Android 如何保存画布图形并在单击按钮时显示它

嘿，我正在尝试创建一个android应用程序，我可以在画布上用底部的两个按钮画画 我设法让绘图正常工作，但是现在我需要添加两个按钮（一个用于将绘图画布保存到数据库（Sqlite，如果可能）或位图中，另一个用于从Sqlite导入图像并将其显示到graphicview中）

现在我不知道我必须在其中输入什么代码才能使“保存和显示”按钮正常工作，因此请帮助我输入代码，并感谢您抽出时间：）

这是我目前的代码（图形绘图工作正常，现在我需要保存和显示按钮的代码，以及我在graphicview.java和MainActivity.java中遗漏的代码）

GraphicsView.java

package org.example.graphics;

import java.util.ArrayList;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.RectF;
import android.graphics.Path.Direction;
import android.view.*;

public class GraphicsView extends View implements View.OnTouchListener {

public GraphicsView(Context context) {
    super(context);
    setBackgroundColor(Color.WHITE);
    setOnTouchListener(this);
}

ArrayList<MyPoint> arrOfPoints=new ArrayList<MyPoint>();

class MyPoint
{
    float x, y;
}
float downx, downy;

@Override
protected void onDraw(Canvas canvas) {
    // Drawing commands go here

    Paint rectPaint = new Paint(Paint.ANTI_ALIAS_FLAG);
    rectPaint.setStyle(Paint.Style.FILL_AND_STROKE);
    rectPaint.setColor(Color.BLACK);
    canvas.drawRoundRect(new RectF(0, 0, 100, 100), 10, 10, rectPaint);

    rectPaint.setColor(Color.BLUE);
    rectPaint.setAlpha(40);
    canvas.drawCircle(300, 300, 200, rectPaint);
    canvas.drawRect(new RectF(40, 40, 200, 200), rectPaint);
    Paint textPaint = new Paint(Paint.ANTI_ALIAS_FLAG
            | Paint.STRIKE_THRU_TEXT_FLAG);
    canvas.drawText("Hello there!", 200, 200, textPaint);

    canvas.drawText("You clicked on " + downx + "," + downy, 200, 600,
            textPaint);
        for(int i=0;i<arrOfPoints.size();i++)
                {
                    canvas.drawCircle(arrOfPoints.get(i).x, arrOfPoints.get(i).y, 20, rectPaint);
                }

}

@Override
public boolean onTouch(View arg0, MotionEvent arg1) {
    int action = arg1.getAction();
    MyPoint p=null;
    switch (action) {
    case MotionEvent.ACTION_DOWN:
        downx = arg1.getX();
        downy = arg1.getY();

        p=new MyPoint();
        p.x=arg1.getX();p.y=arg1.getY();

        arrOfPoints.add(p);
        invalidate();
        break;
    case MotionEvent.ACTION_MOVE:
        downx = arg1.getX();
        downy = arg1.getY();
        p=new MyPoint();
        p.x=arg1.getX();p.y=arg1.getY();
        arrOfPoints.add(p);
        invalidate();
        break;
    case MotionEvent.ACTION_UP:

        break;
    case MotionEvent.ACTION_CANCEL:
        break;
    default:
        break;
    }
    return true;
}

package org.example.graphics;
import android.app.Activity;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Path;
import android.graphics.Path.Direction;
import android.graphics.RectF;
import android.os.Bundle;
import android.view.View;

public class MainActivity extends Activity {
@Override
public void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(new GraphicsView(this));
}

main.xml

 <?xml version="1.0" encoding="utf-8"?>
 <LinearLayout
 xmlns:android="http://schemas.android.com/apk/res/android"
 android:orientation="vertical"
 android:layout_width="fill_parent"
 android:layout_height="fill_parent"
 android:background="@drawable/background">

 <org.example.graphics.GraphicsView
   android:id="@+id/graphics"
   android:layout_width="fill_parent"
   android:layout_height="341dp" />

   <Button
    android:id="@+id/ChoosePictureButton"/>
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Choose Picture"

 <Button
    android:layout_width="fill_parent"
    android:layout_height="wrap_content"
    android:text="Save Picture" android:id="@+id/SavePictureButton"/>

</LinearLayout>

android:layout\u width=“fill\u parent”
android:layout\u height=“包装内容”
android:text=“选择图片”

---

My AndroidManifest.xml仍处于默认状态，因为我尚未编辑其中的任何内容

您可以在保存按钮单击侦听器中使用此代码

int canvasWidth = 500;
int canvasHeight = 500;
View v = new GraphicsView(MainActivity.this);
Bitmap bitmap = Bitmap.createBitmap(canvasWidth, canvasHeight, Bitmap.Config.ARGB_8888);
Canvas canvas = new Canvas(bitmap);
v.draw(canvas);

//now bitmap has your canvas image

//set it to your ImageView
yourImageView.setImageBitmap(bitmap);

//or save to sdcard
File dir = new File("/sdcard/yourAppFolder/");
if (!dir.isDirectory()) {
    dir.mkdirs();
}
File outputFile = new File(dir, "image.jpg");
OutputStream fout = null;
fout = new FileOutputStream(outputFile);
bitmap.compress(Bitmap.CompressFormat.JPEG, 100, fout);
fout.flush();
fout.close();

---

将画布另存为PNG文件，然后通过ImageView加载。我在哪里添加PNG文件的代码？在mainactivity或graphicsview中？那么我必须在mainactivity.java中添加保存按钮的方法吗？抱歉，我还是android新手，我还没有在MainActivity.java中添加任何内容yet@KopArtist：是的，您需要将其添加到MainActivity.java中非常感谢您的回复这是我在MainActivity.java中的新代码。我很确定它是不正确的，你能告诉我我做错了什么吗？@KopArtist:你需要声明按钮，然后你可以添加click listener到它，签出这个答案我在MainActivity.java中修复了我的代码[这是正确的代码吗？为什么我仍然在“v”上出错？”