java - 在随机位置以随机大小绘制随机圆 Android

Question

我在这个作业上取得了很大的进步。最终产品需要在每次点击按钮(圆圈)后添加一个随机颜色/随机大小/随机位置的圆圈。我有另一个按钮(清除)需要清除 Canvas 。这是我现在面临的两个问题。我的圈子没有显示在随机位置。它们都从屏幕的左上角开始。第二个问题是我不知道如何让我的清除按钮工作。其他一切正常，随机圆圈颜色随机圆圈大小。

package com.example.randomcircles;

import android.annotation.SuppressLint;
import android.app.Activity;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.FrameLayout;
import android.widget.FrameLayout.LayoutParams;

public class DisplayRandomCircles extends Activity
{
FrameLayout f1;
@Override
public void onCreate(Bundle b)
{
    super.onCreate(b);
    setContentView(R.layout.activity_display_random_circles);
    Button btn1 = (Button) findViewById(R.id.btn1);
    Button btn2 = (Button) findViewById(R.id.btn2);
    f1 = (FrameLayout) findViewById(R.id.frame);


}
@SuppressLint("WrongCall")
public void doit(View v)
{

    int rand = (int) (Math.random() * 60);
    switch (v.getId())
    {
        case (R.id.btn1):
            DrawCircle c = new DrawCircle(getApplicationContext());
            f1.addView(c);
            break;

        case (R.id.btn2):
            DrawCircle d = new DrawCircle(getApplicationContext());
            f1.addView(d);
            break;
    }
}
}

package com.example.randomcircles;

import java.util.Random;

import android.annotation.SuppressLint;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.view.View;

public class DrawCircle extends View
{
int red = (int) (Math.random() * 255);
int green = (int) (Math.random() * 255);
int blue = (int) (Math.random() * 255);
public DrawCircle(Context con)
{
    super(con);
}
@SuppressLint("DrawAllocation")
@Override
public void onDraw(Canvas c)
{
    super.onDraw(c);
    int color = Color.rgb(red, green, blue);
    int rand = (int)(Math.random() * 200);
    Paint p = new Paint(Paint.ANTI_ALIAS_FLAG);
    p.setAntiAlias(true);
    p.setStyle(Paint.Style.STROKE);
    p.setStrokeWidth(100);
    p.setColor(color);
    p.setStyle(Paint.Style.FILL);
    c.drawCircle(rand, rand, rand, p);
    clear(c);

}
public void clear(Canvas c)
{
    c.drawColor(Color.TRANSPARENT);
}
public void drawColor(int transparent) {
    // TODO Auto-generated method stub

}
}

<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >

<FrameLayout
    android:id="@+id/frame"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:layout_weight=".75"
    android:orientation="vertical" >


</FrameLayout>

<LinearLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:layout_weight=".25"
    android:gravity="bottom|center"
    android:orientation="horizontal" >

    <Button
        android:id="@+id/btn1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_gravity="start|bottom"
        android:layout_weight=".50"
        android:onClick="doit"
        android:text="@string/Circle" />

    <Button
        android:id="@+id/btn2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_weight=".50"
        android:layout_gravity="end|bottom"
        android:onClick="doit"
        android:text="@string/Clear" />
</LinearLayout>

</LinearLayout>

Answer 1

您的随机函数无法在当前 View 上绘制圆圈(很可能是因为您拥有高分辨率设备)，您必须获得 View 的高度才能在其上随机绘制圆圈。

    int minRadius = 100;
    Random random = new Random();//define this outside you onDraw fucntion 
    int w = getWidth();
    int h = getHeight();

    int randX = random.nextInt(w);
    int randY = random.nextInt(h);
    int randR = minRadius + random.nextInt(100);
    ...
    c.drawCircle(randX, randY, randR, p);

还可以通过在整个 Canvas 上绘制颜色来重置 View

canvas.drawColor(Color.WHITLE);