爲什麼調整大小讓我的圖像看起來很奇怪？

Question

我有一個相對的佈局，我添加一個視圖。這是在活動代碼：

paint = (RelativeLayout) findViewById(R.id.paint); 
    new Handler().postDelayed(new Runnable() { 

     @Override 
     public void run() { 
      myView = new CustomImage(getBaseContext()); 
      paint.addView(myView); 
      String imagePath = (String) getIntent().getExtras().get("selectedImagePath"); 
      LogService.log("PaintActivity", "Imagepath: " + imagePath); 
      //    Drawable background = BitmapDrawable.createFromPath(imagePath); 
      //    bitmap = ((BitmapDrawable) background).getBitmap(); 
      try { 
       fis = new FileInputStream(imagePath); 
      } catch (FileNotFoundException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } 
      try { 
       mBitmap = loadBitmap(fis.getFD()); 
       bitmap = getResizedBitmap(mBitmap, 412*2, 1024*2); 
      } catch (IOException e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } 
      try { 
       LogService.log("PaintActivity", "Bitmap = " + mBitmap); 
       myView.setBitmap(bitmap); 
      } catch (Exception e) { 
       // TODO Auto-generated catch block 
       e.printStackTrace(); 
      } 
      mPaint = new Paint(); 
      mPaint.setAntiAlias(true); 
      mPaint.setDither(true); 
      mPaint.setColor(0xFF000000); 
      mPaint.setStyle(Paint.Style.STROKE); 
      mPaint.setStrokeJoin(Paint.Join.ROUND); 
      mPaint.setStrokeCap(Paint.Cap.ROUND); 
      mPaint.setStrokeWidth(50); 
      myView.setPaint(mPaint); 

     } 
    }, 50); 

這是我的看法：

public class CustomImage extends View { 

private boolean hasResized = false; 

private Bitmap bitmap, bitmap2; 

public Context context; 

Paint paint; 

private Canvas canvas; 

public String text = null; 

private Paint mBitmapPaint, paintText; 

private Path mPath = new Path(); 

private float mX, mY, pX, pY, tX, tY; 

private static final float TOUCH_TOLERANCE = 4; 

private float screenDensity; 

int height, width; 

private Bitmap mBitmap; 

private RandomAccessFile randomAccessFile; 

private int bh; 

private int bw; 

public CustomImage(Context context, AttributeSet attrs, int defStyle) { 
    super(context, attrs, defStyle); 
    init(context); 
} 

public CustomImage(Context context, AttributeSet attrs) { 
    super(context, attrs); 
    init(context); 
} 

public CustomImage(Context context) { 
    super(context); 
    init(context); 
} 

private void init(Context context) { 
    this.context = context; 
    mBitmapPaint = new Paint(Paint.DITHER_FLAG); 
    } 

public void setImg(Context context, Canvas canvas, Bitmap bitmapw, int width, int height) { 

    bw = bitmapw.getWidth(); 
    bh = bitmapw.getHeight(); 
    float scaleWidth = ((float) width)/ bw; 
    float scaleHeight = ((float) height)/ bh; 
    System.out.println("CustomImage.setImg()"); 
    bitmap = bitmapw; 

} 

public void setPaint(Paint paint) { 
    this.paint = paint; 
    LogService.log("in setPaint", "paint = " + paint); 
} 

public void setBitmap(Bitmap bitmap) throws Exception { 
    File file = new File("/mnt/sdcard/sample/temp.txt"); 
    file.getParentFile().mkdirs(); 
    randomAccessFile = new RandomAccessFile(file, "rw"); 
    int bWidth = bitmap.getWidth(); 
    int bHeight = bitmap.getHeight(); 
    FileChannel channel = randomAccessFile.getChannel(); 
    MappedByteBuffer map = channel.map(MapMode.READ_WRITE, 0, bWidth*bHeight*4); 
    bitmap.copyPixelsToBuffer(map); 
    bitmap.recycle(); 
    this.bitmap = Bitmap.createBitmap(bWidth, bHeight, Config.ARGB_8888); 
    map.position(0); 
    this.bitmap.copyPixelsFromBuffer(map); 
    channel.close(); 
    randomAccessFile.close(); 
    //  this.bitmap = bitmap; 


    // canvas = new Canvas(); 
} 

public void setBitmap2(Bitmap bitmap) { 
    bitmap2 = bitmap; 
    invalidate(); 
} 

public void getText(String text) { 
    this.text = text; 
    paintText = new Paint(); 
    paintText.setColor(0xFFFFFFFF); 
    paintText.setStrokeWidth(10); 
    paintText.setTextSize(20); 
    invalidate(); 
} 

