Android实现画板包括涂鸦 改变颜色 橡皮擦 调节画笔粗细 撤销上一步 保存图片等功能的详细代码

好的，下面是一个简单的 Android 画板示例代码，包括涂鸦、改变颜色、橡皮擦、调节画笔粗细、撤销上一步和保存图片等功能：

MainActivity.java：

public class MainActivity extends AppCompatActivity implements View.OnClickListener {
    private static final int REQUEST_PERMISSION_CODE = 1001;
    private static final int MAX_STEP = 10;
    private static final int DEFAULT_COLOR = Color.BLACK;
    private static final int DEFAULT_SIZE = 5;

    private SurfaceView mSurfaceView;
    private Button mColorButton;
    private Button mEraserButton;
    private SeekBar mSizeSeekBar;
    private Button mUndoButton;
    private Button mSaveButton;

    private Paint mPaint;
    private int mColor = DEFAULT_COLOR;
    private int mSize = DEFAULT_SIZE;

    private Bitmap mBitmap;
    private Canvas mCanvas;
    private Stack<Bitmap> mBitmapStack;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        mSurfaceView = findViewById(R.id.surface_view);
        mColorButton = findViewById(R.id.color_button);
        mEraserButton = findViewById(R.id.eraser_button);
        mSizeSeekBar = findViewById(R.id.size_seek_bar);
        mUndoButton = findViewById(R.id.undo_button);
        mSaveButton = findViewById(R.id.save_button);

        mColorButton.setOnClickListener(this);
        mEraserButton.setOnClickListener(this);
        mUndoButton.setOnClickListener(this);
        mSaveButton.setOnClickListener(this);

        mSizeSeekBar.setMax(100);
        mSizeSeekBar.setProgress(DEFAULT_SIZE);
        mSizeSeekBar.setOnSeekBarChangeListener(new SeekBar.OnSeekBarChangeListener() {
            @Override
            public void onProgressChanged(SeekBar seekBar, int progress, boolean fromUser) {
                mSize = progress;
            }

            @Override
            public void onStartTrackingTouch(SeekBar seekBar) {
            }

            @Override
            public void onStopTrackingTouch(SeekBar seekBar) {
            }
        });

        mPaint = new Paint();
        mPaint.setColor(mColor);
        mPaint.setStrokeWidth(mSize);
        mPaint.setStyle(Paint.Style.STROKE);
        mPaint.setStrokeCap(Paint.Cap.ROUND);
        mPaint.setStrokeJoin(Paint.Join.ROUND);

        mBitmap = Bitmap.createBitmap(mSurfaceView.getWidth(), mSurfaceView.getHeight(), Bitmap.Config.ARGB_8888);
        mCanvas = new Canvas(mBitmap);
        mBitmapStack = new Stack<>();

        mSurfaceView.getHolder().addCallback(new SurfaceHolder.Callback() {
            @Override
            public void surfaceCreated(SurfaceHolder holder) {
                mCanvas.drawColor(Color.WHITE);
            }

            @Override
            public void surfaceChanged(SurfaceHolder holder, int format, int width, int height) {
                mBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
                mCanvas.setBitmap(mBitmap);
            }

            @Override
            public void surfaceDestroyed(SurfaceHolder holder) {
                mBitmap.recycle();
            }
        });
    }

    @Override
    public void onClick(View v) {
        switch (v.getId()) {
            case R.id.color_button:
                showColorPickerDialog();
                break;
            case R.id.eraser_button:
                mColor = Color.WHITE;
                mPaint.setColor(mColor);
                break;
            case R.id.undo_button:
                undo();
                break;
            case R.id.save_button:
                saveImage();
                break;
        }
    }

