Here is one Google made earlier, except they forgot to flip x/y. Took about an hour to convert. :) Oh, and it might not work with the 1.1 SDK, because of the attribute set changes. It works fine with the 1.0 SDK.
Michael /* * 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 your.package.here; import java.lang.reflect.Field; import java.util.List; import android.content.Context; import android.content.res.TypedArray; import android.graphics.Rect; import android.util.AttributeSet; import android.util.Log; import android.view.FocusFinder; import android.view.KeyEvent; import android.view.MotionEvent; import android.view.VelocityTracker; import android.view.View; import android.view.ViewConfiguration; import android.view.ViewGroup; import android.view.ViewParent; import android.view.animation.AnimationUtils; import android.widget.FrameLayout; import android.widget.LinearLayout; import android.widget.ListView; import android.widget.Scroller; import android.widget.TextView; /** * Layout container for a view hierarchy that can be scrolled by the user, * allowing it to be larger than the physical display. A ScrollView is a * {...@link FrameLayout}, meaning you should place one child in it containing the * entire contents to scroll; this child may itself be a layout manager with a * complex hierarchy of objects. A child that is often used is a * {...@link LinearLayout} in a vertical orientation, presenting a vertical array * of top-level items that the user can scroll through. * * <p> * You should never use a ScrollView with a {...@link ListView}, since ListView * takes care of its own scrolling. Most importantly, doing this defeats all of * the important optimizations in ListView for dealing with large lists, since * it effectively forces the ListView to display its entire list of items to * fill up the infinite container supplied by ScrollView. * * <p> * The {...@link TextView} class also takes care of its own scrolling, so does not * require a ScrollView, but using the two together is possible to achieve the * effect of a text view within a larger container. * * <p> * ScrollView only supports vertical scrolling. */ public class HorizontalScrollView extends FrameLayout { static final String TAG = "HScroll"; private static final int ANIMATED_SCROLL_GAP = 250; /** * When arrow scrolling, ListView will never scroll more than this factor * times the height of the list. */ private static final float MAX_SCROLL_FACTOR = 0.5f; private long mLastScroll; private final Rect mTempRect = new Rect(); private Scroller mScroller; /** * Flag to indicate that we are moving focus ourselves. This is so the code * that watches for focus changes initiated outside this ScrollView knows that * it does not have to do anything. */ private boolean mScrollViewMovedFocus; /** * Position of the last motion event. */ private float mLastMotionX; /** * True when the layout has changed but the traversal has not come through * yet. Ideally the view hierarchy would keep track of this for us. */ private boolean mIsLayoutDirty = true; /** * The child to give focus to in the event that a child has requested focus * while the layout is dirty. This prevents the scroll from being wrong if the * child has not been laid out before requesting focus. */ private View mChildToScrollTo = null; /** * True if the user is currently dragging this ScrollView around. This is not * the same as 'is being flinged', which can be checked by * mScroller.isFinished() (flinging begins when the user lifts his finger). */ private boolean mIsBeingDragged = false; /** * Determines speed during touch scrolling */ private VelocityTracker mVelocityTracker; /** * When set to true, the scroll view measure its child to make it fill the * currently visible area. */ private boolean mFillViewport; /** * Whether arrow scrolling is animated. */ private boolean mSmoothScrollingEnabled = true; public HorizontalScrollView(Context context) { super(context); initScrollView(); setHorizontalScrollBarEnabled(true); setHorizontalFadingEdgeEnabled(true); TypedArray a = context.obtainStyledAttributes (android.R.styleable.View); initializeScrollbars(a); initializeFadingEdge(a); a.recycle(); } public HorizontalScrollView(Context context, AttributeSet attrs) { this(context, attrs, android.R.attr.scrollViewStyle); } public