Android UI实现数字签名效果 Android UI设计系列之自定义DrawView组件实现数字签名效果（5）

public class DrawView extends View { 
 
 /** 
  * 签名画笔 
  */ 
 private Paint paint; 
 /** 
  * 签名画布 
  */ 
 private Canvas cacheCanvas; 
 /** 
  * 画笔路径 
  */ 
 private Path path; 
 /** 
  * 缓存图片 
  */ 
 private Bitmap cacheBitmap; 
 /** 
  * 图片宽度 
  */ 
 private int width; 
 /** 
  * 图片高度 
  */ 
 private int height; 
 /** 
  * 手指触摸屏幕时的X，Y坐标 
  */ 
 private float xDown, yDown; 
 /** 
  * 是否正在绘制 
  */ 
 private boolean isDrawing = false; 
 
 /** 
  * 默认画笔颜色 
  */ 
 private int paintColor = Color.CYAN; 
 
 /** 
  * 默认画板背景色 
  */ 
 private int canvasColor = Color.parseColor("#bbccaa"); 
 
 public DrawView(Context context, int width, int height) { 
  super(context); 
  this.width = width; 
  this.height = height; 
  initWedgits(); 
 } 
 
 /** 
  * 初始化组件 
  */ 
 private void initWedgits() { 
  try { 
   paint = new Paint(Paint.DITHER_FLAG); 
   // 设置抗锯齿 
   paint.setAntiAlias(true); 
   // 设置画笔宽度 
   paint.setStrokeWidth(3); 
   paint.setDither(true); 
   // 设置样式 
   paint.setStyle(Paint.Style.STROKE); 
   paint.setStrokeJoin(Paint.Join.ROUND); 
   paint.setStrokeCap(Paint.Cap.ROUND); 
   // 画笔颜色 
   paint.setColor(paintColor); 
   // 绘制路径 
   path = new Path(); 
   // 创建空缓存图片 
   cacheBitmap = Bitmap.createBitmap(width, height, Config.ARGB_8888); 
   // 把画布内容画到空缓存图片上 
   cacheCanvas = new Canvas(cacheBitmap); 
  } catch (Exception e) { 
   e.printStackTrace(); 
  } 
 } 
  
 @Override 
 protected void onSizeChanged(int w, int h, int oldw, int oldh) { 
  super.onSizeChanged(w, h, oldw, oldh); 
 } 
 
 @Override 
 protected void onDraw(Canvas canvas) { 
  super.onDraw(canvas); 
 
  canvas.drawColor(canvasColor); 
  canvas.drawBitmap(cacheBitmap, 0, 0, paint); 
  canvas.drawPath(path, paint); 
 } 
 
 @Override 
 public boolean onTouchEvent(MotionEvent event) { 
  // 记录手指摁下屏幕时的X坐标 
  final float x = event.getX(); 
  // 记录手指摁下屏幕时的Y坐标 
  final float y = event.getY(); 
  switch (event.getAction()) { 
  case MotionEvent.ACTION_DOWN: 
   // 手指摁下时清空之前的设置 
   path.reset(); 
   // 设置路径起始点 
   path.moveTo(x, y); 
   xDown = x; 
   yDown = y; 
   isDrawing = true; 
   break; 
  case MotionEvent.ACTION_MOVE: 
   // 移动下一点 
   path.quadTo(xDown, yDown, x, y); 
   // 重新设置起点 
   xDown = x; 
   yDown = y; 
   isDrawing = true; 
   break; 
  case MotionEvent.ACTION_UP: 
   path.lineTo(xDown, yDown); 
   // 手指抬起时绘制路径 
   cacheCanvas.drawPath(path, paint); 
   // 路径重置 
   path.reset(); 
   isDrawing = false; 
   break; 
  default: 
   break; 
  } 
  // 刷新界面 
  invalidate(); 
  return true; 
 } 
 
 /** 
  * 设置画笔颜色 
  * 
  * @param color 
  *   画笔颜色 
  */ 
 public void setPaintColor(int color) { 
  paintColor = color; 
 } 
 
 /** 
  * 设置画板颜色 
  * 
  * @param color 
  *   画板颜色 
  */ 
 public void setCanvasColor(int color) { 
  canvasColor = color; 
 } 
 
 /** 
  * 返回绘画状态 
  * 
  * @return【true:正在绘制】【false:绘制完成】 
  */ 
 public boolean getDrawState() { 
  return isDrawing; 
 } 
 
 /** 
  * 返回Bitmap 
  * 
  * @return 返回绘制的图片 
  */ 
 public Bitmap getBitmap() { 
  return cacheBitmap; 
 } 
} 

<?xml version="1.0" encoding="utf-8"?> 
<LinearLayout 
 xmlns:android="http://schemas.android.com/apk/res/android" 
 android:orientation="vertical" 
 android:layout_width="fill_parent" 
 android:layout_height="fill_parent" 
 android:background="#ffffff"> 
 
 <TextView 
  android:id="@+id/title" 
  android:layout_width="fill_parent" 
  android:layout_height="wrap_content" 
  android:text="请绘制签名" 
  android:textSize="18sp" 
  android:layout_margin="5dip" 
  android:gravity="center" 
  android:textColor="#000000" /> 
 
 <FrameLayout 
  android:id="@+id/contents" 
  android:layout_width="fill_parent" 
  android:layout_height="0dip" 
  android:layout_weight="1" 
  android:layout_gravity="center" 
  android:background="#aabbcc"> 
 </FrameLayout> 
 
 <Button 
  android:layout_width="match_parent" 
  android:layout_height="wrap_content" 
  android:onClick="save" 
  android:text="保存签名" /> 
</LinearLayout> 

public class MainActivity extends Activity { 
 
 private FrameLayout frameLayout; 
 private DrawView drawView; 
 private TextView title; 
 
 /** Called when the activity is first created. */ 
 @Override 
 public void onCreate(Bundle savedInstanceState) { 
  super.onCreate(savedInstanceState); 
  setContentView(R.layout.main); 
 
  initWedgits(); 
 } 
 
 /** 
  * 初始化组件 
  */ 
 private void initWedgits() { 
  try { 
   frameLayout = (FrameLayout) findViewById(R.id.contents); 
   title = (TextView) findViewById(R.id.title); 
   title.setText(Html.fromHtml("<b>China中国<tt>中国</tt></b>China真伟大！")); 
 
  } catch (Exception e) { 
   e.printStackTrace(); 
  } 
 } 
 
 @Override 
 public void onWindowFocusChanged(boolean hasFocus) { 
  drawView = new DrawView(MainActivity.this, frameLayout.getWidth(), frameLayout.getHeight()); 
  frameLayout.addView(drawView); 
 } 
 
 /** 
  * 保存图片 
  * 
  * @param view 
  */ 
 public void save(View view) { 
  try { 
   File file = new File(Environment.getExternalStorageDirectory() 
     .getAbsolutePath() + "/handle.png"); 
   if (file.exists()) { 
    file.delete(); 
   } 
   file.createNewFile(); 
   if (drawView.getBitmap().compress(CompressFormat.PNG, 100, new FileOutputStream(file))) { 
    Toast.makeText(getApplicationContext(), "图片保存成功", 1000).show(); 
   } 
  } catch (Exception e) { 
   e.printStackTrace(); 
  } 
 } 
}