在绘图应用程序中保存文件

Question

我正在制作一个笔记应用程序，用户可以在其中在屏幕上绘图并将其保存为图像。我正在关注以下教程 https://www.ssaurel.com/blog/learn-to-create-a-paint-application-for-android/
在这方面我有两个问题：
1。我不知道如何将绘制的图形保存为图像。
2。形成的图像应该保存为外部文件还是保存在 SQLite 数据库中更好

代码MainActivity.java

    public class MainActivity extends AppCompatActivity {

private PaintView paintView;

@Override
protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(R.layout.activity_main);
    paintView = (PaintView) findViewById(R.id.paintView);
    DisplayMetrics metrics = new DisplayMetrics();
    getWindowManager().getDefaultDisplay().getMetrics(metrics);
    paintView.init(metrics);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    MenuInflater menuInflater = getMenuInflater();
    menuInflater.inflate(R.menu.main, menu);
    return super.onCreateOptionsMenu(menu);
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    switch(item.getItemId()) {
        case R.id.normal:
            paintView.normal();
            return true;
        case R.id.emboss:
            paintView.emboss();
            return true;
        case R.id.blur:
            paintView.blur();
            return true;
        case R.id.clear:
            paintView.clear();
            return true;
    }

    return super.onOptionsItemSelected(item);
}
}

PaintView.class

    public class PaintView extends View {

public static int BRUSH_SIZE = 20;
public static final int DEFAULT_COLOR = Color.RED;
public static final int DEFAULT_BG_COLOR = Color.WHITE;
private static final float TOUCH_TOLERANCE = 4;
private float mX, mY;
private Path mPath;
private Paint mPaint;
private ArrayList<FingerPath> paths = new ArrayList<>();
private int currentColor;
private int backgroundColor = DEFAULT_BG_COLOR;
private int strokeWidth;
private boolean emboss;
private boolean blur;
private MaskFilter mEmboss;
private MaskFilter mBlur;
private Bitmap mBitmap;
private Canvas mCanvas;
private Paint mBitmapPaint = new Paint(Paint.DITHER_FLAG);

public PaintView(Context context) {
    this(context, null);
}

public PaintView(Context context, AttributeSet attrs) {
    super(context, attrs);
    mPaint = new Paint();
    mPaint.setAntiAlias(true);
    mPaint.setDither(true);
    mPaint.setColor(DEFAULT_COLOR);
    mPaint.setStyle(Paint.Style.STROKE);
    mPaint.setStrokeJoin(Paint.Join.ROUND);
    mPaint.setStrokeCap(Paint.Cap.ROUND);
    mPaint.setXfermode(null);
    mPaint.setAlpha(0xff);

    mEmboss = new EmbossMaskFilter(new float[] {1, 1, 1}, 0.4f, 6, 3.5f);
    mBlur = new BlurMaskFilter(5, BlurMaskFilter.Blur.NORMAL);
}

public void init(DisplayMetrics metrics) {
    int height = metrics.heightPixels;
    int width = metrics.widthPixels;

    mBitmap = Bitmap.createBitmap(width, height, Bitmap.Config.ARGB_8888);
    mCanvas = new Canvas(mBitmap);

    currentColor = DEFAULT_COLOR;
    strokeWidth = BRUSH_SIZE;
}

public void normal() {
    emboss = false;
    blur = false;
}

public void emboss() {
    emboss = true;
    blur = false;
}

public void blur() {
    emboss = false;
    blur = true;
}

public void clear() {
    backgroundColor = DEFAULT_BG_COLOR;
    paths.clear();
    normal();
    invalidate();
}

@Override
protected void onDraw(Canvas canvas) {
    canvas.save();
    mCanvas.drawColor(backgroundColor);

    for (FingerPath fp : paths) {
        mPaint.setColor(fp.color);
        mPaint.setStrokeWidth(fp.strokeWidth);
        mPaint.setMaskFilter(null);

        if (fp.emboss)
            mPaint.setMaskFilter(mEmboss);
        else if (fp.blur)
            mPaint.setMaskFilter(mBlur);

        mCanvas.drawPath(fp.path, mPaint);

    }

    canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
    canvas.restore();
}

private void touchStart(float x, float y) {
    mPath = new Path();
    FingerPath fp = new FingerPath(currentColor, emboss, blur, strokeWidth, mPath);
    paths.add(fp);

    mPath.reset();
    mPath.moveTo(x, y);
    mX = x;
    mY = y;
}

private void touchMove(float x, float y) {
    float dx = Math.abs(x - mX);
    float dy = Math.abs(y - mY);

    if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
        mPath.quadTo(mX, mY, (x + mX) / 2, (y + mY) / 2);
        mX = x;
        mY = y;
    }
}

private void touchUp() {
    mPath.lineTo(mX, mY);
}

@Override
public boolean onTouchEvent(MotionEvent event) {
    float x = event.getX();
    float y = event.getY();

    switch(event.getAction()) {
        case MotionEvent.ACTION_DOWN :
            touchStart(x, y);
            invalidate();
            break;
        case MotionEvent.ACTION_MOVE :
            touchMove(x, y);
            invalidate();
            break;
        case MotionEvent.ACTION_UP :
            touchUp();
            invalidate();
            break;
    }

    return true;
}
}

Answer 1

我认为图像存储在 mBitmap。

描述如何将 Android 中的位图保存到内部存储器或 SD 卡：Save bitmap to location

FileOutputStream out = null;
try {
    out = new FileOutputStream(filename);
    mBitmap.compress(Bitmap.CompressFormat.PNG, 100, out);
    // PNG is a lossless format, the compression factor (100) is ignored
} catch (Exception e) {
    e.printStackTrace();
} finally {
    try {
        if (out != null) {
            out.close();
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
}

希望对您有所帮助

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