HorizontalScrollView(Context context, AttributeSet attrs, int defStyle) { super(context, attrs, defStyle); initScrollView(); TypedArray a = context.obtainStyledAttributes(attrs, android.R.styleable.ScrollView, defStyle, 0); setFillViewport(a.getBoolean (android.R.styleable.ScrollView_fillViewport, false)); a.recycle(); } @Override protected float getLeftFadingEdgeStrength() { if (getChildCount() == 0) { return 0.0f; } final int length = getHorizontalFadingEdgeLength(); if (getScrollX() < length) { return getScrollX() / (float) length; } return 1.0f; } @Override protected float getRightFadingEdgeStrength() { if (getChildCount() == 0) { return 0.0f; } final int length = getHorizontalFadingEdgeLength(); final int right = getChildAt(0).getRight(); final int span = right - getScrollX() - getWidth(); if (span < length) { return span / (float) length; } return 1.0f; } /** * @return The maximum amount this scroll view will scroll in response to an * arrow event. */ public int getMaxScrollAmount() { return (int) (MAX_SCROLL_FACTOR * (getRight() - getLeft())); } private void initScrollView() { mScroller = new Scroller(getContext()); setFocusable(true); setDescendantFocusability(FOCUS_AFTER_DESCENDANTS); setWillNotDraw(false); } @Override public void addView(View child) { if (getChildCount() > 0) { throw new IllegalStateException("ScrollView can host only one direct child"); } super.addView(child); } @Override public void addView(View child, int index) { if (getChildCount() > 0) { throw new IllegalStateException("ScrollView can host only one direct child"); } super.addView(child, index); } @Override public void addView(View child, ViewGroup.LayoutParams params) { if (getChildCount() > 0) { throw new IllegalStateException("ScrollView can host only one direct child"); } super.addView(child, params); } @Override public void addView(View child, int index, ViewGroup.LayoutParams params) { if (getChildCount() > 0) { throw new IllegalStateException("ScrollView can host only one direct child"); } super.addView(child, index, params); } /** * @return Returns true this ScrollView can be scrolled */ private boolean canScroll() { View child = getChildAt(0); if (child != null) { int childWidth = child.getWidth(); return getWidth() < childWidth + getPaddingLeft() + getPaddingRight (); } return false; } /** * Indicates whether this ScrollView's content is stretched to fill the * viewport. * * @return True if the content fills the viewport, false otherwise. */ public boolean isFillViewport() { return mFillViewport; } /** * Indicates this ScrollView whether it should stretch its content height to * fill the viewport or not. * * @param fillViewport * True to stretch the content's height to the viewport's boundaries, * false otherwise. */ public void setFillViewport(boolean fillViewport) { if (fillViewport != mFillViewport) { mFillViewport = fillViewport; requestLayout(); } } /** * @return Whether arrow scrolling will animate its transition. */ public boolean isSmoothScrollingEnabled() { return mSmoothScrollingEnabled; } /** * Set whether arrow scrolling will animate its transition. * * @param smoothScrollingEnabled * whether arrow scrolling will animate its transition */ public void setSmoothScrollingEnabled(boolean smoothScrollingEnabled) { mSmoothScrollingEnabled = smoothScrollingEnabled; } @Override protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { super.onMeasure(widthMeasureSpec, heightMeasureSpec); if (!mFillViewport) { return; } final int heightMode = MeasureSpec.getMode(heightMeasureSpec); if (heightMode == MeasureSpec.UNSPECIFIED) { return; } final View child = getChildAt(0); int width = getMeasuredWidth(); if (child.getMeasuredWidth() < width) { final FrameLayout.LayoutParams lp = (LayoutParams) child.getLayoutParams(); int childHeightMeasureSpec = getChildMeasureSpec(heightMeasureSpec, getPaddingTop() + getPaddingBottom(), lp.height); width -= getPaddingLeft(); width -= getPaddingRight(); int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(width, MeasureSpec.EXACTLY); child.measure(childWidthMeasureSpec, childHeightMeasureSpec); } } @Override public boolean dispatchKeyEvent(KeyEvent event) { // Let the focused view and/or our descendants get the key first boolean handled = super.dispatchKeyEvent(event); if (handled) { return true; } return executeKeyEvent(event); } /** * You can call this function yourself to have the scroll view perform * scrolling from a key event, just as if the event had been dispatched to it * by the view hierarchy. * * @param event * The key event to execute. * @return Return true if the event was handled, else false. */ public boolean executeKeyEvent(KeyEvent event) { mTempRect.setEmpty(); if (!canScroll()) { if (isFocused()) { View currentFocused = findFocus(); if (currentFocused == this) currentFocused = null; View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, View.FOCUS_DOWN); return nextFocused != null && nextFocused != this && nextFocused.requestFocus(View.FOCUS_DOWN); } return false; } boolean handled = false; if (event.getAction() == KeyEvent.ACTION_DOWN) { switch (event.getKeyCode()) { case KeyEvent.KEYCODE_DPAD_UP: if (!event.isAltPressed()) { handled = arrowScroll(View.FOCUS_UP); } else { handled = fullScroll(View.FOCUS_UP); } break; case KeyEvent.KEYCODE_DPAD_DOWN: if (!event.isAltPressed()) { handled = arrowScroll(View.FOCUS_DOWN); } else { handled = fullScroll(View.FOCUS_DOWN); } break; case KeyEvent.KEYCODE_SPACE: pageScroll(event.isShiftPressed() ? View.FOCUS_UP : View.FOCUS_DOWN); break; } } return handled; } @Override public boolean onInterceptTouchEvent(MotionEvent ev) { /* * This method JUST determines whether we want to intercept the motion. If * we return true, onMotionEvent will be called and we do the actual * scrolling there. */ /* * Shortcut the most recurring case: the user is in the dragging state and * he is moving his finger. We want to intercept this motion. */ final int action = ev.getAction(); if ((action == MotionEvent.ACTION_MOVE) && (mIsBeingDragged)) { return true; } if (!canScroll()) { mIsBeingDragged = false; return false; } final float x = ev.getX(); switch (action) { case MotionEvent.ACTION_MOVE: /* * mIsBeingDragged == false, otherwise the shortcut would have caught it. * Check whether the user has moved far enough from his original down * touch. */ /* * Locally do absolute value. mLastMotionY is set to the y value of the * down event. */ final int xDiff = (int) Math.abs(x - mLastMotionX); if (xDiff > ViewConfiguration.getTouchSlop()) { mIsBeingDragged = true; } break; case MotionEvent.ACTION_DOWN: /* Remember location of down touch */ mLastMotionX = x; /* * If being flinged and user touches the screen, initiate drag; otherwise * don't. mScroller.isFinished should be false when being flinged. */ mIsBeingDragged = !mScroller.isFinished(); break; case MotionEvent.ACTION_CANCEL: case MotionEvent.ACTION_UP: /* Release the drag */ mIsBeingDragged = false; break; } /* * The only time we want to intercept motion events is if we are in the drag * mode. */ return mIsBeingDragged; } @Override public boolean onTouchEvent(MotionEvent ev) { if (ev.getAction() == MotionEvent.ACTION_DOWN && ev.getEdgeFlags() ! = 0) { // Don't handle edge touches immediately -- they may actually belong to // one of our // descendants. return false; } if (!canScroll()) { return false; } if (mVelocityTracker == null) { mVelocityTracker = VelocityTracker.obtain(); } mVelocityTracker.addMovement(ev); final int action = ev.getAction(); final float x = ev.getX(); switch (action) { case MotionEvent.ACTION_DOWN: /* * If being flinged and user touches, stop the fling. isFinished will be * false if being flinged. */ if (!mScroller.isFinished()) { mScroller.abortAnimation(); } // Remember where the motion event started mLastMotionX = x; break; case MotionEvent.ACTION_MOVE: // Scroll to follow the motion event final int deltaX = (int) (mLastMotionX - x); mLastMotionX = x; if (deltaX < 0) { if (getScrollX() > 0) { scrollBy(deltaX, 0); } } else if (deltaX > 0) { final int rightEdge = getWidth() - getPaddingRight(); final int availableToScroll = getChildAt(0).getRight() - getScrollX () - rightEdge; if (availableToScroll > 0) { scrollBy(Math.min(availableToScroll, deltaX), 0); } } break; case MotionEvent.ACTION_UP: final VelocityTracker velocityTracker = mVelocityTracker; velocityTracker.computeCurrentVelocity(1000); int initialVelocity = (int) velocityTracker.getXVelocity(); //Log.i(TAG, "velocity " + initialVelocity); if ((Math.abs(initialVelocity) > ViewConfiguration.getMinimumFlingVelocity()) && (getChildCount() > 0)) { fling(-initialVelocity); } if (mVelocityTracker != null) { mVelocityTracker.recycle(); mVelocityTracker = null; } } return true; } /** * <p> * Finds the next focusable component that fits in this View's bounds * (excluding fading edges) pretending that this View's top is located at the * parameter top. * </p> * * @param topFocus * look for a candidate is the one at the top of the bounds if * topFocus is true, or at the bottom of the bounds if topFocus is * false * @param top * the top offset of the bounds in which a focusable must be found * (the fading edge is assumed to start at this position) * @param preferredFocusable * the View that has highest priority and will be returned if it is * within my bounds (null is valid) * @return the next focusable component in the bounds or null if none can be * found */ private View findFocusableViewInMyBounds(final boolean topFocus, final int left, View preferredFocusable) { /* * The fading edge's transparent side should be considered for focus since * it's mostly visible, so we divide the actual fading edge length by 2. */ final int fadingEdgeLength = getHorizontalFadingEdgeLength() / 2; final int leftWithoutFadingEdge = left + fadingEdgeLength; final int rightWithoutFadingEdge = left + getWidth() - fadingEdgeLength; if ((preferredFocusable != null) && (preferredFocusable.getLeft() < rightWithoutFadingEdge) && (preferredFocusable.getRight() > leftWithoutFadingEdge)) { return preferredFocusable; } return findFocusableViewInBounds(topFocus, leftWithoutFadingEdge, rightWithoutFadingEdge); } /** * <p> * Finds the next focusable component that fits in the specified bounds. * </p> * * @param topFocus * look for a candidate is the one at the top of the bounds if * topFocus is true, or at the bottom of the bounds if topFocus is * false * @param top * the top offset of the bounds in which a focusable must be found * @param bottom * the bottom offset of the bounds in which a focusable must be found * @return the next focusable component in the bounds or null if none can be * found */ private View findFocusableViewInBounds(boolean topFocus, int left, int right) { List<View> focusables = getFocusables(View.FOCUS_FORWARD); View focusCandidate = null; /* * A fully contained focusable is one where its top is below the bound's * top, and its bottom is above the bound's bottom. A partially contained * focusable is one where some part of it is within the bounds, but it also * has some part that is not within bounds. A fully contained focusable is * preferred to a partially contained focusable. */ boolean foundFullyContainedFocusable = false; int count = focusables.size(); for (int i = 0; i < count; i++) { View view = focusables.get(i); int viewLeft = view.getLeft(); int viewRight = view.getRight(); if (left < viewRight && viewLeft < right) { /* * the focusable is in the target area, it is a candidate for focusing */ final boolean viewIsFullyContained = (left < viewLeft) && (viewRight < right); if (focusCandidate == null) { /* No candidate, take this one */ focusCandidate = view; foundFullyContainedFocusable = viewIsFullyContained; } else { final boolean viewIsCloserToBoundary = (topFocus && viewLeft < focusCandidate.getLeft()) || (!topFocus && viewRight > focusCandidate.getRight()); if (foundFullyContainedFocusable) { if (viewIsFullyContained && viewIsCloserToBoundary) { /* * We're dealing with only fully contained views, so it has to be * closer to the boundary to beat our candidate */ focusCandidate = view; } } else { if (viewIsFullyContained) { /* Any fully contained view beats a partially contained view */ focusCandidate = view; foundFullyContainedFocusable = true; } else if (viewIsCloserToBoundary) { /* * Partially contained view beats another partially contained view * if it's closer */ focusCandidate = view; } } } } } return focusCandidate; } /** * <p> * Handles scrolling in response to a "page up/down" shortcut press. This * method will scroll the view by one page up or down and give the focus to * the topmost/bottommost component in the new visible area. If no component * is a good candidate for focus, this scrollview reclaims the focus. * </p> * * @param direction * the scroll direction: {...@link android.view.View#FOCUS_UP} to go one * page up or {...