Question

我想在图像视图中显示的图像的特定坐标处绘制。我使用imageview的src属性将图像加载到视图中。此代码用于自定义imageview中以在图像上绘制：

    protected void onDraw(Canvas canvas) {
    super.onDraw(canvas);
    float scaleh =(float)canvas.getHeight()/(float)orginalheight();
    float scalew = ((float)canvas.getWidth()/(float)orginalwidth());
    canvas.drawRect(10*scaleh,9*scalew,20*scaleh,30*,scalewpaint);
}

此代码在错误的位置绘制矩形。有什么问题？

Answer 1

您应该从ImageView本身而不是Canvas获取视图的尺寸，尤其是当不可靠的目标是在ImageView内绘制图像时。

Canvas适合您作为实际的假装或界面将绘制图形的表面 - 它可以保存您的所有图形 “画”电话。通过画布，您的绘图实际上是在执行底层的Bitmap，放在窗口中。

首先，为了获得坐标，请为onTouchListener实施ImageView。这将为您提供X和Y坐标来绘制Canvas。

imageView.setOnTouchListener(new OnTouchListener(){

@Override
public boolean onTouch(View v, MotionEvent event) {

int action = event.getAction();
switch (action) {
case MotionEvent.ACTION_DOWN:
  xDown = event.getX();
  yDown = event.getY();
  break;
case MotionEvent.ACTION_MOVE:
  xUp = event.getX();
  uUp = event.getY();
  canvas.drawLine(xDown, yDown, xUp, uUp, paint);
  imageView.invalidate();
  xDown = xUp;
  yDown = uUp;
  break;
case MotionEvent.ACTION_UP:
  xUp = event.getX();
  uUp = event.getY();
  canvas.drawLine(xDown, yDown, xUp, uUp, paint);
  imageView.invalidate();
  break;
case MotionEvent.ACTION_CANCEL:
  break;
default:
  break;
}

return true;
}});

然后创建一个Canvas以在ImageView上绘制。

//Create a new image bitmap and attach a brand new canvas to it
Bitmap tempBitmap = Bitmap.createBitmap(myBitmap.getWidth(), myBitmap.getHeight(), Bitmap.Config.RGB_565);
Canvas canvas = new Canvas(tempBitmap);

paint = new Paint();
paint.setColor(YOUR_DESIRED_COLOR);
paint.setStrokeWidth(INT_VALUE);
matrix = new Matrix();
canvas.drawBitmap(bmp, matrix, paint);

//Attach the canvas to the ImageView
imageViewsetImageBitmap(tempBitmap);

如果您想简单地绘制矩形，也可以使用canvas.drawRect(left,top,right,bottom,paint);。

希望它有所帮助。

Android图像的Android地图坐标到Imageview

1 个答案: