Android中View绘制流程详细介绍

final void attach(Context context, ActivityThread aThread, 
    Instrumentation instr, IBinder token, int ident, 
    Application application, Intent intent, ActivityInfo info, 
    CharSequence title, Activity parent, String id, 
    NonConfigurationInstances lastNonConfigurationInstances, 
    Configuration config) { 
  attachBaseContext(context); 
 
  mFragments.attachActivity(this, mContainer, null); 
   
  mWindow = PolicyManager.makeNewWindow(this); 
  mWindow.setCallback(this); 
  mWindow.getLayoutInflater().setPrivateFactory(this); 

protected boolean initializePanelDecor(PanelFeatureState st) { 
  st.decorView = new DecorView(getContext(), st.featureId); 
  st.gravity = Gravity.CENTER | Gravity.BOTTOM; 
  st.setStyle(getContext()); 
 
  return true; 
} 

public void addView(View view, ViewGroup.LayoutParams params, 
Display display, Window parentWindow) { 
if (view == null) { 
throw new IllegalArgumentException("view must not be null"); 
} 
if (display == null) { 
throw new IllegalArgumentException("display must not be null"); 
} 
if (!(params instanceof WindowManager.LayoutParams)) { 
throw new IllegalArgumentException("Params must be WindowManager.LayoutParams"); 
} 
final WindowManager.LayoutParams wparams = (WindowManager.LayoutParams)params; 
if (parentWindow != null) { 
parentWindow.adjustLayoutParamsForSubWindow(wparams); 
} 
ViewRootImpl root; 
View panelParentView = null; 
synchronized (mLock) { 
// Start watching for system property changes. 
if (mSystemPropertyUpdater == null) { 
mSystemPropertyUpdater = new Runnable() { 
@Override public void run() { 
synchronized (mLock) { 
for (ViewRootImpl viewRoot : mRoots) { 
viewRoot.loadSystemProperties(); 
} 
} 
} 
}; 
SystemProperties.addChangeCallback(mSystemPropertyUpdater); 
} 
int index = findViewLocked(view, false); 
if (index  = 0) { 
throw new IllegalStateException("View " + view 
+ " has already been added to the window manager."); 
} 
// If this is a panel window, then find the window it is being 
// attached to for future reference. 
if (wparams.type  = WindowManager.LayoutParams.FIRST_SUB_WINDOW && 
wparams.type <= WindowManager.LayoutParams.LAST_SUB_WINDOW) { 
final int count = mViews != null ? mViews.length : 0; 
for (int i=0; i<count; i++) { 
if (mRoots[i].mWindow.asBinder() == wparams.token) { 
panelParentView = mViews[i]; 
} 
} 
} 
root = new ViewRootImpl(view.getContext(), display); 
view.setLayoutParams(wparams); 
if (mViews == null) { 
index = 1; 
mViews = new View[1]; 
mRoots = new ViewRootImpl[1]; 
mParams = new WindowManager.LayoutParams[1]; 
} else { 
index = mViews.length + 1; 
Object[] old = mViews; 
mViews = new View[index]; 
System.arraycopy(old, 0, mViews, 0, index-1); 
old = mRoots; 
mRoots = new ViewRootImpl[index]; 
System.arraycopy(old, 0, mRoots, 0, index-1); 
old = mParams; 
mParams = new WindowManager.LayoutParams[index]; 
System.arraycopy(old, 0, mParams, 0, index-1); 
} 
index--; 
mViews[index] = view; 
mRoots[index] = root; 
mParams[index] = wparams; 
} 
// do this last because it fires off messages to start doing things 
try { 
root.setView(view, wparams, panelParentView); 
} catch (RuntimeException e) { 
// BadTokenException or InvalidDisplayException, clean up. 
synchronized (mLock) { 
final int index = findViewLocked(view, false); 
if (index  = 0) { 
removeViewLocked(index, true); 
} 
} 
throw e; 
} 
} 

private void performMeasure(int childWidthMeasureSpec, int childHeightMeasureSpec) { 
Trace.traceBegin(Trace.TRACE_TAG_VIEW, "measure"); 
try { 
mView.measure(childWidthMeasureSpec, childHeightMeasureSpec); 
} finally { 
Trace.traceEnd(Trace.TRACE_TAG_VIEW); 
} 
} 

protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) { 
setMeasuredDimension(getDefaultSize(getSuggestedMinimumWidth(), widthMeasureSpec), 
getDefaultSize(getSuggestedMinimumHeight(), heightMeasureSpec)); 
} 