@link android.view.View#FOCUS_DOWN} to go one page * down * @return true if the key event is consumed by this method, false otherwise */ // todo public boolean pageScroll(int direction) { boolean down = direction == View.FOCUS_DOWN; int height = getHeight(); if (down) { mTempRect.top = getScrollY() + height; int count = getChildCount(); if (count > 0) { View view = getChildAt(count - 1); if (mTempRect.top + height > view.getBottom()) { mTempRect.top = view.getBottom() - height; } } } else { mTempRect.top = getScrollY() - height; if (mTempRect.top < 0) { mTempRect.top = 0; } } mTempRect.bottom = mTempRect.top + height; return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); } /** * <p> * Handles scrolling in response to a "home/end" shortcut press. This method * will scroll the view to the top or bottom and give the focus to the * topmost/bottommost component in the new visible area. If no component is a * good candidate for focus, this scrollview reclaims the focus. * </p> * * @param direction * the scroll direction: {...@link android.view.View#FOCUS_UP} to go the * top of the view or {...@link android.view.View#FOCUS_DOWN} to go the * bottom * @return true if the key event is consumed by this method, false otherwise */ // todo public boolean fullScroll(int direction) { boolean down = direction == View.FOCUS_DOWN; int height = getHeight(); mTempRect.top = 0; mTempRect.bottom = height; if (down) { int count = getChildCount(); if (count > 0) { View view = getChildAt(count - 1); mTempRect.bottom = view.getBottom(); mTempRect.top = mTempRect.bottom - height; } } return scrollAndFocus(direction, mTempRect.top, mTempRect.bottom); } /** * <p> * Scrolls the view to make the area defined by <code>top</code> and * <code>bottom</code> visible. This method attempts to give the focus to a * component visible in this area. If no component can be focused in the new * visible area, the focus is reclaimed by this scrollview. * </p> * * @param direction * the scroll direction: {...@link android.view.View#FOCUS_UP} to go * upward {...@link android.view.View#FOCUS_DOWN} to downward * @param top * the top offset of the new area to be made visible * @param bottom * the bottom offset of the new area to be made visible * @return true if the key event is consumed by this method, false otherwise */ private boolean scrollAndFocus(int direction, int left, int right) { boolean handled = true; int width = getWidth(); int containerLeft = getScrollX(); int containerRight = containerLeft + width; boolean up = direction == View.FOCUS_LEFT; View newFocused = findFocusableViewInBounds(up, left, right); if (newFocused == null) { newFocused = this; } if (left >= containerLeft && right <= containerRight) { handled = false; } else { int delta = up ? (left - containerLeft) : (right - containerRight); doScrollX(delta); } if (newFocused != findFocus() && newFocused.requestFocus(direction)) { mScrollViewMovedFocus = true; mScrollViewMovedFocus = false; } return handled; } /** * Handle scrolling in response to an up or down arrow click. * * @param direction * The direction corresponding to the arrow key that was pressed * @return True if we consumed the event, false otherwise */ public boolean arrowScroll(int direction) { View currentFocused = findFocus(); if (currentFocused == this) currentFocused = null; View nextFocused = FocusFinder.getInstance().findNextFocus(this, currentFocused, direction); final int maxJump = getMaxScrollAmount(); if (nextFocused != null && isWithinDeltaOfScreen(nextFocused, maxJump)) { nextFocused.getDrawingRect(mTempRect); offsetDescendantRectToMyCoords(nextFocused, mTempRect); int scrollDelta = computeScrollDeltaToGetChildRectOnScreen (mTempRect); doScrollX(scrollDelta); nextFocused.requestFocus(direction); } else { // no new focus int scrollDelta = maxJump; if (direction == View.FOCUS_LEFT && getScrollX() < scrollDelta) { scrollDelta = getScrollX(); } else if (direction == View.FOCUS_RIGHT) { int daRight = getChildAt(getChildCount() - 1).getRight(); int screenRight = getScrollX() + getWidth(); if (daRight - screenRight < maxJump) { scrollDelta = daRight - screenRight; } } if (scrollDelta == 0) { return false; } doScrollX(direction == View.FOCUS_RIGHT ? scrollDelta : - scrollDelta); } if (currentFocused != null && currentFocused.isFocused() && isOffScreen(currentFocused)) { // previously focused item still has focus and is off screen, give // it up (take it back to ourselves) // (also, need to temporarily force FOCUS_BEFORE_DESCENDANTS so we are // sure to // get it) final int descendantFocusability = getDescendantFocusability(); // save setDescendantFocusability(ViewGroup.FOCUS_BEFORE_DESCENDANTS); requestFocus(); setDescendantFocusability(descendantFocusability); // restore } return true; } /** * @return whether the descendant of this scroll view is scrolled off screen. */ private boolean isOffScreen(View descendant) { return !isWithinDeltaOfScreen(descendant, 0); } /** * @return whether the descendant of this scroll view is within delta pixels * of being on the screen. */ // done private boolean isWithinDeltaOfScreen(View descendant, int delta) { descendant.getDrawingRect(mTempRect); offsetDescendantRectToMyCoords(descendant, mTempRect); return (mTempRect.right + delta) >= getScrollX() && (mTempRect.left - delta) <= (getScrollX() + getWidth()); } /** * Smooth scroll by a Y delta * * @param delta * the number of pixels to scroll by on the X axis */ // done private void doScrollX(int delta) { if (delta != 0) { if (mSmoothScrollingEnabled) { smoothScrollBy(delta, 0); } else { scrollBy(delta, 0); } } } /** * Like {...@link View#scrollBy}, but scroll smoothly instead of immediately. * * @param dx * the number of pixels to scroll by on the X axis * @param dy * the number of pixels to scroll by on the Y axis */ public final void smoothScrollBy(int dx, int dy) { long duration = AnimationUtils.currentAnimationTimeMillis() - mLastScroll; if (duration > ANIMATED_SCROLL_GAP) { mScroller.startScroll(getScrollX(), getScrollY(), dx, dy); invalidate(); } else { if (!mScroller.isFinished()) { mScroller.abortAnimation(); } scrollBy(dx, dy); } mLastScroll = AnimationUtils.currentAnimationTimeMillis(); } /** * Like {...@link #scrollTo}, but scroll smoothly instead of immediately. * * @param x * the position where to scroll on the X axis * @param y * the position where to scroll on the Y axis */ public final void smoothScrollTo(int x, int y) { smoothScrollBy(x - getScrollX(), y - getScrollY()); } /** * <p> * The scroll range of a scroll view is the overall height of all of its * children. * </p> */ @Override protected int computeHorizontalScrollRange() { int count = getChildCount(); return count == 0 ? getWidth() : (getChildAt(0)).getRight(); } @Override protected void measureChild(View child, int parentWidthMeasureSpec, int parentHeightMeasureSpec) { ViewGroup.LayoutParams lp = child.getLayoutParams(); int childWidthMeasureSpec; int childHeightMeasureSpec; childHeightMeasureSpec = getChildMeasureSpec (parentHeightMeasureSpec, getPaddingTop() + getPaddingBottom(), lp.height); childWidthMeasureSpec = MeasureSpec.makeMeasureSpec(0, MeasureSpec.UNSPECIFIED); child.measure(childWidthMeasureSpec, childHeightMeasureSpec); } @Override protected void measureChildWithMargins(View child, int parentWidthMeasureSpec, int widthUsed, int parentHeightMeasureSpec, int heightUsed) { final MarginLayoutParams lp = (MarginLayoutParams) child.getLayoutParams(); final int childHeightMeasureSpec = getChildMeasureSpec (parentHeightMeasureSpec, getPaddingTop() + getPaddingBottom() + lp.topMargin + lp.bottomMargin + heightUsed, lp.height); final int childWidthMeasureSpec = MeasureSpec.makeMeasureSpec (lp.leftMargin + lp.rightMargin, MeasureSpec.UNSPECIFIED); child.measure(childWidthMeasureSpec, childHeightMeasureSpec); } @Override public void computeScroll() { //Log.i(TAG, "computeScroll"); if (mScroller.computeScrollOffset()) { // This is called at drawing time by ViewGroup. We don't want to // re-show the scrollbars at this point, which scrollTo will do, // so we replicate most of scrollTo here. // // It's a little odd to call onScrollChanged from inside the drawing. // // It is, except when you remember that computeScroll() is used to // animate scrolling. So unless we want to defer the onScrollChanged () // until the end of the animated scrolling, we don't really have a // choice here. // // I agree. The alternative, which I think would be worse, is to post // something and tell the subclasses later. This is bad because there // will be a window where mScrollX/Y is different from what the app // thinks it