你好在一个class.am绘制一些行使用myview,之后如果我点击按钮然后去其他类,然后我再回到上一课,但在这里我画的线不存在,但在我的情况,当我回到以前的活动时,我需要显示画出的线条...你能不能建议我......你好吗
MainActivity
public class MainActivity extends Activity {
MyView myview;
RelativeLayout rl;
Button b1;
public boolean action = false;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
b1=(Button)findViewById(R.id.button1);
b1.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
// TODO Auto-generated method stub
Intent i=new Intent(MainActivity.this,Activity2.class);
startActivity(i);
}
});
rl = (RelativeLayout) findViewById(R.id.layout);
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setDither(true);
// mPaint.setColor(0xFFFF0000);
mPaint.setColor(Color.BLACK);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeCap(Paint.Cap.ROUND);
mPaint.setStrokeWidth(6);
myview = new MyView(this);
myview.setId(004);
RelativeLayout.LayoutParams lp6 = new RelativeLayout.LayoutParams(
LayoutParams.WRAP_CONTENT, LayoutParams.WRAP_CONTENT);
myview.setLayoutParams(lp6);
// myview.setBackgroundResource(R.drawable.booklet);
lp6.setMargins(10, 100, 10, 10);
// lp6.setMargins(25, 50, 8,70);
rl.addView(myview, lp6);
}
private Paint mPaint;
private Bitmap mBitmap;
public void colorChanged(int color) {
mPaint.setColor(color);
}
public class MyView extends View {
private Canvas mCanvas;
private Path mPath;
private Paint mBitmapPaint;
public MyView(Context context) {
super(context);
// TODO Auto-generated constructor stub
mPath = new Path();
mBitmapPaint = new Paint(Paint.DITHER_FLAG);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
mCanvas = new Canvas(mBitmap);
// clearAllResources();
}
@Override
protected void onDraw(Canvas canvas) {
if (action) {
invalidate();
}
canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
canvas.drawPath(mPath, mPaint);
}
private float mX, mY;
private final float TOUCH_TOLERANCE = 2;
private void touch_start(float x, float y) {
mPath.reset();
mPath.moveTo(x, y);
mX = x;
mY = y;
}
private void touch_move(float x, float y) {
float dx = Math.abs(x - mX);
float dy = Math.abs(y - mY);
if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
mPath.quadTo(mX, mY, (x + mX) / 2, (y + mY) / 2);
mX = x;
mY = y;
}
}
private void touch_up() {
mPath.lineTo(mX, mY);
// commit the path to our offscreen
mCanvas.drawPath(mPath, mPaint);
// kill this so we don't double draw
mPath.reset();
}
@Override
public boolean onTouchEvent(MotionEvent event) {
float x = event.getX();
float y = event.getY();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
touch_start(x, y);
invalidate();
break;
case MotionEvent.ACTION_MOVE:
touch_move(x, y);
invalidate();
break;
case MotionEvent.ACTION_UP:
touch_up();
invalidate();
break;
}
return true;
}
}
}
活性2
public class Activity2 extends Activity {
Button b1;
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.acticity2);
b1=(Button)findViewById(R.id.button1);
b1.setOnClickListener(new OnClickListener() {
public void onClick(View arg0) {
// TODO Auto-generated method stub
Intent i=new Intent(Activity2.this,MainActivity.class);
startActivityForResult(i, 0);
}
});
}
}
答案 0 :(得分:0)
创建具有以下属性的线类 float startX,float startY,float stopX,float stopY,Paint paint
然后创建List以包含您的行实例。每次创建一行时,都要创建一个新的行实例,设置其数据并将其添加到列表中。在onDraw中,遍历列表并使用您存储的数据绘制每一行。
答案 1 :(得分:0)
代码问题在于,只要单击按钮,就会启动新的活动实例。 而不是startActivity(),尝试从Activity2调用finish()。 或者你可以使用setFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT); 将MainActivity的前一个实例放在前面。
public void onClick(View v) {
Intent intent = new Intent(getApplicationContext(),MainActivity.class);
//finish(); OR
intent.setFlags(Intent.FLAG_ACTIVITY_REORDER_TO_FRONT);
startActivity(intent);
}