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POAndroid custom/compound control: Parcelable state is shared and it shouldn't?
 

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  1. POAndroid custom/compound control: Parcelable state is shared and it shouldn't?
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    <p>I have created a custom View / Compound Control in my Android application, which lets users "draw" their signature.</p> <p>The signature is contained in a Canvas, linked to a Bitmap object.</p> <p>I want the signature "image" to be preserved when the orientation is changed. Therefore, I have implemented onSaveInstanceState / onRestoreInstanceState by storing the Bitmap's pixels:</p> <pre><code>@Override public Parcelable onSaveInstanceState() { // Call superclass method, retrieve Parcelable Parcelable superState = super.onSaveInstanceState(); if (pictureBitmap_ != null) { // Retrieve the current pixels array. int totalSize = pictureBitmap_.getWidth() * pictureBitmap_.getHeight(); int pixels[] = new int[totalSize]; pictureBitmap_.getPixels(pixels, 0, pictureBitmap_.getWidth(), 0, 0, pictureBitmap_.getWidth(), pictureBitmap_.getHeight()); // Create the saved state object. SavedState savedState = new SavedState(superState); savedState.pixels = pixels; // Return the populated saved state object. return savedState; } else { // Simply pass original Parcelable along return superState; } } @Override public void onRestoreInstanceState(Parcelable state) { // Is the Parcelable an instance of our custom SavedState? if (!(state instanceof SavedState)) { // No, simply delegate to superclass. super.onRestoreInstanceState(state); return; } // Retrieve custom state object. SavedState savedState = (SavedState) state; // Use superclass to restore original state. super.onRestoreInstanceState(savedState.getSuperState()); // Restore custom state (transfer pixels). this.transferPixels_ = savedState.pixels; // If the picture bitmap is already initialized... if (pictureBitmap_ != null) { // Transfer the pixels right away. transferBitmap(); // Refresh the canvas drawSignature(); } } </code></pre> <p>The integer array of pixels is stored in a SavedState object, which is a custom subclass of BaseSavedState:</p> <pre><code>private static class SavedState extends BaseSavedState { // Members int[] pixels; // Methods SavedState(Parcelable superState) { super(superState); } private SavedState(Parcel in) { super(in); in.readIntArray(pixels); } @Override public void writeToParcel(Parcel out, int flags) { super.writeToParcel(out, flags); out.writeIntArray(pixels); } // required field that makes Parcelables from a Parcel @SuppressWarnings("unused") public static final Parcelable.Creator&lt;SavedState&gt; CREATOR = new Parcelable.Creator&lt;SavedState&gt;() { public SavedState createFromParcel(Parcel in) { return new SavedState(in); } public SavedState[] newArray(int size) { return new SavedState[size]; } }; } </code></pre> <p>Now, while this is working well if I only have ONE (1) instance of my custom view in my activity... a problem occurs if I have TWO (2) or more instances: when I flip the orientation, all my controls end up displaying the same signature, which was the last control's signature.</p> <p>In other words, the last set of pixels stored in a SavedState object appears to become the "universal" set of pixels for all my control instances within my Activity.</p> <p>How do I ensure that each control has its own independent saved state? </p>
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