Android的 - 触摸绘图 [英] Android - touch drawing

问题描述

我在看<一href="http://developer.android.com/resources/samples/ApiDemos/src/com/example/android/apis/graphics/TouchPaint.html"相对=nofollow>这个样本由谷歌绘图应用，当我运行在模拟器中的应用程序，并尝试绘制我的鼠标，图纸不顺利出现。该圆圈出现与他们之间的差距。只有当我拖我的鼠标慢慢地，我得到一个完整的线。我还没有实际的设备来测试这个，所以我想知道这是怎么会在实际设备上也，或这是一个模拟的行为呢？

I am looking at this sample drawing app by Google, and when I run the app in the simulator and try to draw with my mouse, the drawing does not appear smoothly. The circles are appearing with gaps between them. Only when I drag my mouse slowly I get a unbroken line. I don't yet have an actual device to test this on, so I want to know if this is how it will be on the actual device also, or is this a simulator behavior?

如果这是怎么会出现在设备上。此外，我应该怎么做才能让触摸绘图顺利？

If this is how it will appear on the device also, what should I do to make the touch drawing smooth?

更新：

实际的code，做图纸是：

The actual code that does the drawing is:

private void drawPoint(float x, float y, float pressure, float width) {
    if (width < 1) width = 6; 
    if (mBitmap != null) {
        float radius = width / 2;
        int pressureLevel = (int)(pressure * 255);
        mPaint.setARGB(pressureLevel, 255, 255, 255);
        mCanvas.drawCircle(x, y, radius, mPaint);
        mRect.set((int) (x - radius - 2), (int) (y - radius - 2),
                (int) (x + radius + 2), (int) (y + radius + 2));
        invalidate(mRect);
    }
}

@Override public boolean onTouchEvent(MotionEvent event) {         
    int N = event.getHistorySize();
    int P = event.getPointerCount();

    for (int i = 0; i < N; i++) {
        for (int j = 0; j < P; j++) {
            mCurX = event.getHistoricalX(j, i);
            mCurY = event.getHistoricalY(j, i);
            drawPoint(mCurX, mCurY,
                    event.getHistoricalPressure(j, i),
                    event.getHistoricalTouchMajor(j, i));
        }
    }
    for (int j = 0; j < P; j++) {
        mCurX = event.getX(j);
        mCurY = event.getY(j);
        drawPoint(mCurX, mCurY, event.getPressure(j), event.getTouchMajor(j));
    }           
}

任何帮助改善这将是极大的AP preciated。

Any help in improving it would be greatly appreciated.

推荐答案

这将是参差不齐的，但我相信，code为画点，所以如果你只画一条线，开始在那里的最后端被吸引到新的点，这将是连续的。

It will be jagged, but I believe that code is drawing points, so if you just draw a line, starting where the last end was drawn to the new point, it will be continuous.

是的，它会寻找同样的方式在实际设备上。

And yes, it will look the same way on an actual device.

另一种选择，而我是从内存在做，是有一些pressure值是0和255之间，或0和1，将其设置为最高值，所有的时间。这实际上可能是一个简单的解决你的问题。

The other option, which I am doing from memory, is there was some pressure value that was between 0 and 255, or 0 and 1, set it to the highest value, all the time. That may actually be a simple solution to your problem.

这将帮助，如果你表现出code，实际上是做图纸，顺便说一句。

It would help if you show the code that is actually doing the drawing, btw.

更新：

正如我所提到的变化这一行：

As I mentioned change this line:

int pressureLevel = (int)(pressure * 255);

到

int pressureLevel = (int)(255);

应该解决您的问题。

should fix your problem.

如果说没有的话，而不是使用画圆您可能希望只使用的drawLine ，那么你会跟踪你刚刚绘制的最后一个圆圈。

If that doesn't then rather than using drawCircle you may want to just use drawLine, then you would keep track of the last circle you had just drawn.

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