在android中滚动页面时,如何在画布上显示以前的路径?
我有一个pdf文件,我在迂回的画布上画了一条路径。当滚动pdf页面时,我尝试显示上一个画布。为此,我保存了pdf页码和路径 我的代码: 这是onTouch:在操作中,我每次都为路径创建新的构造函数。当它调用新路径时,是删除旧路径并覆盖旧路径。如果我删除此路径,则工作正常在android中滚动页面时,如何在画布上显示以前的路径?,android,canvas,path,scroll,draw,Android,Canvas,Path,Scroll,Draw,我有一个pdf文件,我在迂回的画布上画了一条路径。当滚动pdf页面时,我尝试显示上一个画布。为此,我保存了pdf页码和路径 我的代码: 这是onTouch:在操作中,我每次都为路径创建新的构造函数。当它调用新路径时,是删除旧路径并覆盖旧路径。如果我删除此路径,则工作正常 switch (event.getAction()) { case MotionEvent.ACTION_DOWN: signaturePaint = new Paint(Paint.DITHER_FL
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
signaturePaint = new Paint(Paint.DITHER_FLAG);
signaturePaint.setAntiAlias(true);
signaturePaint.setDither(true);
signaturePaint.setColor(0xff0000cc);
signaturePaint.setStyle(Paint.Style.STROKE);
signaturePaint.setStrokeJoin(Paint.Join.ROUND);
signaturePaint.setStrokeCap(Paint.Cap.ROUND);
signaturePaint.setStrokeWidth(1);
**signaturePath = new Path();// When calling this my problem occure**
if (Constants.draw) {
Point p = getPagePositionOnScreen(currentPage);
int currentPageWidth = getCurrentPageWidth(currentPage);
int currentPageHeight = (int) getCurrentPageHeight(currentPage);
if (currentPageWidth < x || currentPageHeight < y) {
} else {
if (Constants.isSignatureSelected)
signaturePath.moveTo(x, y);
// pdfcanvas.moveTo(x, y);
}
firstX = x;
firstY = y;
}
break;
case MotionEvent.ACTION_MOVE:
if (Constants.draw) {
mPageNumber.add(currentPage);
// int[][] currentPagesSize = pagesProvider.getPageSizes();
float pageMarginX = getCurrentMarginX();
float pageMarginy = getCurrentMarginY();
// int pageWidth = currentPagesSize[0][0];
// int pageHeight = currentPagesSize[0][1];
int currentPageWidth = getCurrentPageWidth(currentPage);
int currentPageHeight = (int) getCurrentPageHeight(currentPage);
if (currentPageWidth < x || currentPageHeight < y) {
} else {
resetDirtyRect(x, y);
int historySize = event.getHistorySize();
for (int i = 0; i < historySize; i++) {
float historicalX = event.getHistoricalX(i);
float historicalY = event.getHistoricalY(i);
expandDirtyRect(historicalX, historicalY);
if (Constants.isSignatureSelected)
signaturePath.lineTo(historicalX, historicalY);
}
}
}
break;
case MotionEvent.ACTION_UP:
if (Constants.draw) {
firstX = x;
firstY = y;
if (Constants.isSignatureSelected)
saveCanvas();
}
break;
}
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));
firstX = x;
firstY = y;
return true;
用于在画布上显示路径:在else块中的此方法中,我正在重置路径。调用此画布时,我没有绘制路径。但在调试时,我的路径不为null。但它没有在画布上显示路径
private void redoCanvas() {
if (mCanvasHashMap.containsKey(currentPage)) {
mDrawingPath.clear();
mPageNumber.clear();
for (int j = 0; j < mSavingCanvasDrawing.size(); j++) {
int pageNumber = mSavingCanvasDrawing.get(j).getPdfPageNumber();
if (pageNumber == currentPage) {
float xAxis = mSavingCanvasDrawing.get(j).getxAxis();
float yAxis = mSavingCanvasDrawing.get(j).getyAxis();
Path path = mSavingCanvasDrawing.get(j).getPath();
mDrawingPath.add(path);
mPageNumber.add(pageNumber);
} else {
signaturePath.reset();
invalidate();
}
}
} else {
signaturePath.reset();
invalidate();
}
}
是的,我得到了解决方案。在computeScroll()中,我创建了新的路径构造函数,在onDraw()中,我检查了路径数组列表,并将路径添加到画布中是的,我得到了解决方案。在computeScroll()中,我创建了新的路径构造函数,在onDraw()中,我检查了路径数组列表,并将路径添加到画布中。
private void redoCanvas() {
if (mCanvasHashMap.containsKey(currentPage)) {
mDrawingPath.clear();
mPageNumber.clear();
for (int j = 0; j < mSavingCanvasDrawing.size(); j++) {
int pageNumber = mSavingCanvasDrawing.get(j).getPdfPageNumber();
if (pageNumber == currentPage) {
float xAxis = mSavingCanvasDrawing.get(j).getxAxis();
float yAxis = mSavingCanvasDrawing.get(j).getyAxis();
Path path = mSavingCanvasDrawing.get(j).getPath();
mDrawingPath.add(path);
mPageNumber.add(pageNumber);
} else {
signaturePath.reset();
invalidate();
}
}
} else {
signaturePath.reset();
invalidate();
}
}
if (Constants.isSignatureSelected) {
if (Constants.draw) {
canvas.drawPath(signaturePath, signaturePaint);
}
} else {
if (mPageNumber.contains(currentPage)) {
for (Path p : mDrawingPath) {
canvas.drawPath(p, signaturePaint);
}
}
}
}