Android入门之画图详解

<?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"
  >
<Button android:id="@+id/Button01" android:layout_width="fill_parent" android:layout_height="44px" android:text="显示资源图片"></Button>
<Button android:id="@+id/Button02" android:layout_width="fill_parent" android:layout_height="44px" android:text="显示并绘画资源图片"></Button>
<Button android:id="@+id/Button03" android:layout_height="44px" android:layout_width="fill_parent" android:text="在控件上绘图"></Button>
<ImageView android:id="@+id/ImageView01" android:layout_width="wrap_content" android:layout_height="wrap_content"></ImageView>

</LinearLayout>

package com.testDraw;

import android.app.Activity;
import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.Bitmap.Config;
import android.graphics.BitmapFactory;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Typeface;
import android.graphics.drawable.BitmapDrawable;
import android.graphics.drawable.Drawable;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.ImageView;

public class testDraw extends Activity {
  
 ImageView iv;
 Button btn1,btn2,btn3,btn4;
 Resources r;
 @Override
  public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);
    iv=(ImageView)this.findViewById(R.id.ImageView01);
    btn1=(Button)this.findViewById(R.id.Button01);
    btn2=(Button)this.findViewById(R.id.Button02);
    btn3=(Button)this.findViewById(R.id.Button03);

    btn1.setOnClickListener(new ClickEvent());
    btn2.setOnClickListener(new ClickEvent());
    btn3.setOnClickListener(new ClickEvent());
    
    r = this.getResources();
  }
 class ClickEvent implements View.OnClickListener {

 public void onClick(View v) {
  if(v==btn1)//显示资源图片
  {//功能等效
  //iv.setBackgroundResource(R.drawable.icon);//打开资源图片
  Bitmap bmp=BitmapFactory.decodeResource(r, R.drawable.icon);//打开资源图片
  iv.setImageBitmap(bmp);
  }
  else if(v==btn2)//显示并绘画资源图片
  {
     Bitmap bmp=BitmapFactory.decodeResource(r, R.drawable.icon);//只读,不能直接在bmp上画
     Bitmap newb = Bitmap.createBitmap( 300, 300, Config.ARGB_8888 );
     
     Canvas canvasTemp = new Canvas( newb );
     canvasTemp.drawColor(Color.TRANSPARENT);
     
     Paint p = new Paint();
     String familyName ="宋体";
     Typeface font = Typeface.create(familyName,Typeface.BOLD);
     p.setColor(Color.RED);
     p.setTypeface(font);
     p.setTextSize(22);
     canvasTemp.drawText("写字。。。",50,50,p);
     canvasTemp.drawBitmap(bmp, 50, 50, p);//画图
     iv.setImageBitmap(newb);
  }
  else if(v==btn3)//直接在Button上绘图
  {
  Bitmap newb = Bitmap.createBitmap( btn3.getWidth(), btn3.getHeight(), Config.ARGB_8888 );
  Canvas canvasTemp = new Canvas( newb );
    canvasTemp.drawColor(Color.WHITE);
    Paint p = new Paint();
  String familyName = "宋体";
  Typeface font = Typeface.create(familyName, Typeface.BOLD);
  p.setColor(Color.RED);
  p.setTypeface(font);
  p.setTextSize(20);
  canvasTemp.drawText("写字。。。", 30, 30, p);
  Drawable drawable = new BitmapDrawable(newb);
  btn3.setBackgroundDrawable(drawable);
  }
 }
 }
}