Android: 利用Bimap,canvas处理图片（画直线）

转：http://www.eoeandroid.com/thread-114497-1-1.html

 

画直线效果图：

 

	<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
		android:orientation="horizontal" android:layout_weight="1"
		android:layout_width="fill_parent" android:layout_height="fill_parent">

		<Button android:id="@+id/length_btn" 
			android:layout_height="wrap_content"
			android:text="画直线" 
			android:layout_width="wrap_content" />
			
		<TextView android:text="画图区" 
			android:layout_width="wrap_content"
			android:layout_height="wrap_content" />

		<com.android.draw.MyDrawView android:id="@+id/drawView"
			android:layout_weight="1" 
			android:layout_height="fill_parent"
			android:layout_width="fill_parent">
		</com.android.draw.MyDrawView>
	</LinearLayout>

	<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
		android:orientation="horizontal" android:layout_weight="1"
		android:layout_width="fill_parent" android:layout_height="fill_parent">

		<Button android:id="@+id/clear_btn" 
			android:text="显示"
			android:layout_height="wrap_content" 
			android:layout_width="wrap_content" />
			
		<TextView android:text="显示画图区" 
			android:layout_width="wrap_content"
			android:layout_height="wrap_content" />
			
		<ImageView android:id="@+id/imageView1"
			android:layout_height="wrap_content" 
			android:layout_weight="1"
			android:layout_width="wrap_content" />
	</LinearLayout>

 

 import android.app.Activity;

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.os.Bundle;
import android.view.View;
import android.view.Window;
import android.widget.Button;
import android.widget.ImageView;

public class DrawActivity extends Activity {
	static boolean drawFlag = false;
	private Button showBtn; 
	private Button lineBtn;
	private ImageView image;
	private MyDrawView myDrawView;
	private Bitmap bimap;

	@Override
	public void onCreate(Bundle savedInstanceState) {
		super.onCreate(savedInstanceState);
		requestWindowFeature(Window.FEATURE_NO_TITLE);
		setContentView(R.layout.main);

		showBtn = (Button) findViewById(R.id.clear_btn);
		lineBtn = (Button) findViewById(R.id.length_btn);
		lineBtn.setOnClickListener(new MyClickEvent());
		showBtn.setOnClickListener(new MyClickEvent());
		image = (ImageView) findViewById(R.id.imageView1);
		myDrawView = (MyDrawView) findViewById(R.id.drawView);

		// 如果不用copy的方法，直接引用会对资源文件进行修改，而android是不允许在代码里修改res文件里的图片
		bimap = BitmapFactory.decodeResource(getResources(),
				R.drawable.background).copy(Bitmap.Config.ARGB_8888, true);

	}

	class MyClickEvent implements View.OnClickListener {
		public void onClick(View v) {
			if (v == lineBtn) {
				// 传我们需要处理的bimap给画图类
				myDrawView.setBitmap(bimap);
				// 开始画图的标志
				DrawActivity.drawFlag = true; 
			}
			if (v == showBtn) {
				// 显示图片
				image.setImageBitmap(bimap);
			}
		}
	}
}

 

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.widget.ImageView;

public class MyDrawView extends ImageView {
	
	private float beginX = 0, beginY = 0, endX = 0, endY = 0;
	private int eventFlag = 0;// 触屏事件点击
	private Canvas canvasSelf;// 用于保存所画图像的画布
	private Bitmap bimap;// 用于保存所画图像的图画

	public void setBitmap(Bitmap b) {
		bimap = b;
		canvasSelf = new Canvas(bimap);
	}

	@Override
	protected void onDraw(Canvas canvas) {
		super.onDraw(canvas);
		
		if (DrawActivity.drawFlag) {
			Paint paint = new Paint();
			/** 设置画笔 */
			paint.setColor(Color.WHITE);
			paint.setStyle(Paint.Style.STROKE);
			paint.setAntiAlias(true);
			
			// 把之前画出来保存后的图再画出来
			canvas.drawBitmap(bimap, 0, 0, null);
			// 画中间长得线段
			canvas.drawLine(beginX, beginY, endX, endY, paint);
			if (eventFlag == MotionEvent.ACTION_UP) {
				// 这里将直线画到canvasself上，它就保存在了bimap这张图上
				canvasSelf.drawLine(beginX, beginY, endX, endY, paint);
			}
		}
	}

	@Override
	public boolean onTouchEvent(MotionEvent event) {
		endX = event.getX();
		endY = event.getY();
		
		switch (event.getAction()) {
		case MotionEvent.ACTION_DOWN:
			eventFlag = MotionEvent.ACTION_DOWN;
			beginX = endX;
			beginY = endY;
			invalidate();
			break;
		case MotionEvent.ACTION_MOVE:
			eventFlag = MotionEvent.ACTION_MOVE;
			invalidate();
			break;
		case MotionEvent.ACTION_UP:
			eventFlag = MotionEvent.ACTION_UP;
			invalidate();
			break;
		}

		return true;
	}
	
	/**
	 * 在XML中使用自定义View必须要使用含AttributeSet变量参数的构造函数
	 * @param context
	 * @param attrs
	 */
	public MyDrawView(Context context, AttributeSet attrs) {
		super(context, attrs);
	}
	public MyDrawView(Context context) {
		super(context);
	}
}