Merge pull request #196 from claixiang/master

#2 #67 第二次作业

Author: zengsn

AndroidLabs/app/src/main/java/edu/hzuapps/androidlabs/homeworks/net1414080903108/Net1414080903108Activity.java

@@ -1,13 +1,71 @@
-package edu.hzuapps.androidlabs.homeworks.net1414080903108;
+package edu.hzuapps.androidlabs.homeworks.net1414080903108;
 
+import android.graphics.Bitmap;
+import android.graphics.Canvas;
+import android.graphics.Color;
+import android.graphics.Matrix;
+import android.graphics.Paint;
 import android.support.v7.app.AppCompatActivity;
 import android.os.Bundle;
+import android.view.MotionEvent;
+import android.view.View;
+import android.widget.ImageView;
+
+import com.example.myapplication.R;
 
 public class Net1414080903108Activity extends AppCompatActivity {
+    private ImageView iv;
+    private Bitmap baseBitmap;
+    private Canvas canvas;
+    private Paint paint;
 
     @Override
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         setContentView(R.layout.activity_net1414080903108);
+        this.iv = (ImageView) this.findViewById(R.id.iv);
+        // 创建一张空白图片
+        baseBitmap = Bitmap.createBitmap(480, 640, Bitmap.Config.ARGB_8888);
+        // 创建一张画布
+        canvas = new Canvas(baseBitmap);
+        // 画布背景为白色
+        canvas.drawColor(Color.WHITE );
+        // 创建画笔
+        paint = new Paint();
+        // 画笔颜色为黑色
+        paint.setColor(Color.BLACK );
+        // 宽度5个像素
+        paint.setStrokeWidth(8);
+        // 先将白色背景画上
+        canvas.drawBitmap(baseBitmap, new Matrix(), paint);
+        iv.setImageBitmap(baseBitmap);
+
+        iv.setOnTouchListener(new View.OnTouchListener() {
+            int startX;
+            int startY;
+
+            @Override
+            public boolean onTouch(View v, MotionEvent event) {
+                switch (event.getAction()) {
+                    case MotionEvent.ACTION_DOWN:
+                        // 获取手按下时的坐标
+                        startX = (int) event.getX();
+                        startY = (int) event.getY();
+                        break;
+                    case MotionEvent.ACTION_MOVE:
+                        // 获取手移动后的坐标
+                        int stopX = (int) event.getX();
+                        int stopY = (int) event.getY();
+                        // 在开始和结束坐标间画一条线
+                        canvas.drawLine(startX, startY, stopX, stopY, paint);
+                        // 实时更新开始坐标
+                        startX = (int) event.getX();
+                        startY = (int) event.getY();
+                        iv.setImageBitmap(baseBitmap);
+                        break;
+                }
+                return true;
+            }
+        });
     }
 }

AndroidLabs/app/src/main/res/layout/activity_net1414080903108.xml

@@ -8,10 +8,18 @@
     android:paddingLeft="@dimen/activity_horizontal_margin"
     android:paddingRight="@dimen/activity_horizontal_margin"
     android:paddingTop="@dimen/activity_vertical_margin"
-    tools:context="com.example.myapplication.Net1414080903108Activity">
+    tools:context="edu.hzuapps.androidlabs.homeworks.net1414080903108.Net1414080903108Activity">
 
-    <TextView
-        android:layout_width="wrap_content"
-        android:layout_height="wrap_content"
-        android:text="Hello World!" />
+    <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
+        xmlns:tools="http://schemas.android.com/tools"
+        android:layout_width="match_parent"
+        android:layout_height="match_parent"
+        tools:context=".MainActivity" >
+
+        <ImageView
+            android:id="@+id/iv"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            />
+    </RelativeLayout>
 </RelativeLayout>