Java tutorial
/* * Copyright (C) 2006 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ package android.widget; import android.content.Context; import android.content.res.TypedArray; import android.database.DataSetObserver; import android.graphics.Rect; import android.os.Parcel; import android.os.Parcelable; import android.util.AttributeSet; import android.util.Log; import android.util.SparseArray; import android.view.View; import android.view.ViewGroup; import android.view.autofill.AutofillValue; import com.android.internal.R; /** * An abstract base class for spinner widgets. SDK users will probably not * need to use this class. * * @attr ref android.R.styleable#AbsSpinner_entries */ public abstract class AbsSpinner extends AdapterView<SpinnerAdapter> { private static final String LOG_TAG = AbsSpinner.class.getSimpleName(); SpinnerAdapter mAdapter; int mHeightMeasureSpec; int mWidthMeasureSpec; int mSelectionLeftPadding = 0; int mSelectionTopPadding = 0; int mSelectionRightPadding = 0; int mSelectionBottomPadding = 0; final Rect mSpinnerPadding = new Rect(); final RecycleBin mRecycler = new RecycleBin(); private DataSetObserver mDataSetObserver; /** Temporary frame to hold a child View's frame rectangle */ private Rect mTouchFrame; public AbsSpinner(Context context) { super(context); initAbsSpinner(); } public AbsSpinner(Context context, AttributeSet attrs) { this(context, attrs, 0); } public AbsSpinner(Context context, AttributeSet attrs, int defStyleAttr) { this(context, attrs, defStyleAttr, 0); } public AbsSpinner(Context context, AttributeSet attrs, int defStyleAttr, int defStyleRes) { super(context, attrs, defStyleAttr, defStyleRes); // Spinner is important by default, unless app developer overrode attribute. if (getImportantForAutofill() == IMPORTANT_FOR_AUTOFILL_AUTO) { setImportantForAutofill(IMPORTANT_FOR_AUTOFILL_YES); } initAbsSpinner(); final TypedArray a = context.obtainStyledAttributes(attrs, R.styleable.AbsSpinner, defStyleAttr, defStyleRes); final CharSequence[] entries = a.getTextArray(R.styleable.AbsSpinner_entries); if (entries != null) { final ArrayAdapter<CharSequence> adapter = new ArrayAdapter<CharSequence>(context, R.layout.simple_spinner_item, entries); adapter.setDropDownViewResource(R.layout.simple_spinner_dropdown_item); setAdapter(adapter); } a.recycle(); } /** * Common code for different constructor flavors */ private void initAbsSpinner() { setFocusable(true); setWillNotDraw(false); } /** * The Adapter is used to provide the data which backs this Spinner. * It also provides methods to transform spinner items based on their position * relative to the selected item. * @param adapter The SpinnerAdapter to use for this Spinner */ @Override public void setAdapter(SpinnerAdapter adapter) { if (null != mAdapter) { mAdapter.unregisterDataSetObserver(mDataSetObserver); resetList(); } mAdapter = adapter; mOldSelectedPosition = INVALID_POSITION; mOldSelectedRowId = INVALID_ROW_ID; if (mAdapter != null) { mOldItemCount = mItemCount; mItemCount = mAdapter.getCount(); checkFocus(); mDataSetObserver = new AdapterDataSetObserver(); mAdapter.registerDataSetObserver(mDataSetObserver); int position = mItemCount > 0 ? 0 : INVALID_POSITION; setSelectedPositionInt(position); setNextSelectedPositionInt(position); if (mItemCount == 0) { // Nothing selected checkSelectionChanged(); } } else { checkFocus(); resetList(); // Nothing selected checkSelectionChanged(); } requestLayout(); } /** * Clear out all children from the list */ void resetList() { mDataChanged = false; mNeedSync = false; removeAllViewsInLayout(); mOldSelectedPosition = INVALID_POSITION; mOldSelectedRowId = INVALID_ROW_ID; setSelectedPositionInt(INVALID_POSITION); setNextSelectedPositionInt(INVALID_POSITION); invalidate(); } /** * @see android.view.View#measure(int, int) * * Figure out the dimensions of this Spinner. The width comes from * the widthMeasureSpec as Spinnners can't have their width set to * UNSPECIFIED. The height is based on the height of the selected item * plus padding. */ @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { