Launcher 桌面的3D转屏效果实现（1）-matrix setPolyToPoly
从现有方法来讲为了实现桌面的3D转屏效果主要是通过Launcher中的workspace实现（现有的有源码的方法），具体实现见：
???? http://www.eoeandroid.com/viewthread.php?tid=27079&extra=&page=1 （写这篇文章也是为了“报答”该作者开源的贡献，共同学习）
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???? 不过该方法存在以下几个问题：
???? 转载请注明http://ishelf.iteye.com/admin/blogs/836929
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???? 依据以上问题本文从每个屏的dispatchDraw入手，修改CellLayout的dispatchDraw方法，这篇文章先给出2D的实现方式（利用Matrix实现）：
????? 由于代码过多，本文只给出做过修改的代码
///CellLayout.java? @Override public void dispatchDraw(Canvas canvas) { long start_time = System.currentTimeMillis(); startRotate(canvas, currentX, canvas.getWidth(), canvas.getHeight()); super.dispatchDraw(canvas); canvas.restore(); long end_time = System.currentTimeMillis(); Log.d("CellLayout" + currentScrenn, (end_time - start_time) + " ms"); } // 上面的Log信息是用来对比用opengl实现两者效率 //startRotate使用来计算该屏显示的位置以及显示的大小，xCor是手指移动的位置大小 public void startRotate(Canvas mCanvas, float xCor, int width, int height) { boolean flag = true; if (isCurrentScrenn && xCor < 0) { xCor = width + xCor; flag = false; } else if (isCurrentScrenn && xCor >= 0) { // xCor = width - xCor; } else if (!isCurrentScrenn && xCor < 0) { xCor = width + xCor; } else if (!isCurrentScrenn && xCor >= 0) { flag = false; } final float SPAN = 0.000424f; float f = xCor - 10; if (f <= 0) { f = 0; xCor = 10; }// the maximum left float value = f * SPAN; if (f > width) { xCor = width - 10; value = 0.127225f; }// the maximum right if (isBorder) { doDraw(mCanvas, new float[] { 0, 0, width, 0, width, height, 0, height }, new float[] { 0, 0, width, 0, width, height, 0, height }); } else if (!flag) { doDraw(mCanvas, new float[] { 0, 0, width, 0, width, height, 0, height }, new float[] { 0, 0, xCor, height * (1 / 7.0f - value), xCor, height * (6 / 7.0f + value), 0, height }); } else { doDraw(mCanvas, new float[] { 0, 0, width, 0, width, height, 0, height }, new float[] { xCor, height * (1 / 30.0f + value), width, 0, width, height, xCor, height * (29 / 30.0f - value) }); } } private Matrix mMatrix = new Matrix(); private int currentScrenn; private Paint mPaint = new Paint(Paint.ANTI_ALIAS_FLAG); private boolean isBorder; //doDraw使用计算该屏如何变形，这里使用matrix的polyToPoly来实现，具体描述见APIDemo private void doDraw(Canvas canvas, float src[], float dst[]) { canvas.save(); mMatrix.setPolyToPoly(src, 0, dst, 0, src.length >> 1); canvas.concat(mMatrix); switch (currentScrenn) { case 0: mPaint.setColor(Color.RED); break; case 1: mPaint.setColor(Color.BLUE); break; case 2: mPaint.setColor(Color.YELLOW); break; case 3: mPaint.setColor(Color.CYAN); break; case 4: mPaint.setColor(Color.GREEN); break; } mPaint.setStyle(Paint.Style.FILL_AND_STROKE); canvas.drawRect(0, 0, src[4], src[5], mPaint); }?
