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目录
设计一个自定义组件继承于Android.view.View的图形绘制类TestView,在该视图组件中绘制一个小球;再设计一个实现监听触摸屏事件的方法onTouch(View v,MontionEvent event),该方法监听并获取触摸屏的坐标位置,并把坐标值传递给图形绘制类TestView,由TestView在该位置重绘小球。
MainActivity.java
package com.example.administrator.ex_4_4;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.view.MotionEvent;
import android.view.View;
public class MainActivity extends AppCompatActivity {
TestView tView = null;
@Override
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
tView =(TestView)findViewById(R.id.tv1);
tView.setOnTouchListener(new mOnTouch());
}
class mOnTouch implements View.OnTouchListener {
@Override
public boolean onTouch(View v, MotionEvent event) {
int x1, y1;
x1 = (int) event.getX();
y1 = (int) event.getY();
if (event.getAction() == MotionEvent.ACTION_DOWN) {
tView.getXY(x1,y1);
tView.invalidate();
return true;
} else if (event.getAction() == MotionEvent.ACTION_MOVE) {
tView.getXY(x1,y1);
tView.invalidate();
return true;
}
return tView.onTouchEvent(event);
}
}
}
TestView.java
package com.example.administrator.ex_4_4;
import android.view.View;
import android.content.Context;
import android.util.AttributeSet;
import android.graphics.Color;
import android.graphics.Canvas;
import android.graphics.Paint;
public class TestView extends View {
int x = 150, y = 50;
public TestView(Context context, AttributeSet attrs) {
super(context, attrs);
}
void getXY(int _x, int _y) {
x = _x;
y = _y;
}
@Override
protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawColor(Color.CYAN); /*设置背景为青色*/
Paint paint = new Paint();
paint.setAntiAlias(true); /*去锯齿*/
paint.setColor(Color.BLACK); /*设置paint的颜色*/
canvas.drawCircle(x, y, 30, paint); /*画一个实心圆*/
paint.setColor(Color.WHITE);/*画一个实心圆上的小白点*/
canvas.drawCircle(x - 9, y - 9, 6, paint);
}
}
activity_main.xml
<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:tools="http://schemas.android.com/tools"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context=".MainActivity">
<com.example.administrator.ex_4_4.TestView
android:id="@+id/tv1"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentEnd="true"
android:layout_alignParentBottom="true"
android:layout_marginEnd="24dp"
android:layout_marginBottom="24dp" />
</RelativeLayout>
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