017_04Canvas和Paint的用法

　　Canvas类就是表示一块画布，你可以在上面画你想画的东西。当然，你还可以设置画布的属性，如画布的颜色/尺寸等。

　　Paint     画笔 和Canvas搭配使用,用于指定绘制的颜色, 线条的粗细, 过渡, 渐变等效果.

 

 1 package com.example.day17_04simplepainter;
 2 
 3 import java.io.FileNotFoundException;
 4 import java.io.FileOutputStream;
 5 import android.app.Activity;
 6 import android.graphics.Bitmap;
 7 import android.graphics.Bitmap.CompressFormat;
 8 import android.graphics.Bitmap.Config;
 9 import android.graphics.Canvas;
10 import android.graphics.Color;
11 import android.graphics.Paint;
12 import android.os.Bundle;
13 import android.view.MotionEvent;
14 import android.view.View;
15 import android.view.View.OnTouchListener;
16 import android.widget.ImageView;
17 
18 public class MainActivity extends Activity implements OnTouchListener {
19 
20     private ImageView iv_painter;
21     private Bitmap bitmap;
22     private Canvas canvas;
23     private Paint paint;
24     int startX =0;
25     int startY=0;
26     int stopX=0;
27     int stopY =0;
28 
29     @Override
30     protected void onCreate(Bundle savedInstanceState) {
31         super.onCreate(savedInstanceState);
32         setContentView(R.layout.activity_main);
33         iv_painter = (ImageView) findViewById(R.id.iv_painter);    
34         iv_painter.setOnTouchListener(this);
35      }
36 
37     @Override
38     public boolean onTouch(View v, MotionEvent event) {
39         
40         switch (event.getAction()) {
41         case MotionEvent.ACTION_DOWN:
42             
43             if (bitmap==null) {
44                 bitmap = Bitmap.createBitmap(iv_painter.getWidth(), iv_painter.getHeight(), Config.ARGB_8888);
45                 canvas = new Canvas(bitmap);
46                 canvas.drawColor(Color.WHITE);
47                 paint = new Paint();
48                 paint.setStrokeWidth(10);
49                 paint.setColor(Color.GREEN);
50             }
51             startX = (int) event.getX();
52             startY = (int) event.getY();    
53             System.out.println("MainActivity.onTouch()ACTION_DOWN");
54             break;
55             
56         case MotionEvent.ACTION_MOVE:
57             System.out.println("MainActivity.onTouch()ACTION_MOVE");
58             
59             stopX = (int) event.getX();
60             stopY = (int) event.getY();
61             canvas.drawLine(startX, startY, stopX, stopY, paint);
62             iv_painter.setImageBitmap(bitmap);
63         
64             startX=stopX;
65             startY=stopY;
66                
67             break;    
68             
69         case MotionEvent.ACTION_UP:    
70             break;
71         default:
72             break;
73         }
74         return true;
75     }
76     
77     public void save(View v){
78         FileOutputStream fos;
79         try {
80             fos = new FileOutputStream(getFilesDir()+"/mypaint.jpg");
81             bitmap.compress(CompressFormat.JPEG, 100, fos);
82         } catch (FileNotFoundException e) {
83             // TODO Auto-generated catch block
84             e.printStackTrace();
85         }        
86     } 
87 }

 

 1 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 2     xmlns:tools="http://schemas.android.com/tools"
 3     android:layout_width="match_parent"
 4     android:layout_height="match_parent"
 5     android:paddingBottom="@dimen/activity_vertical_margin"
 6     android:paddingLeft="@dimen/activity_horizontal_margin"
 7     android:paddingRight="@dimen/activity_horizontal_margin"
 8     android:paddingTop="@dimen/activity_vertical_margin"
 9     tools:context="com.example.day17_04simplepainter.MainActivity" >
10 
11     <ImageView 
12         android:id="@+id/iv_painter"
13         android:layout_width="300px"
14         android:layout_height="400px" />
15     
16     <Button
17         android:layout_width="wrap_content"
18         android:layout_height="wrap_content"
19         android:text="save" 
20         android:onClick="save"
21         android:layout_alignParentBottom="true"/>
22 </RelativeLayout>

 

posted @ 2015-05-31 20:10  woodrow_woo  阅读(238)  评论(0)  编辑  收藏  举报