繪圖 - Android編程

Question

我想畫一條直線，沿着我的手指觸摸畫布，這樣ACTION_DOWN點是起點，ACTION_UP是終點。手指的路徑可以是任何東西，但最終數字應該是從起點到終點的一條線。請幫助我使用onDraw（）函數。

Answer 1

，當你從一個點觸摸手指到另一個 這是 DrawLineView.java此代碼拉繩

import android.content.Context; 
import android.graphics.Canvas; 
import android.graphics.Color; 
import android.graphics.Paint; 
import android.graphics.Path; 
import android.util.AttributeSet; 
import android.view.MotionEvent; 
import android.view.View; 

public class DrawLineView extends View { 

private Paint paint = new Paint(); 
private Path path= new Path(); 
float eventx; 
float eventy; 

public DrawLineView(Context context, AttributeSet attrs) { 
    super(context, attrs); 
    paint.setAntiAlias(true); 
    paint.setStrokeWidth(5f); 
    paint.setColor(Color.BLUE); 
    paint.setStyle(Paint.Style.STROKE); 
} 
@Override 
protected void onDraw(Canvas canvas) { 
    canvas.drawPath(path, paint); 

} 

@Override 
public boolean onTouchEvent(MotionEvent event) { 
    eventx=event.getX(); 
    eventy=event.getY(); 


    switch(event.getAction()){ 
    case MotionEvent.ACTION_DOWN : 
     path.moveTo(eventx, eventy); 

     return true; 
    case MotionEvent.ACTION_UP : 
     path.lineTo(eventx, eventy); 

     break; 
     default : 
      return false; 

    } 
    invalidate(); 

    return true; 
} 

} 

活動啓動它：

import android.app.Activity; 
import android.os.Bundle; 

public class DrawActivity extends Activity { 

@Override 
protected void onCreate(Bundle savedInstanceState) { 
    super.onCreate(savedInstanceState); 
    setContentView(new DrawLineView(this, null)); 
} 


}