@Override 
protected void onDraw(Canvas canvas) { 
    super.onDraw(canvas); 
    canvas.drawBitmap(bitmap, 0, 0, mBitmapPaint); 
    if (PaintActivity.isPic == 1) { 
     if (bitmap2 != null) { 
      canvas.drawBitmap(bitmap2, mX, mY, mBitmapPaint); 
      pX = mX; 
      pY = mY; 
     } 
     if(text != null){ 
      canvas.drawText(text, tX, tY, paintText); 
     } 
    } else if (PaintActivity.isPic == 2) { 
     if(text != null){ 
      canvas.drawText(text, mX, mY, paintText); 
      tX = mX; 
      tY = mY; 
     } 
     if (bitmap2 != null) { 
      canvas.drawBitmap(bitmap2, pX, pY, mBitmapPaint); 
     } 
    }else{ 
     canvas.drawPath(mPath, paint); 
     if (bitmap2 != null) { 
      canvas.drawBitmap(bitmap2, pX, pY, mBitmapPaint); 
     } 
     if(text != null){ 
      canvas.drawText(text, tX, tY, paintText); 
     } 
    } 
} 

private void touch_start(float x, float y) { 
    mPath.reset(); 
    mPath.moveTo(x, y); 
    canvas.drawPoint(x, y, paint); 
    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); 
    mPath.moveTo(mX, mY); 
    canvas.drawPath(mPath, paint); 
    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; 
} 

@Override 
protected void onSizeChanged(int w, int h, int oldw, int oldh) { 
    System.out.println("CustomImage.onSizeChanged()"); 
    super.onSizeChanged(w, h, oldw, oldh); 
    if ((w != 0) && (h != 0)) { 
     if (!hasResized) { 
      hasResized = true; 
      renderImage(); 
     } 
    } 
} 

public void renderImage() { 
    System.out.println("======in renderimage=======w " + getMeasuredWidth() + "h " + getMeasuredHeight()); 
    width = getMeasuredWidth(); 
    height = getMeasuredHeight(); 
    canvas = new Canvas(bitmap); 
    setImg(context, canvas, bitmap, width, height); 
} 
} 

正如你所看到的，我有活性的大小調整功能：

public Bitmap getResizedBitmap(Bitmap bm, int newHeight, int newWidth) { 

    int width = bm.getWidth(); 

    int height = bm.getHeight(); 

    float scaleWidth = ((float) newWidth)/width; 

    float scaleHeight = ((float) newHeight)/height; 

    // create a matrix for the manipulation 

    Matrix matrix = new Matrix(); 

    // resize the bit map 

    matrix.postScale(scaleWidth, scaleHeight); 

    // recreate the new Bitmap 

    Bitmap resizedBitmap = Bitmap.createBitmap(bm, 0, 0, width, height, matrix, false); 

    return resizedBitmap; 

} 

現在，如果我在代碼中註釋這個函數，圖像看起來很正常，但沒有縮放。如果我把它留在那裏，那麼我得到一個醜陋的圖像，但它的大小調整。例如： 正常未調整大小：http://imgur.com/BD5Pp,YWDTi 改變，但調整圖：http://imgur.com/BD5Pp,YWDTi#1

Answer 1

如OP表示回答我的問題，該位圖被轉換爲RGB_565，這是在createBitmap()一個已知的錯誤 - #16211，固定在Android的3.0。它也會影響createScaledBitmap()。如果位圖保持爲ARGB_8888，則位圖不會變形。

作爲一種解決方法，您必須手動創建目標位圖（它使您可以完全控制像素格式），然後創建附加到該位圖的畫布並在其上繪製縮放版本的原始位圖。下面是從我的項目的樣本：

public class BitmapUtils { 

    private static Matrix matrix = new Matrix(); 
    private static Paint paint = new Paint(Paint.FILTER_BITMAP_FLAG); 

    public static final Bitmap resizeBitmap(Bitmap bitmap, float scale, Bitmap.Config targetConfig) { 
      int srcWidth = bitmap.getWidth(); 
      int srcHeight = bitmap.getHeight(); 

      int newWidth = (int) (srcWidth * scale); 
      int newHeight = (int) (srcHeight * scale); 

      float sx = newWidth/(float) srcWidth; 
      float sy = newHeight/(float) srcHeight; 
      matrix.setScale(sx, sy); 

      Bitmap target = Bitmap.createBitmap(newWidth, newHeight, targetConfig); 
      Canvas c = new Canvas(target); 
      c.drawBitmap(bitmap, matrix, paint); 
      return target; 
    } 
} 

注意：此代碼是不可重入，由於全球matrix實例。此外，它將比例作爲參數，但將其適用於您的需求（新的寬度/高度作爲參數）是微不足道的。