Android onTouch+;画布&x2B;安卓
我想在屏幕上画一个圆圈,当握住手指时,圆圈会移动。在代码中,有一种方法可以在该事件中更改屏幕的颜色,但如何更改圆的位置?帮帮忙Android onTouch+;画布&x2B;安卓,android,Android,我想在屏幕上画一个圆圈,当握住手指时,圆圈会移动。在代码中,有一种方法可以在该事件中更改屏幕的颜色,但如何更改圆的位置?帮帮忙 package com.example.canva; import android.app.Activity; import android.content.Context; import android.graphics.Canvas; import android.graphics.Color; import android.graphics.Paint; imp
package com.example.canva;
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.view.MotionEvent;
import android.view.View;
public class MyActivity extends Activity implements View.OnTouchListener {
/**
* Called when the activity is first created.
*/
private float x;
private float y;
private String sDown;
private String sMove;
private String sUp;
private DrawView dr;
private Paint p;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
dr = new DrawView(this);
dr.setOnTouchListener(this);
setContentView(dr);
}
@Override
public boolean onTouch(View view, MotionEvent motionEvent) {
x = motionEvent.getX();
y = motionEvent.getY();
switch (motionEvent.getAction()) {
case MotionEvent.ACTION_DOWN: // нажатие
sDown = "Down: " + x + "," + y;
sMove = ""; sUp = "";
break;
case MotionEvent.ACTION_MOVE: // движение
sMove = "Move: " + x + "," + y;
dr.changeColor((int)-x);
dr.getX(x);
dr.getY(y);
break;
case MotionEvent.ACTION_UP: // отпускание
case MotionEvent.ACTION_CANCEL:
sMove = "";
sUp = "Up: " + x + "," + y;
break;
}
return true;
}
}
class DrawView extends View {
private Paint p;
public DrawView(Context context) {
super(context);
p = new Paint();
p.setColor(Color.RED);
}
@Override
protected void onDraw(Canvas canvas) {
canvas.drawCircle(getX(),getY(),50,p);
invalidate();
}
public float getX(float X){
return X;
}
public float getY(float Y){
return Y;
}
public void changeColor(int color){
this.setBackgroundColor(color);
}
}
View.getX()
和View.getY()
是在API级别11中引入的。你应该意识到这一点。您的DrawView.getX(float X)和DrawView.getY(float Y)是无用的,因为您返回的值与传递给该方法的值相同。在onTouch方法中,您可能需要调用View.getX()
和View.getY()
对,它们是View.setX(float x)
和View.setY(float y)
。Api级别11中也引入了这些功能
class DrawView extends View {
private Paint p;
int x=getX(),y=getY();
public void refresh(int x,int y){
this.x=x;
this.y=y;
invaliate();
}
@Override
protected void onDraw(Canvas canvas) {
canvas.drawCircle(x,y,50,p);
}
}
在onTouch呼叫中
dr.refresh(x,y);
另外,您的getX
和getY
函数也是无用的
public float getX(float X){
return X;
}
而是在DrawView和setX中创建一个变量x
public void setX(float X){
this.X=X;
}
int x=getX(),y=getY();公共无效刷新(float x,float y){this.x=x;this.y=y;invaliate();}