ANDROID-在画布中撤消和重做
我正在位图上画一个圆圈（触摸），以擦除圆圈中该区域的覆盖位图。如何为此添加撤消和重做功能 编辑：请参考，因为它有我目前面临的问题与给定的解决方案ANDROID-在画布中撤消和重做,android,canvas,bitmap,undo-redo,Android,Canvas,Bitmap,Undo Redo,我正在位图上画一个圆圈（触摸），以擦除圆圈中该区域的覆盖位图。如何为此添加撤消和重做功能 编辑：请参考，因为它有我目前面临的问题与给定的解决方案 @Override protected void onDraw(Canvas canvas) { pcanvas.drawCircle(x, y, 10, mPaint); canvas.drawBitmap(bitmap, 0, 0, null); super.onDraw(canvas);
@Override
protected void onDraw(Canvas canvas) {
pcanvas.drawCircle(x, y, 10, mPaint);
canvas.drawBitmap(bitmap, 0, 0, null);
super.onDraw(canvas);
}
public boolean onTouchEvent(MotionEvent ev)
{
switch (ev.getAction())
{
case MotionEvent.ACTION_DOWN:
{
x = (int) ev.getX();
y = (int) ev.getY();
invalidate();
break;
}
case MotionEvent.ACTION_MOVE:
{
x = (int) ev.getX();
y = (int) ev.getY();
invalidate();
break;
}
case MotionEvent.ACTION_UP:
invalidate();
break;
}
return true;
}
如注释中所述，可以保留堆栈以跟踪xy坐标历史 撤消和重做操作围绕着从单独的堆栈中推送和弹出 帆布 截图 撤销前 撤销后
您可能可以保留一个
堆栈来跟踪xy坐标历史记录。然后要撤消，只需弹出一个。类似的事情也可以用于重做，只要记住在触摸向撤消堆栈添加一个新的对时清除重做堆栈。最好将堆栈中保留的xy对数量限制在50对左右。@Kevin你能帮我编写一些代码吗？这些代码不会还原我单击“撤消”时删除的位图部分。你能再次查看问题以查看刚才添加的mPaint和pcanvas的详细信息并建议我哪里出错了吗？这不是在原来的帖子里。可以保留原始位图并在应用遮罩之前再次绘制。或者，为了提高性能，只绘制受影响的区域（现在将在redoStack中）。你好，kevin，擦除后我无法恢复位图，并且在问题中添加了一个链接，解释了您提供的解决方案的问题。如果你能帮忙，那就太好了。@zek54嗨，Zek，我创建了一个视图，可以解决你的问题。我为我所做的更改添加了一个简短的解释。非常感谢，凯文。
public class UndoCanvas extends View {
private final int MAX_STACK_SIZE = 50;
private Stack<Pair<Float, Float>> undoStack = new Stack<>();
private Stack<Pair<Float, Float>> redoStack = new Stack<>();
private Bitmap originalBitmap;
private Bitmap maskedBitmap;
private Canvas originalCanvas;
private Canvas maskedCanvas;
private Paint paint;
private float drawRadius;
private StackListener listener;
public UndoCanvas(Context context) {
super(context);
init();
}
public UndoCanvas(Context context, AttributeSet attrs) {
super(context, attrs);
init();
}
public UndoCanvas(Context context, AttributeSet attrs, int defStyleAttr) {
super(context, attrs, defStyleAttr);
init();
}
private void init() {
drawRadius = TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_DIP, 5, getResources().getDisplayMetrics());
paint = new Paint();
// paint.setColor(Color.RED);
paint.setAlpha(0);
paint.setXfermode(new PorterDuffXfermode(PorterDuff.Mode.DST_IN));
paint.setAntiAlias(true);
paint.setMaskFilter(new BlurMaskFilter(15, BlurMaskFilter.Blur.SOLID));
}
public void setBitmap(Bitmap bitmap) {
if (bitmap != null) {
originalBitmap = bitmap.copy(bitmap.getConfig(), true); // Copy of the original, because we will potentially make changes to this
maskedBitmap = originalBitmap.copy(originalBitmap.getConfig(), true);
originalCanvas = new Canvas(originalBitmap);
maskedCanvas = new Canvas(maskedBitmap);
} else {
originalBitmap = null;
originalCanvas = null;
maskedBitmap = null;
maskedCanvas = null;
}
int undoSize = undoStack.size();
int redoSize = redoStack.size();
undoStack.clear();
redoStack.clear();
invalidate();
if (listener != null) {
if (undoSize != undoStack.size()) {
listener.onUndoStackChanged(undoSize, undoStack.size());
}
if (redoSize != redoStack.size()) {
listener.onRedoStackChanged(redoSize, redoStack.size());
}
}
}
public StackListener getListener() {
return listener;
}
public void setListener(StackListener listener) {
this.listener = listener;
}
public boolean onTouchEvent(MotionEvent ev) {
switch (ev.getAction()) {
case MotionEvent.ACTION_DOWN: {
int undoSize = undoStack.size();
int redoSize = redoStack.size();
// Max stack size. Remove oldest item before adding new
if (undoStack.size() == MAX_STACK_SIZE) {
// The undo history does not go further back, so make the change permanent by updating the original canvas/bitmap
Pair<Float, Float> pair = undoStack.remove(0);
maskPoint(originalCanvas, pair.first, pair.second);
}
undoStack.push(new Pair<>(ev.getX(), ev.getY()));
redoStack.clear();
invalidate();
if (listener != null) {
if (undoSize != undoStack.size()) {
listener.onUndoStackChanged(undoSize, undoStack.size());
}
if (redoSize != redoStack.size()) {
listener.onRedoStackChanged(redoSize, redoStack.size());
}
}
