Question

我试图在Android的Api演示中的Fingerpaint应用程序上实现擦除功能。我根据自己的需要更改了一些代码。起初擦除功能很好。我用过：

drawPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));

在位图中绘制路径时效果很好。但是当我实现Undo和Redo功能时（我实现它的方式是使用两个arraylist并保存路径），PorterDuffXfermode不起作用。请看一下：

在图像1中，我绘制了一些路径（存储在arraylist中。未在位图画布中绘制）然后在2，那时我按下了擦除图标。我不知道是什么导致所有路径变黑。然后在3我试图擦除我做的路径（PorterDuffXFermode有人说它是黑色的）。然后当我切换回绘图模式。似乎相反或删除，它所做的只是绘制另一条道路。

任何解决方案？或解决方法？这是我的drawingClass的代码：

//this is where the drawing takes place
public class DrawingClass extends View{
//drawing path
private Path drawPath;
//drawing and canvas paint
private Paint drawPaint, canvasPaint;
//initial color
private int paintColor = 0xFF660000;
//canvas
private Canvas drawCanvas;
//canvas bitmap
private Bitmap canvasBitmap;
private float brushSize,lastBrushSize;
private boolean erase = false;
//array list for paths
private ArrayList<PathPoints> paths = new ArrayList<PathPoints>();
private ArrayList<PathPoints> undonePaths = new ArrayList<PathPoints>();

public Context context;


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


public DrawingClass(Context context, AttributeSet attrs) {
    super(context, attrs);
    // TODO Auto-generated constructor stub
    this.context = context;
    setupDrawing();
}

private void setupDrawing(){
    setFocusable(true);
    setFocusableInTouchMode(true);

//instantiate the variable to get the last brush size
    brushSize = getResources().getInteger(R.integer.medium_size);
    lastBrushSize = brushSize;
//get drawing area setup for interaction
    drawCanvas = new Canvas();
    drawPath = new Path();
    drawPaint = new Paint();
    drawPaint.setColor(paintColor);
    //initial properties
    drawPaint.setAntiAlias(true);
    drawPaint.setStrokeWidth(brushSize);
    drawPaint.setStyle(Paint.Style.STROKE);
    drawPaint.setStrokeJoin(Paint.Join.ROUND);
    drawPaint.setStrokeCap(Paint.Cap.ROUND);

    canvasPaint = new Paint(Paint.DITHER_FLAG);

    //paths.add(new PathPoints(drawPath, paintColor, brushSize));

}

public void setBrushSize(float newSize){
    //update brush size
    float pixelAmount = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP,
            newSize, getResources().getDisplayMetrics());
    brushSize = pixelAmount;
    drawPaint.setStrokeWidth(brushSize);
    invalidate();
}

public void setLastBrushSize(float lastSize){
    //set the last brush size
    lastBrushSize = lastSize;
    invalidate();
}

public float getLastBrushSize(){
    //return the last brush size
    return lastBrushSize;
}

public void setErase(boolean isErase){
    //set erase true or false
    erase = isErase;
    if (erase) {
        //drawPaint.setColor(Color.WHITE);
        drawPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
    }
    else drawPaint.setXfermode(null);
}

public void startNew(){
    //creates a new canvass
    drawCanvas.drawColor(0,PorterDuff.Mode.CLEAR);
    drawCanvas.drawBitmap(canvasBitmap, 0, 0, canvasPaint);
    setDrawingCacheEnabled(true);
    String imgSaved = MediaStore.Images.Media.insertImage(
          context.getContentResolver(), getDrawingCache(),
            UUID.randomUUID().toString()+".png", "drawing");
    destroyDrawingCache();
    paths.clear();
    undonePaths.clear();
    invalidate();
}

@Override
protected void onSizeChanged(int w,int h,int oldw,int oldh){
    //view given size
    super.onSizeChanged(w, h, oldw, oldh);
    canvasBitmap = Bitmap.createBitmap(w,h,Bitmap.Config.ARGB_8888);
    drawCanvas = new Canvas(canvasBitmap);
}

@Override
protected void onDraw(Canvas canvas){
    //draw view
    //save the strokes in the bitmap
    //canvas.drawBitmap(canvasBitmap, 0, 0, canvasPaint);

    for (PathPoints p : paths){
        drawPaint.setColor(p.getColor());
        drawPaint.setStrokeWidth(p.getBrush());
        invalidate();
        canvas.drawPath(p.getPath(), drawPaint);
    }
}

private void touch_start(float x, float y){
    drawPath.reset();
    drawPath.moveTo(x, (float) (y+.1));
    drawPath.lineTo(x, y);
    drawPath.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) {
            drawPath.quadTo(mX, mY, (x + mX)/2, (y+ mY)/2);
            mX = x;
            mY = y;
        }
}

private void touch_up(){
    drawPath.lineTo(mX, mY);
    drawCanvas.drawPath(drawPath, drawPaint);
    drawPath = new Path();
    paths.add(new PathPoints(drawPath, paintColor, brushSize));
}

@Override
public boolean onTouchEvent(MotionEvent event){
    //detect user touch
    float touchX = event.getX();
    float touchY = event.getY();

    switch (event.getAction()) {
    case MotionEvent.ACTION_DOWN:
        invalidate();
        touch_start(touchX, touchY);
        break;
    case MotionEvent.ACTION_MOVE:
        invalidate();
        touch_move(touchX, touchY);
        break;
    case MotionEvent.ACTION_UP:
        invalidate();
        touch_up();
        drawPath.reset();
        break;
    default:
        return false;
    }
    invalidate();
    return true;
}

public void undoPath(){
    if (paths.size()>0) {
        undonePaths.add(paths.remove(paths.size()-1));
    } else {
        Log.d("Undo", "No paths left");
    }
    invalidate();
}

public void redoPath(){
    if (undonePaths.size()>0) {
        paths.add(undonePaths.remove(undonePaths.size()-1));
    } else {
        Log.d("Redo", "No paths left");
    }
    invalidate();
}


public void setColor(String newColor){
    //set color
    paintColor = Color.parseColor(newColor);
    drawPaint.setColor(paintColor);
    invalidate();
}

class PathPoints{
    private Path path;
    private int color;
    private float brushsize;
    private int x, y;

    //holds the paths data
    public PathPoints(Path path, int color, float brushsize) {
        this.path = path;
        this.color = color;
        this.brushsize = brushsize;
    }

    public Path getPath() {
        return path;
    }

    public void setPath(Path path) {
        this.path = path;
    }

    public float getBrush(){
        return brushsize;
    }

    public void setBrush(float brushsize){
        this.brushsize = brushsize;
    }

    public int getColor() {
        return color;
    }

    public void setColor(int color) {
        this.color = color;
    }

    public int getX() {
        return x;
    }

    public void setX(int x) {
        this.x = x;
    }

    public int getY() {
        return y;
    }

    public void setY(int y) {
        this.y = y;
    }

}

}

Android：FingerPaint橡皮擦功能

0 个答案: