安卓,Java,；二维绘图

一直在尝试在onDraw（Canvas Canvas）方法之外绘制android视图

我希望在屏幕上绘制另一个字符时保持上面的显示，具体取决于xPosition和yPosition

public void drawPlayer(int x, int y){
        c.drawCircle(x, y, 5, paint);
    }

我对java和android中的2d图形非常陌生

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提前感谢

您需要遵循以下模式：

private boolean isPlayerVisible = false;
private int playerPosX;
private int playerPosY;

@Overrides
public void onDraw(Canvas canvas) {
    c = canvas;
    canvas.drawLine(0, 50, 100, 50, paint);
    if (isPlayerVisible) {
       Paint paint= new Paint();
       paint.setColor(0xFFFFFFFF);
       paint.setStrokeWidth(1);
       c.drawCircle(playerPosX, playerPosY, 5, paint);
    }
}    

private void setPlayersPos(int x, int y) {
  playerPosX = x;
  playerPosY = y;
  isPlayerVisible= true;
  invalidate();
}

所有绘图都以OnDraw方法进行。需要时将调用OnDraw。您可以通过在另一个方法中调用invalidate来强制OnDraw运行。在OnDraw方法中调用invalidate是没有意义的（也许它也会导致不稳定的行为，因为OnDraw需要在刚执行完之后再次运行）

private boolean isPlayerVisible = false;
private int playerPosX;
private int playerPosY;

@Overrides
public void onDraw(Canvas canvas) {
    c = canvas;
    canvas.drawLine(0, 50, 100, 50, paint);
    if (isPlayerVisible) {
       Paint paint= new Paint();
       paint.setColor(0xFFFFFFFF);
       paint.setStrokeWidth(1);
       c.drawCircle(playerPosX, playerPosY, 5, paint);
    }
}    

private void setPlayersPos(int x, int y) {
  playerPosX = x;
  playerPosY = y;
  isPlayerVisible= true;
  invalidate();
}