int widthMode = MeasureSpec.getMode(widthMeasureSpec); int widthSize; int heightSize; mSpinnerPadding.left = mPaddingLeft > mSelectionLeftPadding ? mPaddingLeft : mSelectionLeftPadding; mSpinnerPadding.top = mPaddingTop > mSelectionTopPadding ? mPaddingTop : mSelectionTopPadding; mSpinnerPadding.right = mPaddingRight > mSelectionRightPadding ? mPaddingRight : mSelectionRightPadding; mSpinnerPadding.bottom = mPaddingBottom > mSelectionBottomPadding ? mPaddingBottom : mSelectionBottomPadding; if (mDataChanged) { handleDataChanged(); } int preferredHeight = 0; int preferredWidth = 0; boolean needsMeasuring = true; int selectedPosition = getSelectedItemPosition(); if (selectedPosition >= 0 && mAdapter != null && selectedPosition < mAdapter.getCount()) { // Try looking in the recycler. (Maybe we were measured once already) View view = mRecycler.get(selectedPosition); if (view == null) { // Make a new one view = mAdapter.getView(selectedPosition, null, this); if (view.getImportantForAccessibility() == IMPORTANT_FOR_ACCESSIBILITY_AUTO) { view.setImportantForAccessibility(IMPORTANT_FOR_ACCESSIBILITY_YES); } } if (view != null) { // Put in recycler for re-measuring and/or layout mRecycler.put(selectedPosition, view); if (view.getLayoutParams() == null) { mBlockLayoutRequests = true; view.setLayoutParams(generateDefaultLayoutParams()); mBlockLayoutRequests = false; } measureChild(view, widthMeasureSpec, heightMeasureSpec); preferredHeight = getChildHeight(view) + mSpinnerPadding.top + mSpinnerPadding.bottom; preferredWidth = getChildWidth(view) + mSpinnerPadding.left + mSpinnerPadding.right; needsMeasuring = false; } } if (needsMeasuring) { // No views -- just use padding preferredHeight = mSpinnerPadding.top + mSpinnerPadding.bottom; if (widthMode == MeasureSpec.UNSPECIFIED) { preferredWidth = mSpinnerPadding.left + mSpinnerPadding.right; } } preferredHeight = Math.max(preferredHeight, getSuggestedMinimumHeight()); preferredWidth = Math.max(preferredWidth, getSuggestedMinimumWidth()); heightSize = resolveSizeAndState(preferredHeight, heightMeasureSpec, 0); widthSize = resolveSizeAndState(preferredWidth, widthMeasureSpec, 0); setMeasuredDimension(widthSize, heightSize); mHeightMeasureSpec = heightMeasureSpec; mWidthMeasureSpec = widthMeasureSpec; } int getChildHeight(View child) { return child.getMeasuredHeight(); } int getChildWidth(View child) { return child.getMeasuredWidth(); } @Override protected ViewGroup.LayoutParams generateDefaultLayoutParams() { return new ViewGroup.LayoutParams(ViewGroup.LayoutParams.MATCH_PARENT, ViewGroup.LayoutParams.WRAP_CONTENT); } void recycleAllViews() { final int childCount = getChildCount(); final AbsSpinner.RecycleBin recycleBin = mRecycler; final int position = mFirstPosition; // All views go in recycler for (int i = 0; i < childCount; i++) { View v = getChildAt(i); int index = position + i; recycleBin.put(index, v); } } /** * Jump directly to a specific item in the adapter data. */ public void setSelection(int position, boolean animate) { // Animate only if requested position is already on screen somewhere boolean shouldAnimate = animate && mFirstPosition <= position && position <= mFirstPosition + getChildCount() - 1; setSelectionInt(position, shouldAnimate); } @Override public void setSelection(int position) { setNextSelectedPositionInt(position); requestLayout(); invalidate(); } /** * Makes the item at the supplied position selected. * * @param position Position to select * @param animate Should the transition be animated * */ void setSelectionInt(int position, boolean animate) { if (position != mOldSelectedPosition) { mBlockLayoutRequests = true; int delta = position - mSelectedPosition; setNextSelectedPositionInt(position); layout(delta, animate); mBlockLayoutRequests = false; } } abstract void layout(int delta, boolean animate); @Override public View getSelectedView() { if (mItemCount > 0 && mSelectedPosition >= 0) { return getChildAt(mSelectedPosition - mFirstPosition); } else { return null; } } /** * Override to prevent spamming