Android FingerPaint示例不会绘制点?

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示例 android api demo中的Fingerpaint示例不会通过触摸屏幕上的手指来绘制点/点.在代码中他们使用Path来绘制线条,有没有办法用路径绘制圆圈或点?
public class MyView extends View {
    // int bh = originalBitmap.getHeight();
    // int bw = originalBitmap.getWidth();

    public MyView(Context c,int w,int h) {
        super(c);
        mBitmap = Bitmap.createBitmap(w,h,Bitmap.Config.ARGB_8888);
        // Bitmap mBitmap =
        // Bitmap.createScaledBitmap(originalBitmap,200,true);
        mCanvas = new Canvas(mBitmap);
        mPath = new Path();
        mBitmapPaint = new Paint(Paint.DITHER_FLAG);
        //mBitmapPaint.setColor(Color.YELLOW);
        //mBitmapPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.SRC));
    }

    @Override
    protected void onSizeChanged(int w,int h,int oldw,int oldh) {
        super.onSizeChanged(w,oldw,oldh);
        // mBitmap = Bitmap.createBitmap(bw,bh,Bitmap.Config.ARGB_8888);
        // mCanvas = new Canvas(mBitmap);
    }


    @Override
    protected void onDraw(Canvas canvas) {
        //canvas.drawColor(customColor);
        canvas.drawBitmap(mBitmap,mBitmapPaint);
        canvas.drawPath(mPath,mPaint);
    }

    // //////************touching evants for painting**************///////
    private float mX,mY;
    private static final float TOUCH_TOLERANCE = 5;

    private void touch_start(float x,float y) {
        //mCanvas.drawCircle(x,y,progress+1,mPaint); 

        mPath.reset();          
        mPath.moveTo(x,y);
        //mPaint.setStyle(Paint.Style.FILL);
        //mPath.addCircle(x,(float) (progress+0.15),Direction.CW);  
        mCanvas.drawPath(mPath,mPaint);
        mX = x;
        mY = y;
        //mPaint.setStyle(Paint.Style.STROKE);

    }

    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;
    } // end of touch events for image
}

这是代码,我应该在这段代码中编辑什么才能在finertouch上绘制点/点?

解决方法

is there any way to draw circle or point using path?

而不是尝试这样做使用类Canvas中的方法drawPoint(float x,float y,Paint paint).

要在API演示中使用它,您需要更改3件事:

>有一个私有布尔mDrawPoint;在MyView类中区分点击和幻灯片.
>如果路径已更改(即在if语句中),则在touch_start()中将mDrawPoint设置为true,在touch_move()中将mDrawPoint设置为false.
>在touch_up()中检查mDrawPoint的值.如果它是假的,那么该函数之前做了什么,如果它是真的,那么在画布上绘制点:
mCanvas.drawPoint(mX,mPaint);

新版touch_up():

private void touch_up() {
    if(mDrawPoint == true) {
        mCanvas.drawPoint(mX,mPaint);          
    } else {
        mPath.lineTo(mX,mPaint);
        // kill this so we don't double draw
        mPath.reset();
    }
}

when i move up my finger after drawing a line it automatically draws a point next to it,where the line ended. And when i starts a new line/curve the prevIoUsly drawn line would remove /clear from the canvas leaving only dots behind that were drawn.

您不需要比我的答案更多的修改.你可能忘了实现它的一部分.

我在尝试它时遇到了同样的问题并在发布我的答案之前解决了它.这是因为你在两个不同的画布上绘制,在onDraw方法上,当你的手指起来时它会丢失而另一个是mCanvas,这是在touch_up中保存行的地方.这就是为什么touch_up有一个if:

如果我们没有移动手指(只是点击),那么我们将点绘制到mCanvas,以便它仍然存在于下一个onDraw上(onDraw将mCanvas绘制到它作为参数接收的画布上,以便绘制旧的线条和点mCanvas仍然可见).

如果我们移动了手指,那么我们将传递给onDraw的画布所绘制的路径保存到mCanvas,以便在获得手指后它仍然存在.

您遇到的问题来自touch_up函数的else部分永远不会被执行,因此在touch_up上无论是否应该绘制一个点,并且路径永远不会被提交到mCanvas,因此下次onDraw被调用时会消失.

这很可能源于你在touch_start()中将mDrawPoint设置为true,正如我在第2点中所说的那样.但忘记在touch_move中将mDrawPoint设置为false,正如我在第2点中所说的那样.

这是我的touch_move的样子:

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,(x + mX)/2,(y + mY)/2);
        mX = x;
        mY = y;
        mDrawPoint = false;
        }
    }
原文链接:https://www.f2er.com/android/309930.html

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