view 的繪製和重新整理
阿新 • • 發佈:2019-01-10
view繪製
流程
view重新整理
invalidate()
在UI執行緒中呼叫,重繪當前UI
父view負責重新整理,佈局顯示子view,而當子view需要重新整理時,則是通知父view來完成的。
呼叫view的invalidate函式中,會呼叫到invalidateInternal函式,接著呼叫到 viewGroup. invalidateChild方法 do{}while()迴圈查詢parent,最後走到ViewRootImpl.呼叫到viewRootImpl的scheduleTraversals()方法
public class View implements Drawable.Callback, KeyEvent.Callback,
AccessibilityEventSource {
/**
* Invalidate the whole view. If the view is visible,
* {@link #onDraw(android.graphics.Canvas)} will be called at some point in
* the future.
* <p>
* This must be called from a UI thread. To call from a non-UI thread, call
* {@link #postInvalidate()}.
*/
public void invalidate() {
invalidate(true);
}
/**
* This is where the invalidate() work actually happens. A full invalidate()
* causes the drawing cache to be invalidated, but this function can be
* called with invalidateCache set to false to skip that invalidation step
* for cases that do not need it (for example, a component that remains at
* the same dimensions with the same content).
*
* @param invalidateCache Whether the drawing cache for this view should be
* invalidated as well. This is usually true for a full
* invalidate, but may be set to false if the View's contents or
* dimensions have not changed.
*/
void invalidate(boolean invalidateCache) {
invalidateInternal(0, 0, mRight - mLeft, mBottom - mTop, invalidateCache, true);
}
void invalidateInternal(int l, int t, int r, int b, boolean invalidateCache,
boolean fullInvalidate) {
if (mGhostView != null) {
mGhostView.invalidate(true);
return;
}
if (skipInvalidate()) {
return;
}
...........
// Propagate the damage rectangle to the parent view.
final AttachInfo ai = mAttachInfo;
final ViewParent p = mParent;
if (p != null && ai != null && l < r && t < b) {
final Rect damage = ai.mTmpInvalRect;
damage.set(l, t, r, b);
// 呼叫父控制元件的invalidateChild()
p.invalidateChild(this, damage);
}
// Damage the entire projection receiver, if necessary.
if (mBackground != null && mBackground.isProjected()) {
final View receiver = getProjectionReceiver();
if (receiver != null) {
receiver.damageInParent();
}
}
// Damage the entire IsolatedZVolume receiving this view's shadow.
if (isHardwareAccelerated() && getZ() != 0) {
damageShadowReceiver();
}
}
}
}
public abstract class ViewGroup extends View implements ViewParent, ViewManager {
/**
* Don't call or override this method. It is used for the implementation of
* the view hierarchy.
*/
public final void invalidateChild(View child, final Rect dirty) {
ViewParent parent = this;
final AttachInfo attachInfo = mAttachInfo;
if (attachInfo != null) {
.........
do {
View view = null;
if (parent instanceof View) {
view = (View) parent;
}
if (drawAnimation) {
if (view != null) {
view.mPrivateFlags |= PFLAG_DRAW_ANIMATION;
} else if (parent instanceof ViewRootImpl) {
((ViewRootImpl) parent).mIsAnimating = true;
}
}
// If the parent is dirty opaque or not dirty, mark it dirty with the opaque
// flag coming from the child that initiated the invalidate
if (view != null) {
if ((view.mViewFlags & FADING_EDGE_MASK) != 0 &&
view.getSolidColor() == 0) {
opaqueFlag = PFLAG_DIRTY;
}
if ((view.mPrivateFlags & PFLAG_DIRTY_MASK) != PFLAG_DIRTY) {
view.mPrivateFlags = (view.mPrivateFlags & ~PFLAG_DIRTY_MASK) | opaqueFlag;
}
}
//迴圈找到根view,並呼叫invalidateChildInParent()方法
parent = parent.invalidateChildInParent(location, dirty);
if (view != null) {
// Account for transform on current parent
Matrix m = view.getMatrix();
if (!m.isIdentity()) {
RectF boundingRect = attachInfo.mTmpTransformRect;
boundingRect.set(dirty);
m.mapRect(boundingRect);
dirty.set((int) (boundingRect.left - 0.5f),
(int) (boundingRect.top - 0.5f),
(int) (boundingRect.right + 0.5f),
(int) (boundingRect.bottom + 0.5f));
}
}
} while (parent != null);
}
}
}
public final class ViewRootImpl implements ViewParent,
View.AttachInfo.Callbacks, HardwareRenderer.HardwareDrawCallbacks {
@Override
public ViewParent invalidateChildInParent(int[] location, Rect dirty) {
checkThread();
if (DEBUG_DRAW) Log.v(TAG, "Invalidate child: " + dirty);
if (dirty == null) {
invalidate();
return null;
} else if (dirty.isEmpty() && !mIsAnimating) {
return null;
}
if (mCurScrollY != 0 || mTranslator != null) {
mTempRect.set(dirty);
dirty = mTempRect;
if (mCurScrollY != 0) {
dirty.offset(0, -mCurScrollY);
}
if (mTranslator != null) {
mTranslator.translateRectInAppWindowToScreen(dirty);
}
if (mAttachInfo.mScalingRequired) {
dirty.inset(-1, -1);
}
}
final Rect localDirty = mDirty;
if (!localDirty.isEmpty() && !localDirty.contains(dirty)) {
mAttachInfo.mSetIgnoreDirtyState = true;
mAttachInfo.mIgnoreDirtyState = true;
}
// Add the new dirty rect to the current one
localDirty.union(dirty.left, dirty.top, dirty.right, dirty.bottom);
// Intersect with the bounds of the window to skip
// updates that lie outside of the visible region