ourselves with layout requests * as we place views * * @see android.view.View#requestLayout() */ @Override public void requestLayout() { if (!mBlockLayoutRequests) { super.requestLayout(); } } @Override public SpinnerAdapter getAdapter() { return mAdapter; } @Override public int getCount() { return mItemCount; } /** * Maps a point to a position in the list. * * @param x X in local coordinate * @param y Y in local coordinate * @return The position of the item which contains the specified point, or * {@link #INVALID_POSITION} if the point does not intersect an item. */ public int pointToPosition(int x, int y) { Rect frame = mTouchFrame; if (frame == null) { mTouchFrame = new Rect(); frame = mTouchFrame; } final int count = getChildCount(); for (int i = count - 1; i >= 0; i--) { View child = getChildAt(i); if (child.getVisibility() == View.VISIBLE) { child.getHitRect(frame); if (frame.contains(x, y)) { return mFirstPosition + i; } } } return INVALID_POSITION; } @Override protected void dispatchRestoreInstanceState(SparseArray<Parcelable> container) { super.dispatchRestoreInstanceState(container); // Restores the selected position when Spinner gets restored, // rather than wait until the next measure/layout pass to do it. handleDataChanged(); } static class SavedState extends BaseSavedState { long selectedId; int position; /** * Constructor called from {@link AbsSpinner#onSaveInstanceState()} */ SavedState(Parcelable superState) { super(superState); } /** * Constructor called from {@link #CREATOR} */ SavedState(Parcel in) { super(in); selectedId = in.readLong(); position = in.readInt(); } @Override public void writeToParcel(Parcel out, int flags) { super.writeToParcel(out, flags); out.writeLong(selectedId); out.writeInt(position); } @Override public String toString() { return "AbsSpinner.SavedState{" + Integer.toHexString(System.identityHashCode(this)) + " selectedId=" + selectedId + " position=" + position + "}"; } public static final Parcelable.Creator<SavedState> CREATOR = new Parcelable.Creator<SavedState>() { public SavedState createFromParcel(Parcel in) { return new SavedState(in); } public SavedState[] newArray(int size) { return new SavedState[size]; } }; } @Override public Parcelable onSaveInstanceState() { Parcelable superState = super.onSaveInstanceState(); SavedState ss = new SavedState(superState); ss.selectedId = getSelectedItemId(); if (ss.selectedId >= 0) { ss.position = getSelectedItemPosition(); } else { ss.position = INVALID_POSITION; } return ss; } @Override public void onRestoreInstanceState(Parcelable state) { SavedState ss = (SavedState) state; super.onRestoreInstanceState(ss.getSuperState()); if (ss.selectedId >= 0) { mDataChanged = true; mNeedSync = true; mSyncRowId = ss.selectedId; mSyncPosition = ss.position; mSyncMode = SYNC_SELECTED_POSITION; requestLayout(); } } class RecycleBin { private final SparseArray<View> mScrapHeap = new SparseArray<View>(); public void put(int position, View v) { mScrapHeap.put(position, v); } View get(int position) { // System.out.print("Looking for " + position); View result = mScrapHeap.get(position); if (result != null) { // System.out.println(" HIT"); mScrapHeap.delete(position); } else { // System.out.println(" MISS"); } return result; } void clear() { final SparseArray<View> scrapHeap = mScrapHeap; final int count = scrapHeap.size(); for (int i = 0; i < count; i++) { final View view = scrapHeap.valueAt(i); if (view != null) { removeDetachedView(view, true); } } scrapHeap.clear(); } } @Override public CharSequence getAccessibilityClassName() { return AbsSpinner.class.getName(); } @Override public void autofill(AutofillValue value) { if (!isEnabled()) return; if (!value.isList()) { Log.w(LOG_TAG, value + " could not be autofilled into " + this); return; } setSelection(value.getListValue()); } @Override public @AutofillType int getAutofillType() { return isEnabled() ? AUTOFILL_TYPE_LIST : AUTOFILL_TYPE_NONE; } @Override public AutofillValue getAutofillValue() { return isEnabled() ? AutofillValue.forList(getSelectedItemPosition()) : null; } }