal.policy.impl.PhoneWindow$DecorView.superDispatchTouchEvent(PhoneWindow.java:1691)
08-06 13:13:24.162: E/AndroidRuntime(329):  at com.android.internal.policy.impl.PhoneWindow.superDispatchTouchEvent(PhoneWindow.java:1125)
08-06 13:13:24.162: E/AndroidRuntime(329):  at android.app.Activity.dispatchTouchEvent(Activity.java:2096)
08-06 13:13:24.162: E/AndroidRuntime(329):  at com.android.internal.policy.impl.PhoneWindow$DecorView.dispatchTouchEvent(PhoneWindow.java:1675)
08-06 13:13:24.162: E/AndroidRuntime(329):  at android.view.ViewRoot.deliverPointerEvent(ViewRoot.java:2194)
08-06 13:13:24.162: E/AndroidRuntime(329):  at android.view.ViewRoot.handleMessage(ViewRoot.java:1878)
08-06 13:13:24.162: E/AndroidRuntime(329):  at android.os.Handler.dispatchMessage(Handler.java:99)
08-06 13:13:24.162: E/AndroidRuntime(329):  at android.os.Looper.loop(Looper.java:123)
08-06 13:13:24.162: E/AndroidRuntime(329):  at android.app.ActivityThread.main(ActivityThread.java:3683)
08-06 13:13:24.162: E/AndroidRuntime(329):  at java.lang.reflect.Method.invokeNative(Native Method)
08-06 13:13:24.162: E/AndroidRuntime(329):  at java.lang.reflect.Method.invoke(Method.java:507)
08-06 13:13:24.162: E/AndroidRuntime(329):  at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:839)
08-06 13:13:24.162: E/AndroidRuntime(329):  at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:597)
08-06 13:13:24.162: E/AndroidRuntime(329):  at dalvik.system.NativeStart.main(Native Method)


    </RelativeLayout>

Answer 1

v.layout(0, 0, v.getLayoutParams().width, v.getLayoutParams().height);

这里得到值“0”，但布局至少需要值“1”。您尝试在此处提供不同的值吗？

Answer 2

当你在loadBitmapFromView中致电onCreate时，布局还没有被测量和膨胀。在UI测量了所有视图并且它们的大小大于0 x 0之后，您需要调用它。

查看onSizeChanged并考虑覆盖您的观点。

在尝试使图像的透明区域按钮时，获取IllegalArgumentException是不可点击的

2 个答案: