Android开发 View的UI刷新Invalidate和postInvalidate
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内容图文
Invalidate
正常刷新
/**
* 使整个视图无效。如果视图可见，
* {
@link
#onDraw(android.graphics.Canvas)} 调用此方法后将在后续的UI刷新里调用onDraw(android.graphics.Canvas)方法
* <p>
* 必须从UI线程调用此方法。要从非UI线程调用，请调用{@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.
* @hide
*/
public
void invalidate(boolean invalidateCache) {
invalidateInternal(0, 0, mRight - mLeft, mBottom - mTop, invalidateCache, true);
}
一些解释
1.首先invalidate() 也是调用 invalidate(boolean invalidateCache) 这个方法的,只有设置为true时才会让这个View刷新
2.上面的注释已经说了invalidate()的刷新是必需在UI线程的
设置布局位置,重新调整View的刷新位置
/**
* Mark the area defined by dirty as needing to be drawn. 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()}.
* <p>
* <b>WARNING:</b> In API 19 and below, this method may be destructive to
* {
@code
dirty}.
*
*
@param
dirty the rectangle representing the bounds of the dirty region
*
*
@deprecated
The switch to hardware accelerated rendering in API 14 reduced
* the importance of the dirty rectangle. In API 21 the given rectangle is
* ignored entirely in favor of an internally-calculated area instead.
* Because of this, clients are encouraged to just call {
@link
#invalidate()}.
*/
@Deprecated
public
void
invalidate(Rect dirty) {
final
int scrollX = mScrollX;
finalint scrollY = mScrollY;
invalidateInternal(dirty.left - scrollX, dirty.top - scrollY,
dirty.right - scrollX, dirty.bottom - scrollY, true, false);
}
/**
* Mark the area defined by the rect (l,t,r,b) as needing to be drawn. The
* coordinates of the dirty rect are relative to the 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()}.
*
* @param l the left position of the dirty region
* @param t the top position of the dirty region
* @param r the right position of the dirty region
* @param b the bottom position of the dirty region
*
* @deprecated The switch to hardware accelerated rendering in API 14 reduced
* the importance of the dirty rectangle. In API 21 the given rectangle is
* ignored entirely in favor of an internally-calculated area instead.
* Because of this, clients are encouraged to just call {@link #invalidate()}.
*/
@Deprecated
publicvoid invalidate(int l, int t, int r, int b) {
finalint scrollX = mScrollX;
finalint scrollY = mScrollY;
invalidateInternal(l - scrollX, t - scrollY, r - scrollX, b - scrollY, true, false);
}
postInvalidate
这个方法可以非UI线程中调用
正常刷新
/**
* <p>导致在事件循环的后续循环中发生无效。使用此选项使非UI线程中的View无效</p>
*
* <p>仅当此视图附加到窗口时，才能从UI线程*外部调用此方法。</p>
*
*
@see
#invalidate()
*
@see
#postInvalidateDelayed(long)
*/
public
void
postInvalidate() {
postInvalidateDelayed(0);
}
改变位置后刷新
/**
* <p>Cause an invalidate of the specified area 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>
*
*
@param
left The left coordinate of the rectangle to invalidate.
*
@param
top The top coordinate of the rectangle to invalidate.
*
@param
right The right coordinate of the rectangle to invalidate.
*
@param
bottom The bottom coordinate of the rectangle to invalidate.
*
*
@see
#invalidate(int, int, int, int)
*
@see
#invalidate(Rect)
*
@see
#postInvalidateDelayed(long, int, int, int, int)
*/
public
void postInvalidate(int left, int top, int right, int bottom) {
postInvalidateDelayed(0, left, top, right, bottom);
}
延迟刷新
/**
* <p>导致在事件*循环的后续循环中发生无效。等待指定的时间。</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 windowfinal AttachInfo attachInfo = mAttachInfo;
if (attachInfo != null) {
attachInfo.mViewRootImpl.dispatchInvalidateDelayed(this, delayMilliseconds);
}
}
改变位置,并且延迟刷新
/**
* <p>Cause an invalidate of the specified area 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
*
@param
left The left coordinate of the rectangle to invalidate.
*
@param
top The top coordinate of the rectangle to invalidate.
*
@param
right The right coordinate of the rectangle to invalidate.
*
@param
bottom The bottom coordinate of the rectangle to invalidate.
*
*
@see
#invalidate(int, int, int, int)
*
@see
#invalidate(Rect)
*
@see
#postInvalidate(int, int, int, int)
*/
public
void postInvalidateDelayed(long delayMilliseconds, int left, int top,
int right, int bottom) {
// We try only with the AttachInfo because there‘s no point in invalidating
// if we are not attached to our windowfinal AttachInfo attachInfo = mAttachInfo;
if (attachInfo != null) {
final AttachInfo.InvalidateInfo info = AttachInfo.InvalidateInfo.obtain();
info.target = this;
info.left = left;
info.top = top;
info.right = right;
info.bottom = bottom;
attachInfo.mViewRootImpl.dispatchInvalidateRectDelayed(info, delayMilliseconds);
}
}
end
原文：https://www.cnblogs.com/guanxinjing/p/11558790.html
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