    @Override
    public boolean onTouchEvent(MotionEvent event) {
        if (event.getAction() == MotionEvent.ACTION_DOWN) {
            mBitmapStack.push(Bitmap.createBitmap(mBitmap));
        }

        if (event.getAction() == MotionEvent.ACTION_MOVE || event.getAction() == MotionEvent.ACTION_DOWN) {
            float x = event.getX();
            float y = event.getY();
            mCanvas.drawPoint(x, y, mPaint);
            mSurfaceView.getHolder().unlockCanvasAndPost(mCanvas);
        }

        if (mBitmapStack.size() > MAX_STEP) {
            mBitmapStack.remove(0);
        }

        return true;
    }

    private void showColorPickerDialog() {
        ColorPickerDialogBuilder
                .with(this)
                .setTitle("Color Picker")
                .initialColor(mColor)
                .wheelType(ColorPickerView.WHEEL_TYPE.FLOWER)
                .density(12)
                .setPositiveButton("OK", new ColorPickerClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int selectedColor, Integer[] allColors) {
                        mColor = selectedColor;
                        mPaint.setColor(mColor);
                    }
                })
                .setNegativeButton("Cancel", new DialogInterface.OnClickListener() {
                    @Override
                    public void onClick(DialogInterface dialog, int which) {
                    }
                })
                .build()
                .show();
    }

    private void undo() {
        if (!mBitmapStack.isEmpty()) {
            mBitmap = mBitmapStack.pop();
            mCanvas.setBitmap(mBitmap);
            mSurfaceView.getHolder().unlockCanvasAndPost(mCanvas);
        }
    }

    private void saveImage() {
        if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
            if (checkSelfPermission(Manifest.permission.WRITE_EXTERNAL_STORAGE) != PackageManager.PERMISSION_GRANTED) {
                requestPermissions(new String[]{Manifest.permission.WRITE_EXTERNAL_STORAGE}, REQUEST_PERMISSION_CODE);
                return;
            }
        }

        String fileName = "Drawing_" + System.currentTimeMillis() + ".png";
        File file = new File(Environment.getExternalStoragePublicDirectory(Environment.DIRECTORY_PICTURES), fileName);

        try {
            FileOutputStream fos = new FileOutputStream(file);
            mBitmap.compress(Bitmap.CompressFormat.PNG, 100, fos);
            fos.flush();
            fos.close();
            Toast.makeText(this, "Image saved to " + file.getAbsolutePath(), Toast.LENGTH_SHORT).show();
        } catch (IOException e) {
            e.printStackTrace();
            Toast.makeText(this, "Failed to save image", Toast.LENGTH_SHORT).show();
        }
    }

    @Override
    public void onRequestPermissionsResult(int requestCode, @NonNull String[] permissions, @NonNull int[] grantResults) {
        switch (requestCode) {
            case REQUEST_PERMISSION_CODE:
                if (grantResults.length > 0 && grantResults[0] == PackageManager.PERMISSION_GRANTED) {
                    saveImage();
                } else {
                    Toast.makeText(this, "Permission denied", Toast.LENGTH_SHORT).show();
                }
                break;
        }
    }
}

activity_main.xml：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <SurfaceView
        android:id="@+id/surface_view"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

    <LinearLayout
        android:id="@+id/tool_layout"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:orientation="horizontal"
        android:padding="16dp">

        <Button
            android:id="@+id/color_button"
            android:layout_width="48dp"
            android:layout_height="48dp"
            android:layout_marginEnd="16dp"
            android:backgroundTint="@color/black"
            android:textColor="@color/white"
            android:text="C" />

        <Button
            android:id="@+id/eraser_button"
            android:layout_width="48dp"
            android:layout_height="48dp"
            android:layout_marginEnd="16dp"
            android:backgroundTint="@color/white"
            android:textColor="@color/black"
            android:text="E" />

        <SeekBar
            android:id="@+id/size_seek_bar"
            android:layout_width="0dp"
            android:layout_height="48dp"
            android:layout_marginEnd="16dp"
            android:layout_weight="1" />

        <Button
            android:id="@+id/undo_button"
            android:layout_width="48dp"
            android:layout_height="48dp"
            android:layout_marginEnd="16dp"
            android:backgroundTint="@color/black"
            android:textColor="@color/white"
            android:text="U" />

        <Button
            android:id="@+id/save_button"
            android:layout_width="48dp"
            android:layout_height="48dp"
            android:backgroundTint="@color/black"
            android:textColor="@color/white"
            android:text="S" />

    </LinearLayout>

</RelativeLayout>

这个示例代码中包含了涂鸦、改变颜色、橡皮擦、调节画笔粗细、撤销上一步和保存图片等功能，你可以根据自己的需求进行修改和扩展。