我的代码基本上来自这个示例（http://corner.squareup.com/2010/07/smooth-signatures.html）和Google API（FingerPaint），但现在我想使用类VelocityTracker来根据我的手指速度更改笔画宽度。
我以为我可以将路径分成更小的部分，但我没有找到任何例子。还有第二篇文章（http://corner.squareup.com/2012/07/smoother-signatures.html），但我没有特定的贝塞尔曲线类，也没有收集ArrayList中的所有点，所以他们调整笔画宽度的例子不是很有用。
有谁知道如何处理这个问题？两个星期前我开始学习代码，所以我对这些东西都很新。
编辑：我试图实现MotionEvents的速度，我使用LogCat来跟踪运行应用程序时的当前速度。它确实有效，但当我尝试使用速度作为mPaint.setStrokeWidth参数的一部分时，我没有得到我真正想要的东西。我从画布上绘制的路径的宽度从我开始绘制线条的那一刻起一直在变化，直到我将手指向上移动。所以这就是为什么我想把路径分成更小的部分，因为现在只有最后一个跟踪的速度会影响strokeWidth。
public class SignatureView extends View {
private static final String TAG = SignatureView.class.getSimpleName();
private static final float STROKE_WIDTH = 10;
private static final float HALF_STROKE_WIDTH = STROKE_WIDTH / 2;
private final double TOUCH_TOLERANCE = 5;
private int h = getResources().getDisplayMetrics().heightPixels;
private int w = getResources().getDisplayMetrics().widthPixels;
private Path mPath = new Path();
private Paint mPaint = new Paint();
private Paint mBitmapPaint = new Paint(Paint.DITHER_FLAG);
private Bitmap mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
private Canvas mCanvas = new Canvas(mBitmap);
private float mX, mY;
private float lastTouchX, lastTouchY;
private final RectF dirtyRect = new RectF();
public SignatureView(Context context, AttributeSet attrs) {
super(context, attrs);
mPaint.setAntiAlias(true);
mPaint.setColor(Color.BLACK);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setStrokeJoin(Paint.Join.ROUND);
mPaint.setStrokeWidth(INITIAL_STROKE_WIDTH);
Log.d(TAG, "TOUCH_TOLERANCE = " +TOUCH_TOLERANCE);
}
@Override
protected void onDraw(Canvas canvas) {
canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
canvas.drawPath(mPath, mPaint);
}
@Override
public boolean onTouchEvent(MotionEvent event) {
float eventX = event.getX();
float eventY = event.getY();
int historySize = event.getHistorySize();
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
resetDirtyRect(eventX, eventY);
mPath.reset();
mPath.moveTo(eventX, eventY);
mX = eventX;
mY = eventY;
break;
case MotionEvent.ACTION_MOVE:
float dx = Math.abs(eventX - mX);
float dy = Math.abs(eventY - mY);
if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
mPath.quadTo(mX, mY, (eventX + mX)/2, (eventY + mY)/2);
mX = eventX;
mY = eventY;
}
for (int i = 0; i < historySize; i++) {
float historicalX = event.getHistoricalX(i);
float historicalY = event.getHistoricalY(i);
expandDirtyRect(historicalX, historicalY);
}
break;
case MotionEvent.ACTION_UP:
for (int i = 0; i < historySize; i++) {
float historicalX = event.getHistoricalX(i);
float historicalY = event.getHistoricalY(i);
expandDirtyRect(historicalX, historicalY);
}
mPath.lineTo(mX, mY);
mCanvas.drawPath(mPath, mPaint);
mPath.reset();
break;
default:
Log.d(TAG, "Ignored touch event: " + event.toString());
return false;
}
// Include half the stroke width to avoid clipping.
invalidate( (int) (dirtyRect.left - HALF_STROKE_WIDTH),
(int) (dirtyRect.top - HALF_STROKE_WIDTH),
(int) (dirtyRect.right + HALF_STROKE_WIDTH),
(int) (dirtyRect.bottom + HALF_STROKE_WIDTH));
lastTouchX = eventX;
lastTouchY = eventY;
return true;
}
private void expandDirtyRect(float historicalX, float historicalY) {
if (historicalX < dirtyRect.left) {
dirtyRect.left = historicalX;
} else if (historicalX > dirtyRect.right) {
dirtyRect.right = historicalX;
}
if (historicalY < dirtyRect.top) {
dirtyRect.top = historicalY;
} else if (historicalY > dirtyRect.bottom) {
dirtyRect.bottom = historicalY;
}
}
private void resetDirtyRect(float eventX, float eventY) {
dirtyRect.left = Math.min(lastTouchX, eventX);
dirtyRect.right = Math.max(lastTouchX, eventX);
dirtyRect.top = Math.min(lastTouchY, eventY);
dirtyRect.bottom = Math.max(lastTouchY, eventY);
}
}
答案 0 :(得分：2)
每次笔触值根据速度变化时，您都可以使用分割路径对象。在你SignatureView课程中添加
private Path mPath = new Path();
ArrayList<Path> mPaths = new ArrayList<Path>();
并使用另一个ArrayList来保存每个路径的笔画值
ArrayList<int> strokes = new ArrayList<int>();
添加变量lastStroke以及lastTouchX和lastTouchY。我建议您制作lastStroke类型的int。
private int lastStroke = -1; //give an initial value
现在你的onTouchEvent方法应该是这样的
@Override
public boolean onTouchEvent(MotionEvent event) {
float eventX = event.getX();
float eventY = event.getY();
int historySize = event.getHistorySize();
int eventStroke= //calculate stroke size with velocity and make it between 1-10 or any range you seem fit
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
resetDirtyRect(eventX, eventY);
mPath.reset();
mPath.moveTo(eventX, eventY);
mX = eventX;
mY = eventY;
break;
case MotionEvent.ACTION_MOVE:
float dx = Math.abs(eventX - mX);
float dy = Math.abs(eventY - mY);
if (dx >= TOUCH_TOLERANCE || dy >= TOUCH_TOLERANCE) {
if(lastStroke != evetnStroke){
mPath = new Path();
mPath.moveTo(mX,mY);
mPaths.Add(mPath);
mStrokes.Add(eventStroke);
}
mPath.quadTo(mX, mY, (eventX + mX)/2, (eventY + mY)/2);
mX = eventX;
mY = eventY;
}
for (int i = 0; i < historySize; i++) {
float historicalX = event.getHistoricalX(i);
float historicalY = event.getHistoricalY(i);
expandDirtyRect(historicalX, historicalY);
}
break;
case MotionEvent.ACTION_UP:
for (int i = 0; i < historySize; i++) {
float historicalX = event.getHistoricalX(i);
float historicalY = event.getHistoricalY(i);
expandDirtyRect(historicalX, historicalY);
}
mPath.lineTo(mX, mY);
break;
default:
Log.d(TAG, "Ignored touch event: " + event.toString());
return false;
}
// Include half the stroke width to avoid clipping.
invalidate( (int) (dirtyRect.left - HALF_STROKE_WIDTH),
(int) (dirtyRect.top - HALF_STROKE_WIDTH),
(int) (dirtyRect.right + HALF_STROKE_WIDTH),
(int) (dirtyRect.bottom + HALF_STROKE_WIDTH));
lastTouchX = eventX;
lastTouchY = eventY;
lastStroke = eventStroke;
return true;
}
你的退出方法是
@Override
protected void onDraw(Canvas canvas) {
for(int i=0; i<mPaths.size();i++){
mPaint.setStrokeWidth(strokes.get(i));
canvas.drawPath(mPaths.get(i), mPaint);
}
}
这是基本的想法。你需要修改它才能使它工作。