Question

我有一个油漆示例程序。

          package deck_flight.com;

          import android.app.Activity;
          import android.content.Context;
          import android.graphics.*;
          import android.os.Bundle;
          import android.view.Menu;
          import android.view.MenuItem;
          import android.view.MotionEvent;
          import android.view.View;

      public class paint extends  Activity
      {    

  @Override
   protected void onCreate(Bundle savedInstanceState) {
    super.onCreate(savedInstanceState);
    setContentView(new MyView(this));

    mPaint = new Paint();
    mPaint.setAntiAlias(true);
    mPaint.setDither(true);
    mPaint.setColor(0xFFFF0000);
    mPaint.setStyle(Paint.Style.STROKE);
    mPaint.setStrokeJoin(Paint.Join.ROUND);
    mPaint.setStrokeCap(Paint.Cap.ROUND);
    mPaint.setStrokeWidth(12);

    mEmboss = new EmbossMaskFilter(new float[] { 1, 1, 1 },
                                   0.4f, 6, 3.5f);

    mBlur = new BlurMaskFilter(8, BlurMaskFilter.Blur.NORMAL);
}

private Paint       mPaint;
private MaskFilter  mEmboss;
private MaskFilter  mBlur;
private Canvas  mCanvas;
private Path    mPath;
private Bitmap  mBitmap;
private Paint   mBitmapPaint;

public void colorChanged(int color) {
    mPaint.setColor(color);
}

public class MyView extends View {

    private static final float MINP = 0.25f;
    private static final float MAXP = 0.75f;



    public MyView(Context c) {
        super(c);

        mBitmap = Bitmap.createBitmap(800, 480, Bitmap.Config.ARGB_8888);
        mCanvas = new Canvas(mBitmap);
        mPath = new Path();
        mBitmapPaint = new Paint(Paint.DITHER_FLAG);
    }

    @Override
    protected void onSizeChanged(int w, int h, int oldw, int oldh) {
        super.onSizeChanged(w, h, oldw, oldh);
    }

    @Override
    protected void onDraw(Canvas canvas) {
        canvas.drawColor(0xFFAAAAAA);

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

        canvas.drawPath(mPath, mPaint);
    }

    private float mX, mY;
    private static final float TOUCH_TOLERANCE = 4;

    private void touch_start(float x, float y) {
        mPath.reset();
        mPath.moveTo(x, y);
        mX = x;
        mY = y;
    }
    private void touch_move(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 touch_up() {
        mPath.lineTo(mX, mY);
        // commit the path to our offscreen
        mCanvas.drawPath(mPath, mPaint);
        // kill this so we don't double draw
        mPath.reset();
    }

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

        switch (event.getAction()) {
            case MotionEvent.ACTION_DOWN:
                touch_start(x, y);
                invalidate();
                break;
            case MotionEvent.ACTION_MOVE:
                touch_move(x, y);
                invalidate();
                break;
            case MotionEvent.ACTION_UP:
                touch_up();
                invalidate();
                break;
        }
        return true;
    }
}

private static final int COLOR_MENU_ID = Menu.FIRST;
private static final int EMBOSS_MENU_ID = Menu.FIRST + 1;
private static final int BLUR_MENU_ID = Menu.FIRST + 2;
private static final int ERASE_MENU_ID = Menu.FIRST + 3;
private static final int SRCATOP_MENU_ID = Menu.FIRST + 4;

@Override
public boolean onCreateOptionsMenu(Menu menu) {
    super.onCreateOptionsMenu(menu);

    menu.add(0, COLOR_MENU_ID, 0, "Color").setShortcut('3', 'c');
    menu.add(0, EMBOSS_MENU_ID, 0, "Emboss").setShortcut('4', 's');
    menu.add(0, BLUR_MENU_ID, 0, "Blur").setShortcut('5', 'z');
    menu.add(0, ERASE_MENU_ID, 0, "Erase").setShortcut('5', 'z');
    menu.add(0, SRCATOP_MENU_ID, 0, "SrcATop").setShortcut('5', 'z');

    /****   Is this the mechanism to extend with filter effects?
    Intent intent = new Intent(null, getIntent().getData());
    intent.addCategory(Intent.CATEGORY_ALTERNATIVE);
    menu.addIntentOptions(
                          Menu.ALTERNATIVE, 0,
                          new ComponentName(this, NotesList.class),
                          null, intent, 0, null);
    *****/
    return true;
}

@Override
public boolean onPrepareOptionsMenu(Menu menu) {
    super.onPrepareOptionsMenu(menu);
    return true;
}

@Override
public boolean onOptionsItemSelected(MenuItem item) {
    mPaint.setXfermode(null);
    mPaint.setAlpha(0xFF);

    switch (item.getItemId()) {
        case COLOR_MENU_ID:
           // new ColorPickerDialog(this, this, mPaint.getColor()).show();
            return true;
        case EMBOSS_MENU_ID:
            if (mPaint.getMaskFilter() != mEmboss) {
                mPaint.setMaskFilter(mEmboss);
            } else {
                mPaint.setMaskFilter(null);
            }
            return true;
        case BLUR_MENU_ID:
            if (mPaint.getMaskFilter() != mBlur) {
                mPaint.setMaskFilter(mBlur);
            } else {
                mPaint.setMaskFilter(null);
            }
            return true;
        case ERASE_MENU_ID:
            mPaint.setXfermode(new PorterDuffXfermode(
                                                    PorterDuff.Mode.CLEAR));
            return true;
        case SRCATOP_MENU_ID:
            mPaint.setXfermode(new PorterDuffXfermode(
                                                PorterDuff.Mode.SRC_ATOP));
            mPaint.setAlpha(0x80);
            return true;
    }
    return super.onOptionsItemSelected(item);
  }
    @Override
     public void onResume(){
   super.onResume();

   mCanvas.drawPath(mPath, mPaint);
    }
}

示例程序工作得很好。一旦我绘制它就画线。我想要的是一旦我从应用程序中出来，我绘制的内容应该在画布中。但我是无法获取我之前绘制的内容。此代码中的错误是什么。请帮助我。谢谢。提前感谢。

Answer 1

在您的应用程序中，您使用mCanvas绘制链接到mBitmap的内容。每次完成绘图时都需要将mBitmap保存到apllication的目录中，尽管这取决于你应该保存它的频率。

重新启动活动/应用程序时，如果有上一个绘图的路径，则应检入已保存的首选项，然后将其加载到mBitmap中，以便继续绘制它。

以下是如何保存位图的代码：

        String myImageFileName = "my_image.jpg";
        try {
            mBitmap.compress(CompressFormat.JPEG, 80, openFileOutput(myImageFileName, MODE_PRIVATE));
        } catch (Exception e) {
            Log.e(DEBUG_TAG, "Image compression and save failed.", e);
        }

        Uri uriToSaveImageTo = Uri.fromFile(new File(myActivity.this.getFilesDir(), myImageFilename));

现在您将uriToSaveImageTo保存到首选项中......

Paint中的Android-onResume（）

1 个答案: