撤消和重做功能不使用以下代码。下面是我的绘图代码实现。
以下代码有问题吗?
public class DrawingArea extends View { private Path drawPath; private Paint drawPaint, canvasPaint; private int paintColor = 0xFF660000; private Canvas drawCanvas; private Bitmap canvasBitmap; private ArrayList paths = new ArrayList(); private ArrayList undonePaths = new ArrayList(); private float mX, mY; private static final float TOUCH_TOLERANCE = 4; // for Undo, Redo private int historyPointer = 0; private boolean erase = false; public DrawingArea(Context context) { super(context); setupDrawing(); } public DrawingArea(Context context, AttributeSet attrs) { super(context, attrs); setupDrawing(); } public void setupDrawing() { drawPath = new Path(); drawPaint = new Paint(); drawPaint.setAntiAlias(true); drawPaint.setStrokeWidth(20); drawPaint.setStyle(Paint.Style.STROKE); drawPaint.setStrokeJoin(Paint.Join.ROUND); drawPaint.setStrokeCap(Paint.Cap.ROUND); canvasPaint = new Paint(Paint.DITHER_FLAG); //paths.add(drawPath); } public void setColor(String newColor) { invalidate(); paintColor = Color.parseColor(newColor); drawPaint.setColor(paintColor); } @Override protected void onDraw(Canvas canvas) { super.onDraw(canvas); canvas.drawBitmap(canvasBitmap, 0, 0, canvasPaint); canvas.drawPath(drawPath, drawPaint); } @Override protected void onSizeChanged(int w, int h, int oldw, int oldh) { super.onSizeChanged(w, h, oldw, oldh); canvasBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888); drawCanvas = new Canvas(canvasBitmap); } @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; } private void touch_start(float x, float y) { drawPath.reset(); 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); // commit the path to our offscreen drawCanvas.drawPath(drawPath, drawPaint); // kill this so we don't double draw drawPath = new Path(); paths.add(drawPath); } public void setErase() { canvasBitmap.eraseColor(Color.TRANSPARENT); drawPath.reset(); invalidate(); } public void startNew() { drawCanvas.drawColor(0, PorterDuff.Mode.CLEAR); invalidate(); } public void undo() { if (paths.size() > 0) { undonePaths.add(paths.remove(paths.size() - 1)); invalidate(); } } public void redo() { if (undonePaths.size() > 0) { paths.add(undonePaths.remove(undonePaths.size() - 1)); invalidate(); } } }
答案 0 :(得分:1)
像这样
更改您的 OnDraw()protected void onDraw(Canvas canvas) {
super.onDraw(canvas);
canvas.drawBitmap(mBitmap, 0, 0, canvasPaint);
canvas.drawPath(mPath,drawPaint);
for (Path p : paths) {
canvas.drawPath(p, drawPaint);
}
}
并且不要忘记添加路径所持有的数据类型 arraylist
ArrayList<Path> paths = new ArrayList<Path>();