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：

Main.xml代码

<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;@Overridepublic 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);}@Overrideprotected 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);}}}@Overridepublic 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);}}

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