is. // int oldX = getScrollX(); int oldY = getScrollY(); int x = mScroller.getCurrX(); int y = mScroller.getCurrY(); int msx = 0; int msy = 0; if (getChildCount() > 0) { View child = getChildAt(0); msx = clamp(x, this.getWidth(), child.getWidth()); msy = clamp(y, this.getHeight(), child.getHeight()); } else { msx = x; msy = y; } //Log.i(TAG, "x: " + msx + " y: " + msy); // setScrollXY(msx,msy); super.scrollTo(msx, msy); if (oldX != msx || oldY != msy) { onScrollChanged(msx, msy, oldX, oldY); postInvalidate(); // So we draw again } } } /** * Scrolls the view to the given child. * * @param child * the View to scroll to */ private void scrollToChild(View child) { child.getDrawingRect(mTempRect); /* Offset from child's local coordinates to ScrollView coordinates */ offsetDescendantRectToMyCoords(child, mTempRect); int scrollDelta = computeScrollDeltaToGetChildRectOnScreen (mTempRect); if (scrollDelta != 0) { scrollBy(scrollDelta, 0); } } /** * If rect is off screen, scroll just enough to get it (or at least the first * screen size chunk of it) on screen. * * @param rect * The rectangle. * @param immediate * True to scroll immediately without animation * @return true if scrolling was performed */ private boolean scrollToChildRect(Rect rect, boolean immediate) { final int delta = computeScrollDeltaToGetChildRectOnScreen(rect); final boolean scroll = delta != 0; if (scroll) { if (immediate) { scrollBy(delta, 0); } else { smoothScrollBy(delta, 0); } } return scroll; } /** * Compute the amount to scroll in the Y direction in order to get a rectangle * completely on the screen (or, if taller than the screen, at least the first * screen size chunk of it). * * @param rect * The rect. * @return The scroll delta. */ protected int computeScrollDeltaToGetChildRectOnScreen(Rect rect) { int width = getWidth(); int screenLeft = getScrollX(); int screenRight = screenLeft + width; int fadingEdge = getHorizontalFadingEdgeLength(); // leave room for top fading edge as long as rect isn't at very top if (rect.left > 0) { screenLeft += fadingEdge; } // leave room for bottom fading edge as long as rect isn't at very bottom if (rect.right < getChildAt(0).getWidth()) { screenRight -= fadingEdge; } int scrollXDelta = 0; if (rect.right > screenRight && rect.left > screenLeft) { // need to move down to get it in view: move down just enough so // that the entire rectangle is in view (or at least the first // screen size chunk). if (rect.width() > width) { // just enough to get screen size chunk on scrollXDelta += (rect.left - screenLeft); } else { // get entire rect at bottom of screen scrollXDelta += (rect.right - screenRight); } // make sure we aren't scrolling beyond the end of our content int right = getChildAt(getChildCount() - 1).getRight(); int distanceToRight = right - screenRight; scrollXDelta = Math.min(scrollXDelta, distanceToRight); } else if (rect.left < screenLeft && rect.right < screenRight) { // need to move up to get it in view: move up just enough so that // entire rectangle is in view (or at least the first screen // size chunk of it). if (rect.width() > width) { // screen size chunk scrollXDelta -= (screenRight - rect.right); } else { // entire rect at top scrollXDelta -= (screenLeft - rect.left); } // make sure we aren't scrolling any further than the top our content scrollXDelta = Math.max(scrollXDelta, -getScrollX()); } return scrollXDelta; } @Override public void requestChildFocus(View child, View focused) { if (!mScrollViewMovedFocus) { if (!mIsLayoutDirty) { scrollToChild(focused); } else { // The child may not be laid out yet, we can't compute the scroll yet mChildToScrollTo = focused; } } super.requestChildFocus(child, focused); } /** * When looking for focus in children of a scroll view, need to be a little * more careful not to give focus to something that is scrolled off screen. * * This is more expensive than the default {...