??? 以下是workspace，该类主要是要传给cellLayout移动的参数
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// 该方法用来画屏 protected void dispatchDraw(Canvas canvas) { boolean restore = false; int restoreCount = 0; // ViewGroup.dispatchDraw() supports many features we don't need: // clip to padding, layout animation, animation listener, disappearing // children, etc. The following implementation attempts to fast-track // the drawing dispatch by drawing only what we know needs to be drawn. boolean fastDraw = mTouchState != TOUCH_STATE_SCROLLING && mNextScreen == INVALID_SCREEN; Log.d("Scroller","dispatchDraw"+mScrollX); // If we are not scrolling or flinging, draw only the current screen if (fastDraw) { ((CellLayout) getChildAt(mCurrentScreen)).setPara(mCurrentScreen, (mCurrentScreen - mCurrentScreen) >= 0 ? true : false, true, mChangeMotionX - mLastMotionX); drawChild(canvas, getChildAt(mCurrentScreen), getDrawingTime()); } else { final long drawingTime = getDrawingTime(); final float scrollPos = (float) mScrollX / getWidth(); final int leftScreen = (int) scrollPos; final int rightScreen = leftScreen + 1; if (leftScreen >= 0) { ((CellLayout) getChildAt(leftScreen)).setPara(leftScreen, (leftScreen - mCurrentScreen) >= 0 ? true : false, scrollPos == leftScreen, mChangeMotionX - mLastMotionX); drawChild(canvas, getChildAt(leftScreen), drawingTime); } if (scrollPos != leftScreen && rightScreen < getChildCount()) { ((CellLayout) getChildAt(rightScreen)).setPara(rightScreen, mCurrentScreen - rightScreen >= 0 ? true : false, scrollPos == leftScreen, mChangeMotionX - mLastMotionX); drawChild(canvas, getChildAt(rightScreen), drawingTime); } } if (restore) { canvas.restoreToCount(restoreCount); } } @Override public boolean onTouchEvent(MotionEvent ev) { if (mLauncher.isWorkspaceLocked()) { return false; // We don't want the events. Let them fall through to // the all apps view. } if (mLauncher.isAllAppsVisible()) { // Cancel any scrolling that is in progress. if (!mScroller.isFinished()) { mScroller.abortAnimation(); } snapToScreen(mCurrentScreen); return false; // We don't want the events. Let them fall through to // the all apps view. } if (mVelocityTracker == null) { mVelocityTracker = VelocityTracker.obtain(); } mVelocityTracker.addMovement(ev); final int action = ev.getAction(); switch (action & MotionEvent.ACTION_MASK) { 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 = ev.getX(); mChangeMotionX = mLastMotionX; mActivePointerId = ev.getPointerId(0); if (mTouchState == TOUCH_STATE_SCROLLING) { enableChildrenCache(mCurrentScreen - 1, mCurrentScreen + 1); } break; case MotionEvent.ACTION_MOVE: if (mTouchState == TOUCH_STATE_SCROLLING) { // Scroll to follow the motion event final int pointerIndex = ev.findPointerIndex(mActivePointerId); final float x = ev.getX(pointerIndex); final float deltaX = mLastMotionX - x; mLastMotionX = x; if (deltaX < 0) { if (mTouchX > 0) { mTouchX += Math.max(-mTouchX, deltaX); mSmoothingTime = System.nanoTime() / NANOTIME_DIV; invalidate(); } } else if (deltaX > 0) { final float availableToScroll = getChildAt(getChildCount() - 1).getRight() - mTouchX - getWidth(); if (availableToScroll > 0) { mTouchX += Math.min(availableToScroll, deltaX); mSmoothingTime = System.nanoTime() / NANOTIME_DIV; invalidate(); } } else { awakenScrollBars(); } } break; case MotionEvent.ACTION_UP: if (mTouchState == TOUCH_STATE_SCROLLING) { final VelocityTracker velocityTracker = mVelocityTracker; velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity); final int velocityX = (int) velocityTracker.getXVelocity(mActivePointerId); final int screenWidth = getWidth(); final int whichScreen = (mScrollX + (screenWidth / 2)) / screenWidth; final float scrolledPos = (float) mScrollX / screenWidth; mChangeMotionX = mLastMotionX; if (velocityX > SNAP_VELOCITY && mCurrentScreen > 0) { // Fling hard enough to move left. // Don't fling across more than one screen at a time. final int bound = scrolledPos < whichScreen ? mCurrentScreen - 1 : mCurrentScreen; snapToScreen(Math.min(whichScreen, bound), velocityX, true); } else if (velocityX < -SNAP_VELOCITY && mCurrentScreen < getChildCount() - 