我想在我的绘图应用程序中执行撤消/重做操作，但它仍然无法正常工作。
我知道关于这个话题有很多线索，但我尝试了很多。所以请不要将此主题标记为重复。
以下是执行绘图的代码：
public class Drawing extends View {
private Path mPath;
private static Canvas canvas;
public static Paint mPaint;
private static Paint mBitmapPaint;
public static Bitmap mBitmap;
private BlurMaskFilter mBlur;
private MaskFilter mEmboss;
public static String drawKreis;
public static int radius;
public static String kreisFarbe;
public static String hintergrundFarbe;
private int paintColor = 0xFF660000;
private float mX, mY;
private static final float TOUCH_TOLERANCE = 4;
public static String strichFarbeHex;
public static int stroke = 12;
/*
* ArrayList<Pair<Path, Paint>> paths = new ArrayList<Pair<Path, Paint>>();
*
* ArrayList<Pair<Path, Paint>> undonePaths = new ArrayList<Pair<Path, Paint>>();
*
* // ArrayList<Pair<Rect, Paint>> rectPaths = new ArrayList<Pair<Rect, Paint>>();
*/
public ArrayList<Path> paths = new ArrayList<Path>();
public ArrayList<Paint> paints = new ArrayList<Paint>();
public ArrayList<Path> undonePaths = new ArrayList<Path>();
public ArrayList<Paint> undonePaints = new ArrayList<Paint>();
// private Map<Path, Integer> colorsMap = new HashMap<Path, Integer>();
public Drawing(final Context context, AttributeSet attrs) {
super(context, attrs);
mPaint = new Paint();
mPaint.setAntiAlias(true);
mPaint.setDither(true);
mPaint.setStrokeWidth(stroke);
mPaint.setStyle(Paint.Style.STROKE);
mPaint.setColor(paintColor);
mPath = new Path();
mPaint.setXfermode(null);
mBitmapPaint = new Paint(Paint.DITHER_FLAG);
// paths.add(new Pair<Path, Paint>(mPath, mPaint));
this.setDrawingCacheEnabled(true);
mEmboss = new EmbossMaskFilter(new float[] { 1, 1, 1 }, 0.4f, 6, 3.5f);
mBlur = new BlurMaskFilter(8, BlurMaskFilter.Blur.NORMAL);
this.setOnTouchListener(new OnTouchListener() {
public boolean onTouch(View v, MotionEvent event) {
float x = event.getX();
float y = event.getY();
Log.d("onTouch", "onTouch");
Log.d("x", String.valueOf(x));
Log.d("y", String.valueOf(y));
switch (event.getAction()) {
case MotionEvent.ACTION_DOWN:
Log.d("a", "down");
Log.d("hier", "hier1");
touch_start(x, y, context);
invalidate();
break;
case MotionEvent.ACTION_MOVE:
Log.d("onTouch", "onTouch2");
touch_move(x, y);
invalidate();
break;
case MotionEvent.ACTION_UP:
Log.d("onTouch", "onTouch3");
touch_up();
invalidate();
break;
}
return true;
}
});
}
// mBlur = new BlurMaskFilter(8, BlurMaskFilter.Blur.NORMAL);
private void touch_start(float x, float y, Context context) {
undonePaths.clear();
mPath.reset();
mPath.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) {
mPath.quadTo(mX, mY, (x + mX) / 2, (y + mY) / 2);
mX = x;
mY = y;
}
}
private void touch_up() {
mPath.lineTo(mX, mY);
// commit the path to our offscreen
canvas.drawPath(mPath, mPaint);
paths.add(mPath);
mPath = new Path();
}
public static int getStroke() {
return stroke;
}
@Override
public void onDraw(Canvas c) {
int strichdicke = OpenProject.getStrichdicke();
int durchsichtigkeitswert = OpenProject.getDurchsichtigkeit() * 255 / 100;
Log.d("strichdicke", "strichdicke " + strichdicke);
for (/* Pair<Path, Paint> p */Path p : paths) {
if (strichdicke == 0) {
mPaint.setStrokeWidth(stroke);
} else {
mPaint.setStrokeWidth(strichdicke);
}
mPaint.setAlpha(durchsichtigkeitswert);
c.drawPath(p, mPaint);
}
c.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
c.drawPath(mPath, mPaint);
}
@Override
protected void onSizeChanged(int w, int h, int oldw, int oldh) {
super.onSizeChanged(w, h, oldw, oldh);
mBitmap = Bitmap.createBitmap(w, h, Bitmap.Config.ARGB_8888);
canvas = new Canvas(mBitmap);
if (hintergrundFarbe != null) {
mBitmap.eraseColor(Color.parseColor(hintergrundFarbe));
} else {
mBitmap.eraseColor(Color.WHITE);
}
}
@Override
public boolean onKeyDown(int keyCode, KeyEvent event) {
// wenn die Zurücktaste das erste Mal gedrückt wurde
if (keyCode == KeyEvent.KEYCODE_BACK) {
}
return true;
}
public void onClickUndo() {
Log.d("onClickUndo5", "onClickUndo5 " + paths.size());
if (paths.size() > 0) {
Log.d("onClickUndo", "onClickUndo " + paths.size());
undonePaths.add(this.paths.remove(this.paths.size() - 1));
clearCanvasCache();
this.invalidate();
Log.d("onClickUndo1", "onClickUndo1 " + paths.size());
} else {
}
}
public static String setStrichFarbe(String strichFarbe) {
strichFarbeHex = strichFarbe;
Log.d("strichFarbeHex", "strichFarbeHex " + strichFarbeHex);
return strichFarbeHex;
}
// update color
public void setColor(String newColor) {
Log.d("setColor", "setColor " + newColor);
invalidate();
paintColor = Color.parseColor(newColor);
Log.d("paintColor", "paintColor " + paintColor);
mPaint.setColor(paintColor);
int color = mPaint.getColor();
Log.d("color", "color " + color);
}
public void drawKreis(Drawing drawing) {
invalidate();
drawing.canvas.drawBitmap(mBitmap, 0, 0, mBitmapPaint);
drawing.canvas.drawCircle(30, 30, 5, mPaint);
invalidate();
Log.d("drawKreis", "drawKreis " + canvas + "|" + mPaint.getColor());
}
public static void erase() {
// mBitmapPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
mBitmap.eraseColor(Color.TRANSPARENT);
canvas = new Canvas(mBitmap);
}
public static void startErasing() {
mPaint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.CLEAR));
}
public String getStrichFarbe() {
return strichFarbeHex;
}
public void clearCanvasCache() {
mBitmap = Bitmap.createBitmap((int) 400, (int) 400, Bitmap.Config.ARGB_8888);
canvas = new Canvas(mBitmap);
}
}
非常感谢您的帮助