Android: 利用Bimap,canvas处置图片（画直线）

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

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画直线效果图：

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	<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);			}		}	}}

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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);	}}