1) { // Fling hard enough to move right // Don't fling across more than one screen at a time. final int bound = scrolledPos > whichScreen ? mCurrentScreen + 1 : mCurrentScreen; snapToScreen(Math.max(whichScreen, bound), velocityX, true); } else { snapToScreen(whichScreen, 0, true); } if (mVelocityTracker != null) { mVelocityTracker.recycle(); mVelocityTracker = null; } } mTouchState = TOUCH_STATE_REST; mActivePointerId = INVALID_POINTER; break; case MotionEvent.ACTION_CANCEL: mTouchState = TOUCH_STATE_REST; mActivePointerId = INVALID_POINTER; break; case MotionEvent.ACTION_POINTER_UP: onSecondaryPointerUp(ev); break; } return true; } //修改该方法主要目的是记录滑动的距离 @Override public boolean onInterceptTouchEvent(MotionEvent ev) { final boolean workspaceLocked = mLauncher.isWorkspaceLocked(); final boolean allAppsVisible = mLauncher.isAllAppsVisible(); if (workspaceLocked || allAppsVisible) { return false; // We don't want the events. Let them fall through to // the all apps view. } /* * This method JUST determines whether we want to intercept the motion. * If we return true, onTouchEvent 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) && (mTouchState != TOUCH_STATE_REST)) { return true; } if (mVelocityTracker == null) { mVelocityTracker = VelocityTracker.obtain(); } mVelocityTracker.addMovement(ev); switch (action & MotionEvent.ACTION_MASK) { 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. mLastMotionX is set to the y value * of the down event. */ final int pointerIndex = ev.findPointerIndex(mActivePointerId); final float x = ev.getX(pointerIndex); final float y = ev.getY(pointerIndex); final int xDiff = (int) Math.abs(x - mLastMotionX); final int yDiff = (int) Math.abs(y - mLastMotionY); final int touchSlop = mTouchSlop; boolean xMoved = xDiff > touchSlop; boolean yMoved = yDiff > touchSlop; if (xMoved || yMoved) { if (xMoved) { // Scroll if the user moved far enough along the X axis mTouchState = TOUCH_STATE_SCROLLING; mLastMotionX = x; mTouchX = mScrollX; mSmoothingTime = System.nanoTime() / NANOTIME_DIV; enableChildrenCache(mCurrentScreen - 1, mCurrentScreen + 1); } // Either way, cancel any pending longpress if (mAllowLongPress) { mAllowLongPress = false; // Try canceling the long press. It could also have been // scheduled // by a distant descendant, so use the mAllowLongPress // flag to block // everything final View currentScreen = getChildAt(mCurrentScreen); currentScreen.cancelLongPress(); } } break; } case MotionEvent.ACTION_DOWN: { final float x = ev.getX(); final float y = ev.getY(); // Remember location of down touch mLastMotionX = x; mChangeMotionX = x; mLastMotionY = y; mActivePointerId = ev.getPointerId(0); mAllowLongPress = true; /* * If being flinged and user touches the screen, initiate drag; * otherwise don't. mScroller.isFinished should be false when * being flinged. */ mTouchState = mScroller.isFinished() ? TOUCH_STATE_REST : TOUCH_STATE_SCROLLING; break; } case MotionEvent.ACTION_CANCEL: case MotionEvent.ACTION_UP: if (mTouchState != TOUCH_STATE_SCROLLING) { final CellLayout currentScreen = (CellLayout) getChildAt(mCurrentScreen); if (!currentScreen.lastDownOnOccupiedCell()) { getLocationOnScreen(mTempCell); // Send a tap to the wallpaper if the last down was on // empty space final int pointerIndex = ev.findPointerIndex(mActivePointerId); mWallpaperManager.sendWallpaperCommand(getWindowToken(), "android.wallpaper.tap", mTempCell[0] + (int) ev.getX(pointerIndex), mTempCell[1] + (int) ev.getY(pointerIndex), 0, null); } } // Release the drag clearChildrenCache(); mTouchState = TOUCH_STATE_REST; mActivePointerId = INVALID_POINTER; mAllowLongPress = false; if (mVelocityTracker != null) { mVelocityTracker.recycle(); mVelocityTracker = null; } break; case MotionEvent.ACTION_POINTER_UP: onSecondaryPointerUp(ev); break; } /* * The only time we want to intercept motion events is if we are in the * drag mode. */ return mTouchState != TOUCH_STATE_REST; }?
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??? 这些类的修改特别是变换时一定要注意canvas的save和restore方法，不清楚的先百度一下，不然很容易就变形了。下篇讨论使用openGL实现的方法
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