break;
}
case MotionEvent.ACTION_MOVE: {
int undoSize = undoStack.size();
int redoSize = redoStack.size();
// Max stack size. Remove oldest item before adding new
if (undoStack.size() == MAX_STACK_SIZE) {
// The undo history does not go further back, so make the change permanent by updating the original canvas/bitmap
Pair<Float, Float> pair = undoStack.remove(0);
maskPoint(originalCanvas, pair.first, pair.second);
}
maskPoint(maskedCanvas, ev.getX(), ev.getY());
undoStack.push(new Pair<>(ev.getX(), ev.getY()));
redoStack.clear();
invalidate();
if (listener != null) {
if (undoSize != undoStack.size()) {
listener.onUndoStackChanged(undoSize, undoStack.size());
}
if (redoSize != redoStack.size()) {
listener.onRedoStackChanged(redoSize, redoStack.size());
}
}
break;
}
case MotionEvent.ACTION_UP:
invalidate();
break;
}
return true;
}
@Override
protected void onDraw(Canvas canvas) {
if (maskedBitmap != null) {
canvas.drawBitmap(maskedBitmap, 0, 0, null);
}
super.onDraw(canvas);
}
public boolean undo() {
if (!undoStack.empty()) {
int undoSize = undoStack.size();
int redoSize = redoStack.size();
Pair<Float, Float> pair = undoStack.pop();
// Redraw a single part of the original bitmap
//unmaskPoint(maskedCanvas, pair.first, pair.second);
// Redraw the original bitmap, along with all the points in the undo stack
remaskCanvas(maskedCanvas);
redoStack.push(pair); // Do not need to check for > 50 here, since redoStack can only contain what was in undoStack
invalidate();
if (listener != null) {
if (undoSize != undoStack.size()) {
listener.onUndoStackChanged(undoSize, undoStack.size());
}
if (redoSize != redoStack.size()) {
listener.onRedoStackChanged(redoSize, redoStack.size());
}
}
return true;
}
return false;
}
public boolean redo() {
if (!redoStack.empty()) {
int undoSize = undoStack.size();
int redoSize = redoStack.size();
Pair<Float, Float> pair = redoStack.pop();
maskPoint(maskedCanvas, pair.first, pair.second);
undoStack.push(pair); // Do not need to check for > 50 here, since redoStack can only contain what was in undoStack
invalidate();
if (listener != null) {
if (undoSize != undoStack.size()) {
listener.onUndoStackChanged(undoSize, undoStack.size());
}
if (redoSize != redoStack.size()) {
listener.onRedoStackChanged(redoSize, redoStack.size());
}
}
return true;
}
return false;
}
private void maskPoint(Canvas canvas, float x, float y) {
if (canvas != null) {
canvas.drawCircle(x, y, drawRadius, paint);
}
}
private void unmaskPoint(Canvas canvas, float x, float y) {
if (canvas != null) {
Path path = new Path();
path.addCircle(x, y, drawRadius, Path.Direction.CW);
canvas.save();
canvas.clipPath(path);
canvas.drawBitmap(originalBitmap, 0, 0, new Paint());
canvas.restore();
}
}
private void remaskCanvas(Canvas canvas) {
if (canvas != null) {
canvas.drawBitmap(originalBitmap, 0, 0, new Paint());
for (int i = 0; i < undoStack.size(); i++) {
Pair<Float, Float> pair = undoStack.get(i);
maskPoint(canvas, pair.first, pair.second);
}
}
}
public interface StackListener {
void onUndoStackChanged(int previousSize, int newSize);
void onRedoStackChanged(int previousSize, int newSize);
}
}
public class MainActivity extends AppCompatActivity {
@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
final UndoCanvas canvas = (UndoCanvas) findViewById(R.id.undoCanvas);
final Button undoButton = (Button) findViewById(R.id.buttonUndo);
final Button redoButton = (Button) findViewById(R.id.buttonRedo);
undoButton.setEnabled(false);
redoButton.setEnabled(false);
canvas.setListener(new UndoCanvas.StackListener() {
@Override
public void onUndoStackChanged(int previousSize, int newSize) {
undoButton.setEnabled(newSize > 0);
}
@Override
public void onRedoStackChanged(int previousSize, int newSize) {
redoButton.setEnabled(newSize > 0);
}
});
undoButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
canvas.undo();
}
});
redoButton.setOnClickListener(new View.OnClickListener() {
@Override
public void onClick(View v) {
canvas.redo();
}
});
canvas.setBitmap(BitmapFactory.decodeResource(getResources(), R.drawable.image));
}
}