@link android.view.ViewGroup} * implementation, otherwise this behavior might have been made the default. */ @Override protected boolean onRequestFocusInDescendants(int direction, Rect previouslyFocusedRect) { // convert from forward / backward notation to up / down / left / right // (ugh). if (direction == View.FOCUS_FORWARD) { direction = View.FOCUS_DOWN; } else if (direction == View.FOCUS_BACKWARD) { direction = View.FOCUS_UP; } final View nextFocus = previouslyFocusedRect == null ? FocusFinder.getInstance().findNextFocus(this, null, direction) : FocusFinder.getInstance() .findNextFocusFromRect(this, previouslyFocusedRect, direction); if (nextFocus == null) { return false; } if (isOffScreen(nextFocus)) { return false; } return nextFocus.requestFocus(direction, previouslyFocusedRect); } @Override public boolean requestChildRectangleOnScreen(View child, Rect rectangle, boolean immediate) { // offset into coordinate space of this scroll view rectangle.offset(child.getLeft() - child.getScrollX(), child.getTop () - child.getScrollY()); // note: until bug 1137695 is fixed, disable smooth scrolling for this api return scrollToChildRect(rectangle, true);// immediate); } @Override public void requestLayout() { mIsLayoutDirty = true; super.requestLayout(); } @Override protected void onLayout(boolean changed, int l, int t, int r, int b) { super.onLayout(changed, l, t, r, b); mIsLayoutDirty = false; // Give a child focus if it needs it if (mChildToScrollTo != null && isViewDescendantOf(mChildToScrollTo, this)) { scrollToChild(mChildToScrollTo); } mChildToScrollTo = null; // Calling this with the present values causes it to re-clam them scrollTo(getScrollX(), getScrollY()); } /** * Return true if child is an descendant of parent, (or equal to the parent). */ private boolean isViewDescendantOf(View child, View parent) { if (child == parent) { return true; } final ViewParent theParent = child.getParent(); return (theParent instanceof ViewGroup) && isViewDescendantOf((View) theParent, parent); } /** * Fling the scroll view * * @param velocityY * The initial velocity in the Y direction. Positive numbers mean * that the finger/curor is moving down the screen, which means we * want to scroll towards the top. */ public void fling(int velocityX) { //Log.i(TAG, "flinging: " + velocityX); int width = getWidth(); int right = getChildAt(getChildCount() - 1).getRight(); mScroller.fling(getScrollX(), getScrollY(), velocityX, 0, 0, right - width, 0, 0); final boolean movingRight = velocityX > 0; View newFocused = findFocusableViewInMyBounds(movingRight, mScroller.getFinalX(), findFocus()); if (newFocused == null) { newFocused = this; } if (newFocused != findFocus() && newFocused.requestFocus (movingRight ? View.FOCUS_RIGHT : View.FOCUS_LEFT)) { mScrollViewMovedFocus = true; mScrollViewMovedFocus = false; } invalidate(); } /** * {...@inheritdoc} * * <p> * This version also clamps the scrolling to the bounds of our child. */ public void scrollTo(int x, int y) { // we rely on the fact the View.scrollBy calls scrollTo. if (getChildCount() > 0) { View child = getChildAt(0); x = clamp(x, this.getWidth(), child.getWidth()); y = clamp(y, this.getHeight(), child.getHeight()); if (x != getScrollX() || y != getScrollY()) { super.scrollTo(x, y); } } } private int clamp(int n, int my, int child) { if (my >= child || n < 0) { /* * my >= child is this case: |--------------- me ---------------| |------ * child ------| or |--------------- me ---------------| |------ child * ------| or |--------------- me ---------------| |------ child ------| * * n < 0 is this case: |------ me ------| |-------- child --------| |-- * mScrollX --| */ return 0; } if ((my + n) > child) { /* * this case: |------ me ------| |------ child ------| |-- mScrollX --| */ return child - my; } return n; } private void setScrollXY(int sx, int sy) { try { Field scrollX = Class.forName("android.view.View").getField ("mScrollX"); Field scrollY = Class.forName("android.view.View").getField ("mScrollY"); scrollX.setInt(this, sx); scrollY.setInt(this, sy); } catch (SecurityException e) { Log.e("HSCROLL", e.toString()); e.printStackTrace(); } catch (NoSuchFieldException e) { Log.e("HSCROLL", e.toString()); e.printStackTrace(); } catch (IllegalArgumentException e) { // TODO Auto-generated catch block Log.e("HSCROLL", e.toString()); e.printStackTrace(); } catch (IllegalAccessException e) { // TODO Auto-generated catch block Log.e("HSCROLL", e.toString()); e.printStackTrace(); } catch (ClassNotFoundException e) { Log.e("HSCROLL", e.toString()); e.printStackTrace(); } } } --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Android Developers" group. 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