我想用自定义画笔和撤消/重做操作来实现一个画布绘图应用程序。首先，我的代码在不使用自定义画笔（包括撤消/重做操作）的情况下完美运行。根据这个答案How to make custom brush for canvas in android? 我使用简单的图像尖峰进行位图绘制。
现在的问题是，
撤消，重做操作不起作用，每当移动触摸点时，自定义画笔一遍又一遍地绘制。
问：如何使撤消/重做操作起作用？
定制的刷子炉子并不像他们应该的那样光滑。现在它们看起来很粗糙和做作。
Q. 如何使用自定义笔触使绘画流畅自然？
在这里查看我的示例代码，
public class DrawingView extends View {
private Context ctx;
private ArrayList<Path> paths = new ArrayList<Path>();
private ArrayList<Path> undonePaths = new ArrayList<Path>();
private Map<Path, Float> brushMap = new HashMap<Path, Float>();
private Map<Path, List<Vector2>> customBrushMap = new HashMap<Path, List<Vector2>>();
private Bitmap mBitmapBrush;
private Vector2 mBitmapBrushDimensions;
private List<Vector2> mPositions = new ArrayList<Vector2>(100);
private boolean isCustomBrush = false;
private int selectedColor;
private float brushSize, lastBrushSize;
private float mX, mY;
private static final float TOUCH_TOLERANCE = 4;
private Path drawPath;
private Paint drawPaint, canvasPaint;
private int paintColor = 0xFF660000, paintAlpha = 255;
private Canvas drawCanvas;
private Bitmap canvasBitmap;
private static final class Vector2 {
public Vector2(float x, float y) {
this.x = x;
this.y = y;
}
public final float x;
public final float y;
}
public DrawingView(Context context, AttributeSet attrs) {
super(context, attrs);
ctx = context;
setupDrawing();
}
private void setupDrawing() {
brushSize = getResources().getInteger(R.integer.small_size);
lastBrushSize = brushSize;
drawPath = new Path();
drawPaint = new Paint();
drawPaint.setColor(paintColor);
drawPaint.setAntiAlias(true);
drawPaint.setDither(true);
drawPaint.setStrokeWidth(brushSize);
drawPaint.setStyle(Paint.Style.STROKE);
drawPaint.setStrokeJoin(Paint.Join.ROUND);
drawPaint.setStrokeCap(Paint.Cap.ROUND);
canvasPaint = new Paint(Paint.DITHER_FLAG);
}
@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);
}
private void touch_start(float x, float y) {
undonePaths.clear();
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;
}
customBrushMap.put(drawPath, mPositions);
}
private void touch_up() {
drawPath.lineTo(mX, mY);
drawCanvas.drawPath(drawPath, drawPaint);
paths.add(drawPath);
brushMap.put(drawPath, brushSize);
drawPath = new Path();
drawPath.reset();
invalidate();
}
public void onClickUndo() {
if (paths.size() > 0) {
undonePaths.add(paths.remove(paths.size() - 1));
invalidate();
}
}
public void onClickRedo() {
if (undonePaths.size() > 0) {
paths.add(undonePaths.remove(undonePaths.size() - 1));
invalidate();
}
}
@Override
public boolean onTouchEvent(MotionEvent event) {
//detect user touch
float x = event.getX();
float y = event.getY();
switch (event.getAction() & MotionEvent.ACTION_MASK) {
case MotionEvent.ACTION_DOWN:
touch_start(x, y);
invalidate();
break;
case MotionEvent.ACTION_MOVE:
touch_move(x, y);
if (isCustomBrush) {
mPositions.add(new Vector2(x - mBitmapBrushDimensions.x / 2, y - mBitmapBrushDimensions.y / 2));
}
touch_move(x, y);
invalidate();
break;
case MotionEvent.ACTION_POINTER_DOWN:
invalidate();
break;
case MotionEvent.ACTION_UP:
touch_up();
invalidate();
break;
}
return true;
}
@Override
protected void onDraw(Canvas canvas) {
canvas.save();
for (Path p : paths) {
drawPaint.setColor(colorsMap.get(p));
drawPaint.setShader(shaderMap.get(p));
drawPaint.setStrokeWidth(brushMap.get(p));
drawPaint.setAlpha(opacityMap.get(p));
if (isCustomBrush) {
if (customBrushMap.get(p) != null) {
for (Vector2 pos : customBrushMap.get(p)) {
Paint paint = new Paint();
ColorFilter filter = new PorterDuffColorFilter(selectedColor, PorterDuff.Mode.SRC_IN);
paint.setColorFilter(filter);
canvas.drawBitmap(mBitmapBrush, pos.x, pos.y, paint);
}
}
} else {
canvas.drawPath(p, drawPaint);
drawPaint.setColor(selectedColor);
drawPaint.setStrokeWidth(brushSize);
canvas.drawPath(drawPath, drawPaint);
}
}
canvas.restore();
}
public void setCustomBrush(Activity activity, String customBrush) {
isCustomBrush = true;
invalidate();
int patternID = getResources().getIdentifier(customBrush, "drawable", "com.androidapp.drawingstutorial");
mBitmapBrush = BitmapFactory.decodeResource(getResources(), patternID);
mBitmapBrushDimensions = new Vector2(mBitmapBrush.getWidth(), mBitmapBrush.getHeight());
}
}