final float appScale = mAttachInfo.mApplicationScale;
final boolean intersected = localDirty.intersect(0, 0,
(int) (mWidth * appScale + 0.5f), (int) (mHeight * appScale + 0.5f));
if (!intersected) {
localDirty.setEmpty();
}
if (!mWillDrawSoon && (intersected || mIsAnimating)) {
// 呼叫scheduleTraversals()方法
scheduleTraversals();
}
return null;
}
void scheduleTraversals() {
if (!mTraversalScheduled) {
mTraversalScheduled = true;
mTraversalBarrier = mHandler.getLooper().postSyncBarrier();
mChoreographer.postCallback(
Choreographer.CALLBACK_TRAVERSAL, mTraversalRunnable, null);
if (!mUnbufferedInputDispatch) {
scheduleConsumeBatchedInput();
}
notifyRendererOfFramePending();
}
}
//TraversalRunnable 就是實現了Runnable 介面
final class TraversalRunnable implements Runnable {
@Override
public void run() {
doTraversal();
}
}
//TraversalRunnable 呼叫performTraversals() 繪製view
final TraversalRunnable mTraversalRunnable = new TraversalRunnable();
void doTraversal() {
if (mTraversalScheduled) {
mTraversalScheduled = false;
mHandler.getLooper().removeSyncBarrier(mTraversalBarrier);
if (mProfile) {
Debug.startMethodTracing("ViewAncestor");
}
Trace.traceBegin(Trace.TRACE_TAG_VIEW, "performTraversals");
try {
performTraversals();
} finally {
Trace.traceEnd(Trace.TRACE_TAG_VIEW);
}
if (mProfile) {
Debug.stopMethodTracing();
mProfile = false;
}
}
}
}
PostInvalidate()
在非UI執行緒中呼叫,通知UI執行緒重繪。利用Handler 從子執行緒給主執行緒發訊息 重新整理介面
/**
* <p>Cause an invalidate to happen on a subsequent cycle through the event loop.
* Use this to invalidate the View from a non-UI thread.</p>
*
* <p>This method can be invoked from outside of the UI thread
* only when this View is attached to a window.</p>
*
* @see #invalidate()
* @see #postInvalidateDelayed(long)
*/
public void postInvalidate() {
postInvalidateDelayed(0);
}
/**
* <p>Cause an invalidate to happen on a subsequent cycle through the event
* loop. Waits for the specified amount of time.</p>
*
* <p>This method can be invoked from outside of the UI thread
* only when this View is attached to a window.</p>
*
* @param delayMilliseconds the duration in milliseconds to delay the
* invalidation by
*
* @see #invalidate()
* @see #postInvalidate()
*/
public void postInvalidateDelayed(long delayMilliseconds) {
// We try only with the AttachInfo because there's no point in invalidating
// if we are not attached to our window
final AttachInfo attachInfo = mAttachInfo;
if (attachInfo != null) {
//呼叫根view 的dispatchInvalidateDelayed()方法
attachInfo.mViewRootImpl.dispatchInvalidateDelayed(this, delayMilliseconds);
}
}
public final class ViewRootImpl implements ViewParent,
View.AttachInfo.Callbacks, HardwareRenderer.HardwareDrawCallbacks {
// 根view 的dispatchInvalidateDelayed()方法
public void dispatchInvalidateDelayed(View view, long delayMilliseconds) {
//通過handler 給主執行緒發訊息 重新整理view 再呼叫view的invalidate()方法
Message msg = mHandler.obtainMessage(MSG_INVALIDATE, view);
mHandler.sendMessageDelayed(msg, delayMilliseconds);
}
final class ViewRootHandler extends Handler {
@Override
public void handleMessage(Message msg) {
switch (msg.what) {
case MSG_INVALIDATE:
((View) msg.obj).invalidate();
break;
}
}
}
requestLayout()
位置沒有變化不會呼叫 draw 方法
/**
* Call this when something has changed which has invalidated the
* layout of this view. This will schedule a layout pass of the view
* tree. This should not be called while the view hierarchy is currently in a layout
* pass ({@link #isInLayout()}. If layout is happening, the request may be honored at the
* end of the current layout pass (and then layout will run again) or after the current
* frame is drawn and the next layout occurs.
*
* <p>Subclasses which override this method should call the superclass method to
* handle possible request-during-layout errors correctly.</p>
*/
public void requestLayout() {
if (mMeasureCache != null) mMeasureCache.clear();
if (mAttachInfo != null && mAttachInfo.mViewRequestingLayout == null) {
// Only trigger request-during-layout logic if this is the view requesting it,
// not the views in its parent hierarchy
ViewRootImpl viewRoot = getViewRootImpl();
if (viewRoot != null && viewRoot.isInLayout()) {
if (!viewRoot.requestLayoutDuringLayout(this)) {
return;
}
}
mAttachInfo.mViewRequestingLayout = this;
}
mPrivateFlags |= PFLAG_FORCE_LAYOUT;
mPrivateFlags |= PFLAG_INVALIDATED;
if (mParent != null && !mParent.isLayoutRequested()) {
//找到父控制元件的requestLayout()
mParent.requestLayout();
}
if (mAttachInfo != null && mAttachInfo.mViewRequestingLayout == this) {
mAttachInfo.mViewRequestingLayout = null;
}
}
//根view
public final class ViewRootImpl implements ViewParent,
View.AttachInfo.Callbacks, HardwareRenderer.HardwareDrawCallbacks {
@Override
public void requestLayout() {
if (!mHandlingLayoutInLayoutRequest) {
checkThread();
mLayoutRequested = true;
scheduleTraversals();
}
}
}