protected final void setMeasuredDimension(int measuredWidth, int measuredHeight) { 
boolean optical = isLayoutModeOptical(this); 
if (optical != isLayoutModeOptical(mParent)) { 
Insets insets = getOpticalInsets(); 
int opticalWidth = insets.left + insets.right; 
int opticalHeight = insets.top + insets.bottom; 
measuredWidth += optical ? opticalWidth : -opticalWidth; 
measuredHeight += optical ? opticalHeight : -opticalHeight; 
} 
mMeasuredWidth = measuredWidth; 
mMeasuredHeight = measuredHeight; 
mPrivateFlags |= PFLAG_MEASURED_DIMENSION_SET; 
} 

private void performLayout(WindowManager.LayoutParams lp, int desiredWindowWidth, 
int desiredWindowHeight) { 
mLayoutRequested = false; 
mScrollMayChange = true; 
mInLayout = true; 
final View host = mView; 
if (DEBUG_ORIENTATION || DEBUG_LAYOUT) { 
Log.v(TAG, "Laying out " + host + " to (" + 
host.getMeasuredWidth() + ", " + host.getMeasuredHeight() + ")"); 
} 
Trace.traceBegin(Trace.TRACE_TAG_VIEW, "layout"); 
try { 
host.layout(0, 0, host.getMeasuredWidth(), host.getMeasuredHeight()); 
mInLayout = false; 
int numViewsRequestingLayout = mLayoutRequesters.size(); 
if (numViewsRequestingLayout   0) { 
// requestLayout() was called during layout. 
// If no layout-request flags are set on the requesting views, there is no problem. 
// If some requests are still pending, then we need to clear those flags and do 
// a full request/measure/layout pass to handle this situation. 
ArrayList<View  validLayoutRequesters = getValidLayoutRequesters(mLayoutRequesters, 
false); 
if (validLayoutRequesters != null) { 
// Set this flag to indicate that any further requests are happening during 
// the second pass, which may result in posting those requests to the next 
// frame instead 
mHandlingLayoutInLayoutRequest = true; 
// Process fresh layout requests, then measure and layout 
int numValidRequests = validLayoutRequesters.size(); 
for (int i = 0; i < numValidRequests; ++i) { 
final View view = validLayoutRequesters.get(i); 
Log.w("View", "requestLayout() improperly called by " + view + 
" during layout: running second layout pass"); 
view.requestLayout(); 
} 
measureHierarchy(host, lp, mView.getContext().getResources(), 
desiredWindowWidth, desiredWindowHeight); 
mInLayout = true; 
host.layout(0, 0, host.getMeasuredWidth(), host.getMeasuredHeight()); 
mHandlingLayoutInLayoutRequest = false; 
// Check the valid requests again, this time without checking/clearing the 
// layout flags, since requests happening during the second pass get noop'd 
validLayoutRequesters = getValidLayoutRequesters(mLayoutRequesters, true); 
if (validLayoutRequesters != null) { 
final ArrayList<View  finalRequesters = validLayoutRequesters; 
// Post second-pass requests to the next frame 
getRunQueue().post(new Runnable() { 
@Override 
public void run() { 
int numValidRequests = finalRequesters.size(); 
for (int i = 0; i < numValidRequests; ++i) { 
final View view = finalRequesters.get(i); 
Log.w("View", "requestLayout() improperly called by " + view + 
" during second layout pass: posting in next frame"); 
view.requestLayout(); 
} 
} 
}); 
} 
} 
} 
} finally { 
Trace.traceEnd(Trace.TRACE_TAG_VIEW); 
} 
mInLayout = false; 
} 

protected void onLayout(boolean changed, int left, int top, int right, int bottom) { 
} 

public void layout(int l, int t, int r, int b) { 
int oldL = mLeft; 
int oldT = mTop; 
int oldB = mBottom; 
int oldR = mRight; 
boolean changed = isLayoutModeOptical(mParent) ? 
setOpticalFrame(l, t, r, b) : setFrame(l, t, r, b); 
if (changed || (mPrivateFlags & PFLAG_LAYOUT_REQUIRED) == PFLAG_LAYOUT_REQUIRED) { 
onLayout(changed, l, t, r, b); 
mPrivateFlags &= ~PFLAG_LAYOUT_REQUIRED; 
ListenerInfo li = mListenerInfo; 
if (li != null && li.mOnLayoutChangeListeners != null) { 
ArrayList<OnLayoutChangeListener  listenersCopy = 
(ArrayList<OnLayoutChangeListener )li.mOnLayoutChangeListeners.clone(); 
int numListeners = listenersCopy.size(); 
for (int i = 0; i < numListeners; ++i) { 
listenersCopy.get(i).onLayoutChange(this, l, t, r, b, oldL, oldT, oldR, oldB); 
} 
} 
} 
mPrivateFlags &= ~PFLAG_FORCE_LAYOUT; 
}